Dietary Fiber and Early Weaning on Growth and Rumen Development of Calves1

Dietary Fiber and Early Weaning on Growth and Rumen Development

o f Calves 1 R. D. KLEIN, R. L. KINCAID, A. S. HODGSON, J. H. HARRISON, J. K, HILLERS, and J. D. CRONRATH Department of Animal Sciences Washington State University Pu{Iman 99164-6320

ABSTRACT

Holstein calves were assigned to treatments of 1) pelleted prestarter (22% protein and 12% fat) and starter containing 10% alfalfa; 2) prestarter and starter containing 20% alfalfa; 3) no prestarter and starter containing 10% alfalfa; and 4) no prestarter and starter containing 20% alfalfa. Calves assigned to treatments 1 and 2 were fed 3.64 kg milk/d for 2 wk and calves assigned to treatments 3 and 4 were fed 3.64 kg milk/d for 3 wk and 1.82 kg milk/d for wk 4. Calves on treatments 2 and 3 were heavier at 10 wk but body weights and heights were similar by 6 mo. Rumen fluid and plasma measures were similar among treatments. Bull calves were assigned to treatments 1 and 3 and necropsied at 3 or 6 wk. Dry feed intakes to 3 wk and volatile fatty acid concentrations were greater for calves on treatment 1 than those on treatment 3. Wet weights of the empty reticulorumens were greater for calves on treatment 1 than those on treatment 3. Papillary development was not affected by weaning system. Calves weaned at 17 d and fed a prestarter have earlier rumen development than calves fed no prestarter and weaned later. INTRODUCTION

The early weaning of dairy calves holds several advantages over the prolonged feeding of milk or milk replacers. Among these are i)

Received March 5, 1987. Accepted June 5, 1987. 1Scientific Paper Number 7696. College of Agriculture and Home Economics Research Center, Washington State University, Pullman. Project Number 0434.

1987 J Dairy Sci 70:2095-2104

labor involved in rearing calves after weaning is reduced; 2) feeds commonly used after weaning are cheaper than milk or milk replacers; and 3) calves that have been weaned have fewer digestive disorders (11, 21, 25, 27). After weaning, the calves depend on dry feeds for nourishment. Therefore, before calves may be weaned successfully they must be consuming adequate amounts of dry feed and have sufficient tureen development to utilize feed efficiently. Calves weaned before these criteria are met demonstrate poor performance and depressed weight gains (9, 14, 25). Because rumen development occurs primarily in response to the presence and subsequent fermentation of feed in the rumen, and because most milk bypasses the rumen, early consumption of dry feed is essential for successful early weaning (8, 10, 25, 26, 28). To facilitate early consumption of dry feed, prestarters have been developed. The prestarter is highly palatable and highly digestible, and therefore, better able to supply nutrients to young calves than standard starter rations. Using a prestarter, a weaning system has been developed whereby calves can be weaned from milk at 2 wk of age (18). In early weaning systems, calves are usually given access to a complete calf starter. The amount of roughage necessary in the starter is unclear. Too little roughage causes reduced rumen development and weight gains (3, 6, 8, 12, 15, 17, 20, 24). However, too much roughage in starters also reduces weight gains (3, 17). The first objective of this research was to study the growth, performance, and rumen development of calves weaned at 2 wk of age and fed a prestarter compared with calves weaned at 4 wk of age without a prestarter. The second objective was to compare the effects on growth of feeding either 10 or 20% roughage in the calf starter.

2095

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KLEIN ET AL. MATERIALS AND METHODS

TABLE 1. Composition of starter rations.

