Physiological responses of the adult male collared peccary, Tayassu tajacu (tayassuidae), to severe dietary restriction

Camp. Biochem. Physiol. Vol. 82A, No. 1, pp. 49-58, 1985

0300-9629/85 $3.00 + 0.00

cs 1985 Pergamon Press Ltd

Printedin Great Britain

PHYSIOLOGICAL RESPONSES COLLARED PECCARY, 2-A YASSU TO SEVERE DIETARY R. L. LOCHMILLER, E. C. HELLGREN, L. W. S. W.

Department

of Wildlife and Fisheries

J. SEAGER~

OF THE ADULT MALE TAJACU (TAYASSUIDAE), RESTRICTION

VARNER ,* L. W.

and W. E.

GREENE,? M.

S. AMOSS,~

GRANT

Sciences, Texas A & M University,

College Station,

TX 77843. USA

(Received 7 December 1984) Abstract-l. Metabolic and hormonal responses of eight adult male collared peccaries (Tayussu tujacu) to an ad libitum diet intake, or 25% of an ad libitum intake, were examined. Blood samples for hematological, serum-biochemical and hormonal profiles were collected at three week intervals during the nine week experiment starting 4 August 1983. 2. Males fed on the restricted diet lost an average of 26% of their body weight during the trial, compared to a slight weight gain for those fed ad libifum. 3. Characteristics of the red and white blood cell populations were not influenced by diet intake, with the exception of mean corpuscular volume, which was consistently lower amongst males fed on the restricted diet. 4. Restricted food intake resulted in significantly elevated serum values for urea nitrogen, urea nitrogen:creatinine, urea index, alpha globulin:beta globulin, gamma globulin, gamma globulin:albumin, nonesterified fatty acids, alkaline phosphatase and lactate dehydrogenase isozymes (LD, and LD,). 5. Restricted food intake resulted in significantly lowered serum values for total alpha globulin, alpha-l globulin, total beta globulin, beta-l globulin, beta-2 globulin, glucose, triglycerides, calcium, magnesium, sodium, chloride, copper and triiodothyronine. 6. Serum levels of creatinine, total protein, albumin, alpha-2 globulin, uric acid, total bilirubin, cholesterol, aspartate aminotransferase, alanine aminotransferase, gamma glutamyltransferase, lactate dehydrogenase, phosphorus, calcium:phosphorus, potassium, iron, zinc and thyroxine were unaffected by diet intake level. 7. Semen evaluation indicated spermatogenesis was not affected by dietary restriction despite reductions in scrotal circumference and ejaculate gel volume. Serum testosterone levels were significantly lower among males fed on the restricted diet after nine weeks. These data suggest male libido might be depressed during poor range conditions, while maintenance of spermatogenesis might permit them to take immediate advantage of improved range conditions. 8. Blood analysis of metabolic and hormonal function can provide useful information for predicting the adult male’s nutritional and reproductive condition.

unknown dysfunction (Low, 1970; Hellgren et al., 1985) may contribute to lowered herd recruitment. The physiological contribution of the male in regulating recruitment is presently speculative, but could involve endocrine-induced changes in libido or spermatogenesis. A quantitative means of assessing peccary nutritional status would be a valuable tool in harvest management. Currently, condition-assessment methodologies specific for the peccary are undeveloped. Sowls and Maurer (1983) suggested that body weight was probably a good condition indicator for peccaries. Our research supports this idea; however, body weight alone does not provide sufficient diagnostic information. For example, a suboptimal protein intake may have profound negative effects on herd recruitment (lowered reproduction), but given an adequate energy intake adult body weights may reflect little or no change. The objective of this study was to examine metabolic and reproductive responses of mature male peccaries to severe dietary restriction. Changes in various blood parameters were monitored through a nine-week trial to assess their usefulness as condition indicators. Hormone levels and semen characteristics were monitored to assess reproductive condition.

INTRODUCTION

Metabolic and reproductive physiology of the male collared peccary (r~yussu tuj,cu) is undoubtedly one of the least understood aspects of this species’ biology. Field studies have consistently shown strong relationships amongst vegetative quality and quantity, rainfall and peccary herd recruitment (Low, 1970; Bissonette, 1982; Sowls and Maurer, 1983). The mechanisms which are responsible for limiting herd recruitment during periods of prolonged nutritional stress (e.g. droughts) are not known. There has been some indication that postpartum mortality among nurslings due to abandonment, depressed milk yield, predation, or other unknown causes (Bissonette, 1982) and/or lowered conception rates due to depressed libido, ovulation, fertilization, or other

*Agricultural Research and Extension Center, Texas A & M University, Uvalde, TX 78801, U.S.A.; TDepartment of Animal Science, Texas A & M University, College Station, TX 77843, USA. iDepartment of Veterinary Physiology and Pharmacology, School of Veterinary Medicine, Texas A & M University, College Station, TX 77843, USA. c BP **‘IA-D

