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Digestive physiology of East African wild ruminants
Camp. Eiothem. Phvsiol. Vol. 76A. No. 2, Printed in Great B&in
DIGESTIVE
pp. 319-333,
1983 8
PHYSIOLOGY OF EAST AFRICAN RUMINANTS
0300-9629/X3 $3.00 + 0.00 1983 Pergamon Press Ltd
WILD
E. T. CLEMENS and G. M. 0. MALOIY Department of Veterinary Physiology, University of Nairobi, Nairobi, Kenya, East Africa and Department of Veterinary Science, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln, Lincoln. NE 68583-0905, U.S.A. Telephone: (402) 4’72-2952 (Recessed 18 January 1983)
Abstract-I. The physiology of digestion of wild ruminants in their natural habitat was determined. The study consisted of fifty-one adult male animals representing sixteen species. 2. While diet and body weight were both related to the gastrointestinal composition, body weight
appeared to he the more influential factor. 3. Reticula-rumen and caecal-colon composition, relative to abomasal and small intestinal composition, showed the greater species, diet and body weight effects. 4. The buffalo, oryx and gerenuk were somewhat more unique in gastrointestinal composition than were other species of wild ruminants, and were deserving of special consideration.
INTRODUCTION
With the continued studies of both domestic and wild ruminants, knowledge of reticula-rumen physiology is rapidly expanding. Comparative information and, to a lesser extent, post-ruminal digestion studies have not been as fruitful. Furthermore, quantitative information derived from studies of different species is difficult to compare, owing to the variation in technique. The present investigation allowed for an intensive, comparative study without the variance due to technique. In addition, these animals were studied in their natural habitat, thus providing a more reaiistic comparison of wild ruminants. MATERIAL AND METHODS Fifty-one adult, male animals representing 16 species of East African wild ruminants were used in the study. These included: five Kirk’s dik-dik (~u~oq~~ ~j~~i), two suni (Nesoiraqus moschatus), three giraffe (Girafla camelopard&s), three gerenuk (Litocrumius walleri), three eland (Turotragus oryx), four Grant’s gazelle (Gazelle gruti), two steenbok (Ruph~ce~ cumpesfrjs), four impala (Aepyceros meiampus), four Thomson’s gazelle (Gazella thomsoni), three buffalo (Bubalus cuffer), two waterbuck (Kobus ellipsiprymmts), three wildebeest (Connochaefes tantinus), three hartebeest (Alcepha~~~ b~se~aph~s), three topi ~DarnuI~sc~ lunatus), three mountain reedbuck (Redunca fuiuorufuia), and four oryx (oryx gaze/la). All animals were collected from their natural habitat in conjunction with wildlife management programs. Field analysis and sample collection were begun immediately after sacrifice and generally completed within 1 hour after the death of the animal. Body weights of the animals were taken as those reported for the average species weight (Hofmann, 1973). The abdominal cavity of each animal was opened immediately after death. Urine and blood samples were collected and refrigerated. Ligatures were used to tie off the oesophagus at the cardia and the large bowel at the rectal-anal junction, and the gastrointestinal tract removed. The gastrointestinal tract of each animal was further separated by ligatures into six selected segments. These consisted of the
reticula-rumen, abomasum, small intestine, caecum, and proximal and distal halves of the colon. TotaI contents were removed from each segment, weighed, and a representative sample refrigerated for later analysis. Additional samples were strained through cheese cloth, the supematant acidified with concentrated H,SO, (approx 0.5 ml per 20 ml sample), and refrigerated for later analyses of volatile fatty acids. The dry matter content was determined by drying a portion of each sample to a constant weight in a forced-air oven at 105°C. Samples of whole gut contents were centrifuged and the supematant collected for laboratory analysis. The osmolality of the supernatant fraction was determined on a laboratory osmometer, the sodium and potassium concentrations by flame photometry, and the chloride concentration was determined with the aid of a chloridometer. The lactic acid concentration of each sample was determined by the methods of Barker and Summerson (1941). Volatile fatty acid concentrations were determined‘ by the steam distillation method of Markham (1942), and by partition chromatography of short chain fatty acids. Data were subject to analysis of variance. Duncan’s Multiple Range test, and regression analysis for determination of significant differences (Steel and Torrie, 1960). RESULTS
The series of Tables 2-8 present the analytical data for seven parameters measured in this study. Tables are further divided according to species, major and sub-feeding groups, and weight of the animal. Table 1 presents the live weight, food selection and mean weight of gastrointestinal contents, by species and for the six primary gut segments. The percent dry matter within the reticula-rumen showed considerable variability for the species investigated, ranging from a low of 10.5% (suni) to 21.8% (oryx) (Table 2A). However, when comparing sub-feeding groups, dry region grazers’ reticuIorumen dry matter was significantly greater (P < 0.05) than other groups (Table 2B). The intermediated feeders also appeared to have a higher dry matter value than most browsers or grazers. Abomasal 319
E. T. CLEMENSand G. M. 0. MALLXY
320
contents showed considerably more variability in dry matter consistency than reiticulo-rumen contents. No correlation was noted with the dry matter content of these two segments. Lowest abomasal values were noted for the buffalo (6.5%), and highest for the oryx (16.273. Intermediate feeders had abomasal dry matter values significantly lower than either browsers or grazers. However, when considering the subfeeding groups, most grazers’ abomasal dry matters were generally lower than browsers’ and comparable to intermediate feeders’, except fcr the dry region grazers. Percent dry matter within the small intestine was the only segment to show a significant (P < 0.01)
relationship with major feeding groups. Dry matter composition decreased with the ingestion of more grasses. There was a noted relationship between dry matter percent and weight of the animal for the small
intestinal contents (P < 0.01) {Table 2C). Caecal dry matters were 2-6 percentage units greater than that of the small intestine (except for the suni) and ranged from a low of 9.5% (suni) to a high of 22.2% (dik-dik). Statistically significant differences (P < 0.05) were not detected for caecal dry matter between feeding groups. However, within the group of grazers, dry region grazers had dry matter percents significantly greater (P < 0.01) than the roughage grazers.
Table I. Average live weight, food selection and total weight (kg) of gastrointestinal contents as observed in sixteen species of wild ruminants Species
Average* live weight (kg)
Food Selection Kirk’s Dik-Dik: Fruit and dicotyledon (Browsers) Suni: Fruit and dicotyledon (Browsers) Giraffe: Trees and shrub (Browsers) Gerenuk: Trees and shrub (Browsers) Eland: Prefers browse (Intermediate) Grant’s Gazelle: Prefers browse (Intermediate) Steenbok: Prefers browse (Intermediate) Impala: Prefers graze (Intermediate) Thomson’s Gazelle: Prefers graze (Intermediate) African Buffalo: Fresh grass (Grazers) Waterbuck: Fresh grass (Grazers) Wildebeest: Fresh grass (Grazers) Hartebeest: Roughage (Grazers) Topi: Roughage (Grazers) Mountain Reedbuck: Roughage (Grazers) Oryx: Dry region (Grazers) *Data
for average
live weight
Section Small intestine ---~ 10.1
of tract
S-6
Reticuiorumen -_-_-_ 0.3
S--l
0.3
500-750
85.9
8.8
7.2
9.2
3.5
I.9
N-52
4.4
0.3
0.3
0.5
0.2
0.1
78.4
6.5
5.3
3.1
3.4
2.6
4.2
0.2
0.2
0.2
0.1
0.1
8-11
0.8
CO.1
CO.1
CO.1
CO.1
53-71
4.7
0.3
0.4
0.2
0.2
22-25
2.1
400-650
4664
Abomasum __ 10.1
10.1
0.1
Caecum
Proximal colon
Distal colon
CO.1
CO.1
10.1
CO.1
10.1
0.3
CO.1
600-850
87.3
4.4
4.7
3.8
3.3
2.6
192-286
31.9
1.9
2.2
2.4
2.0
1.6
171-242
28.0
1.8
2.3
2.0
1.2
0.7
116-160
13.6
1.0
0.9
1.1
0.6
0.4
III-147
13.4
0.9
0.8
0.6
0.6
0.3
23-28
1.8
0.1
25.4
1.7
168-209
and food selection
obtained
from Hofmann,
1.9
1973.
0.2
1.9
1.6
1.4
East African wild ruminants
321
Table 2A. Mean (+ SEM) dry matter percent as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species --___~Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck oryx
Reticula-rumen 16.4 (0.6) 10.5 (1.5) 13.5 (0.5) 17.0 (1.2) 14.5 (1.5) 16.0 (1.8) 16.5 (0.5) 16.2 (1.6) 15.8 (1.6) 18.0 (7.0) 14.0 (1.0) 13.3 (0.7) 12.0 (0.8) 16.0 (1.6) 12.0 (0.6) 21.8
(2.8)
Table 28. Mean (&SEM)
Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit & dicotyledon (Browsers) Trees & shrub
(Browsers) Prefers browse (Intermediate) Prefers graze IIntermediate) Fresh grass
(Grazers) Roughage (Grazers) Dry region (Grazers)
Abomasum I_____13.0 (1.6) 11.0 (1.0) 14.0 (0.1) 15.0 (1.2) 10.0 (5.0) 9.2 (;:;I (2.1) 8.0 (1.1) 7.8 (0.5) 6.5 (3.5) 7.5
Section of tract Small intestine Caecum 17.0 (0.5) 14.0 (0.1)
22.2 (16) 9.5 (4.5)
14.0 (0.8) 1:‘:)
18.0 (0.9) 17.0 (3.7) 13.8 (1.1) 18.0 (1.0) 18.0 (1.5) 13.2 (1.6) 15.5 (5.5) 13.0 (1.0) 20.0 (3.6) 14.0 (2.1) 16.7 (0.7) 13.0 (0.6) 20.2 (1.5)
(&
lo:o (1.7) 14.5 (1.5) 13.5 (2.5) 12.0 (2.6) (Z) (::I)
(0.5) 12.7
10.0 (1.0) 9.0 (1.2) 11.7 (1.2) 9.3 (1.4) 13.5 (2.3)
(2.6) 12.0 (1.0) 14.3 (3.5) 5.3 (2.3) 16.2
(1.2)
i 6.0 (0.1)
Proximal colon -____ 22.0 (0.4) 20.0 (4.1) 17.0 (4.0) 20.0 (3.9) 22.5 (6.5) 18.2 (1.7) 18.5 (4.2) 18.5 (1.4) 15.0 (0.9) 11.0 (1.0) 18.5 (0.5) 24.3 (2.4) 18.0 0.7) 21.3 (1.2) 16.3 (1.3) 22.6 (l..J)
dry matter per cent as observed at various sites along the gastrointestinal and sub-feeding groups
Reticula-rumen
Abomasum
Section of tract Small intestine Caecum
14.7 (0.9) 15.9 (0.7) 15.9 (1.2)
13.0” (0.8) 8.6h (0.6) 11.2”b (1.3)
14.5 (1.0) I I 8”’ (1:l) 10.5b (0.7)
18.0 (1.9) 15.6 (0.9) 16.7 (1.0)
14.7 (1.2) 14.7 0.2) 15.8 (0.9) 16.0 (1.1) 14.8 (1.8) 13.7 (1.0) 21.8 (2.8)
12.4 (1.2) 14.3 (0.3) 9.4 (1.1) 7.9
16.1 (0.7) 10.7 (1.7) 10.9 (1.4) 12.8 (;.;)
18.6 (2.8) 16.7 (0.7) 15.6 (1.2) 15.6 (1.4) 16.7 (2.2) 14.1 (0.8) 20.2 (1.5)
%) (1.7) 10.1 (2.4) 16.3 (1.2)
*Values within a column with unlike superscripts are
Distal
colon 39.0 (1.1) 27.5 (4.5) 33.5 (7.5) 65.0 (13.2) 27.0 (8.1) 32.2 (4.1) 31.5 (4.5) 29.5 (2.5) 24.5 (4.1) 15.0 0.0) 23.3 (1.5) 29.0 (4.7) 42.2 (7.1) 40.3 (2.4) 32.0 (3.6) 35.0 (6.1)
tract of the major
Proximal colon
Distal colon
20.5 (1.1) 18.1 (1.3) 19.7 (1.1)
39.2 (4.5) 31.4 (1.8) 31.3 (2.4)
21.6 (j-0) 18.0 (2.5) 19.4 (1.6) 16.7 (2.1) 18.9 (2.4) &) 18.7 (0:9) (1.2) 13.5 22.8 (2.3) (1.5) statisticatly different at the 0.0s level of significance.
35.7 (2.5) 47.3 (14.5) 30.8 (2.7) 32.0 (2.4) 23.4 (3.0) 37.0 (2.4) 35.0 (6.1)
E. T. CLEMENSand G. M. 0. MALOIY
322
Table ZC. Mean (+ SEM) dry matter per cent as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group
Reticula-rumen
Less than 20 kg 20-50 kg 51-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
15.1 (1.0) 14.5 (1.1) 16.1 (1.1) 16.0 (0.6) 19.8 (2.9) 13.6 (0.5) 15.3 (2.0)
Abomasum 11.7 (1.1) 7.8 (&) (0.6) 14.3 (3.6) 15.4 (1.3) 10.6 (1.9) 10.2 (2.1)
Section of tract Small intestine Caecum 15.x* (0.6) 11.2 (1.4) 11.8 (1.5) 11.7 (1.2) 12.6 (2.0) 9.8 (0.6) 8.3 (1.1)
-18.4 (2.1) 13.8 (1.0) 15.9 (1.2) 16.7 (0.7) 19.0 (1.9) 17.2 (2.6) 16.2 0.8)
Proximal colon
Distal colon
20.9 (0.9) 16.1 (0.8) 18.4 (2.1) 21.3 (1.2) 21.8 (1.5) 22.0 (1.9) 16.8 (2.9)
34.8 (2.1) 38.6 (5.7) 30.9 (2.3) 40.3 (2.4) 36.4 (4.9) 26.8 (2.9) 25.2 (4.4)
-..-._
*Regression analysis (P < 0.006); Y = 15.2 - 0.9X.