Experiment 1

A trial was c o n d u c t e d with 40 Holstein heifer calves f r o m the Washington State University research herd. A c o m p l e t e l y r a n d o m i z e d design with a 2 × 2 factorial arrangement of t r e a t m e n t s was e m p l o y e d to compare the effects of two early weaning systems and t w o c o m p l e t e calf starters containing different roughage amounts. T r e a t m e n t s consisted of feeding: 1) a pelleted prestarter (.23 kg/d) and a starter containing 10% alfalfa meal; 2) a pelleted prestarter (.23 kg/d) and a starter containing 20% alfalfa meal; 3) no prestarter and a starter containing 10% alfalfa meal; and 4) no prestarter and a starter containing 20% alfalfa meal. The prestarter 2 was c o m p o s e d primarily o f milk p r o d u c t s and was f o r m u l a t e d to contain a p p r o x i m a t e l y 22% CP, 12% crude fat, and 0% A D F . A more c o m p l e t e description is given in A n d e r s o n et al. (2). Calves were trained to eat the prestarter. We initially put a small a m o u n t of it in the milk buckets near the end o f each milk feeding. Thereafter, prestarter was placed on top of the starter. Calves were consuming all prestarter by 2 to 3 wk. C o m p o sition of starters is in Table 1. Both starters c o n t a i n e d 16% CP; A D F was 14 and 18%, respectively. All calves were bucket-fed whole milk. Calves assigned to t r e a t m e n t s 1 and 2 were fed 3.64 kg/d whole milk until 17 d of age and t h e n weaned abruptly (weaning system 1). Calves assigned to t r e a t m e n t s 3 and 4 were fed 3.64 kg/d whole milk until 21 d of age then were fed 1.82 kg/d milk until weaning at 28 d of age (weaning system 2). Calves were assigned to t r e a t m e n t s w h e n r e m o v e d f r o m their dams at 3 d of age. Calves were housed in a well-ventilated barn and k e p t in individual pens b e d d e d with w o o d shavings. Water was supplied ad libitum. All calves were weighed weekly and f e e d intake was recorded daily until 12 wk of age. F e e d intake, average daily gain, and feed efficiency were calculated for each 2-wk period. Calf age periods were 2 to 4, 4 to 6, 6 to 8, and 8 to 10 wk of age. R u m e n fluid and b l o o d

2 Merrick Foods, Inc., P.O. Box 99, Union Center, Wl 53962. Journal of Dairy Science Vol. 70, No. 10, 1987

Alfalfa starter Item

10%

20% (%)

Barley Alfalfa pellets Soybean meal Molasses Trace-mineralized salt I Limestone Vitamin A premix z Vitamin D premix 3 Selenium premix 4 Cellulose gum

70.525 10.000 13.000 5.000 .500 .800 .050 .025 .050 .050

63.825 20.000 10.000 5.000 .500 .500 .050 .025 .050 .050

1Consisted of 96 to 98% sodium chloride, .2% manganese, .35% zinc, .20% iron, .15% magnesium, .03% copper, .007% iodine, and .005% cobalt. 2 Vitamin A, 6000 IU/g. 3Vitamin D, 8810 IU/g. 4Premix contained .02% selenium as sodium selenite, 99.98% sodium chloride.

samples were taken 90 min postfeeding at 2, 3, 4, 6, and 8 wk of age. R u m e n fluid was obtained by s t o m a c h tube, diluted 10:2 with .1 M m e t a p h o s p h o r i c acid, and frozen. A f t e r centrifugation the r u m e n fluid was analyzed for V F A c o n c e n t r a t i o n by gas c h r o m a t o g r a p h y (4). Blood samples were collected f r o m the jugular vein in heparinized containers. Hematocrits were d e t e r m i n e d and the remaining blood sample was centrifuged for plasma. Plasma glucose (23) and plasma urea nitrogen (5) were analyzed on samples that had been frozen. A t 12 wk of age calves were m o v e d to group pens of three calves and fed alfalfa hay free choice and 2 kg/d of a barley-based supplement. Height and weight m e a s u r e m e n t s were taken at 6 m o o f age. Experiment 2

A trial was c o n d u c t e d in the milder climate of Buckley, WA using 32 Holstein heifer calves f r o m the Washington State University Forage Research C e n t e r dairy herd. The trial was similar to t h a t in E x p e r i m e n t 1 except it was c o n d u c t e d primarily in spring instead of winter and the t r e a t m e n t period was 10 w k instead of 12 wk.