49

50

R. L. LKHMILLER et ai. MATERIALS AND METHODS

Eight sexually mature male collared peccaries were assigned randomly to one of two experimental diet treatments, beginning 4 August 1983. Animals were obtained from the wild along the southern Texas Rio Grande Plain and were housed singly in 2 m x 3 m outdoor covered pens. Daily feedings were made between 1800 and 1900hr CST. Ad lib-fed animals were provided with a weighed amount of pelleted ration containing 3500 kcal digestible energy/kg and 16”;, crude protein and the uneaten portion remaining after each day reweighed. The restricted diet was calculated as 25”, of the previous day’s mean ad lib. consumption (not corrected for body weight). There was no significant difference in body weight between treatment groups at the start of the experiment (Table 1). Morphologic measurements and blood samples were obtained from all animals every 21 days for nine weeks, until 7 October 1983. Sampling was done during the period 0700 and 1000 hr CST. Peccaries were immobilized with ketamine hydrochloride at a dosage of 20 mg/kg administered intramuscularly in the hindlimb by blow-gun syringe (Lochmillcr and Grant, 1983). Body weights were measured to nearest 0.1 kg using a portable dial scale. The following testicular measurements were made to the nearest I mm using vernier calipers; individual testicular length. and width and combined testicular width. Scrotal circumference was measured to the nearest 5 mm with a flexible cloth tape. Blood samples were taken from the anterior vena cava using vacuum tube assemblies (Lochmiller et ul., 1984a). A 7 ml tube containing sodium EDTA for hematologies and three IOml tubes for serum were collected from each animal and placed on ice.

Codguhtted blood was centrifuged for IS-20min at 3000 rpm at 4 C. Serum was stored at - 2wC until assayed. Hematologies were performed within 4 hr of collection. Red blood cell count (RBC). hematocrit (HCT), hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), white blood cell count (WRC) and differential white blood cell counts were determined as described by Lochmiller et of. (19850). Total plasma protein and fibrinogen concentration were determined using the method of Low et al. (1967). Serum samples were analyzed in a batch on a Technicon SMAC biochemical analyzer (Technicon Instruments Corp., Tarrytown. N.Y.) for concentrations of total protein, albumin. globulins, urea nitrogen, creatinine, total bilirubin, cholesterol, glucose, triglycerides, uric acid, alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), aspartate aminotransferase (AST), alanine aminotransferases (ALT). lactate dehydrogenase (LD), calcium, phosphorus. sodium. chloride and potassium, using reagent systems specified by the manufacturer (Lochmiller and Grant, 1984). The urea index was calculated as the ratio of the concentration of nitrogen (mgidl) to total serum protein (gidl). Serum concentrations of magnesium, iron, copper Table

and zinc were determined by atomic absorption spectrophotometry, using a Varion Techtron Model AA-6 instrument and procedures outlined by Eerndndez and Kahn (1971). Nonesterified fatty acids (NEFA) were determined enzymatically using a kit provided by Wako Chemicals USA, Inc. Serum proteins were separated by agarose gel electrophoresis using the procedure described by Lochmiller et al. (19856). Relative concentrations of albumin, alpha-l, alpha-2. beta-l, beta-2 and gamma globulin were determined by densitometry. Absolute concentrations of protein fractions were determined by multiplying relative concentration by total protein content of sera. LD isozymes were also separated by agarose gel electrophoresis using trisbarbiturate buffer at pH I I .3. Relative activity of each of the live LD isozymes was reported as a ratio to the total LD activity after densitometric scanning. The isozyme closest to the anode was called LD, and furthest from the anode LD,, as described by Kaldor (1983). The cardiac:liver ratio was calculated as LD, + LDJLD, + LD,. Total serum thyroxine (T4) and triiodothyronine (T3) concentrations were assayed by radioimmunoassay (RIA) using kits supplied by Nuclear-Medical Laboratories, Inc. Serum testosterone levels were assayed by RIA as described by Abraham ef al. (1971). Sensitivity of the assay was 3.25 pg and intrassay coefficient of variation was 9.0”$ Semen an&se.7 Semen was collected in a plastic measuring cup by electroejaculation after I. 6 and 9 weeks of dietary restriction, as described by Seager et ul. (1984). A drop of semen was placed on a prewarmed slide (37 ‘C) immediately after collection and a visual estimate of motility (“,:, motile sperm) and status (rate of progressive motility on a scale of O-5, 5 being optimal) was made. The ejaculate was then placed in a graduated centrifuge tube in a 37’C water bath and liquid and gel volume recorded. Sperm concentration was estimated following dilution using a hemacytometer and total sperm count was calculated by multiplying sperm concentration by liquid volume. A minimum of 200 sperm were examined for gross morphology.