Drying of faecal material was readily apparent in the proximal and distal colon of all species except the buffalo. Values ranged from 15% (buffalo) to 65% (gerenuk). Browsers had significantly drier contents ~thin the distal colon than did grazers or intermediate feeders. Considerable variability was observed for the concentration of volatile fatty acids (VFA) within the
reticula-rumen of each species (range, 93.4 mmol/l (buffalo) to 183.5 mmol/l (oryx)) (Table 3A). A relationship was apparent for feeding group and VFA concentration within the reticuio-rumen, with browsers having higher values and grazers having lower values (Table 3B). Sub-feeding groups showed a similar pattern except for dry region grazers. There was also a statistically significant (P < 0.01) re-
Table 3A. Mean ( &SEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ~minants
.-~ Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Reticula-rumen 151.6 (8.4) 141.2 (9.0) 106.4 (10.6) 154.2 (8.3) 98.6 (1.5) 148.3 (12.3) 127.2 (16.9) 146.1 (21.0) 117.4 (14.4) 83.4 (9.0) 123.9 (6.4) 103.2 (7.2) 84.7 (7.0) 101.6 (6.9) 107.7 (6.1) 183.5 (9.1)
Abomasum 12.5 (3.5) 15.6 (1.5) 17.0 (0.2) $?!5j 17.9 (0.8) 19.9 (7.7) 27.8 (2.9) 19.2 (9.2) 12.9 (;:;I (1.0) 11.0 (4.2) 17.0 (1.8) 17.2 (1.9) 8.2 (1.9) 10.1 (2.0) 29.0 (6.9)
Section of tract Small intestine Caecum 8.1 (1.8) 20.7 (10.0) 10.6 (4.6) 37.0
68.7 (7.6) 59.6 (10.2) 68.8 ($)
(8.4) 16.8 (2.3) 14.9 (2.8) 7.2 (0.7) 14.0 (3.1) 10.2 (2.6) 13.3 (I 1.3) 17.6 (11.8) 7.1 (2.0) 3.0 (1.0) 3.2 (0.4) 9.4 (3.3) 42.8 (6.3)
(6.1) 62.6 (3.6) 71.8 (8.2) 83.1 (13.1) 63.5 (13.6) 59.2 (7.4) 37.0 (12.4) 45.4 (3.0) 43.2 (2.5) 39.8 (2.1) 33.2 (3.8) 49.8 (3.3) 90.6 (5.0)
Proximal colon 64.6 (9.9) 77.6 (6.8) 63.6 (17.0) 52.3 (6.9) 74.9 (10.9) 57.0 (5.1) 61.2 (27.2) 60.6 (13.8) 51.8 (4.6) 18.6 (3.8) 38.8 (12.6) 50.1 (6.2) 51.7 (3.5) 30.8 (4.4) 30.6 (8.1) 74.0 (5.3)
Distal colon ___~ 49.1 (14.6) 57.8 (1.0) 45.4 (16.6) 74.8 (10.3) 54.3 (9.3) 52.9 (7.6) 69.8 (16.2) 53.2 (11.6) 39.0 (13.0) 15.0 (6.3) 33.0 (6.2) 55.0 (12.3) 45.3 (9.9) 42.0 (4.3) 52.5 (20.1) 54.9 (11.0)
East African wild ~minants
323
Table 38. Mean (_fSEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Section of tract
Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Rou~a~ (Grazers) Dry region (Grazers)
Small
Proximal
~eticulo-amen
Abomasum _.
intestine
Caecum
colon
Distal colon
149.7’
(10.9)
13.1 (2.1) 18.7 (3.0) 15.2 (2.5)
14.0 (3.5) 12.8 (1.4) 16.4 (4.0)
65.1 (5.9) 66.9 (4.4) 52.5 (5.4)
65.8” (5.9) 59.2” (4.7) 44.3b (5.0)
52.7 (7.8) 51.8 (5.2) 44.7 (5.3)
148.6 (6.4) 122.3 (17.1) 130.6 (10.1) 131.8 (13.0) 89.3 (15.3) 101.8 (4.6) 183.5 (9.1)
13.4 (2.5) 12.5 (4.5) 21.4 (3.9) 16.0 (4.7) 12.3 (2.2) 10.3 (1.6) 29.0 (1.2)
11.7 (3.4) 19.4 (9.2) 13.4 (1.9) 12.1 (2.1) 11.8 (4.1)
66.1 (5.9) 62.6 (16.5) 72.4
68.3 (7.4) 59.9 (;;:;)
(5.3) 61.4 (7.2) 42. I (3.3) 41.2 (3.7) 90.6 (5.0)
(6.6) 56.0 (6.8) 37.8 (6.5) 33.7 (4.6) 74.0 (5.3)
(7.4) 131.2”h (8.0)
I iS.Ob
(:::) 42.8 (6.3)
51.6 0;;) (13:7) 57.5 (5.7) 46.1
(8.5) 36.7 (9.4) 46.9 (8.0) 54.9 (11.1)
*Values within a column with unlike superscripts are statistically different at the 0.05 level of significance.
lationship between the weight of the animal and reticula-rumen VFA concentrations (Table 3C). However, this relationship is less clear when comparing the individual mean values for weight groups.
Abomasal and small intestinal VFA ~oneentrations were considerably lower than that of the reticulorumen contents. VFA concentrations within the animal’s caecum were l/3-1/2 that observed within the forestomach (33.2-90.6 mmolj). WhiIe no significant difference was noted, browsers and intermediate feeders generally had higher caecal VFA values than grazers. VFA concentrations tended to decrease from caecum to distal colon for most species, and feeding groups. VFA concentration and feeding group were
significantly (P < 0.005) related within the proximal colon. Concentrations were noted to increase with the ingestion of more browse. Reticula-rumen lactic acid concentrations were less than 5% of that for VFA’s. Lactic acid concentrations remained low throughout the entire gastrointestinal tract of all species (Table 4A). Caecal and colonic lactic acid concentrations were significantly higher (P < 0.05) in browsers and intermediate feeders than in grazers (TabIe 4B). There was also a signi~cant negative relationship between lactic acid concentrations and an increase in body weight for the caecum and colonic segments of the tract (Table 4C). Reticula-rumen osmolality ranged from 232 mOsm
Table 3C. Mean (_+SEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group Less than 20 kg 20--50 kg 51.-100 kg lOI--150kg 151-200 kg 201-300 kg More than 300 kg
Reticula-rumen
Abomasum
143.8” (6.4) 118.3 (8.8) 147.2 (11.3) 101.6 (6.9) 163.8 (20.9) 111.5 (6.7) 79.4 (15.0)
16.6 (2.9) 10.7 (1.9) 19.5 (;I;)
*Regression analysis (P < 0.01); Y = 151.26.8X.
(1.9) 26.7 (5.8) 14.6 (2.2) 13.8 (2.3)
Section of tract Small intestine Caecum 10.7 (2.7) 13.3 (3.8) 14.4 (1.9) 3.2 (0.1) 34.8 (9.3) 11.3 (4.7) 13.6 (3.4)
69.9 (0.3) 54.6 (4.0) 67.7 (7.5) 33.2 (3.9) 80.4 (Jo:;) (1.8) 56. I (9.8)
Proximal colon
Distal colon
66.7 (7.4) 43.7 (5.1) 58.8 (6.7) 30.8 (4.4) 69.5 (6.0) 45.6 (5.9) 52.4 (12.0)
55.6 (86) 48.5 (9.9) 53.0 (6.4) 42.0 (4.3) 53.0 (8.8) 26.8 (2.9) 37.5 (9.4)
E. T. CLEMENSand G. M. 0.
324
MALOIY
Table 4A. Mean (+ SEM) lactic acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle
Reticuio-rumen 3.2 (0.8) 12.6 (0.6) 0.6 (0.1) 0.8 (0.2) 1.4 (0.2) 4.2 (1.3)
Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi
(Z) 8.2 (2.4) 9.4 (4.8) 1.7 (1 .O) 5.0 (2.1) 3.6 (0.9) 0.6 (0.2) 1.9 (@i)
Mountain Reedbuck oryx
(0.4) 11.7 (4.7)
Section of tract Small intestine Caecum
Abomasum
(6::) 2.9
0.2 (0.1)
(1.0)
($)
(“0::) 0.3 (;:;)
(0.9)
(0.1) 1.1 (0.2) 1.8 (0.1) (Z) (:%) 0.9 (‘;‘.A) (0:i) 0.8 (0.2) ($ (::;) 0.7 (0.1) 2.7 (1.1)
c:::, 0.9 (0.7) 2.8 (1.7) 3.2 (0.2) (ii;,
1.9 (0.8) 0.2 (0.1) 1.3 (0.8) 2.2 (1.1) 0.0 (0.0) 0.1 (0.1) 0.4 (0.4) 0.6 (0.5)
2.5 (0.4) 1.6 (0.4) 1.0 (0.4) 1.1 (0.4) 0.8 (0.5) 3.7 (2.0) 2.4 (0.6) 0.8 (0.3) 1.4 (0.3) 0.4 (0.1) 0.4 (0.l) 0.6 (0.2) 0.1 (0.3) 0.7 (0.2) 0.4 (0.2) 0.4 (0.1)
Proximal colon - _--__ 1.9 (0.3) 0.0 (0.0) 1.6 (1.0) 6.1 (2.0) 0.9 (0.8) 3.2 (0.9) 4.0 (2.0) 0.7 (0.3) 3.4 (1.1) 0.4 (0.2) 0.4 (0.2) 0.4 (0.2) 0.7 (0.4) 0.6 (0.1) 0.3 10.2t 1.8 (1.4)
Distal colon 3.5 (0.8) 0.0 (0.0) 0.1 (0.1) 9.8 (2.7) 1.0 (0.7) (Z) (Z) 4.8 (2.4) 1:::) 0.6 (0.4) (SY) 0.5 (0.3) 1.1
(0.5) 0.6 (0.1) 0.3 (0.2) 1.8 (1.4)
Table 4B. Mean (+SEM) lactic acid concentration as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection ~-MAJOR GROUPS Browsers Intermediate Grazers SUB GROUPS Fruit and d~cotyiedon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen --. ----.~-_..~_.--3.3 (1.3) 5.9 (1.5) 4.6 (1.4) 4.8 (1.7) 0.7 (0.1) 2.9 (0.8) 8.8 (::;I (0.8) 1.7 (0.3) 11.7 (4.9)
Abomasum _ (A:!, r:.:, (A::)
(Z, 0.7 (y.;) (0:2) (‘0::) I.1 (0.2) $1 d::)
Section of tract Small intestine Caecum __._ ._~ ___ _ 0.8dh (0.5) 2.0” (0.5) 0.7h (0.3) 0.1 (;:;) (1.0) ($ 1.6 (0.6) 1.4 (0.6) 0.2 (0.1) 0.6 (0.4)
1.9” (0.3) 10:; 0.5h (0.1) 2.4 (0.4) 1.1 (0.3) 2.7 (t-0) 1.1 (0.2) (:::) 0.6 (0.1) 0.4 (0.1)
Proximal colon
Distal colon
2.1” (0.6) 2.4” (0.5) 0.4h (0.1)
3.0” (1.1) 3.4” (0.7) 0.9” (0.3)
1.6 (0.4) 3.3 (1.8) 2.8 (0.4) 2.0 (0.7) 0.4 (0.1) 0.4 (0.1) 0.6 (0.1)
2.9 (0.8) 3.3 (i:i)
*Values within a coiumn with unlike superscripts are statistically different at the 0.05 level of significance.
(0.8) 3.2 (1.3) 0.6 (0.1) 0.6 (0. I)
__
_-
East African wild ruminants
325
Table 4C. Mean (+ SEM) lactic acid concentration (mmol/l) as observed at various sites along the gastrointestinal of the seven weight groups of wild ruminants Weight group Less than 20 kg 20-50 kg Zf-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
Reticula-rumen
Abomasum
4.0 (1.3) 5.5 (2.9) 4.2
(Z) 1.4 (0.6) 1.5
(1.5) 1.9 (0.3) 9.4 (4.4) 4.1 1.2 (0.9)
(0.4) 0.6 (0.1) 2.2 (0.1) 1.1 (0.2)
(0.4)
(K)
Section of tract Small intestine Caecum
1.1 (0.5) 2.0
I.0 (;:;I
(0.9)
(1.1)
(0”::) 0.4
(i::)
Proximal colon
Distal colon
2.2t (0.6) 2.6 (1.0)
3.8$ (0.9) 2.3 (0.1) (Z)
(:::)
(A:;) 0.6 (0.1) 0.6 (0.1)
(;:;) (0.7) 1.4
(00::) 0.8
(“o?) 0.9
1:::) 0.6 (o”.;)
(0.6)
(0.2)
(0.4)
(0:3)
tract
(oO:t
*Regression analysis (P < 0.01); Y = 2.3 - 0.3X. t(P < 0.~9); Y = 2.7 -0.3X. $iP < 0.005); Y = 4.3 -0.5X.
(buffalo) to 518 mOsm (oryx) (TabIe SA). There was an apparent relationship between osmolality and diet, with browsers having higher values than intermediate feeders, followed by grazers. There was also a highly significant relationship (P < 0.004) between reticula-rumen osmolality and body weight
(Table 32). Abomasal osmolality was generally isotonic to plasma. Only the oryx demonstrated hypertonicity of abomasal contents. Small intestinal contents were consistently hypertonic to plasma for all species (Table 5A). However, small intestinal osmolality significantly decreased (P < 0.006) with the
Table 5A. Mean (k SEM) osmolahty (mOsm) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Wdterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Reticu~o-rumen 456 (27) 500 (3) 314 (15) 444 (26) 362 (5) 420 (30) 571 (64) 335 (31) 405 (44) 234 (59) 349 (75) 287 (18) 242 (24) 353 (44) 400 (28) 518 (48)
Abomasum 308 (26) 318 (9) 300 (20) 348 (19) 314 (58) 344 (32) 359 (11) 284 (31) 282 (68) 216 (8) 278 (18) 247 (61 273 (37) 269 (4) 278 (12) 429 (59)
Section of tract Small intestine Caecum 633 (35) 715 (115) 471 (102) 611 (98) 518 (74) 542 (126) 696 (67) 588 (66) 546 (48) 435 (7) 480 (140) 397 (43) 406 (46) 437 (8) 547 (38) 415 (25)
359 (38) 267 (41) 260 (10) 410 (69) 338 (87) 387 (29) 415 (5) 386 (54) 308 (36) 296 (11) 315 (4) 249 (12) 292 (29) 317 (26) 367 (6) 378 (16)
Proximal colon 355 (13) 257 (3) 274 (33) 302 (30) 408 (83) 350 (41) 347 (32) 314 (34) 329 (29) 222 (15) 296 (33) 271 (44) 326 (54) 277 (34) 345 (44) 333 (40)
Distal colon 206 (18) 306 (80) 218 (40) 445 (38) 377 (62) 348 (89) 456 (34) 375 (43) 245 (16) 205 (3) 298 (83) 302 (34) 190 (45) 309 (8) 321 (74) 352 (52)
326
E. T.
CLEMENSand
G. M. 0.
MALOIY
Table 5B. Mean (+_SEM) osmolality (mOsm) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection
Section of tract Small Caecum intestine
Reticula-rumen
MAJOR GROUP* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Inte~ediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
615”
Proximal colon
Distal colon
435* (25) 407 (24) 367 (27)
293 (18) 312 (21) 298 (21)
(42) 571” (37) 449b (19)
326 (26) 364 (20) 324 (12)
314”h (16) 367” 09) 299h (16)
252b (29) 346” (29) 30Pb (21)
468 (21) 357 (44) 443 (34) 370 (28) 289 (28) 351 (29) 518 (49)
282 (25) 316 09) 340 (19) 283 (35) 246 (11) 214 (5) 439 (59)
656 (38) 518 (99) 547 (67) 567 (39) 431 (38) 480 (28) 415 (25)
333 (32) 310 (50) 382 03) 347 (16) 281 03) 335 (16) 378 06)
321 (20) 284 (21) 382 (33) 352 (22) 264 (20) 313 (23) 333 (40)
234 (28) 293 (79) 383 (46) 310 (32) 273 (30) 297 (33) 352 (35)
*Values within a column with unlike superscripts at-e statistically different at the 0.05 level of significance.
consumption of grasses (Table 5B). The osmolality of caecum and colonic contests were near isotonic to plasma. Only the gerenuk demonstrated a significantly elevated osmolality of distal colon contents. Osmolaiity of the teticulo-rumen, small intestine and caecum contents showed an important relationship to body weight, being higher in lighter animals (Table 5C). Sodium ion concentrations within the reticulorumen of the 16 species of wild ruminants ranged from 55mEq/l (suni) to 122mEq/l (gerenuk) (Table 6A). Intermediate feeders had significantly (P < 0.05) lower reticula-rumen values than did browsers or grazers (Table 68). Body weight was not related to increased
reticula-rumen sodium ion concentrations; these were diminished within the abomasum of all species. However, small intestinal sodium levels were similar to that of the reticula-rumen. Concentrations generally decreased from small intestine to distal colon in all species. No apparent sodium effect was noted at any site for either major feeding group, sub-feeding group or weight group. Potassium ion concentrations within the reticulorumen varied almost four-fold for the species investigated (giraffe 34 mEq/l to dik-dik 126 mEq/l) (Table 7A). Significant regressions were noted for major and sub-feeding groups as well as weight groups (Tables 7B, C). Statistically significant re-
Table SC. Mean (+SEM) osmolality (mOsm) as observed at various sites along the gastrointestinal tract of the seven groups of wild ruminants Weight group
Reticula-rumen
Less than 20 kg 2@-50kg 51-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
491* (24) 408 (23) 377 (26) 353 (44) 462 (67) 312 (29) 304 (28)
Abomasum 300 (22) 289 (32) 314 (23) 269 (4) 398 (55) 259 (10) 277 (25)
*Regression analysis (P < 0.004); Y = 486.&24.8X.
t(P < 0.001); Y = 658.9-35.8X. :(P < 0.04); Y = 377.1-10.6X.