RUMEN DEVELOPMENT IN CALVES Experiment 3

A completely randomized design with a 2 × 2 factorial arrangement of treatments was used in an experiment conducted to determine the effects of two early weaning systems and age on the rumen development of dairy calves. The trial involved 16 bull calves that were assigned to treatments at 3 d of age. The calves were either 1) fed a prestarter with a starter and weaned at 17 d of age or 2) fed only the starter and weaned at 28 d of age. Milk was fed as described for Experiment 1 and the starter was the 10% alfalfa meal starter from Experiments 1 and 2. F o u r calves from each group were necropsied at 3 wk and four from each group were necropsied at 6 wk of age. Necropsies were performed between 7000 and 1000 h. Calves were weighed prior to transport to the necropsy site. Jugular blood samples were taken for plasma glucose and urea nitrogen determinations and calves were injected with a euthanasia solution and exsanguinated. An incision was made along the linea alba, through the abdominal wall, and as far as was possible, through the sternum. The gastrointestinal (GI) tract was ligated at the caudal ends of the esophagus and the rectum and the entire GI tract was removed. The individual organs of the GI tract were Iigated to prevent movement of digesta, and the weight of the entire tract was recorded. The reticulorumen, omasum, abomasum, small intestine, and large intestine were separated and weighed individually with their contents. A rumen fluid sample was taken from the reticulorumen for VFA analysis. Each organ was emptied of contents, rinsed repeatedly with water until dean, drained of excess water, and reweighed. The weight of the contents of each organ was calculated as the difference of the full compartment weight and empty tissue weight. Tissue samples, about 4 cm 2 in size, were taken from the reticulorumen for papillary measurements. One tissue sample was taken from the ventral sac approximately 3 to 5 cm caudal to the reticulorumen pillar. A second sample was taken from the most caudal point of the dorsal blind sac. The samples were immediately placed in a 30% formalin solution and stored in glass jars until measurements were made. For papillary measurements, two 1-cm 2 pieces of tissue were cut from a random site on the main tissue

2097

sample. Each piece was then cut into four equal slices. The slices were counted for papillae density under a 20× dissecting microscope. Two randomly selected papillae from each slice were measured for length and width. The total number of papillae for the two 1-cm 2 sections was averaged and recorded as the mean number of papillae per square centimeter. The average length and width of papillae also were recorded. Data were analyzed using analysis of variance [GLM procedure (22)]. The model used to analyze the data from Experiments 1 and 2 included the effects of location, calf age period, weaning system, and alfalfa amount and their two-way interactions. The model used to analyze data from Experiment 3 included weaning system and age at necropsy and their interaction.

RESULTS A N D DISCUSSION Experiments 1 and 2

Data from Experiments 1 and 2 were combined and analyzed together. Treatment means for dry feed intake, average daily gain (ADG), and feed efficiency are shown in Table 2. There was a significant interaction between weaning system and alfalfa amount in the starter with regard to feed intake. Calves receiving the prestarter consumed more total dry feed when fed 20% alfalfa meal in their starter, whereas calves not fed the prestarter ate more when they were fed the starter containing 10% alfalfa meal. An interaction also was present between calf age period and weaning system on feed intake. Calves fed the prestarter and weaned at 17 d initially ate more dry feed, but by 8 to 10 wk they were consuming less than calves fed no prestarter and weaned at 28 d (Figure 1). The increased consumption of dry feed in the earlier weaned calves was probably due to the presence of the prestarter and the early removal of whole milk from calves' diets (18). An interaction between weaning system and starter alfalfa amount was found for 10-wk body weights (LBW) (Table 2). Of the calves receiving prestarter and weaned at 17 d, those fed the 20% alfalfa meal starter weighed more at 10 wk. Among those calves that did not receive the prestarter and were weaned at 28 d,

Journal of Dairy Science Vol. 70, No. 10, 1987

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KLEIN ET AL.