Statistical

urudy~es

The general linear models procedure of the statistical analysis system was used in data analysis (Helwig and Council, 1979). Differences between dietary treatments and amongst samples were tested by a two-factor analysis of variance. Sources of variation in the statistical model were partitioned and tested as described by Warren et al, (1981). When diet treatment or sample main elfects were significant (P < 0.05), differences between specific means were tested using Duncan’s New Multiple Range test. RESULTS AND DISCUSSION

Body weight and feed consumption Ad lib.-fed adult males consumed from 322 533 g/animal/day during the experiment (Fig.

I. Body weight changes among adult

male collared peccaries during nine

weeks of ad libitum or restricted (25”/, ad libitum) feed intake Ad libitum

Initial body weight (kg) Three-week sample, N Weight (kg) Change in weight (kg) Six-week sample, N Weight (kg) Change in weight (kg) Nine-week sample, N Weight (kg) Change in- weight (kg)

Restricted

x

SE

x

SE

23.6 4 23.4 -0.11 4 24.0 + 0.41 4 24.8 + 1.28

2.2

27.4 4 24.4

1.3

2.1 0.12 1.9 0.31 2.0 0.30

- 3.02 3 23.2 -3.98 3 20.0 -7.18

1.3 0. I7 I.7 0.24 1.6 I .03

to I),

Diet restricted male peccary

51

WEEK OF EXPERIMENT

Fig. 1. Mean weekly consumption of a high energy-high protein pelleted ration by ad libitum- and 25% ad libitm-fed adult male collared peccaries.

largely dependent upon ambient temperatures (inverse relationship). Overall, the mean energy and protein intake of ad t&.-fed males was 137.6 kcal, digestible energy/kgo.75 body weight and 0.982 g N!kg’.” body weight per day, respectively. Mean digestible energy intake of ad [%.-fed animals was similar to estimated maintenance energy requirements for non-reproductive adults (148.5 kcal/ kg’.“/day) reported by Gallagher er al., (1984). At this level of intake the adult males were consuming about 20% more than maintenance nitrogen requirements (0.8 15 g N/kg’ “/day) reported by Brown (1983). Mineral composition of the experimental concentrate ration can be found in Gallagher et al. (1984). A 75% restriction of intake was chosen to approximate probable conditions during prolonged periods of drought in the southern Texas Rio Grande Plain. Work by Gallagher et al. (1984) showed that peccaries are affected by seasonal differences in diet quality. They reported that peccary consumption of a natural winter diet of prickly pear cactus amounted to only 32.2 kcal of digestible energy/kg’-” body weight, or 22$;/, of the intake of a concentrate diet. Protein intake was even more effected. Zervanos and Day (1977) used tritiated water turnover to estimate that a free-ranging peccary would have to consume 1.54 kg (wet weight) of cactus to meet daily water requirements. The energy obtained from this amount of cactus was 87 kcal/kg0-‘5. This amounts to only about 58% of maintenance energy requirements. The ability of the peccary gastrointestinal tract to assimilate abundant intakes of prickly pear cactus over prolonged periods remains questionable. Shiveley (1979) noted severe diarrhea in peccaries fed only prickly pear pads for longer than four days, apparently the result of high oxalic acid levels in cactus.

Sowls (1967) reported the need to administer Bvitamin supplements to peccaries fed prickly pear for prolonged periods. These results suggest that food intake may be well below maintenance needs when peccaries must rely on cactus as a principal food source during drought conditions. Thus, 25% of ad lib. consumption appeared to be an appropriate restriction. The severity of the restriction imposed during this study was reflected in body weight dynamics. Males subjected to a 25% ad lib. restriction lost an average of 7.18 + 1.03 (SE) kg, or 2604 of their original body weight during the nine-week trial (Table 1). In comparison, ad lib.-fed males gained an average of 1.28 + 0.30 (SE) kg of body weight over the same period. One male on the 25% ad fib. treatment died as a result of drug-induced hyperthermia following blood samphng after the third week of experiment; he had lost approximately 12”/, of his body weight during this period. Mean body weight after nine weeks of dietary restriction was 20.0 kg, close to the average weight of adult male peccaries wild-caught from southern Texas (20.2 f 0.9 (SE) kg) (Lochmiller et at., 198%).

Nine weeks of dietary restriction apparently was not sufficient to produce a substantial change in the hematological profile of adult male peccaries. RBC, HCT, Hb, MCH, MCHC, WBC and differential white blood cell counts showed no relationship to dietary intake (Table 2). Because of the relatively long lifespan of a red blood cell (Bush er al., 195.5), nutritional deficiencies over a short duration may not elicit a detectable clinical change in an animal. Only MCV of adult male peccaries responded to diet intake level, as indicated by a significant diet-sample

52

R. L.

LQCHMILLER

et al.