Section of tract Small intestine Caecum 665t (32) 555 (27) 565 (67) 437 (8) 413 (19) 430 (55) 474 (46)
351$ (27) 343 (22) 2x7 (29) 317 (26) 361 (21) 215 (17) 298 (27)
Proximal colon
Distal colon
332 06) 332 (21) 362 (25) 277 (35) 332 (31) 281 (22) 325 (55)
824 (39) 298 (35) 361 (46) 309 (8) 320 (52) 300 (36) 266 (40)
East African
Table 6A. Mean (k SEM) sodium
Species Kirk’s
Dik-Dik
Suni Giraffe Gerenuk Eland Grant’s
Gazelle
Steenbok Impala Thomson’s African
Gazelle
Buffalo
Waterbuck Wildebeest Hartebeest Topi Mountain
Reedbuck
Oryx
Table 68.
Mean (_+SEM)
Food selection MAJOR Browsers
wild ruminants
327
ion concentration (mEq/l) as observed at various of sixteen species of wild ruminants
Reticula-rumen
Abomasum
91.3 (6.6) 55.5 (4.5) 95.8 (15.8) 121.5 (14.1) 56.1 (29.3) 77.2 (14.8) 76.5 (12.9) 57.4
50. I (7.2) 14.2 (0.6) 48.2 (6.9) 55.0 (9.8) 72.0 (22.0) 49.2 (8.4) 79.9
(7.6) 72.8 (13.4) 63.4 (6.6) 84.8 (14.4) 70.3 (4.0) 63.5 (10.9) 101.0 (22.5) 101.9 (5.8) 97.7 (10.8)
(8.0) 40.0 (7.7) 51.0 (19.0) 47.0 (3.0) 39.7 (8.4) 32.0 (8.7) 65.3 (4.4) 58.0 (4.6) 74.0 (2.6)
sodium
(;;:;)
Section Small intestine ___. 83.1 (5.2) 73.2 (21.2) 77.5 (7.5) 97.0 (13.9) 84.8 (23.1) 85.2 (14.0) 93.8 (10.2) 83.5 (10.1) 62.0 (8.1) 91.0
(1.0) 77.5 (21.5) 65.0 (29.0) 86.0 (21.7) 121.3
Caecum 77.4 (14.4) 24.4 (1.4) 44.8 (14.8) 90.4 (18.7) 40.6 (13.0) 73.5 (6.3) 38.8 (12.2) 60.2 (11.4) 55.9 (13.0) 48.6 (11.4) 64.7 (12.7) 19.8 (3.8) 51.0 (10.0) 81.0 (7.1) 37.4
(7.0) 74.0 (21.3)
(5.9) 85.2 (20.4)
ion concentration (mEq/l) as observed at various of the major and sub-feeding groups
Reticula-rumen
Abomasum
colon 63.9 (10.9) 24.2 (6.4) 32.6 (0.3) 93.3 (19.2) 28.2 (19.6) 55.5 (10.4) 25.2 (2.0) 36.7 (11.1) 58.1 (12.1) 23.4 (11.4) 30.6 (6.8) 30.7 (5.8) 53.1 (8.9) 67.4 (13.9) 28.2 (0.6) 69.6 (27.6)
sites along
Distal colon 21.9 (5.2) 12.4 (3.2) 19.4 (2.8) 30.7 (9.1) 25.0 (20.2) 32.1 (9.3) 30.7 (15.1) 29.7 (16.3) 17.6 (6.3) 14.0 (3.0) 24.1 (19.0) 55.6 (24.0) 16.2 (8.4) 49.0 (22. I) 17.5 (3.1) 27.4 (7.9)
the gastrointestinal
of tract Proximal colon
Distal colon
61.6 (10.6) 57.3 (5.5) 57.4 (7.4)
52.6 (9.0) 44.3 (7.8) 45.5 (7.6)
20.4 (3.0) 26.8 (5.2) 31.6
62.2 (14.1) 60.0 (I 7.4) 56.6 (8.0) 58.0 (8.1) 40.9 (8.8) 58.0 (9.0) 85.2 (20.4)
52.6 (10.6) 52.8 (20.8) 41.1 (8.2) 47.4 (8.6) 28.6 (3.9) 48.6 (9.1) 69.6 (27.6)
19.2
Caecum
GROUPS 88.1
43.0
Intermediate
(7.4) 68.4
$0:
Grazers
(6.1) 87.2
(5.7) 56.3
(5.6)
(3.9)
(5.6) 85.7 (6.5)
81.1
39.8
80.2
(8.1) 104.3 (12.5) 71.8 (9.1) 65.1 (7.7) 72.5
(8.3) 50.5
(5.3) 45.0
(5.1) 96.0 (10.3) 97.7 (10.8)
(5.6) 57.4 (5.1) 74.0 (2.6)
(6.1) 84.0 (7.8) 87.2 (8.3) 72.7 (7.2) 76.0 (6.5) 102.0 (8.1) 74.0 (21.3)
SUB GROUPS Fruit and dicotyleoon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
(4.5) 62.6 (9.2) 43.8
81.4 (4.7) 80.0
tract
of tract
(9.3) 88.0
Section Small intestine
sites along the gastrointestinal
(6.4)
(4.0) 23.2 (4.1) 30.0 (6.5) 23.6 (8.4) 34.7 (12.8) 30.8 (10.6) 27.4 (7.9)
tract
E. T. CLEMENS and G. M. 0.
328 Table 6C. Mean (+SE?4)
sodium
ion concentration (mEq/l) as observed at various of the seven weight groups of wild ruminants
Weight group Less than
Reticula-rumen RO.I (6.6) 89.8
20 kg
20-50 kg
(9.4) 61.3 (6.8) 101.0 (22.5) 90.9 (10.8) 76. I (6.2) 71.7 (I 1.7)
51~100 kg 101-150 kg 151~200 kg 20@300 kg More than
300 kg
gressions were also noted for feeding groups for all segments
potassium
Abomasum 48.7 (9.7) 48.6 (5.1) 48.5 (5.3) 65.3 (4.3) 65.6 (6.8) 42.6 (5.0) 57.1 (9.0)
and
major
of tract from reticulorumen to proximal colon (Table 7B). Furthermore, potassium ions were observed to decrease in concentration from caecum to distal colon in browsers and to increase in grazers. Reticula-rumen chloride values ranged from 6.0 mEq/l (hartebeest) to 24.2 mEq/l (Grant’s gazelle)
Table 7A. Mean (+SEM)
Kirk’s
Abomasum
Dik-Dik
126.4 (17.3) 125.8 (2.8) 34.4 (5.5) 45.9 (5.9) 47.8 (9.5) 65.4 (7.1) 97.6 (13.6) 62.8 (6.4) 78.6 (8.5) 63.4 (6.6) 58.2 (5.4) 39.8 (5.4) 42.3 (7.8) 37.2 (8.4) 46.9 (5.4) 39.4 (7.5)
17.3 (2.3) 101.0 (42.2) 27.2 (1.7) 24.0 (4.0) 34.2 (1.8) 40.9 (1.8) 54.2 (9.6) 38.8 (2.9) 44.2 (7.2) 30.5 (6.5) 54.0 (2.0) 53.6 (8.7) 60.0 (11.2) 36.0 (4.6) 37.7 (1.7) 26.1 (2.6)
Gerenuk Eland Grant’s
Gazelle
Steenbok Impala Thomson’s African
Gazelle
Buffalo
Waterbuck Wildebeest Hartebeest Topi Mountain
Reedbuck
Section Small intestine
sites along
the gastrointestinal
tract
of tract Caecum
83.2 (5.4) 76. I
57.0 (11.5) 53.2
(7.0) 84.4 (8.1) 121.3 (9.3) 76.4 (16.7) 70.0 (7.6) 84.4 (6.7)
(8.9) 66.9 (6.5) 81.0 (7.1) 78.4 (17.3) 37.8 (11.9) 44.7 (6.5)
Proximal colon
Distal colon
46.5 (9.1) 51.3 (9.8) 46. I (7.9) 67.4 (13.9) 66.3 (21.6) 30.7 (3.8) 28.0 (6.1)
21.7 (4.3) 19.2 (3.5) 30.9 (8.7) 49.0 (22.1) 25.2 (6.5) 43.0 (16.8) 19.5 (5.6)
(Table 8A), and were noted to decrease in concentration with the increase in body weight and grass consumption (Table 8C). There were no relationships between chloride ion and body weight or feeding group for the remaining segments of tract. Chloride ions were highest within the abomasum and diminished in concentration with subsequent distal segments of tract for all species (Table 8A).
ion concentration (mEq/l) as observed at various of sixteen species of wild ruminants
Reticula-rumen
Giraffe
Oryx
potassium
Species
Suni
MALOIY
Section Small intestine 91.9 (9.0) 52.7 (12.2) 33.2 (3.8) 31.0 (8.5) 73.8 (0.6) 26. I (3.6) 53.2 (7.0) 62.8 (8.6) 41.2 (7.3) 38.0 (2.0) 39.0 (3.0) 50.3 (3.1) 34.0 (4.8) 28.7 (2.4) 38.0 (4.0) 26.2 (8.9)
sites along the gastrointestinal
of tract Caecum
Proximal colon
Distal colon
120.6 (19.6) 46.4 (0.4) 90.0 (20.0) 15.1 (2.1) 97.2 (1.3) 33.0 (2.0) 65.2 (0.4) 78.7 (14.8) 64.8 (13.7) 75.3 (12.7) 44.8 (6.2) 81.9 (4.0) 60.8 (3.4) 45.4 (5.8) 66.6 (4.9) 41.1 (15.4)
107.4 (13.5) 37.5 (10.8) 94.4 (13.7) 51.5 (8.3) 100.3 (5.3) 34.0 (5.8) 52.2 (17.6) 75.8 (17.3) 66.4 (4.5) 67.4 (19.5) 69.8 (6.8) 80.3 (8.4) 72.0 (7.1) 45.5 (8.6) 66. I (4.9) 44.8 (14.9)
50.4 (7.0) 31.7 (7.2) 79.9 (15.3) 30.7 (6.4) 93.6 (21.0) 49.6 (11.7) 48.6 (4.8) 87.2 (15.3) 53.9 (7.1) 77.2 (19.6) 74.0 (12.4) 83.8 (14.5) 60.6 (9.3) 71.7 (19.8) 53.9 (15.5) 41.9 (5.7)
tract
East African wild ruminants
329
Table 7B. Mean (It SEM) potassium ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection
~ --~-. MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen
Abomasum
Section of tract Small intestine Caecum
Proximal colon
Distal colon _______-
99.8” (15.8) 69.9b (4.8) 42.4’ (3.0)
66.7” (I 1.7) 42.0” (2.4) 38.1h (3.4)
66.3” (10.0) 48.2” (5.0) 35.8 (2.7)
89.1” (15.8) 64.4”” (7.0) 5?.7b (5.3)
85.2” (I 1.8) 63.1ah (5.8) 61.2b t5.01
53.7 (6.7) 65.4 (6.9) 64.4 (5.9)
126.1 0;:;’
84.1 (10.3) 26. I (1.4) 42.6 (3.4) 41.4 (3.7) 47.1 (5.6) 35.8 (4.9) 26. I (2.6)
80.7 (9.9) 32.5 (2.3) 44.8 (7.8) 51.6 (6.5) 43.6 (2.8) 33.4 (2.5) 26.2 (8.9)
99.4 (19.3) 65.0 (27.5) 57. I
87.4 (16.1) 80. I (16.4) 55.1 (11.1) 71.1 (8.5) 73.6 (5.8) 58. I (5.7) 44.8 (14.9)
45.0 (6.2) 73.7 (10.8) 60.3 (9.9) 70.5 (10.0) 79.1 (7.7) 62.5 (10.1) 41.9 (5.71
(5.01 69.0 (8.1) 70.7 (5.81 44.6 (5.6) 42. I (4.2) 39.4 (7.5)
(10.1) 71.8 (9.7) 69.4 (7.4) 55.4 (5.4) 41.1 (15.4)
*Values within a column with unlike superscripts are statistically different at the 0.05 level of significance.
DISCU~ION
Twenty-six species of wild ruminants can be found in East Africa (Hofmann, 1973). The majority of
these species still abound and are dispersed throughout the diverse environmental habitat of Kenya. The arld range, mountainous, savanna, and tropical forest regions of this country support a variety of animal life. Wild ruminants inhabit each of these ecosystems. Hofmann (1973) has categorized these animals into three major feeding groups: concentrate selectors (browsers) which have a diet of high nutritive value, low fiber, and high protein content; bulk and roughage eaters (grazers) whose diet is largely grass, which is often of high fiber and low protein content; and
inte~ediate feeders whose diet consists of grasses and browse. He further subdivides the species into seven categories based according to their food preference within the major feeding groups. In the present study sixteen of the twenty-six species of wild ruminants were investigated. These animals represent members from all major and subfeeding groups. The immense diversity of weight range is also present within the sixteen species-from the tightest weight (suni and dik-dik) to the heaviest (giraffe, buffalo and eland). With the exception of the omasum, an analysis of the total gastrointestinal contents was conducted for each species. Composition of the contents at the six
Table 7C. Mean (*SEM) potassium ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group
-.Less than 20 kg 2g-50 kg 51-100 kg lol--1.50 kg 15I--200 kg 201-300kg More than 300 kg
Reticula-rumen _..119.8* (10.3) 62.6 (7.4) 64. I (4.4) 37.2 (8.4) 40.0 (5.8) 47.2 (5.6) 40.1 (11.6)
Abomasum IlSf (9.2) 39.2 (4.2) 39.8 (1.6) 26.0 (4.6) 32.9 (7.1) 53.8 (4.8) 30.6 (2.2)
*Regression analysis (P < 0.001); Y = 106.l-l I .3X. t(P < 0.002); Y = 63.8-5.0X $(P < 0.003), Y = 43.8 + 5.1X.