2.6f

2.5 2.4

2.3! A

>,

"0 c~ v

¢l 4" _c "0 (I) U.

2.2 2.1 2.0 1.9 1.8 1.7' 1.6 1.5 1.4 1.3 1.2 1.1 1.0 .9 .8 .7 .6 .5 0

•

0

i 2-4

Weaning System 2

I 4-6 Age

I 6-8

8-10

(weeks)

Figure 1. In teractio n of age and weaning system on dry feed intake of calves from 2 to I 0 w k of age (Experiments I and 2).

TABLE 2. Effect of age at weaning and level of alfalfa in the starter ration on measures of performance of calves ( E x p e r i m e n t s 1 and 2). 1 Weaning system 1 ~

Weaning system 23

Variable

10% Alfalfa in starter

20% Alfalfa in starter

10% Alfalfa in starter

20% Alfalfa in starter

Pooled SD

Feed intake, 4,s k g/d Average daily s gain, kg Feed:gain s'6 lO-week LBW, 4 kg 6-too LBW, kg 6-mo height, cm Plasma glucose, a mg/dl Plasma urea nitrogen,* mg/dl

1.62 .57 3.61 74.10 167.10 103.40 63.20 10.50

1.74 .57 3.84 77.20 171.50 103.30 67.10 9.90

1.74 .65 2.60 82.20 170.20 103.70 70.30 10.30

1.56 .56 3.21 75.60 167.40 101.70 67.60 10.00

.22 .20 2.52 9.55 22.2 3.37 13.13 3.63

1 Observations: n = 280. 2Calves fed prestarter until 4 wk old and weaned at 17 d o f age. 3 Calves not fed prestarter and weaned at 28 d of age. a Designates a significant interaction among treatments (P<.05). SMeasured from 3 to 10 wk of age. 6 Observations: n = 268. If the gain was less than O, the d a t u m was o m i t t e d . Journal o f Dairy Science Vol. 70, No. 10, 1987

RUMEN DEVELOPMENT IN CALVES those fed the 10% alfalfa meal weighed more at 10 wk. No significant differences were found among treatments for average daily gain or feed 'efficiency nor was any interaction found between weaning system or alfalfa amount. Dry feed intakes and average daily gain had a significant quadratic relationship with age similar to that reported previously (1, 9, 13, 17). There were no significant effects of the treatments on 6-too body weights or heights. The interaction of weaning system and roughage amount observed in LBW at 10 wk did not exist at 6 mo of age. Additional roughage in the calf starter did not appear to depress 6-mo LBW, as would be expected if gains to 10 wk of age had been due primarily to increased rumen fill (3, 17). There was no significant effect of treatment on plasma glucose or plasma urea nitrogen (Table 2). There was a significant calf age by weaning system interaction for total VFA

2099

(Figure 2). Calves reared with weaning system 1 had a more rapid rise in total VFA than with system 2. Increased ruminal VFA in early weaned calves have been recently reported (2). This is consistent with their conclusion of higher ruminal microbial activity in calves on an early weaning program (2). Calves reared at Buckley had greater dry feed intakes and average daily gains than calves reared in Pullman (Table 3). Similar findings have been reported previously (19). Significantly higher rumen acetate and butyrate concentrations and higher acetate to propionate ratios were found for calves reared in Buckley. In addition, Buckley calves had lower plasma glucose concentrations. Elevated rumen fluid VFA and depressed plasma glucose are indicators of onset of rumen development (13, 16).

Experiment 3

One of the calves fed prestarter and necropsled at 6 wk of age was removed from the data

125 120 115 110

A

105 :z v

100 <

U>

95

¢0

90

<.J

•

o

Weaning System

2

85 80 75

of0

I 1

I 2

I 3

I 4

I 5

I 6

I 7

I 8

Age ( w e e k s ) Figure 2. Interaction of age and weaning system on total volatile fatty acid concentration in rumen fluid of calves 2 to 8 weeks of age (Experiments 1 and 2). Journal of Dairy Science Vol. 70, No. 10, 1987

2100

KLEIN ET AL.