Table 2. Physiological and morphological parameters of all adult male collared peccaries combined not affected bv level of feed intake Parameter Blood characteristics Red blood cells Haematocrit Hemoglobin Mean corpuscular hemoglobin Mean corpuscular hemoglobin concentration White blood cells Neutrophils Lymphocytes Eosinophils Basophils Monocytes Total plasma protein Fibrinogen Plasma protein:fibrinogen Creatinine Total serum protein Albumin

Mean

x 106/mm’ % g/d1 Pg g% x I O’/mm’ % cells/mm’ % cells/mm’ % cells/mm’ % ce!ls/mm’ % cells/mm’ g/d1 mgidl

IU”i1 % IUjl % mgidl ratio mmol/l rgidl rgldl rgidl

6.44 36.6 12.6 19.7 34.5 12.5 54.8 6832 40.3 5037 2.0 243 1.3 167 1.4 185 8.0 341 23.5 1.6 7.9 41.5 3.28 4.0 0.32 0.12 0.10 70 16 21 2.4 1181 31.6 20.7 91 7.9 62 5.4 4.8 2.03 3.8 215 67 3.19

0.12 0.6 0.2 0.3 0.3 0.6 2.9 484 1 3.0 460 0.3 40 0.3 41 0.4 64 0.1 19 1.3 0.1 0.1 0.9 0.06 0.2 0.02 0.02 0.01 3 3 4 0.5 88 0.5 1.0 9 0.6 7 0.5 0.1 0.03 0.1 18 2 0.25

ml x 106/ml x 106 % % % o/ 10

1.3 354 719 49.5 28.3 7.2 64.4

1.1 173 786 15.8 15.2 6.9 15.2

ratio

Alpha-2 globulin Uric acid Total bilirubin Cholesterol Aspartate aminotransferase Alanine aminotransferase Gammma glutamyltransferase Lactate dehydrogenase LQ LD, LD, LQ Phosphorus Calcium:phosphorus Potassium Iron Zinc Thyroxine Semen characteristics Liquid volumes Sperm concentration Sperm count Motility Normal sperm Primary abnormalities Secondary abnormahtles

interaction. MCV was consistently lower and showed a greater serial decline among restricted males compared to ad lib.-fed adults during the trial. Total plasma protein and fibrinogen concentrations were unaffected by diet intake (Table 2). The plasma protein:fibrinogen ratio was higher among restricted males, but the difference was not significant. In a previous study, nonpregnant female peccaries receiving a 55% ad lib. diet experienced a 23% reduction in RBC after 84 days (Lochmiller et al., 1985b). HCT and Hb paralleled the changes in RBC in the above study. In another study, Lochmiller et al. (198%) observed significant seasonal variations in peccary hematology in southern Texas which coincided with changes in forage quality. Well-fed captives possessed higher RBC, HCT, Hb, MCH and MCHC values than did wild peccaries. Zervanos and Hadley (1973) also reported significant seasonal

SE

Unit

mgidl g/d1 % g/d1 % g/d1 mg/dl mgidl mg/dl IUjl w/1 lU/l IUjl $

differences in HCT of peccaries in Arizona. Swine research has suggested that protein and not energy intake, determines red blood cell population characteristics (Atminmo et al., 1974). Protein and nonprotein nitrogen Protein and carbohydrate deficiencies probably had a severe wasting effect on body protein reserves (Munro, 1964). Metabolic adjustments during protein-calorie malnutrition frequently are expressed in the serum proteins and nonprotein nitrogen constituents (Dimopoullos, 1970). Urea nitrogen levels decrease when inadequate amounts of protein are consumed, yet also are related inversely to dietary energy intake in deer (Kirkpatrick et al., 1975). In this study, concentration of urea nitrogen was strongly related to intake level, but the main effect was not significant (Table 3). There was no difference in the

&W

=

%I

Calcium (mg/dl) Magnesium (mg/dl) Sodium (mmol/l) Chloride (mmol/l) Copper olg/dl) Triiodothyronine (w/d0 Testosterone (pg/ml) Scrotal circumference (mm) Ejaculate gel volume

LW’J/I)

LW’J/k

(W/I) =

Alpha globulin: beta globulin, ratio Gamma globulin (X g/dl) Gamma globulin: albumin ratio Glucose (mg/dl) Triglyceride (mg/dl) NEFA (mEq/l) Alkaline ohosohatase

(x

Beta-2 globulin

(%. g/d11

Mean corpuscular volume (f I) Urea nitrogen (mgidlf urea nitrogen: creatinine, ratio Urea index, ratio Total alpha globulin (x g/d11 Alpha-l globulin (%. g/d0 Total beta globulin (%, gidl) Beta-l globulin