Section of tract Small intestine Caecum 74.6 (8.6) 38.7 (3.8) 44.1 (8.0) 28.7 (2.4) 27.8 (7.11 45.8 (3.4) 48.3 (8.2)
91.8 (15.5) 59.3 (9.1) 55.9 (11.1) 42.4 (5.%) 45.0 (12.6) 67.1 (9.5) 87.4 (7.3)
Proximal colon 19.6 (13.6) 64.4 (2.9) 54.9 (I 1.6) 45.5 (8.6) 50.3 (12.8) 76. I (5.3) 87.4 (9.0)
Distal colon 45.81 (4.8) 54.8 (6.0) 68.4 (11.4) 71.7 (19.%) 45.7 (5.8) 79.9 (9.2) 83.6 (9.0)
330
E. T. CLEMENSand G. M. 0. MALOIY
Table 8A. Mean (& SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni
Reticula-rumen
Abomasum
19.5 (2.3) 15.0
128.6 (13.8) 84.0 (9.0) 98.7 (19.7) 152.0 (21.5) 88.2 (5.8) 151.5 (31.8) 110.2 (14.0) 62.6 (5.2) 13.5 (22.5) 117.0 (3.0) 116.1 (8.8) 116.0 (9.3) 123.3 (1.3) 96.7 (4.1) 119.2 (6.6)
(0.1) Giraffe
8.4
Gerenuk
12.2 (1.3) 7.6 (2.5) 10.0 (4.0) 13.4 (2.3) 13.1 (2.1) 7.6 (2.3) 19.5 (5.7) 10.7 (1.8) 6.0 (1.8) 10.9 (1.1) 10.0 (0.4) 10.3 (0.9)
(0.1) Eland Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Section of tract Small Caecum intestine 41.9 (1.3) 52.8
(2.8) 61.2
(8.2) 48.3 (4.3) 39.2 (7.2) 46.8 (7.0) 66.2
(8.0) 41.3 (11.2) ‘75.0’ (34.0) 49.0 (1.0) 63.2 (10.9) 105.0 (27.3) 52.7 (4.9) 57.7 (10.4) 54.2 (19.1)
37.8 (2.4) 29.6 (0.8) 32.6 (7.2) 27.1 (3.1) 31.2 (8.1) 37.3 (4.6) 44.4 (3.3) 32.8 (5.6) 36.6 (5.4) 35.6 (3.4) 30.8 (0.9) 48.6 (5.2) 30.9 (1.6) 39.9 (2.4) 33.1 (4.2)
Proximal colon
Distal colon
34.6 (2.0) 17.8 (0.1) 31.8 (1.0) 9.0 (1.1) 36.2 (11.7) 31.2 (2.8) 38.4 (9.3) 39.9 (7.1) 30.9 (9.3) 21.4 (1.6) 37.5
23.9 (4.7) 17.0 (1.4) 28.4 (1.7) 9.0 (2.6) 32.9 (15.5) 29.2 (8.9) 33.8 (5.3) 19.5 (7.6) 27.2 (4.6) 24.2 (3.6) 32.0 (5.3) 12.1 (3.1) 37.3 (7.7) 27.2 (9.6) 5.9 (0.8)
(6.0) 36.0
(2.1) 35.0 (5.2) 45.1 (2.0) 27.2 (4.5)
Table 8B. Mean (k SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen 15.7” (1.8) 12.7ab (1.5) 10.9s (1.0)
Abomasum 101.8 (14.0) 97.6 (11.1) 110.1 (4.6)
Section of tract Small intestine Caecum 59.0 (11.5) 52.2 (6.1) 60.7 (5.3)
34.0 (2.1) 37.1 (2.8) 35.0 (1.5)
Proximal colon
Distal colon
32.1 (3.0) 37.3 (3.9) 34.2 (2.3)
22.6 (2.7) 28.1 (4.0) 23.8 (3.3)
115.9 45.0 35.4 29.8 (12.7) (3.4) (2.3) (2.2) 9.6 118.8 61.5 30.7 37.3 (18.0) (1.3) (4.3) (4.5) (5.5) 11.9 119.8 43.0 34.2 33.7 (22.5) (3.5) (4.4) (4.2) (5.1) 13.2 86.4 56.8 38.6 39.2 (11.4) (1.4) (7.3) (3.7) (5.4) 12.3 104.2 62.8 33.8 32.7 (2.4) (9.9) (1.8) (3.5) (9.4) 9.8 110.8 62.3 37.3 39.7 (0.8) (5.4) (2.8) (8.4) (3.0) 10.3 119.2 54.2 33.1 27.1 (19.0) (0.9) (6.6) (4.2) (4.5) *Values within a column with unlike superscripts are statistically different at the 0.05 level of significance. 18.2
(1.8)
22.0 (3.5) 24.0 (4.5) 31.0 (7.4) 26.6 (5.1) 28.4 (2.7) 29.4 (5.8) 5.9 (0.8)
East African wild ruminants
331
Table 8C. Mean (+ SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group Less than 20 kg 20-50 kg 51-100 kg 101-150 kg
-__
Reticula-rumen 16.4* (1.9) 11.8 (1.1) 15.5 (2.8) 10.9
(2.8) 151-200 kg
9.4
Abomasum 123.8 (12.8) 68.7 (10.3) 110.2 (14.0) 123.3 (1.3) 118.5
(1.1) 201-300 kg More than 300 kg
14.2 (3.0) 7.9 (0.9)
(5.2) 116.5 (4.9) 86.8 (9.1)
Section of tract Small intestine Caecum ._______ 45.4 35.8 (2.1) (1.9) 34,7 (E) (3.2) 66.2 44.4 (SO) (3.3) 52.7 30.9 (5.0) (1.6) 64.4 36.2 (I 7.9) (4.5) 57.6 32.7 (I.71 (6.9) 58.8 33.5 (13.4) (3.3)
Proximal colon
Distal colon
30.1 (2.6) 43. i (3.6) 38.4 (9.3) 35.0 (5.2) 28.9 (3.9) 33.4 (4. Li 33.0 (4.0)
23.6 (3.2) 21.9 (5.0) 33.8 (5.3) 37.3 (7.i) 7.2 (4.1) 28.8 (3.6) 29.5 (4.3)
*Regression analysis (P < 0.008); Y = 16.2-1.0X.
primary sites-the reticula-rumen, the abomasum, the small intestine, the caecum, the proximal, and the distal colon-is presented herein. Additional information concerning the electrolyte absorptionsecretion, partition VFA’s, etc. will be presented in subsequent publications. Analysis of gastrointestinal contents as a means of assessing nutritional and physjoio~cal functions of the digestive tract is an established and accepted procedure (Elsden et al., 1946; Alexander, 1965; Stevens et al., 1979). While limitations are inherent in the technique, such procedures may reveal valuable information, particularly when they are comparative. The forestomach of domestic and wiId ruminants has been the subject of several investigations. Researchers have suggested that both diet (Bath and Rook, 1963; Hoppe et al., 1977a) and size of the animal (Hungate et al., 1959; Hoppe, 1977; Maloiy et al., 1982) influence reticula-rumen fermentation rates. VFA concentrations noted in the present study support these earlier findings, since the VFA concentrations were observed to decrease with the increase in body weight and the increased consumption of grasses. In addition, the molar proportion of propionic acid and the acetate to propionate ratio suggest the occurrence of a more rapid fermentation rate, in accordance with the VFA concentration (unpublished data). However, the reticula-rumen lactic acid values were apparently not altered by the rate of fe~entation, as reported by other investigators. Assuming that both diet and body mass influence reticula-rumen fermentation rate, the question arises as to which factor exerts the more prominent effect. Present evidence suggests that body weight is most influential. Such evidence is derived from the test of higher significance for body weight compared to feeding groups, and from dn vitro fermentation data. For example, the giraffe and gerenuk are both browsers preferring trees and shrubs, yet they have a IO-fold difference in body weight. However, fermentation rates (pm01 gas NTDP/gDM/hr) were 587; more rapid in the smaller animal (Maloiy et ai., 1982). Similar examples are demonstrated with the intermediate feeders (eland and Grant’s gazelle)
(Hoppe et al., 1977b; Maloiy et al., 1982) and for the grazers (buffalo and wildebeest) (Hoppe et al., 1977a; Maloiy et af., 1982). Conversely, those animals of similar weight but different dietary habits (e.g. giraffe and buffalo) have comparable reticula-rumen fermentation rates (Maloiy et al., 1982). Within the pH range of reticula-rumen contents, most organic acids are dissociated and are subsequently osmotically active (Dobson, 1959). Therefore, the association between reticula-rumen osmolality and diet, or body weight, tends to reflect VFA concentrations. Potassium, rather than sodium, ion concentration appears to be the major cation influencing forestomach osmolality. Like osmolality and VFA concentration, potassium concentrations significantly decrease with an increased proportion of grass in the diet, and with an increase in body weight. However, in this instance, dietary effect appears to be a more prevalent factor than body weight. It follows that, in general, dicotyledons (browse) contain greater potassium levels than monocotyledon (grasses). Few investigators of ruminant physiology and nutrition consider the gastrointestinal tract beyond the point of reticula-rumen functions. Thus, the comparative data from the abomasum to the distal colon provides considerable new information. The abomasum of wild ruminants may contain as much as 8.8 kg of ingesta (giraffe) or as little as 0.1 kg (several species). The dry matter consistency of abomasal contents is generally depressed by 1-8 percentage units over that of reticula-rumen contents. Browsers, compared to inte~ediate feeders and grazers, show the least variation between gut segments. Body weight has no measurable relationship to abomasal dry matter. The organ is, however, a major site for electrolyte absorption-secretion and/or dilution. Thus, relative to reticula-rumen contents, abomasal composition is markedly different. VFA concentratjons within the glandular stomach are reduced by 70 to 9.5%. Lactic acid values were much less affected. Significant effects of diet and of body weight on these organic acids, on osmolality, and on chloride values, were not apparent within the abomasal con-
332
E. T. CLEMENS and G. M. 0. MALOII
Only potassium values within the organ appeared to have a carry-over effect from the reticulorumen. The small intestine of all mammals is the site of intensive digestion, absorption and secretion activities. The composition of small intestinal contents of these sixteen species of wild ruminants appears sensitive to diet and body weight. Small intestinal dry matter, osmolality. and potassium concentrations were each influenced significantly by diet and/or body weight, The drier intestinal consistency, hypertonicity and increased potassium concentrations suggest a greater intestinal fluid absorption within browsers and light animals than in their respective counterparts. The caecum-colon of herbivorous mammals represents the second major site of fermentative activity. A recent review (Hoover, 1978) describes the present knowledge of digestive processes within the hindgut of domestic ruminants. Minimal information is available on the hindgut of wild ruminants (Skadhauge et al., 1980; Maloiy et cd., 1982). While the reticulorumen area of browsers is relatively smaller than that of grazers (Hofmann, 1969; Hofmann and Stewart, 1972; Arman and Hopcraft, 1975) the reverse is true for the caecum and colon. From present data, it appears that browsers retain an average of 13. I”/; of the total ingesta within the large bowel compared to I 1.57; for grazers. Reticula-rumen contents were 74.6 and 77.5”: for browsers and grazers, respectively. It is also apparent that the caecum of browsers is the more voluminous segment of the large bowel, while the colon of grazers generally contains more ingesta. The volume of ingesta within the large intestine of domestic sheep has been shown to vary with diet (Grovum and Hecker, 1973). Similarly, hindgut fermentation rates of domestic ruminants respond to available substrate with increased microbial numbers, decreased pH and changing VFA ratios (Mrskov et al., 1970, 1971; Mann and 0rskov, 1973; Allison et al., 1975). However, in the present study, neither VFA concentrations nor acetate to propionate ratios within the hindgut of browsers and grazers were appreciably different (unpublished data). On the other hand, lactic acid values were significantly different for the feeding groups. The data does, however, clearly show the ability of each species to conserve colonic fluid, VFA and sodium, and to a lesser extent. potassium and chloride ions. Certain members within the sixteen species of wild ruminants deserve special consideration. The African buffalo is one such animal. It is unique among East African wild ruminants in that it is the only species which does not form a faecal pellet. The dry matter consistency of contents within the distal colon (15%) was significantly less than all other species investigated. Subsequently, the buffalo’s ability to conserve faecal water loss appears limited. Colonic drying of ingesta entering the large bowel (caecum to distal colon) was evident in all species except the buffalo. However, while a significantly greater proportion of fluids were lost in the faeces of the buffalo, less VFA and sodium ions were excreted per unit of fluid volume, even when these values were adjusted to a comparable dry matter consistency of other species. What appears most unusual is the high dry matter tents.
consistency of the buffalo’s reticula-rumen contents. The 17% dry matter is 2-6 percentage units greater than most wild ruminants. And even though the African buffalo depends on available drinking water (Sinclair, 1974; Field, 1976) these values are comparable only to those of arid range ruminants (i.e. gerenuk and oryx) which rely almost exclusively upon plants for their source of fluids (Hofmann, 1973). The unusually high dry reticula-rumen contents of the buffalo have been reported elsewhere (Maloiy et al., 1982). As mentioned earlier, the gerenuk and oryx inhabit the arid regions of East Africa. The gerenuk is a strict browser, while the oryx is a grazer (Hofmann, 1973). Like the buffalo, they exhibit an elevated reticulorumen percent dry matter, the oryx significantly so. On the other hand, the gerenuk demonstrates a significantly higher faecal dry matter. The data would suggest a greater ability of the gerenuk to conserve faecal water loss, and greater reticula-rumen recycling of these fluids relative to the oryx. The oryx also demonstrated a high reticula-rumen VFA concentration which did not fit well with the pattern of fermentation rate and diet or body size.
Acknow~ledgements-We are most grateful to Mr D. Sindiyo, Director, Department of Wildlife Conservation and Management, for permits and assistance in obtaining research specimens, and to Dr J. Sutton, National Institute for Research in Dairying, Reading, England, for VFA analysis, Mr S. Ngonga of the Nutrition Laboratory, University of Nairobi conducted the proximate analyses for which we are most grateful. The component technical assistance in the field and laboratory from Dr P. Hoppe. Dr V. Langman, Mr J. Gatihi and Mr J. Nturibi. The study was supported by research grants from the University of Nairobi, Dean’s Committee Research Funds. and from the Leverhulme Trust, London, England. Published with the approval of the Director, Nebraska Agricultural Experiment Station, Paper No. 7071, Journal Series,
REFERENCES Alexander F. (1965) The concentration of electrolytes in the alimentary tract of the rabbit, guinea pig, dog and cat. Res. Vet. Sci. 6, 238-245. Allison M. J., Robinson I. M., Dougherty R. W. and Bucklin J. A. (1975) Grain overload in cattle and sheep. Changes in microbial population in the cecum and rumen. Am. J. Vet. Res. 36, 18lll87. Arman P. and Hopcraft D. (1975) Nutritional studies on East African herbivores-I. Digestibilities of dry matter, crude fiber and crude protein in antelope. cattle and sheep. J. Nutr. 33, 255-264. Barker S. R. and Summerson W. H. (1941) The calorimetric determination of lactic acid in biological material. J. ho/. Chem. 138, 535-548. Bath I. H. and Rook J. A. F. (1963) The evaluation of cattle foods and diets in terms of the ruminal concentration of volatile fatty acids-I. The effects of level of intake. frequency of feeding, the ratio of hay to concentrate in the diet, and of supplementary feeds. J. Agric. Sci. 61, 341-348. Dobson A. (1959) Active transport through the epithelium of the reticula-rumen sac. J. Physiol. 146, 2355251. Elsden S. R., Hitchcock M. W. S., Marshall R. A. and Phillipson A. T. (I 946) Volatile fatty acids in the digesta of ruminants and other animals. J. e.rp. Biol. 22, 191-198.
East African vfiid ruminants Field C. E. (1976)Palatability factors and nutritive value of the food of buffalo (S_rnt’rrus cqfir) in Uganda. E. @r. Wifdi. J. 14, 181-201.
Grovum W. L. and Hecker J. F. (1973) Rate of passage of digesta in sheep-2 The effects of level of food intake on digesta retention times and on water and electrolyte absorntion in the large intestine. Br. f. Nurr. 30,221&230. Hofma~n R. R. (196S)~~~~aris~as of rumen and omasum structure in East African game ruminants in relation to their feeding habits. In Comparative Nutrition of Wild Animals (Edited by Crawford M. A.). Symposium Zoological Society of London. Hofmann R. R. (1973) The R~rn~nunfStomach. EastAfrican Literature Bureau, Nairobi, Kenya. Hofmann R. R. and Stewart D. R. M. (1972) Grazer or Browser: A classitication based on the stomach structure and feeding habits of East African ruminants. Mammaliu 36, 226-240.
Hoover W. H. (1978) Digestion and absorption in the hindgut of ruminants. .I-Anim. Sci. 46, 1789-1798. Hoooe . P. P. (1977) Rumen fermentation and bodv weight in African ruminants. Proc. 13rk Congress Game Bioioqisfs, A~~an~uf4l- 150. Hoppe P. P., Qvortrup S. A. and Woodford M. H. (1977a) Rumen fermentation and food selection in East African Zebu cattle, wildebeest, Coke’s hartebeest and topi. J. 2001.. Land. 181, l-9. Hoppe P. P., Qvortrup S. A. and Woodford, M. H. (1977b) Rumen fermentation and food selection of East African sheep, goats, Thomson’s gazelle, Grant’s gazelle and Impala. J. Agric. Sci. Camh. 89, 1299135. Hungate R. E., Phillips G. D., McGregor A., Hungate D. P. and Buechner H. K. (19S9) ,~icrobiai fe~entation m certain mammals. Science, N. Y. 130, I 192. I
333
Maloiy G. M. O., Clemens E. T. and Kamau J. M. Z. (1982) Aspects of digestion and in oitro rumen fermentation rate in six species of East African wild ruminants. Camp. Eiochem. Physiol.