TABLE 3. Mean performance, blood, and rumen fluid measures in calves reared in two Washington locations, Pullman and Buckley (Experiments 1 and 2). 1 Location Variable

Pooled

Pullman

Buckley

1.56 a .55 a 3.07

1.76 b .62 b 2.82

Feed intake, kg/d 2 Average daily gain, kg 2 Feed:gain 2'3 Live body weight 10 wk, kg 6 mo, kg Height, 6 too, cm R u m e n fluid Acetate, tool/100 mol Propionate, mol/100 mol Butyrate, tool/100 mol Acetate:propionate Plasma glucose, mg/dl 2 Plasma urea nitrogen, mg/dl 2

SD .22 .20 2.52

77.3 181.8 a 102.9

77.3 156.3 b 103.1

9.55 22.20 3.37

48.3 a 36.3 10.4 a 1.5 a 71.6 a 9.9

56.7 b 38.8 22.3 b 1.6 b 62.5 b 10.5

13.38 13.05 7.29 .51 13.13 3.63

a'bMeans with different superscripts in the same row differ (P<.05). a Observations: n = 280. 2 Measured from 3 to 10 wk of age. 3 Observations: n = 268. If the gain was less than O, the datum was omitted. TABLE 4. Least square means of the gastrointestinal (GI) tract organ and content weights per kilogram live body weight in bull calves reared on weaning system 11 or 22 (Experiment 3). Weaning system GI Tract organ Reticulorumen, g/kg Full Empty Contents Omasum, g/kg Full Empty Contents Abomasum, g/kg Full Empty Contents Small intestine, g/kg Full Empty Contents Large intestine, g/kg Full Empty Contents Total, g/kg Full Empty Contents

1

Pooled 2

SD

68.2 14.9 a 53.4

61.5 12.0 b 49.5

3.9 2.7 1.2

4.4 2.8 1.6

1.42 .87 .71

16.5 6.0 10.6

18.2 5.8 12.5

5.49 .85 5.63

45.1 33.8 11.3

47.6 34.4 13.3

10.69 7.93 5.31

21.4 10.9 10.5

20.5 9.6 10.9

6.19 1.72 5.79

164.8 68.2 96.6

157.5 64.6 92.9

22.01 11.22 17.48

a'bMeans in the same row with different superscripts differ (P<.05). Calves fed prestarter until 4 wk old and weaned at 17 d of age. 2 Calves not fed prestarter and weaned at 28 d of age. Journal of Dairy Science Vol. 70, No. 10, 1987

14.28 2.05 14.07

RUMEN DEVELOPMENT IN CALVES set. This was b e c a u s e t h e calf h a d a n e x t r e m e l y enlarged liver a n d gall b l a d d e r (2 to 3× normal), t h e a b o m a s u m was grossly d i s t e n d e d , a n d t h e r u m e n was filled w i t h b e d d i n g material. D u r i n g t h e first 3 w k o f t h e trial, calves fed t h e p r e s t a r t e r a n d w e a n e d at 17 d o f age ( w e a n i n g s y s t e m 1) c o n s u m e d m o r e d r y feed ( P < . 0 5 ) t h a n calves f e d o n l y t h e s t a r t e r a n d w e a n e d at 28 d of age ( w e a n i n g s y s t e m 2). M e a n F I were .51 a n d .30 k g / d , respectively. This is c o n s i s t e n t w i t h results in E x p e r i m e n t s 1 a n d 2. T h e r e was n o i n t e r a c t i o n b e t w e e n w e a n i n g s y s t e m a n d age at n e c r o p s y f o r LBW n o r was t h e r e a n y significant e f f e c t o f w e a n i n g s y s t e m o n LBW. Average LBW was 52.7 kg f o r w e a n i n g s y s t e m 1 a n d 55.0 kg f o r w e a n i n g s y s t e m 2. No i n t e r a c t i o n s o f age at n e c r o p s y a n d w e a n i n g s y s t e m was f o u n d f o r e i t h e r t h e full w e t tissue w e i g h t s (FWTW) o f t h e G I t r a c t organs or t h e FWTW divided b y t h e LBW o f t h e calves ( F W T W / L B W ) (Tables 4 a n d 5). Like-