Parameter

Table 3. Physiological

0.3

149 10

730 184

0.09

41 2.0 63 0.2 0.02 I I IO 4.8

304 28.4 358 10.1 2.00 146 110 304 77.5

0.3

819 184

144 104 327 35.0

1.82

466 35.7 411 9.5

88 8.0 0.50 96

4 3.4 0.05 10

105 14.8 0.14 48

0.1

260 6

70 2.1 65 0.1 0.05 2 2 12 3.5

8 2.8 0.07 23

1.3 0.14 0.09

39.9 3.36 1.08

1.1 0.09 0.03

33.0 2.63 0.82

0.24 0.8 0.08 0.4 0.04 0.3 0.02 0.3 0.03 0.2 0.01 0.10

I .07 12.1 1.02 7.6 064 11.1 0.93 6.6 0.55 4.5 0.38 1.10

0.13 0.2 0.02 0.6 0.05 0.7 0.05 0.1 0.01 0.6 0.04 0.04

1.35 11.3 0.90 6.9 0.54 If.2 0.21 7.6 0.61 7.6 0.60 0.75

1.1

4.8

0.3

7.6

2.0

9.0

1.0

10.8

58.9

2.0

SE -_-_ 0.9

x

62.2

-

of adult

samoles Restricted

parameters

Three-week Ad libitum x SE

and mo~holo~ical

peccaries

0.3

557 181

318 28.6 338 10.0 I .99 146 Ill 309 66.2

113 16.2 0.08 46

28.6 2.25 0.67

1.47 11.5 0.90 7.8 0.61 15.8 1.24 7.8 0.61 8.0 0.63 0.73

8.2

11.5

57.6

0.3

71 9

1 12 10.4

I

43 1.4 45 0.1 0.04

7 2.9 0.02 8

2.8 0.24 0.11

0.07 0.6 0.05 0.2 0.01 0.7 0.06 0.3 0.06 0.5 0.64 0.03

0.4

0.6

2.4

0.2

558 180

533 37.6 421 9.3 1.81 140 100 293 25.0

0.1

182 9

121 2.0 89 0.2 0. 9 1 1 32 2.9

6 1.0 0.10 24

0.6 0.18 0.03

39.7 3.22 0.96 86 10.0 0.31 57

0.49 0.7 0.08 0.6 0.06 0.4 0.05 0.2 0.03 0.2 0.02 0.04

1.8

3.4

0.7

1.85 9.9 0.80 6.6 0.54 9.5 0.77 5.4 0.44 4.1 0.33 1.03

7.7

14.7

52.4

1.0

935 186

146 110 297 78.8

1.99

266 34.2 258 10.0

112 11.2 0.11 43

27.3 2.07 0.64

1.22 12.1 0.91 8.0 0.61 17.6 1.33 9.1 0.69 8.5 0.64 0.69

7.6

9.2

57.0

0.5

152 9

17 2.2 28 0.1 0.03 1 1 5 11.6

3 1.8 0.04 13

2.3 0.20 0.09

0.16 0.3 0.02 0.2 0.02 0.8 0.05 0.4 0.03 0.5 0.03 0.02

0.5

1.3

2.2

Nine-week Ad libitum SE X

as intIuenced by level and duration are presented

Six-week samules Ad libitum Restricted x SE x SE

male cc&red

restriction.

0.1

432 170

671 44.7 494 9.1 1.74 143 105 246 40.0

98 7.6 0.21 48

39.2 2.99 0.94

3.14 9.7 0.74 6.1 0.47 10.0 0.77 5.5 0.42 4.5 0.34 0.97

15.6

23.0

52.0

0.0

160 9

153 1.8 104 0.3 0.05 1 3 41 10.0

4 2.3 0.06 22

0.7 0.20 0.02

1.13 0.7 0.07 0.5 0.06 0.8 0.09 0.5 0.06 0.5 0.04 0.05

6.9

7.2

1.1

samoles Restricted X SE

of dietary

7.54

0.38 0.12

6.39 14.4 2.04 10.2 9.76 11.0 8.36 0.13 122.7

40.1 8.05 12.7 1.02

18.7 13.4 8.78

I .46 2.31 0.58 2.24 0.45 43.9 35.0 46.1 257 36.9 34.6 25.6

0.22

I.77

3.25

(0.03)

(0.001)

(0.02) (0.02) (0.021 (0.03j

(0.41) (0.01)

(0.001) (0.03) (0.01)

(0.005) (0.01) (0.02)

(0.001) (0.001) (0.001) (0.02)

(0.001)

(0.001) (0.001)

analysis

0.24

3.46 2.39

1.40 9.68 0.01 1.70 0.76 1.31 2.14 6.56 0.94

0.80 0.71 5.72 9.96

3.16 7.32 4.46

5.16 7.39 11.7 0.07 1.21 3.82 1.05 2.86 1.37 2.28 0.24 2.34

3.64

5.56

238.8

(0.02)

(0.005)

(0.02) (0.004)

(0.01) (0.04)

(0.05)

(0.01) (0.002)

(0.02)

(0.001)