Mann 0. S. and Orskov E. R. (1973) The effect of rumen and post-rumen feeding of carbohydrates on cecal microfiora of sheep. J. appl. Butt. 36, 475481. ‘Markham R. A. (1942) Steam djstjflation apparatus suitable for micro-Kjeldahl analysis. Biochem. J. 36, 790-796. Orskov E. R., Fraser C., Manson V. C. and Mann S. 0. (1970) Influence of starch digestion in the large intestine of sheep on caecal fermentation, caecal microflora and faecal nitrogen excretian. Br. J. Nufr. 20, 3970-1978. Orskov E. R.. Fraser C. and McDonald I. (1971) Digestion of concentrates in sheep-2. The effect of urea or fiihmeal supplementation of barley diets on the apparent digestion of protein, fat, starch and ash in the rumen, the small intestine and the large intestine and calculation of volatile fatty acid production. f3r. J. Nztfr. 25, 2433251. Sinclair A. R. E. (1974) The natural regulation of buffalo population in East Africa-IV. The food supply as a regulating factor and competition. E. Afr. Wildl. J. 10, 77-89.
Skadhauge E., Clemens E. T. and Maloiy G. M. 0. (1980) The effects of dehydration on electrolyte concentration and water content along the large intestine of a small ruminant: The dik-dik antelope. J. romp. Physiol. 135, 165173. Steel R. G. D. and Torrie J. H. (1960) PrincQles and Procedures of Statistics. McGraw-Hill, New York, Stevens C. E., Argenzio R. A. and Clemens E. T. (1979) Microbial digestion: rumen versus large intestine. In Physiolo.~y qf Digestion and ~e~abo~~~rn in Rum~~anrs (Edited by Ruckebusch Y.). Beaumont, France.
DIGESTIVE
pp. 319-333,
1983 8
PHYSIOLOGY OF EAST AFRICAN RUMINANTS
0300-9629/X3 $3.00 + 0.00 1983 Pergamon Press Ltd
WILD
E. T. CLEMENS and G. M. 0. MALOIY Department of Veterinary Physiology, University of Nairobi, Nairobi, Kenya, East Africa and Department of Veterinary Science, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln, Lincoln. NE 68583-0905, U.S.A. Telephone: (402) 4’72-2952 (Recessed 18 January 1983)
Abstract-I. The physiology of digestion of wild ruminants in their natural habitat was determined. The study consisted of fifty-one adult male animals representing sixteen species. 2. While diet and body weight were both related to the gastrointestinal composition, body weight
appeared to he the more influential factor. 3. Reticula-rumen and caecal-colon composition, relative to abomasal and small intestinal composition, showed the greater species, diet and body weight effects. 4. The buffalo, oryx and gerenuk were somewhat more unique in gastrointestinal composition than were other species of wild ruminants, and were deserving of special consideration.
INTRODUCTION
With the continued studies of both domestic and wild ruminants, knowledge of reticula-rumen physiology is rapidly expanding. Comparative information and, to a lesser extent, post-ruminal digestion studies have not been as fruitful. Furthermore, quantitative information derived from studies of different species is difficult to compare, owing to the variation in technique. The present investigation allowed for an intensive, comparative study without the variance due to technique. In addition, these animals were studied in their natural habitat, thus providing a more reaiistic comparison of wild ruminants. MATERIAL AND METHODS Fifty-one adult, male animals representing 16 species of East African wild ruminants were used in the study. These included: five Kirk’s dik-dik (~u~oq~~ ~j~~i), two suni (Nesoiraqus moschatus), three giraffe (Girafla camelopard&s), three gerenuk (Litocrumius walleri), three eland (Turotragus oryx), four Grant’s gazelle (Gazelle gruti), two steenbok (Ruph~ce~ cumpesfrjs), four impala (Aepyceros meiampus), four Thomson’s gazelle (Gazella thomsoni), three buffalo (Bubalus cuffer), two waterbuck (Kobus ellipsiprymmts), three wildebeest (Connochaefes tantinus), three hartebeest (Alcepha~~~ b~se~aph~s), three topi ~DarnuI~sc~ lunatus), three mountain reedbuck (Redunca fuiuorufuia), and four oryx (oryx gaze/la). All animals were collected from their natural habitat in conjunction with wildlife management programs. Field analysis and sample collection were begun immediately after sacrifice and generally completed within 1 hour after the death of the animal. Body weights of the animals were taken as those reported for the average species weight (Hofmann, 1973). The abdominal cavity of each animal was opened immediately after death. Urine and blood samples were collected and refrigerated. Ligatures were used to tie off the oesophagus at the cardia and the large bowel at the rectal-anal junction, and the gastrointestinal tract removed. The gastrointestinal tract of each animal was further separated by ligatures into six selected segments. These consisted of the
reticula-rumen, abomasum, small intestine, caecum, and proximal and distal halves of the colon. TotaI contents were removed from each segment, weighed, and a representative sample refrigerated for later analysis. Additional samples were strained through cheese cloth, the supematant acidified with concentrated H,SO, (approx 0.5 ml per 20 ml sample), and refrigerated for later analyses of volatile fatty acids. The dry matter content was determined by drying a portion of each sample to a constant weight in a forced-air oven at 105°C. Samples of whole gut contents were centrifuged and the supematant collected for laboratory analysis. The osmolality of the supernatant fraction was determined on a laboratory osmometer, the sodium and potassium concentrations by flame photometry, and the chloride concentration was determined with the aid of a chloridometer. The lactic acid concentration of each sample was determined by the methods of Barker and Summerson (1941). Volatile fatty acid concentrations were determined‘ by the steam distillation method of Markham (1942), and by partition chromatography of short chain fatty acids. Data were subject to analysis of variance. Duncan’s Multiple Range test, and regression analysis for determination of significant differences (Steel and Torrie, 1960). RESULTS
The series of Tables 2-8 present the analytical data for seven parameters measured in this study. Tables are further divided according to species, major and sub-feeding groups, and weight of the animal. Table 1 presents the live weight, food selection and mean weight of gastrointestinal contents, by species and for the six primary gut segments. The percent dry matter within the reticula-rumen showed considerable variability for the species investigated, ranging from a low of 10.5% (suni) to 21.8% (oryx) (Table 2A). However, when comparing sub-feeding groups, dry region grazers’ reticuIorumen dry matter was significantly greater (P < 0.05) than other groups (Table 2B). The intermediated feeders also appeared to have a higher dry matter value than most browsers or grazers. Abomasal 319
E. T. CLEMENSand G. M. 0. MALLXY
320
contents showed considerably more variability in dry matter consistency than reiticulo-rumen contents. No correlation was noted with the dry matter content of these two segments. Lowest abomasal values were noted for the buffalo (6.5%), and highest for the oryx (16.273. Intermediate feeders had abomasal dry matter values significantly lower than either browsers or grazers. However, when considering the subfeeding groups, most grazers’ abomasal dry matters were generally lower than browsers’ and comparable to intermediate feeders’, except fcr the dry region grazers. Percent dry matter within the small intestine was the only segment to show a significant (P < 0.01)
relationship with major feeding groups. Dry matter composition decreased with the ingestion of more grasses. There was a noted relationship between dry matter percent and weight of the animal for the small
intestinal contents (P < 0.01) {Table 2C). Caecal dry matters were 2-6 percentage units greater than that of the small intestine (except for the suni) and ranged from a low of 9.5% (suni) to a high of 22.2% (dik-dik). Statistically significant differences (P < 0.05) were not detected for caecal dry matter between feeding groups. However, within the group of grazers, dry region grazers had dry matter percents significantly greater (P < 0.01) than the roughage grazers.
Table I. Average live weight, food selection and total weight (kg) of gastrointestinal contents as observed in sixteen species of wild ruminants Species
Average* live weight (kg)
Food Selection Kirk’s Dik-Dik: Fruit and dicotyledon (Browsers) Suni: Fruit and dicotyledon (Browsers) Giraffe: Trees and shrub (Browsers) Gerenuk: Trees and shrub (Browsers) Eland: Prefers browse (Intermediate) Grant’s Gazelle: Prefers browse (Intermediate) Steenbok: Prefers browse (Intermediate) Impala: Prefers graze (Intermediate) Thomson’s Gazelle: Prefers graze (Intermediate) African Buffalo: Fresh grass (Grazers) Waterbuck: Fresh grass (Grazers) Wildebeest: Fresh grass (Grazers) Hartebeest: Roughage (Grazers) Topi: Roughage (Grazers) Mountain Reedbuck: Roughage (Grazers) Oryx: Dry region (Grazers) *Data
for average
live weight
Section Small intestine ---~ 10.1
of tract
S-6
Reticuiorumen -_-_-_ 0.3
S--l
0.3
500-750
85.9
8.8
7.2
9.2
3.5
I.9
N-52
4.4
0.3
0.3
0.5
0.2
0.1
78.4
6.5
5.3
3.1
3.4
2.6
4.2
0.2
0.2
0.2
0.1
0.1
8-11
0.8
CO.1
CO.1
CO.1
CO.1
53-71
4.7
0.3
0.4
0.2
0.2
22-25
2.1
400-650
4664
Abomasum __ 10.1
10.1
0.1
Caecum
Proximal colon
Distal colon
CO.1
CO.1
10.1
CO.1
10.1
0.3
CO.1
600-850
87.3
4.4
4.7
3.8
3.3
2.6
192-286
31.9
1.9
2.2
2.4
2.0
1.6
171-242
28.0
1.8
2.3
2.0
1.2
0.7
116-160
13.6
1.0
0.9
1.1
0.6
0.4
III-147
13.4
0.9
0.8
0.6
0.6
0.3
23-28
1.8
0.1
25.4
1.7
168-209
and food selection
obtained
from Hofmann,
1.9
1973.
0.2
1.9
1.6
1.4
East African wild ruminants
321
Table 2A. Mean (+ SEM) dry matter percent as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species --___~Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck oryx
Reticula-rumen 16.4 (0.6) 10.5 (1.5) 13.5 (0.5) 17.0 (1.2) 14.5 (1.5) 16.0 (1.8) 16.5 (0.5) 16.2 (1.6) 15.8 (1.6) 18.0 (7.0) 14.0 (1.0) 13.3 (0.7) 12.0 (0.8) 16.0 (1.6) 12.0 (0.6) 21.8
(2.8)
Table 28. Mean (&SEM)
Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit & dicotyledon (Browsers) Trees & shrub
(Browsers) Prefers browse (Intermediate) Prefers graze IIntermediate) Fresh grass
(Grazers) Roughage (Grazers) Dry region (Grazers)
Abomasum I_____13.0 (1.6) 11.0 (1.0) 14.0 (0.1) 15.0 (1.2) 10.0 (5.0) 9.2 (;:;I (2.1) 8.0 (1.1) 7.8 (0.5) 6.5 (3.5) 7.5
Section of tract Small intestine Caecum 17.0 (0.5) 14.0 (0.1)
22.2 (16) 9.5 (4.5)
14.0 (0.8) 1:‘:)
18.0 (0.9) 17.0 (3.7) 13.8 (1.1) 18.0 (1.0) 18.0 (1.5) 13.2 (1.6) 15.5 (5.5) 13.0 (1.0) 20.0 (3.6) 14.0 (2.1) 16.7 (0.7) 13.0 (0.6) 20.2 (1.5)
(&
lo:o (1.7) 14.5 (1.5) 13.5 (2.5) 12.0 (2.6) (Z) (::I)
(0.5) 12.7
10.0 (1.0) 9.0 (1.2) 11.7 (1.2) 9.3 (1.4) 13.5 (2.3)
(2.6) 12.0 (1.0) 14.3 (3.5) 5.3 (2.3) 16.2
(1.2)
i 6.0 (0.1)
Proximal colon -____ 22.0 (0.4) 20.0 (4.1) 17.0 (4.0) 20.0 (3.9) 22.5 (6.5) 18.2 (1.7) 18.5 (4.2) 18.5 (1.4) 15.0 (0.9) 11.0 (1.0) 18.5 (0.5) 24.3 (2.4) 18.0 0.7) 21.3 (1.2) 16.3 (1.3) 22.6 (l..J)
dry matter per cent as observed at various sites along the gastrointestinal and sub-feeding groups
Reticula-rumen
Abomasum
Section of tract Small intestine Caecum
14.7 (0.9) 15.9 (0.7) 15.9 (1.2)
13.0” (0.8) 8.6h (0.6) 11.2”b (1.3)
14.5 (1.0) I I 8”’ (1:l) 10.5b (0.7)
18.0 (1.9) 15.6 (0.9) 16.7 (1.0)
14.7 (1.2) 14.7 0.2) 15.8 (0.9) 16.0 (1.1) 14.8 (1.8) 13.7 (1.0) 21.8 (2.8)
12.4 (1.2) 14.3 (0.3) 9.4 (1.1) 7.9
16.1 (0.7) 10.7 (1.7) 10.9 (1.4) 12.8 (;.;)
18.6 (2.8) 16.7 (0.7) 15.6 (1.2) 15.6 (1.4) 16.7 (2.2) 14.1 (0.8) 20.2 (1.5)
%) (1.7) 10.1 (2.4) 16.3 (1.2)
*Values within a column with unlike superscripts are
Distal
colon 39.0 (1.1) 27.5 (4.5) 33.5 (7.5) 65.0 (13.2) 27.0 (8.1) 32.2 (4.1) 31.5 (4.5) 29.5 (2.5) 24.5 (4.1) 15.0 0.0) 23.3 (1.5) 29.0 (4.7) 42.2 (7.1) 40.3 (2.4) 32.0 (3.6) 35.0 (6.1)
tract of the major
Proximal colon
Distal colon
20.5 (1.1) 18.1 (1.3) 19.7 (1.1)
39.2 (4.5) 31.4 (1.8) 31.3 (2.4)
21.6 (j-0) 18.0 (2.5) 19.4 (1.6) 16.7 (2.1) 18.9 (2.4) &) 18.7 (0:9) (1.2) 13.5 22.8 (2.3) (1.5) statisticatly different at the 0.0s level of significance.
35.7 (2.5) 47.3 (14.5) 30.8 (2.7) 32.0 (2.4) 23.4 (3.0) 37.0 (2.4) 35.0 (6.1)
E. T. CLEMENSand G. M. 0. MALOIY
322
Table ZC. Mean (+ SEM) dry matter per cent as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group
Reticula-rumen
Less than 20 kg 20-50 kg 51-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
15.1 (1.0) 14.5 (1.1) 16.1 (1.1) 16.0 (0.6) 19.8 (2.9) 13.6 (0.5) 15.3 (2.0)
Abomasum 11.7 (1.1) 7.8 (&) (0.6) 14.3 (3.6) 15.4 (1.3) 10.6 (1.9) 10.2 (2.1)
Section of tract Small intestine Caecum 15.x* (0.6) 11.2 (1.4) 11.8 (1.5) 11.7 (1.2) 12.6 (2.0) 9.8 (0.6) 8.3 (1.1)
-18.4 (2.1) 13.8 (1.0) 15.9 (1.2) 16.7 (0.7) 19.0 (1.9) 17.2 (2.6) 16.2 0.8)
Proximal colon
Distal colon
20.9 (0.9) 16.1 (0.8) 18.4 (2.1) 21.3 (1.2) 21.8 (1.5) 22.0 (1.9) 16.8 (2.9)
34.8 (2.1) 38.6 (5.7) 30.9 (2.3) 40.3 (2.4) 36.4 (4.9) 26.8 (2.9) 25.2 (4.4)
-..-._
*Regression analysis (P < 0.006); Y = 15.2 - 0.9X.