2101

wise, n o s i g n i f i c a n t i n t e r a c t i o n o f w e a n i n g s y s t e m and age at n e c r o p s y was s h o w n f o r m e a n e m p t y w e t tissue weights o f t h e G I t r a c t o r g a n s (EWTW) a n d EWTW/LBW. Calves t h a t received t h e p r e s t a r t e r a n d were w e a n e d at 17 d did h a v e a significantly h i g h e r m e a n reticulor u m e n w e i g h t t h a n calves raised w i t h w e a n i n g s y s t e m 2. T h i s was t r u e f o r b o t h t h e EWTW a n d E W T W / L B W . T h e heavier r e t i c u l o r u m e n tissue w e i g h t s of calves raised w i t h w e a n i n g s y s t e m 1 i n d i c a t e t h a t r u m e n d e v e l o p m e n t in t h e s e calves was m o r e a d v a n c e d t h a n in calves raised w i t h w e a n i n g s y s t e m 2 (7, 8, 28). Age at n e c r o p s y h a d a s i g n i f i c a n t e f f e c t o n m o s t GI t r a c t organs ( T a b l e 5). R e t i c u l o r u m e n a n d o m a s u m w e i g h t s were heavier, a n d t h e a b o m a s u m w e i g h t s were lighter f o r 6-wk-old calves t h a n f o r 3-wk-old calves. R e t i c u l o r u m e n a n d o m a s u m w e i g h t s increase rapidly d u r i n g t h e first 6 w k of life w h e n a d e q u a t e d r y feed is c o n s u m e d b y t h e calf (6, 10, 24, 26, 28). T h e r e was n o significant i n t e r a c t i o n b e t w e e n

TABLE 5. Least square means of gastrointestinal (GI) tract content and organ weights per kilogram live body weight in bull calves necropsied at 3 or 6 wk of age (Experiment 3). Age at necropsy GI Tract organ Reticulorumen, g/kg Full Empty Contents Omasum, g/kg Full Empty Contents Abomasum, g/kg Full Empty Contents Small intestine, g/kg Full Empty Contents Large intestine, g/kg Full Empty Contents Total, g/kg Full Empty Contents

3 wk

6 wk

Pooled SD

33.6 a 8.3 a 25.3 a

96.1 b 18.6 b 77.5 b

14.28 2.05 14.07

2.9 a 2.1a 0.8

5.4 b 3.4 b 2.0

1.42 .87 .71

21.5 a 6.0 15.5 a

13.2 b 5.7 7.5 b

5.49 .85 5.63

39.7 a 29.8 9.8

53.1 b 38.3 14.7

10.69 7.93 5.31

17.7 9.3 8.3

24.2 11.1 13.1

119.8 a 55.6 a 64.2a

202.5 b 77.2 b 125.3b

a'bMeans in the same row with different superscripts differ (P<.05). Journal of Dairy Science Vol. 70, No. 10, 1987

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KLEIN ET AL.

TABLE 6. Measurements of rumen papillary development for calves reared on weaning system 1 t or 22 (Experiment 3). Weaning system Papillary measurement Ventral sac: Length, mm Width, mm Number/cm 2 Dorsal blind sac: Length, mm Width, mm Number/cm 2

1

2

.7 .7 477.5

.9 .8 471.1

1.3 .8 448.9

1.1 .8 513.1

Pooled SD

.34 .29 176 .36 .25 238

1Calves fed prestarter until 4 wk old and weaned at 17 d of age. 2 Calves not fed prestarter and weaned at 28 d of age.