0.95

7.06 12.9

3.60 0.13 7.17 0.51 0.52 1.40 4.09 4.21 0.03

0.46 0.15 3.55 6.72

1.47 0.38 0.01

7.69 16.8 13.4 6.81 5.76 7.43 5.23 7.57 5.37 1.94 2.02 0.61

3.89

9.09

(0.01) (0.001)

(0.05) (0.05)

(0.01)

(0.07) (0.01)

(0.01) (0.001) (0.001) (0.01) (0.02) (0.01) (0.003) (0.001) (0.03)

(0.05)

(0.006)

(0.008)

Interaction

(ANOVA)

8.09

of variance

ANOVA-F ratio (Pl Sample

of two-way

Diet

Results

also

Y

54

R. L.

LQCHMILLER

urea nitrogen concentration between ad fib. and restricted males in the three-week sample. However, restricted males showed a serial increase of urea nitrogen from 9.0 to 23.0 mg/dl between the threeand nine-week samples. Urea nitrogen levels of ad lib.-fed males remained unchanged among samples. This suggested a gradual depletion of lipid reserves, followed by an increasing need for alternate energy and gluconeogenic precursors such as tissue protein constituents. Lipid stores probably were exhausted by the nine-week sample. Nonpregnant female peccaries fed 550/, ad lib. for 84 days showed no significant difference from ad lib.-fed peccaries in urea nitrogen (Lochmill~r ei al., 39853). Creatinine levels were not affected by intake level (Table 2). Creatinine production has been shown to be related positively to the amount of skeletal muscle mass in an organism (Baum et al., 1975) and normally is not affected by protein intake (Woo et al., 1979). The urea nitrogen:creatinine ratio was related to diet as indicated by a significant diet-sample interaction (Table 3). Restricted males showed a near three-fold increase in the urea nitrogen:~reatinine ratio over the 3-9 week period. The urea index seemed to be more sensitive to intake than the urea nitrogen:creatinine ratio in this study. Total serum protein and albumin concentrations were not affected by intake levels (Table 2), although swine fed restricted protein diets generally show reductions in total serum protein concentration (Rippel et al., 1965) and albumin concentration (Pond and Houpt, 1978; Yen ei al., 1982). Total serum protein and albumin concentrations in nonpregnant female peccaries fed restricted rations were similarly unaffected (Lochmiller et al., 19856). Total alpha globulin (absolute and relative) concentration was related to intake, but the main effects were not significant (Table 3). Males fed on restricted rations showed a serial reduction in total alpha globulin level with increased duration of restriction. In comparison, ad lib.-fed males experienced serial increases in total alpha globulin. Differences were primarily the result of changes in the alpha-l globulin concentration (Table 3). Alpha-2 globulin concentration was unaffected by intake (Table 2). Elevated alpha globulin levels during periods of protein malnutrition have been reported for humans (Bjornesjo et al., 1966; Baptist et al., 1959), pregnant swine (Rippel et al., 1965) and growing swine (Tumbteson, 1972). Total beta globulin levels were influenced by diet intake (Table 3). Males on ad fib. rations had the greatest concentration of beta globulins. These differences were the result of higher beta- 1 and beta-2 globulin Levels in ad lib.-fed males (Table 3). The alpha globulin:beta globulin ratio was very sensitive to intake, being greatest for restricted males (Table 3). Yen et al. (1982) have shown serum transferrin, the major component of beta-l globulin, to be a reliable predictor of protein status in swine. Hypotransferrinemia is often associated with protein malnutrition, primarily as a result of reduced liver synthesis (McFarIane et al., 1970). Transferrin is also thought to serve an important function in bacteriostasis, where individuals with reduced levels have difficulty fighting bacterial infections (Ritchie, 1979).

et al.