Drying of faecal material was readily apparent in the proximal and distal colon of all species except the buffalo. Values ranged from 15% (buffalo) to 65% (gerenuk). Browsers had significantly drier contents ~thin the distal colon than did grazers or intermediate feeders. Considerable variability was observed for the concentration of volatile fatty acids (VFA) within the
reticula-rumen of each species (range, 93.4 mmol/l (buffalo) to 183.5 mmol/l (oryx)) (Table 3A). A relationship was apparent for feeding group and VFA concentration within the reticuio-rumen, with browsers having higher values and grazers having lower values (Table 3B). Sub-feeding groups showed a similar pattern except for dry region grazers. There was also a statistically significant (P < 0.01) re-
Table 3A. Mean ( &SEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ~minants
.-~ Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Reticula-rumen 151.6 (8.4) 141.2 (9.0) 106.4 (10.6) 154.2 (8.3) 98.6 (1.5) 148.3 (12.3) 127.2 (16.9) 146.1 (21.0) 117.4 (14.4) 83.4 (9.0) 123.9 (6.4) 103.2 (7.2) 84.7 (7.0) 101.6 (6.9) 107.7 (6.1) 183.5 (9.1)
Abomasum 12.5 (3.5) 15.6 (1.5) 17.0 (0.2) $?!5j 17.9 (0.8) 19.9 (7.7) 27.8 (2.9) 19.2 (9.2) 12.9 (;:;I (1.0) 11.0 (4.2) 17.0 (1.8) 17.2 (1.9) 8.2 (1.9) 10.1 (2.0) 29.0 (6.9)
Section of tract Small intestine Caecum 8.1 (1.8) 20.7 (10.0) 10.6 (4.6) 37.0
68.7 (7.6) 59.6 (10.2) 68.8 ($)
(8.4) 16.8 (2.3) 14.9 (2.8) 7.2 (0.7) 14.0 (3.1) 10.2 (2.6) 13.3 (I 1.3) 17.6 (11.8) 7.1 (2.0) 3.0 (1.0) 3.2 (0.4) 9.4 (3.3) 42.8 (6.3)
(6.1) 62.6 (3.6) 71.8 (8.2) 83.1 (13.1) 63.5 (13.6) 59.2 (7.4) 37.0 (12.4) 45.4 (3.0) 43.2 (2.5) 39.8 (2.1) 33.2 (3.8) 49.8 (3.3) 90.6 (5.0)
Proximal colon 64.6 (9.9) 77.6 (6.8) 63.6 (17.0) 52.3 (6.9) 74.9 (10.9) 57.0 (5.1) 61.2 (27.2) 60.6 (13.8) 51.8 (4.6) 18.6 (3.8) 38.8 (12.6) 50.1 (6.2) 51.7 (3.5) 30.8 (4.4) 30.6 (8.1) 74.0 (5.3)
Distal colon ___~ 49.1 (14.6) 57.8 (1.0) 45.4 (16.6) 74.8 (10.3) 54.3 (9.3) 52.9 (7.6) 69.8 (16.2) 53.2 (11.6) 39.0 (13.0) 15.0 (6.3) 33.0 (6.2) 55.0 (12.3) 45.3 (9.9) 42.0 (4.3) 52.5 (20.1) 54.9 (11.0)
East African wild ~minants
323
Table 38. Mean (_fSEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Section of tract
Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Rou~a~ (Grazers) Dry region (Grazers)
Small
Proximal
~eticulo-amen
Abomasum _.
intestine
Caecum
colon
Distal colon
149.7’
(10.9)
13.1 (2.1) 18.7 (3.0) 15.2 (2.5)
14.0 (3.5) 12.8 (1.4) 16.4 (4.0)
65.1 (5.9) 66.9 (4.4) 52.5 (5.4)
65.8” (5.9) 59.2” (4.7) 44.3b (5.0)
52.7 (7.8) 51.8 (5.2) 44.7 (5.3)
148.6 (6.4) 122.3 (17.1) 130.6 (10.1) 131.8 (13.0) 89.3 (15.3) 101.8 (4.6) 183.5 (9.1)
13.4 (2.5) 12.5 (4.5) 21.4 (3.9) 16.0 (4.7) 12.3 (2.2) 10.3 (1.6) 29.0 (1.2)
11.7 (3.4) 19.4 (9.2) 13.4 (1.9) 12.1 (2.1) 11.8 (4.1)
66.1 (5.9) 62.6 (16.5) 72.4
68.3 (7.4) 59.9 (;;:;)
(5.3) 61.4 (7.2) 42. I (3.3) 41.2 (3.7) 90.6 (5.0)
(6.6) 56.0 (6.8) 37.8 (6.5) 33.7 (4.6) 74.0 (5.3)
(7.4) 131.2”h (8.0)
I iS.Ob
(:::) 42.8 (6.3)
51.6 0;;) (13:7) 57.5 (5.7) 46.1
(8.5) 36.7 (9.4) 46.9 (8.0) 54.9 (11.1)
*Values within a column with unlike superscripts are statistically different at the 0.05 level of significance.
lationship between the weight of the animal and reticula-rumen VFA concentrations (Table 3C). However, this relationship is less clear when comparing the individual mean values for weight groups.
Abomasal and small intestinal VFA ~oneentrations were considerably lower than that of the reticulorumen contents. VFA concentrations within the animal’s caecum were l/3-1/2 that observed within the forestomach (33.2-90.6 mmolj). WhiIe no significant difference was noted, browsers and intermediate feeders generally had higher caecal VFA values than grazers. VFA concentrations tended to decrease from caecum to distal colon for most species, and feeding groups. VFA concentration and feeding group were
significantly (P < 0.005) related within the proximal colon. Concentrations were noted to increase with the ingestion of more browse. Reticula-rumen lactic acid concentrations were less than 5% of that for VFA’s. Lactic acid concentrations remained low throughout the entire gastrointestinal tract of all species (Table 4A). Caecal and colonic lactic acid concentrations were significantly higher (P < 0.05) in browsers and intermediate feeders than in grazers (TabIe 4B). There was also a signi~cant negative relationship between lactic acid concentrations and an increase in body weight for the caecum and colonic segments of the tract (Table 4C). Reticula-rumen osmolality ranged from 232 mOsm
Table 3C. Mean (_+SEM) volatile fatty acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group Less than 20 kg 20--50 kg 51.-100 kg lOI--150kg 151-200 kg 201-300 kg More than 300 kg
Reticula-rumen
Abomasum
143.8” (6.4) 118.3 (8.8) 147.2 (11.3) 101.6 (6.9) 163.8 (20.9) 111.5 (6.7) 79.4 (15.0)
16.6 (2.9) 10.7 (1.9) 19.5 (;I;)
*Regression analysis (P < 0.01); Y = 151.26.8X.
(1.9) 26.7 (5.8) 14.6 (2.2) 13.8 (2.3)
Section of tract Small intestine Caecum 10.7 (2.7) 13.3 (3.8) 14.4 (1.9) 3.2 (0.1) 34.8 (9.3) 11.3 (4.7) 13.6 (3.4)
69.9 (0.3) 54.6 (4.0) 67.7 (7.5) 33.2 (3.9) 80.4 (Jo:;) (1.8) 56. I (9.8)
Proximal colon
Distal colon
66.7 (7.4) 43.7 (5.1) 58.8 (6.7) 30.8 (4.4) 69.5 (6.0) 45.6 (5.9) 52.4 (12.0)
55.6 (86) 48.5 (9.9) 53.0 (6.4) 42.0 (4.3) 53.0 (8.8) 26.8 (2.9) 37.5 (9.4)
E. T. CLEMENSand G. M. 0.
324
MALOIY
Table 4A. Mean (+ SEM) lactic acid concentration (mmol/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle
Reticuio-rumen 3.2 (0.8) 12.6 (0.6) 0.6 (0.1) 0.8 (0.2) 1.4 (0.2) 4.2 (1.3)
Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi
(Z) 8.2 (2.4) 9.4 (4.8) 1.7 (1 .O) 5.0 (2.1) 3.6 (0.9) 0.6 (0.2) 1.9 (@i)
Mountain Reedbuck oryx
(0.4) 11.7 (4.7)
Section of tract Small intestine Caecum
Abomasum
(6::) 2.9
0.2 (0.1)
(1.0)
($)
(“0::) 0.3 (;:;)
(0.9)
(0.1) 1.1 (0.2) 1.8 (0.1) (Z) (:%) 0.9 (‘;‘.A) (0:i) 0.8 (0.2) ($ (::;) 0.7 (0.1) 2.7 (1.1)
c:::, 0.9 (0.7) 2.8 (1.7) 3.2 (0.2) (ii;,
1.9 (0.8) 0.2 (0.1) 1.3 (0.8) 2.2 (1.1) 0.0 (0.0) 0.1 (0.1) 0.4 (0.4) 0.6 (0.5)
2.5 (0.4) 1.6 (0.4) 1.0 (0.4) 1.1 (0.4) 0.8 (0.5) 3.7 (2.0) 2.4 (0.6) 0.8 (0.3) 1.4 (0.3) 0.4 (0.1) 0.4 (0.l) 0.6 (0.2) 0.1 (0.3) 0.7 (0.2) 0.4 (0.2) 0.4 (0.1)
Proximal colon - _--__ 1.9 (0.3) 0.0 (0.0) 1.6 (1.0) 6.1 (2.0) 0.9 (0.8) 3.2 (0.9) 4.0 (2.0) 0.7 (0.3) 3.4 (1.1) 0.4 (0.2) 0.4 (0.2) 0.4 (0.2) 0.7 (0.4) 0.6 (0.1) 0.3 10.2t 1.8 (1.4)
Distal colon 3.5 (0.8) 0.0 (0.0) 0.1 (0.1) 9.8 (2.7) 1.0 (0.7) (Z) (Z) 4.8 (2.4) 1:::) 0.6 (0.4) (SY) 0.5 (0.3) 1.1
(0.5) 0.6 (0.1) 0.3 (0.2) 1.8 (1.4)
Table 4B. Mean (+SEM) lactic acid concentration as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection ~-MAJOR GROUPS Browsers Intermediate Grazers SUB GROUPS Fruit and d~cotyiedon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen --. ----.~-_..~_.--3.3 (1.3) 5.9 (1.5) 4.6 (1.4) 4.8 (1.7) 0.7 (0.1) 2.9 (0.8) 8.8 (::;I (0.8) 1.7 (0.3) 11.7 (4.9)
Abomasum _ (A:!, r:.:, (A::)
(Z, 0.7 (y.;) (0:2) (‘0::) I.1 (0.2) $1 d::)
Section of tract Small intestine Caecum __._ ._~ ___ _ 0.8dh (0.5) 2.0” (0.5) 0.7h (0.3) 0.1 (;:;) (1.0) ($ 1.6 (0.6) 1.4 (0.6) 0.2 (0.1) 0.6 (0.4)
1.9” (0.3) 10:; 0.5h (0.1) 2.4 (0.4) 1.1 (0.3) 2.7 (t-0) 1.1 (0.2) (:::) 0.6 (0.1) 0.4 (0.1)
Proximal colon
Distal colon
2.1” (0.6) 2.4” (0.5) 0.4h (0.1)
3.0” (1.1) 3.4” (0.7) 0.9” (0.3)
1.6 (0.4) 3.3 (1.8) 2.8 (0.4) 2.0 (0.7) 0.4 (0.1) 0.4 (0.1) 0.6 (0.1)
2.9 (0.8) 3.3 (i:i)
*Values within a coiumn with unlike superscripts are statistically different at the 0.05 level of significance.
(0.8) 3.2 (1.3) 0.6 (0.1) 0.6 (0. I)
__
_-
East African wild ruminants
325
Table 4C. Mean (+ SEM) lactic acid concentration (mmol/l) as observed at various sites along the gastrointestinal of the seven weight groups of wild ruminants Weight group Less than 20 kg 20-50 kg Zf-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
Reticula-rumen
Abomasum
4.0 (1.3) 5.5 (2.9) 4.2
(Z) 1.4 (0.6) 1.5
(1.5) 1.9 (0.3) 9.4 (4.4) 4.1 1.2 (0.9)
(0.4) 0.6 (0.1) 2.2 (0.1) 1.1 (0.2)
(0.4)
(K)
Section of tract Small intestine Caecum
1.1 (0.5) 2.0
I.0 (;:;I
(0.9)
(1.1)
(0”::) 0.4
(i::)
Proximal colon
Distal colon
2.2t (0.6) 2.6 (1.0)
3.8$ (0.9) 2.3 (0.1) (Z)
(:::)
(A:;) 0.6 (0.1) 0.6 (0.1)
(;:;) (0.7) 1.4
(00::) 0.8
(“o?) 0.9
1:::) 0.6 (o”.;)
(0.6)
(0.2)
(0.4)
(0:3)
tract
(oO:t
*Regression analysis (P < 0.01); Y = 2.3 - 0.3X. t(P < 0.~9); Y = 2.7 -0.3X. $iP < 0.005); Y = 4.3 -0.5X.
(buffalo) to 518 mOsm (oryx) (TabIe SA). There was an apparent relationship between osmolality and diet, with browsers having higher values than intermediate feeders, followed by grazers. There was also a highly significant relationship (P < 0.004) between reticula-rumen osmolality and body weight
(Table 32). Abomasal osmolality was generally isotonic to plasma. Only the oryx demonstrated hypertonicity of abomasal contents. Small intestinal contents were consistently hypertonic to plasma for all species (Table 5A). However, small intestinal osmolality significantly decreased (P < 0.006) with the
Table 5A. Mean (k SEM) osmolahty (mOsm) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni Giraffe Gerenuk Eland Grant’s Gazelle Steenbok Impala Thomson’s Gazelle African Buffalo Wdterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Reticu~o-rumen 456 (27) 500 (3) 314 (15) 444 (26) 362 (5) 420 (30) 571 (64) 335 (31) 405 (44) 234 (59) 349 (75) 287 (18) 242 (24) 353 (44) 400 (28) 518 (48)
Abomasum 308 (26) 318 (9) 300 (20) 348 (19) 314 (58) 344 (32) 359 (11) 284 (31) 282 (68) 216 (8) 278 (18) 247 (61 273 (37) 269 (4) 278 (12) 429 (59)
Section of tract Small intestine Caecum 633 (35) 715 (115) 471 (102) 611 (98) 518 (74) 542 (126) 696 (67) 588 (66) 546 (48) 435 (7) 480 (140) 397 (43) 406 (46) 437 (8) 547 (38) 415 (25)
359 (38) 267 (41) 260 (10) 410 (69) 338 (87) 387 (29) 415 (5) 386 (54) 308 (36) 296 (11) 315 (4) 249 (12) 292 (29) 317 (26) 367 (6) 378 (16)
Proximal colon 355 (13) 257 (3) 274 (33) 302 (30) 408 (83) 350 (41) 347 (32) 314 (34) 329 (29) 222 (15) 296 (33) 271 (44) 326 (54) 277 (34) 345 (44) 333 (40)
Distal colon 206 (18) 306 (80) 218 (40) 445 (38) 377 (62) 348 (89) 456 (34) 375 (43) 245 (16) 205 (3) 298 (83) 302 (34) 190 (45) 309 (8) 321 (74) 352 (52)
326
E. T.
CLEMENSand
G. M. 0.
MALOIY
Table 5B. Mean (+_SEM) osmolality (mOsm) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection
Section of tract Small Caecum intestine
Reticula-rumen
MAJOR GROUP* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Inte~ediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
615”
Proximal colon
Distal colon
435* (25) 407 (24) 367 (27)
293 (18) 312 (21) 298 (21)
(42) 571” (37) 449b (19)
326 (26) 364 (20) 324 (12)
314”h (16) 367” 09) 299h (16)
252b (29) 346” (29) 30Pb (21)
468 (21) 357 (44) 443 (34) 370 (28) 289 (28) 351 (29) 518 (49)
282 (25) 316 09) 340 (19) 283 (35) 246 (11) 214 (5) 439 (59)
656 (38) 518 (99) 547 (67) 567 (39) 431 (38) 480 (28) 415 (25)
333 (32) 310 (50) 382 03) 347 (16) 281 03) 335 (16) 378 06)
321 (20) 284 (21) 382 (33) 352 (22) 264 (20) 313 (23) 333 (40)
234 (28) 293 (79) 383 (46) 310 (32) 273 (30) 297 (33) 352 (35)
*Values within a column with unlike superscripts at-e statistically different at the 0.05 level of significance.