age o f n e c r o p s y and w e a n i n g s y s t e m on the w e i g h t o f t h e c o n t e n t s o f the individual GI t r a c t organs. Weaning s y s t e m had no significant e f f e c t o n c o n t e n t w e i g h t s (Table 4), b u t age at n e c r o p s y did (Table 5). Mean weights o f t h e r e t i c u l o r u m e n and small i n t e s t i n e c o n t e n t s were higher in o l d e r calves and t h e average w e i g h t o f t h e abomasal c o n t e n t s per kilogram LBW was lower. Previously, t h e w e i g h t o f the c o n t e n t s o f t h e r e t i c u l o r u m e n and o m a s u m have been r e p o r t e d to increase dramatically, b u t abomasal c o n t e n t s decrease or remain the same with increasing age o f t h e calf (10, 24). Measures o f r u m e n papillary d e v e l o p m e n t are in Tables 6 and 7. No weaning s y s t e m by age at n e c r o p s y i n t e r a c t i o n was s h o w n f o r papillary d e v e l o p m e n t . T y p e o f w e a n i n g s y s t e m

did n o t affect any m e a s u r e o f papillary developm e n t ; h o w e v e r , age at n e c r o p s y had a significant e f f e c t ( P < . 0 5 ) . R u m e n papilli at 6 wk o f age w e r e longer, w i d e r , and f e w e r in n u m b e r per square c e n t i m e t e r . T h e s e measures indicate more advanced papillary d e v e l o p m e n t in 6-wk-old calves. Previous research has s h o w n t h a t r u m e n papillary d e v e l o p m e n t is s t i m u l a t e d by t h e p r e s e n c e o f f e r m e n t a t i o n e n d p r o d u c t s (8, 24, 26, 28). T h e same research has s h o w n t h a t age alone, w i t h o u t dry f e e d c o n s u m p t i o n , has little e f f e c t on papillary d e v e l o p m e n t . All in this trial were c o n s u m i n g e n o u g h dry f e e d to s t i m u l a t e papillary d e v e l o p m e n t b y 6 wk o f age. T h e r e was no significant t r e a t m e n t e f f e c t on r u m e n V F A , plasma glucose, or plasma urea

TABLE 7. Measurements of rumen papillary development for calves necropsied at 3 or 6 wk of age (Experiment 3). Age at necropsy Papillary measurement Ventral sac Length, mm Width, mm Number/cm 2 Dorsal blind sac Length, mm Width, mm Number/cm 2

3 wk

6 wk

.4 a .4 a 730.6 a

1.2 b 1.2 b 218.0 b

.6 a .4 a 726.4 a

1.8 b 1.1 b 235.7 b

a 'b Means xn the same row with different superscripts differ (P<.05). Journal of Dairy Science Vol. 70, No. 10, 1987

Pooled SD

.34 .29

176 .36 .25 238

R U M E N DEVELOPMENT IN CALVES

2103

TABLE 8.'Blood and r u m e n fluid values for bull calves reared o n weaning system 11 or 22 and necropsied at 3 or 6 wk of age 3 (Experiment 3). Weaning system 1

Weaning s y s t e m 2

Variable

Necropsied at 3 wk

Necropsied at 6 wk

Necropsied at 3 wk

Necropsied at 6 wk

Pooled SD

R u m e n fluid Acetate, m o l / 1 0 0 mol Propionate, m o l / 1 0 0 mol Butyrate, m o l / l O 0 tool Acetate: propionate Blood glucose, mg/dl Plasma urea nitrogen, mg/dl

55.8 47.7 14.0 1.2 42.6 13.0

66.5 68.1 14.5 1.0 44.2 5.7

48.8 44.7 18.7 1.1 51.6 12.5

79.8 46.9 14.8 4.2 44.7 10.6

15.36 18.77 5.54 2.96 11.28 4.69

1 Calves fed prestarter until 4 wk old and weaned at 17 d of age. 2Calves n o t fed prestarter and weaned at 28 d of age. 3 No significant t r e a t m e n t effects or interaction.