Gamma globulin levels were also related to dietary intake (Table 3). Restricted males possessed elevated gamma globulin concentrations in comparison to ad lib.-fed males. This was reflected in the gamma globulin:albumin ratio. As was observed in this study, hypergammaglobulinemia often occurs during malnutrition in swine (Beatz and Mengeling, 1971; Tumbleson, 1972). Serum glucose, uric acid, bi~~rubi~ and lipids Serum glucose concentration was strongly related to intake (Table 3), while concentrations of uric acid and total bilirubin were unaffected (Table 2). Despite extensive catabolism of lipid and protein tissues for carbohydrate intermediates and energy, restricted male peccaries were unable to maintain a glycemia at a level comparable to ad lib.-fed males. Serum glucose levels were consistently greater among ad lib.-fed males, than restricted males, ranging from 14 to 31% greater. A similar glucose response was observed among nonpregnant female peccaries subjected to a 55% ad lib. intake (Lochmiller et al., 19856). Swine have the ability to maintain serum glucose at normal levels during fasting (Baetz and Mengeling, 1971; Grandhi and Strain, 1982; Doornenbal et al., 1983), or when fed low protein diets (Tumbleson, 1972; Atinmo et al., 1974). Lipolytic activity was very high in restricted males because of the dietary calorie deficit, particularly in the first three-week sample. Serum triglyceride levels were consistently higher in ad lib.-fed males, ranging from 47 to 85% higher than respective levels of restricted males (Table 3). Serum NEFA levels also were related to intake and showed variation among samples (Table 3). NEFA levels of restricted males were consistently higher than males fed ad lib. Levels of NEFA in restricted males were highest in the three-week sample and decreased serially thereafter. In contrast to triglyceride and NEFA, serum cholesterol levels were unaffected by diet (Table 2). Since NEFA production in adipose tissue controls the serum NEFA concentraton (Mayes, 1983), the progressive decline in NEFA levels among restricted males suggests a depletion of fat stores. Serum triglycerides showed trends inverse to those for serum NEFA in response to dietary restriction. Reductions in fat absorption, reesterification of fatty acids and increased lipolysis of triglycerides for NEFA probably contributed to lowered levels of triglycerides in serum (Mayes, 1983). Concomitant to the drop in NEFA levels was a significant increase in urea nitrogen, indicating a metabolic switch from fat to tissue proteins for energy. Nonpregnant female peccaries restricted to 55% of ad lib. intake also had elevated levels of NEFA (Lochmiller et ai., 1985b). However, these restricted females showed no decrease in serum triglyceride levels. Serum enzymes

Aithough enzymes are often useful in the diagnostic assessment of liver function and muscle-wasting diseases, they do not appear to be reliable indicators of protein-energy status in the peccary. Alkaline phosphatase concentration was the only enzyme showing a relationship to dietary intake (Table 3). The mean ALP level of restricted males was double

Diet restricted male peccary

55

the level in ad. lib.-fed males at three weeks. Thereafter, levels of ALP decreased serially among restricted males to levels comparable with males fed ad kb. The ad lib.-fed group showed no variation in ALP concentration among samples. Concentrations of LD, AST, ALT and GGT were unaffected by intake (Table 2). In swine, Platt et al. (1964) stated that ALP level may be reduced or elevated in cases of either protein or energy restriction. Baetz and Mengeling (1971) noted that short-term fasting decreased ALP levels in swine. While adult male AST concentration was unaffected by dietary restriction, nonpregnant female peccaries showed a significant increase when restricted diets were fed (Lochmiller et al., 19853). Although total LD activity showed no relationship to intake level, the isoenzyme profile did reflect some diet differences. Males receiving restricted rations had elevated LD, (absolute and relative) concentrations (Table 3). Absolute LD2 concentration was also related to diet, but the main effect was not significant (Table 3). The isoenzymes LD,, LD, and LD, were not affected by intake level (Table 2).

thyroid activity probably provides a mechanism for sparing catabolism of lipid and protein stores for energy (Ganong, 1979). The hypothyroid state is usually regarded as a reduced metabolic state. Reduced peripheral monodeiodination of T4 in fasted animals contributes to the reduced metabolic state, as well as by lowering circulating T3 (Ingbar and Galton, 1975). Similar metabolic adaptations in the male peccary fed restricted intakes were probably operable, which may have accounted for the reductions in T3. Results from the present study differed from observations made on nonpregnant female peccaries fed restricted diets (Lochmiller et al., 19856). T4 levels were significantly lower among females given restricted diets than ad lib. diets. Although T3 levels were also lower, the differences due to the level of food intake was not significant amongst the females. These contradictions between sexes may be the result of differences in levels of restriction imposed, or possibly due to dimorphisms in the mechanisms or routes of metabolic adaptation.

Serum minerals

Seminal traits (liquid volume, total volume, sperm concentration, sperm count, motility and abnormalities) did not differ with intake (Table 2) with the exception of gel volume (Table 3) which was greater in ad lib.-fed males. Percent motile sperm was greater in the ad lib.-fed males, however, this difference was not significant (Table 2). Semen samples collected 26 days after termination of the trial also revealed no differences in seminal traits between diet groups. Serum testosterone concentration and scrotal circumference were related to intake as indicated by a diet-sample interaction (Table 3). Both parameters were higher in the ad lib.-fed males than in the restricted group at nine weeks. The acute decrease in serum testosterone concentraton and scrotal circumference in restricted males between six and nine weeks of the trial indicates a reduction in testicular function. Similar responses have been observed in underfed rats (Grewal et al., 1971; Howland, 1975) and bulls (Gauthier and Berbigier, 1982). Low circulating testosterone levels may impair libido and breeding ability. The significant reduction in gel volume is consistent with reductions in accessory gland weights seen in underfed rats (Howland, 1975) and with reductions in semen volume in restricted pigs (Stevermer et al., 1961). Maintenance of accessory gland function is under androgen control (Sorenson, 1979). Merson et al. (1983) and Blank and Desjardins (1984) reported decreases in testicular sperm in whitefooted mice (Peryomyscus leucopus) and deer mice (P. maniculatus), respectively, following mild food restriction (70% ad lib.). Blank and Desjardins (1984) hypothesize that any interpretations of the effect of food intake on male reproductive performance should incorporate the life-history strategy of the species as well. Their evidence suggests that food availability alone can act to curtail male reproduction in some seasonally breeding species. On the other hand, it would be adaptive for the male collared peccary to maintain spermatogenesis under poor range conditions in order to take advantage of rapid onset of favorable conditions following rainfall. It