consumption of grasses (Table 5B). The osmolality of caecum and colonic contests were near isotonic to plasma. Only the gerenuk demonstrated a significantly elevated osmolality of distal colon contents. Osmolaiity of the teticulo-rumen, small intestine and caecum contents showed an important relationship to body weight, being higher in lighter animals (Table 5C). Sodium ion concentrations within the reticulorumen of the 16 species of wild ruminants ranged from 55mEq/l (suni) to 122mEq/l (gerenuk) (Table 6A). Intermediate feeders had significantly (P < 0.05) lower reticula-rumen values than did browsers or grazers (Table 68). Body weight was not related to increased
reticula-rumen sodium ion concentrations; these were diminished within the abomasum of all species. However, small intestinal sodium levels were similar to that of the reticula-rumen. Concentrations generally decreased from small intestine to distal colon in all species. No apparent sodium effect was noted at any site for either major feeding group, sub-feeding group or weight group. Potassium ion concentrations within the reticulorumen varied almost four-fold for the species investigated (giraffe 34 mEq/l to dik-dik 126 mEq/l) (Table 7A). Significant regressions were noted for major and sub-feeding groups as well as weight groups (Tables 7B, C). Statistically significant re-
Table SC. Mean (+SEM) osmolality (mOsm) as observed at various sites along the gastrointestinal tract of the seven groups of wild ruminants Weight group
Reticula-rumen
Less than 20 kg 2@-50kg 51-100 kg 101-150 kg 151-200 kg 201-300 kg More than 300 kg
491* (24) 408 (23) 377 (26) 353 (44) 462 (67) 312 (29) 304 (28)
Abomasum 300 (22) 289 (32) 314 (23) 269 (4) 398 (55) 259 (10) 277 (25)
*Regression analysis (P < 0.004); Y = 486.&24.8X.
t(P < 0.001); Y = 658.9-35.8X. :(P < 0.04); Y = 377.1-10.6X.
Section of tract Small intestine Caecum 665t (32) 555 (27) 565 (67) 437 (8) 413 (19) 430 (55) 474 (46)
351$ (27) 343 (22) 2x7 (29) 317 (26) 361 (21) 215 (17) 298 (27)
Proximal colon
Distal colon
332 06) 332 (21) 362 (25) 277 (35) 332 (31) 281 (22) 325 (55)
824 (39) 298 (35) 361 (46) 309 (8) 320 (52) 300 (36) 266 (40)
East African
Table 6A. Mean (k SEM) sodium
Species Kirk’s
Dik-Dik
Suni Giraffe Gerenuk Eland Grant’s
Gazelle
Steenbok Impala Thomson’s African
Gazelle
Buffalo
Waterbuck Wildebeest Hartebeest Topi Mountain
Reedbuck
Oryx
Table 68.
Mean (_+SEM)
Food selection MAJOR Browsers
wild ruminants
327
ion concentration (mEq/l) as observed at various of sixteen species of wild ruminants
Reticula-rumen
Abomasum
91.3 (6.6) 55.5 (4.5) 95.8 (15.8) 121.5 (14.1) 56.1 (29.3) 77.2 (14.8) 76.5 (12.9) 57.4
50. I (7.2) 14.2 (0.6) 48.2 (6.9) 55.0 (9.8) 72.0 (22.0) 49.2 (8.4) 79.9
(7.6) 72.8 (13.4) 63.4 (6.6) 84.8 (14.4) 70.3 (4.0) 63.5 (10.9) 101.0 (22.5) 101.9 (5.8) 97.7 (10.8)
(8.0) 40.0 (7.7) 51.0 (19.0) 47.0 (3.0) 39.7 (8.4) 32.0 (8.7) 65.3 (4.4) 58.0 (4.6) 74.0 (2.6)
sodium
(;;:;)
Section Small intestine ___. 83.1 (5.2) 73.2 (21.2) 77.5 (7.5) 97.0 (13.9) 84.8 (23.1) 85.2 (14.0) 93.8 (10.2) 83.5 (10.1) 62.0 (8.1) 91.0
(1.0) 77.5 (21.5) 65.0 (29.0) 86.0 (21.7) 121.3
Caecum 77.4 (14.4) 24.4 (1.4) 44.8 (14.8) 90.4 (18.7) 40.6 (13.0) 73.5 (6.3) 38.8 (12.2) 60.2 (11.4) 55.9 (13.0) 48.6 (11.4) 64.7 (12.7) 19.8 (3.8) 51.0 (10.0) 81.0 (7.1) 37.4
(7.0) 74.0 (21.3)
(5.9) 85.2 (20.4)
ion concentration (mEq/l) as observed at various of the major and sub-feeding groups
Reticula-rumen
Abomasum
colon 63.9 (10.9) 24.2 (6.4) 32.6 (0.3) 93.3 (19.2) 28.2 (19.6) 55.5 (10.4) 25.2 (2.0) 36.7 (11.1) 58.1 (12.1) 23.4 (11.4) 30.6 (6.8) 30.7 (5.8) 53.1 (8.9) 67.4 (13.9) 28.2 (0.6) 69.6 (27.6)
sites along
Distal colon 21.9 (5.2) 12.4 (3.2) 19.4 (2.8) 30.7 (9.1) 25.0 (20.2) 32.1 (9.3) 30.7 (15.1) 29.7 (16.3) 17.6 (6.3) 14.0 (3.0) 24.1 (19.0) 55.6 (24.0) 16.2 (8.4) 49.0 (22. I) 17.5 (3.1) 27.4 (7.9)
the gastrointestinal
of tract Proximal colon
Distal colon
61.6 (10.6) 57.3 (5.5) 57.4 (7.4)
52.6 (9.0) 44.3 (7.8) 45.5 (7.6)
20.4 (3.0) 26.8 (5.2) 31.6
62.2 (14.1) 60.0 (I 7.4) 56.6 (8.0) 58.0 (8.1) 40.9 (8.8) 58.0 (9.0) 85.2 (20.4)
52.6 (10.6) 52.8 (20.8) 41.1 (8.2) 47.4 (8.6) 28.6 (3.9) 48.6 (9.1) 69.6 (27.6)
19.2
Caecum
GROUPS 88.1
43.0
Intermediate
(7.4) 68.4
$0:
Grazers
(6.1) 87.2
(5.7) 56.3
(5.6)
(3.9)
(5.6) 85.7 (6.5)
81.1
39.8
80.2
(8.1) 104.3 (12.5) 71.8 (9.1) 65.1 (7.7) 72.5
(8.3) 50.5
(5.3) 45.0
(5.1) 96.0 (10.3) 97.7 (10.8)
(5.6) 57.4 (5.1) 74.0 (2.6)
(6.1) 84.0 (7.8) 87.2 (8.3) 72.7 (7.2) 76.0 (6.5) 102.0 (8.1) 74.0 (21.3)
SUB GROUPS Fruit and dicotyleoon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
(4.5) 62.6 (9.2) 43.8
81.4 (4.7) 80.0
tract
of tract
(9.3) 88.0
Section Small intestine
sites along the gastrointestinal
(6.4)
(4.0) 23.2 (4.1) 30.0 (6.5) 23.6 (8.4) 34.7 (12.8) 30.8 (10.6) 27.4 (7.9)
tract
E. T. CLEMENS and G. M. 0.
328 Table 6C. Mean (+SE?4)
sodium
ion concentration (mEq/l) as observed at various of the seven weight groups of wild ruminants
Weight group Less than
Reticula-rumen RO.I (6.6) 89.8
20 kg
20-50 kg
(9.4) 61.3 (6.8) 101.0 (22.5) 90.9 (10.8) 76. I (6.2) 71.7 (I 1.7)
51~100 kg 101-150 kg 151~200 kg 20@300 kg More than
300 kg
gressions were also noted for feeding groups for all segments
potassium
Abomasum 48.7 (9.7) 48.6 (5.1) 48.5 (5.3) 65.3 (4.3) 65.6 (6.8) 42.6 (5.0) 57.1 (9.0)
and
major
of tract from reticulorumen to proximal colon (Table 7B). Furthermore, potassium ions were observed to decrease in concentration from caecum to distal colon in browsers and to increase in grazers. Reticula-rumen chloride values ranged from 6.0 mEq/l (hartebeest) to 24.2 mEq/l (Grant’s gazelle)
Table 7A. Mean (+SEM)
Kirk’s
Abomasum
Dik-Dik
126.4 (17.3) 125.8 (2.8) 34.4 (5.5) 45.9 (5.9) 47.8 (9.5) 65.4 (7.1) 97.6 (13.6) 62.8 (6.4) 78.6 (8.5) 63.4 (6.6) 58.2 (5.4) 39.8 (5.4) 42.3 (7.8) 37.2 (8.4) 46.9 (5.4) 39.4 (7.5)
17.3 (2.3) 101.0 (42.2) 27.2 (1.7) 24.0 (4.0) 34.2 (1.8) 40.9 (1.8) 54.2 (9.6) 38.8 (2.9) 44.2 (7.2) 30.5 (6.5) 54.0 (2.0) 53.6 (8.7) 60.0 (11.2) 36.0 (4.6) 37.7 (1.7) 26.1 (2.6)
Gerenuk Eland Grant’s
Gazelle
Steenbok Impala Thomson’s African
Gazelle
Buffalo
Waterbuck Wildebeest Hartebeest Topi Mountain
Reedbuck
Section Small intestine
sites along
the gastrointestinal
tract
of tract Caecum
83.2 (5.4) 76. I
57.0 (11.5) 53.2
(7.0) 84.4 (8.1) 121.3 (9.3) 76.4 (16.7) 70.0 (7.6) 84.4 (6.7)
(8.9) 66.9 (6.5) 81.0 (7.1) 78.4 (17.3) 37.8 (11.9) 44.7 (6.5)
Proximal colon
Distal colon
46.5 (9.1) 51.3 (9.8) 46. I (7.9) 67.4 (13.9) 66.3 (21.6) 30.7 (3.8) 28.0 (6.1)
21.7 (4.3) 19.2 (3.5) 30.9 (8.7) 49.0 (22.1) 25.2 (6.5) 43.0 (16.8) 19.5 (5.6)
(Table 8A), and were noted to decrease in concentration with the increase in body weight and grass consumption (Table 8C). There were no relationships between chloride ion and body weight or feeding group for the remaining segments of tract. Chloride ions were highest within the abomasum and diminished in concentration with subsequent distal segments of tract for all species (Table 8A).
ion concentration (mEq/l) as observed at various of sixteen species of wild ruminants
Reticula-rumen
Giraffe
Oryx
potassium
Species
Suni
MALOIY
Section Small intestine 91.9 (9.0) 52.7 (12.2) 33.2 (3.8) 31.0 (8.5) 73.8 (0.6) 26. I (3.6) 53.2 (7.0) 62.8 (8.6) 41.2 (7.3) 38.0 (2.0) 39.0 (3.0) 50.3 (3.1) 34.0 (4.8) 28.7 (2.4) 38.0 (4.0) 26.2 (8.9)
sites along the gastrointestinal
of tract Caecum
Proximal colon
Distal colon
120.6 (19.6) 46.4 (0.4) 90.0 (20.0) 15.1 (2.1) 97.2 (1.3) 33.0 (2.0) 65.2 (0.4) 78.7 (14.8) 64.8 (13.7) 75.3 (12.7) 44.8 (6.2) 81.9 (4.0) 60.8 (3.4) 45.4 (5.8) 66.6 (4.9) 41.1 (15.4)
107.4 (13.5) 37.5 (10.8) 94.4 (13.7) 51.5 (8.3) 100.3 (5.3) 34.0 (5.8) 52.2 (17.6) 75.8 (17.3) 66.4 (4.5) 67.4 (19.5) 69.8 (6.8) 80.3 (8.4) 72.0 (7.1) 45.5 (8.6) 66. I (4.9) 44.8 (14.9)
50.4 (7.0) 31.7 (7.2) 79.9 (15.3) 30.7 (6.4) 93.6 (21.0) 49.6 (11.7) 48.6 (4.8) 87.2 (15.3) 53.9 (7.1) 77.2 (19.6) 74.0 (12.4) 83.8 (14.5) 60.6 (9.3) 71.7 (19.8) 53.9 (15.5) 41.9 (5.7)
tract
East African wild ruminants
329
Table 7B. Mean (It SEM) potassium ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection
~ --~-. MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen
Abomasum
Section of tract Small intestine Caecum
Proximal colon
Distal colon _______-
99.8” (15.8) 69.9b (4.8) 42.4’ (3.0)
66.7” (I 1.7) 42.0” (2.4) 38.1h (3.4)
66.3” (10.0) 48.2” (5.0) 35.8 (2.7)
89.1” (15.8) 64.4”” (7.0) 5?.7b (5.3)
85.2” (I 1.8) 63.1ah (5.8) 61.2b t5.01
53.7 (6.7) 65.4 (6.9) 64.4 (5.9)
126.1 0;:;’
84.1 (10.3) 26. I (1.4) 42.6 (3.4) 41.4 (3.7) 47.1 (5.6) 35.8 (4.9) 26. I (2.6)
80.7 (9.9) 32.5 (2.3) 44.8 (7.8) 51.6 (6.5) 43.6 (2.8) 33.4 (2.5) 26.2 (8.9)
99.4 (19.3) 65.0 (27.5) 57. I
87.4 (16.1) 80. I (16.4) 55.1 (11.1) 71.1 (8.5) 73.6 (5.8) 58. I (5.7) 44.8 (14.9)
45.0 (6.2) 73.7 (10.8) 60.3 (9.9) 70.5 (10.0) 79.1 (7.7) 62.5 (10.1) 41.9 (5.71
(5.01 69.0 (8.1) 70.7 (5.81 44.6 (5.6) 42. I (4.2) 39.4 (7.5)
(10.1) 71.8 (9.7) 69.4 (7.4) 55.4 (5.4) 41.1 (15.4)
*Values within a column with unlike superscripts are statistically different at the 0.05 level of significance.
DISCU~ION
Twenty-six species of wild ruminants can be found in East Africa (Hofmann, 1973). The majority of
these species still abound and are dispersed throughout the diverse environmental habitat of Kenya. The arld range, mountainous, savanna, and tropical forest regions of this country support a variety of animal life. Wild ruminants inhabit each of these ecosystems. Hofmann (1973) has categorized these animals into three major feeding groups: concentrate selectors (browsers) which have a diet of high nutritive value, low fiber, and high protein content; bulk and roughage eaters (grazers) whose diet is largely grass, which is often of high fiber and low protein content; and
inte~ediate feeders whose diet consists of grasses and browse. He further subdivides the species into seven categories based according to their food preference within the major feeding groups. In the present study sixteen of the twenty-six species of wild ruminants were investigated. These animals represent members from all major and subfeeding groups. The immense diversity of weight range is also present within the sixteen species-from the tightest weight (suni and dik-dik) to the heaviest (giraffe, buffalo and eland). With the exception of the omasum, an analysis of the total gastrointestinal contents was conducted for each species. Composition of the contents at the six
Table 7C. Mean (*SEM) potassium ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group
-.Less than 20 kg 2g-50 kg 51-100 kg lol--1.50 kg 15I--200 kg 201-300kg More than 300 kg
Reticula-rumen _..119.8* (10.3) 62.6 (7.4) 64. I (4.4) 37.2 (8.4) 40.0 (5.8) 47.2 (5.6) 40.1 (11.6)
Abomasum IlSf (9.2) 39.2 (4.2) 39.8 (1.6) 26.0 (4.6) 32.9 (7.1) 53.8 (4.8) 30.6 (2.2)
*Regression analysis (P < 0.001); Y = 106.l-l I .3X. t(P < 0.002); Y = 63.8-5.0X $(P < 0.003), Y = 43.8 + 5.1X.