Concentrations of calcium, magnesium, sodium, chloride and copper were influenced by intake (Table 3). Ad lib.-fed males had consistently higher levels of serum calcium, magnesium, sodium and chloride, than restricted males. Copper was the only trace element related to diet, as indicated by a significant diet-sample interaction. Restricted males showed a 25% reduction in serum copper levels between the three- and nine-week samples. Copper levels of ad lib.-fed males remained constant during the experiment. Concentrations of phosphorus, potassium, zinc and iron showed no relationship to intake (Table 2). It is not possible to differentiate among protein, energy or mineral intake effects since restricted animals were not fed ad lib. The lower levels of calcium, magnesium and copper among restricted males were probably a reflection of decreased consumption of these minerals and possibly intestinal malabsorption. The low sodium and chloride concentrations were probably due to low salt intake. Dehydrated collared peccaries have elevated levels of sodium, chloride and potassium (Zervanos and Hadley, 1973). The low calcium levels of restricted males were similar to levels observed among adult wild peccaries (Lochmiller and Grant, 1984). High concentrations of oxalic acid in prickly pear cactus may cause deficiencies in calcium in the peccary when consumed in large quantities due to the formation of insoluble calcium oxalates. It is not known if the low mineral levels observed among restricted males are pathological. Evidence suggests that decreased immunity and increased susceptibility to infection may result from mineral deficiencies during malnutrition (Chandra and Dayton, 1982). Thyroid Status Thyroid status was assessed in adult male peccaries from measurements of T3 and T4 levels. Concentration of T3 was strongly related to diet intake (Table 3). Ad lib.-fed males consistently had T3 levels nearly twice that of restricted males. In contrast, T4 was not influenced by intake (Table 2). Depressed

Steroid hormones and semen characteristics

R. L. LOCHMILL~ et al.

56

should be noted that the semen sampling undertaken may have been too infrequent to detect depressed spermatogenesis that the ejaculates collected represented stored reserves.

CONCLUSIONS Severe restrictions of food intake have dramatic effects on the metabolic and hormonal physiology of the adult male collared peccary. Although the nutritional quality of food presented was high, animals on the 25% of ad lib. intake did not satisfy daily metabolic needs for protein and energy. Thus, metabolic adaptations resulting from imposed dietary reof quantitative strictions were a consequence deficiencies and not quality of feed. Total alpha globulin, beta- 1 globulin, gamma globulin, urea nitrogen, urea nitrogen:creatinine and the urea index showed potential as useful indices for assessing protein deficiences in the male peccary. Glucose appears to offer a good index of carbohydrate metabolism. Lipid metabolism was best assessed from serum levels of triglycerides and NEFA, whereas calcium and magnesium levels of serum appeared to offer a good index of mineral dynamics. T3 levels suggested a change in thyroid status, hence metabolic rate in the adult male. The evaluation of a particular metabolite or hormone will probably not enable the biologist to assess a peccary’s nutritional condition adequately. A broad assessment of protein, lipid, carbohydrate, mineral and thyroid metabolism and interrelationships among them will surely provide a more accurate diagnostic approach. From this study, it is suggested that condition assessments using blood profiles of adult male peccaries include the following measurements (ranked in decreasing priority): beta-l globulin, beta-2 globulin, glucose. T3, gamma globulin, alpha globulin:beta globulin ratio, NEFA, urea nitrogen, calcium and magnesium concentrations. Acute reductions in serum testosterone concentrations and maintenance of spermatogenesis characterizes malnutrition in the collared peccary. Droughtinduced nutritional stress could lead to reductions in male breeding activity. which probably mirrors female anestrus (Lochmiller, 1984).

Acknowledgements-This research was supported by the National Rifle Assoc. of Am. and the Caesar Kleberg Prog. in Wildl. Ecol.. Dept. of Wildl. and Fish. Sci., Texas A & M Univ. We thank the personnel of the Chaparrosa Ranch, La Pryor, Texas and the Chaparral Wildl. Manage. Area> Artesia Wells, Texas for providing the research animals. We gratefully acknowledge the assistance of P. J. Ettestad, S. J. Magyar, K. P. Coscarelli, T. G. Biediger and R. E. Hoekstra with animal handling and semen collection and L.A. Rund with hormone assays.

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