Section of tract Small intestine Caecum 74.6 (8.6) 38.7 (3.8) 44.1 (8.0) 28.7 (2.4) 27.8 (7.11 45.8 (3.4) 48.3 (8.2)
91.8 (15.5) 59.3 (9.1) 55.9 (11.1) 42.4 (5.%) 45.0 (12.6) 67.1 (9.5) 87.4 (7.3)
Proximal colon 19.6 (13.6) 64.4 (2.9) 54.9 (I 1.6) 45.5 (8.6) 50.3 (12.8) 76. I (5.3) 87.4 (9.0)
Distal colon 45.81 (4.8) 54.8 (6.0) 68.4 (11.4) 71.7 (19.%) 45.7 (5.8) 79.9 (9.2) 83.6 (9.0)
330
E. T. CLEMENSand G. M. 0. MALOIY
Table 8A. Mean (& SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of sixteen species of wild ruminants
Species Kirk’s Dik-Dik Suni
Reticula-rumen
Abomasum
19.5 (2.3) 15.0
128.6 (13.8) 84.0 (9.0) 98.7 (19.7) 152.0 (21.5) 88.2 (5.8) 151.5 (31.8) 110.2 (14.0) 62.6 (5.2) 13.5 (22.5) 117.0 (3.0) 116.1 (8.8) 116.0 (9.3) 123.3 (1.3) 96.7 (4.1) 119.2 (6.6)
(0.1) Giraffe
8.4
Gerenuk
12.2 (1.3) 7.6 (2.5) 10.0 (4.0) 13.4 (2.3) 13.1 (2.1) 7.6 (2.3) 19.5 (5.7) 10.7 (1.8) 6.0 (1.8) 10.9 (1.1) 10.0 (0.4) 10.3 (0.9)
(0.1) Eland Steenbok Impala Thomson’s Gazelle African Buffalo Waterbuck Wildebeest Hartebeest Topi Mountain Reedbuck Oryx
Section of tract Small Caecum intestine 41.9 (1.3) 52.8
(2.8) 61.2
(8.2) 48.3 (4.3) 39.2 (7.2) 46.8 (7.0) 66.2
(8.0) 41.3 (11.2) ‘75.0’ (34.0) 49.0 (1.0) 63.2 (10.9) 105.0 (27.3) 52.7 (4.9) 57.7 (10.4) 54.2 (19.1)
37.8 (2.4) 29.6 (0.8) 32.6 (7.2) 27.1 (3.1) 31.2 (8.1) 37.3 (4.6) 44.4 (3.3) 32.8 (5.6) 36.6 (5.4) 35.6 (3.4) 30.8 (0.9) 48.6 (5.2) 30.9 (1.6) 39.9 (2.4) 33.1 (4.2)
Proximal colon
Distal colon
34.6 (2.0) 17.8 (0.1) 31.8 (1.0) 9.0 (1.1) 36.2 (11.7) 31.2 (2.8) 38.4 (9.3) 39.9 (7.1) 30.9 (9.3) 21.4 (1.6) 37.5
23.9 (4.7) 17.0 (1.4) 28.4 (1.7) 9.0 (2.6) 32.9 (15.5) 29.2 (8.9) 33.8 (5.3) 19.5 (7.6) 27.2 (4.6) 24.2 (3.6) 32.0 (5.3) 12.1 (3.1) 37.3 (7.7) 27.2 (9.6) 5.9 (0.8)
(6.0) 36.0
(2.1) 35.0 (5.2) 45.1 (2.0) 27.2 (4.5)
Table 8B. Mean (k SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the major and sub-feeding groups Food selection MAJOR GROUPS* Browsers Intermediate Grazers SUB GROUPS Fruit and dicotyledon (Browsers) Trees and shrub (Browsers) Prefers browse (Intermediate) Prefers graze (Intermediate) Fresh grass (Grazers) Roughage (Grazers) Dry region (Grazers)
Reticula-rumen 15.7” (1.8) 12.7ab (1.5) 10.9s (1.0)
Abomasum 101.8 (14.0) 97.6 (11.1) 110.1 (4.6)
Section of tract Small intestine Caecum 59.0 (11.5) 52.2 (6.1) 60.7 (5.3)
34.0 (2.1) 37.1 (2.8) 35.0 (1.5)
Proximal colon
Distal colon
32.1 (3.0) 37.3 (3.9) 34.2 (2.3)
22.6 (2.7) 28.1 (4.0) 23.8 (3.3)
115.9 45.0 35.4 29.8 (12.7) (3.4) (2.3) (2.2) 9.6 118.8 61.5 30.7 37.3 (18.0) (1.3) (4.3) (4.5) (5.5) 11.9 119.8 43.0 34.2 33.7 (22.5) (3.5) (4.4) (4.2) (5.1) 13.2 86.4 56.8 38.6 39.2 (11.4) (1.4) (7.3) (3.7) (5.4) 12.3 104.2 62.8 33.8 32.7 (2.4) (9.9) (1.8) (3.5) (9.4) 9.8 110.8 62.3 37.3 39.7 (0.8) (5.4) (2.8) (8.4) (3.0) 10.3 119.2 54.2 33.1 27.1 (19.0) (0.9) (6.6) (4.2) (4.5) *Values within a column with unlike superscripts are statistically different at the 0.05 level of significance. 18.2
(1.8)
22.0 (3.5) 24.0 (4.5) 31.0 (7.4) 26.6 (5.1) 28.4 (2.7) 29.4 (5.8) 5.9 (0.8)
East African wild ruminants
331
Table 8C. Mean (+ SEM) chloride ion concentration (mEq/l) as observed at various sites along the gastrointestinal tract of the seven weight groups of wild ruminants Weight group Less than 20 kg 20-50 kg 51-100 kg 101-150 kg
-__
Reticula-rumen 16.4* (1.9) 11.8 (1.1) 15.5 (2.8) 10.9
(2.8) 151-200 kg
9.4
Abomasum 123.8 (12.8) 68.7 (10.3) 110.2 (14.0) 123.3 (1.3) 118.5
(1.1) 201-300 kg More than 300 kg
14.2 (3.0) 7.9 (0.9)
(5.2) 116.5 (4.9) 86.8 (9.1)
Section of tract Small intestine Caecum ._______ 45.4 35.8 (2.1) (1.9) 34,7 (E) (3.2) 66.2 44.4 (SO) (3.3) 52.7 30.9 (5.0) (1.6) 64.4 36.2 (I 7.9) (4.5) 57.6 32.7 (I.71 (6.9) 58.8 33.5 (13.4) (3.3)
Proximal colon
Distal colon
30.1 (2.6) 43. i (3.6) 38.4 (9.3) 35.0 (5.2) 28.9 (3.9) 33.4 (4. Li 33.0 (4.0)
23.6 (3.2) 21.9 (5.0) 33.8 (5.3) 37.3 (7.i) 7.2 (4.1) 28.8 (3.6) 29.5 (4.3)
*Regression analysis (P < 0.008); Y = 16.2-1.0X.
primary sites-the reticula-rumen, the abomasum, the small intestine, the caecum, the proximal, and the distal colon-is presented herein. Additional information concerning the electrolyte absorptionsecretion, partition VFA’s, etc. will be presented in subsequent publications. Analysis of gastrointestinal contents as a means of assessing nutritional and physjoio~cal functions of the digestive tract is an established and accepted procedure (Elsden et al., 1946; Alexander, 1965; Stevens et al., 1979). While limitations are inherent in the technique, such procedures may reveal valuable information, particularly when they are comparative. The forestomach of domestic and wiId ruminants has been the subject of several investigations. Researchers have suggested that both diet (Bath and Rook, 1963; Hoppe et al., 1977a) and size of the animal (Hungate et al., 1959; Hoppe, 1977; Maloiy et al., 1982) influence reticula-rumen fermentation rates. VFA concentrations noted in the present study support these earlier findings, since the VFA concentrations were observed to decrease with the increase in body weight and the increased consumption of grasses. In addition, the molar proportion of propionic acid and the acetate to propionate ratio suggest the occurrence of a more rapid fermentation rate, in accordance with the VFA concentration (unpublished data). However, the reticula-rumen lactic acid values were apparently not altered by the rate of fe~entation, as reported by other investigators. Assuming that both diet and body mass influence reticula-rumen fermentation rate, the question arises as to which factor exerts the more prominent effect. Present evidence suggests that body weight is most influential. Such evidence is derived from the test of higher significance for body weight compared to feeding groups, and from dn vitro fermentation data. For example, the giraffe and gerenuk are both browsers preferring trees and shrubs, yet they have a IO-fold difference in body weight. However, fermentation rates (pm01 gas NTDP/gDM/hr) were 587; more rapid in the smaller animal (Maloiy et ai., 1982). Similar examples are demonstrated with the intermediate feeders (eland and Grant’s gazelle)
(Hoppe et al., 1977b; Maloiy et al., 1982) and for the grazers (buffalo and wildebeest) (Hoppe et al., 1977a; Maloiy et af., 1982). Conversely, those animals of similar weight but different dietary habits (e.g. giraffe and buffalo) have comparable reticula-rumen fermentation rates (Maloiy et al., 1982). Within the pH range of reticula-rumen contents, most organic acids are dissociated and are subsequently osmotically active (Dobson, 1959). Therefore, the association between reticula-rumen osmolality and diet, or body weight, tends to reflect VFA concentrations. Potassium, rather than sodium, ion concentration appears to be the major cation influencing forestomach osmolality. Like osmolality and VFA concentration, potassium concentrations significantly decrease with an increased proportion of grass in the diet, and with an increase in body weight. However, in this instance, dietary effect appears to be a more prevalent factor than body weight. It follows that, in general, dicotyledons (browse) contain greater potassium levels than monocotyledon (grasses). Few investigators of ruminant physiology and nutrition consider the gastrointestinal tract beyond the point of reticula-rumen functions. Thus, the comparative data from the abomasum to the distal colon provides considerable new information. The abomasum of wild ruminants may contain as much as 8.8 kg of ingesta (giraffe) or as little as 0.1 kg (several species). The dry matter consistency of abomasal contents is generally depressed by 1-8 percentage units over that of reticula-rumen contents. Browsers, compared to inte~ediate feeders and grazers, show the least variation between gut segments. Body weight has no measurable relationship to abomasal dry matter. The organ is, however, a major site for electrolyte absorption-secretion and/or dilution. Thus, relative to reticula-rumen contents, abomasal composition is markedly different. VFA concentratjons within the glandular stomach are reduced by 70 to 9.5%. Lactic acid values were much less affected. Significant effects of diet and of body weight on these organic acids, on osmolality, and on chloride values, were not apparent within the abomasal con-
332
E. T. CLEMENS and G. M. 0. MALOII
Only potassium values within the organ appeared to have a carry-over effect from the reticulorumen. The small intestine of all mammals is the site of intensive digestion, absorption and secretion activities. The composition of small intestinal contents of these sixteen species of wild ruminants appears sensitive to diet and body weight. Small intestinal dry matter, osmolality. and potassium concentrations were each influenced significantly by diet and/or body weight, The drier intestinal consistency, hypertonicity and increased potassium concentrations suggest a greater intestinal fluid absorption within browsers and light animals than in their respective counterparts. The caecum-colon of herbivorous mammals represents the second major site of fermentative activity. A recent review (Hoover, 1978) describes the present knowledge of digestive processes within the hindgut of domestic ruminants. Minimal information is available on the hindgut of wild ruminants (Skadhauge et al., 1980; Maloiy et cd., 1982). While the reticulorumen area of browsers is relatively smaller than that of grazers (Hofmann, 1969; Hofmann and Stewart, 1972; Arman and Hopcraft, 1975) the reverse is true for the caecum and colon. From present data, it appears that browsers retain an average of 13. I”/; of the total ingesta within the large bowel compared to I 1.57; for grazers. Reticula-rumen contents were 74.6 and 77.5”: for browsers and grazers, respectively. It is also apparent that the caecum of browsers is the more voluminous segment of the large bowel, while the colon of grazers generally contains more ingesta. The volume of ingesta within the large intestine of domestic sheep has been shown to vary with diet (Grovum and Hecker, 1973). Similarly, hindgut fermentation rates of domestic ruminants respond to available substrate with increased microbial numbers, decreased pH and changing VFA ratios (Mrskov et al., 1970, 1971; Mann and 0rskov, 1973; Allison et al., 1975). However, in the present study, neither VFA concentrations nor acetate to propionate ratios within the hindgut of browsers and grazers were appreciably different (unpublished data). On the other hand, lactic acid values were significantly different for the feeding groups. The data does, however, clearly show the ability of each species to conserve colonic fluid, VFA and sodium, and to a lesser extent. potassium and chloride ions. Certain members within the sixteen species of wild ruminants deserve special consideration. The African buffalo is one such animal. It is unique among East African wild ruminants in that it is the only species which does not form a faecal pellet. The dry matter consistency of contents within the distal colon (15%) was significantly less than all other species investigated. Subsequently, the buffalo’s ability to conserve faecal water loss appears limited. Colonic drying of ingesta entering the large bowel (caecum to distal colon) was evident in all species except the buffalo. However, while a significantly greater proportion of fluids were lost in the faeces of the buffalo, less VFA and sodium ions were excreted per unit of fluid volume, even when these values were adjusted to a comparable dry matter consistency of other species. What appears most unusual is the high dry matter tents.
consistency of the buffalo’s reticula-rumen contents. The 17% dry matter is 2-6 percentage units greater than most wild ruminants. And even though the African buffalo depends on available drinking water (Sinclair, 1974; Field, 1976) these values are comparable only to those of arid range ruminants (i.e. gerenuk and oryx) which rely almost exclusively upon plants for their source of fluids (Hofmann, 1973). The unusually high dry reticula-rumen contents of the buffalo have been reported elsewhere (Maloiy et al., 1982). As mentioned earlier, the gerenuk and oryx inhabit the arid regions of East Africa. The gerenuk is a strict browser, while the oryx is a grazer (Hofmann, 1973). Like the buffalo, they exhibit an elevated reticulorumen percent dry matter, the oryx significantly so. On the other hand, the gerenuk demonstrates a significantly higher faecal dry matter. The data would suggest a greater ability of the gerenuk to conserve faecal water loss, and greater reticula-rumen recycling of these fluids relative to the oryx. The oryx also demonstrated a high reticula-rumen VFA concentration which did not fit well with the pattern of fermentation rate and diet or body size.
Acknow~ledgements-We are most grateful to Mr D. Sindiyo, Director, Department of Wildlife Conservation and Management, for permits and assistance in obtaining research specimens, and to Dr J. Sutton, National Institute for Research in Dairying, Reading, England, for VFA analysis, Mr S. Ngonga of the Nutrition Laboratory, University of Nairobi conducted the proximate analyses for which we are most grateful. The component technical assistance in the field and laboratory from Dr P. Hoppe. Dr V. Langman, Mr J. Gatihi and Mr J. Nturibi. The study was supported by research grants from the University of Nairobi, Dean’s Committee Research Funds. and from the Leverhulme Trust, London, England. Published with the approval of the Director, Nebraska Agricultural Experiment Station, Paper No. 7071, Journal Series,
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