n i t r o g e n in b u l l c a l v e s ( T a b l e 8). R u m e n V F A c o n c e n t r a t i o n s a n d p l a s m a g l u c o s e o f calves in Experiment 3 were similar to adult values by 3 w k o f age. T h i s c o i n c i d e s w i t h t h e s i m i l a r i t y o f development found among calves reared with either weaning system 1 or 2 and with the r e s u l t s f o u n d f o r t h e s e m e a s u r e m e n t s in E x p e r i m e n t s 1 a n d 2. Rumen development appeared to occur s u f f i c i e n t l y e a r l y in c a l v e s f e d p r e s t a r t e r t o a l l o w s u c c e s s f u l w e a n i n g a t 17 d o f a g e . R o u g h a g e ( 1 0 o r 2 0 % ) in t h e c a l f s t a r t e r d i d n o t a f f e c t 3 or 6-mo body weights of calves and, within t h i s r a n g e , w a s n o t a f a c t o r in a s u c c e s s f u l e a r l y weaning system.

REFERENCES

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precise m e t h o d for the determination of urea. J. Clin. Pathol. 13:156. Godfrey, N. W. 1961. The functional development of the calf. 1. G r o w t h of the s t o m a c h of the calf. J. Agric. Sci. 57:173. Godfrey, N. W. 1961. The functional development o f the calf. 2. Development of r u m e n f u n c t i o n in the calf. J. Agric. Sci. 57:177. Hamada, T., S. Maeda, and K. Kameoka. 1976. Factors influencing growth of rumen, liver and other organs in kids weaned f r o m milk replacers to solid foods. J. Dairy Sci. 59:1110. Hibbs, J. W., W. D. Pounden, and H. R. Conrad. 1953. A high roughage system for raising calves based on the early development of r u m e n function. I. Effect of variations in the ration on growth, feed c o n s u m p t i o n , and utilization. J. Dairy Sci. 36:717. Hodgson, J. 1971. The development of solid food intake in calves. 3. The relationship between solid food intake and the development of the alimentary tract. Anim. Prod. 13:449. James, R. E., M. L. McGilliard, and D. A. Hartman. 1984. Calf m o r t a l i t y in Virginia dairy herd improvem e n t herds. J. Dairy Sci. 67:908. Kincaid, R. L. 1980. Alternate m e t h o d s o f feeding alfalfa to calves. J. Dairy Sci. 63:91. Lambert, M. R., N. L. Jacobson, R. S. Allen, and M. R. Bell. 1955. The relation of growth, feed c o n s u m p t i o n and certain blood constituents to changes in t h e dietary of y o u n g dairy calves. J. Dairy Sci. 38:6. Lawrence, T.L.J., and J. Pierce. 1983. A note on t h e effect of certain variables on t h e performance o f early-weaned calves. Anita. Prod. 36: 393. Leibholz, J. 1975. G r o u n d roughage in the diet of t h e early-weaned calf. A n i m . Prod. 20:93. McCarthy, R. D., and E. M. Kesler. 1956. Relationship between age of calf, blood glucose, blood and r u m e n levels of volatile f a t t y acids, and in vitro cellulose digestion. J. Dairy Sci. 39 : 1280. Journal o f Dairy Science Vol. 70, No. 10, 1987

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24 Stobo, I.J.F., J.H.B. Roy, and H. J. Gaston. 1966. R u m e n d e v e l o p m e n t in the calf. 1. The effects of diets containing different proportions of concentrates to hay o n r u m e n development. Br. J. Nutr. 20:171. 25 Stobo, I.J.F. 1983. Development of the calf gastrointestinal tract and its nutritional implication. Page 85 in Br. Cattle Vet. Assoc. Proc. 26 Tamate, H., A. D. McGilliard, N. L. Jacobson, and R. Getty. 1962. Effect of various dietaries on the anatomical development of the s t o m a c h in the calf. J. Dairy Sci. 4 5 : 4 0 8 . 27 Van Horn, H. H., M. B. Olayiwole, C. J. Wilcox, B. Harris Jr., and J. M. Wing. 1976. Effects of housing, feeding m a n a g e m e n t , and ration formulation on calf growth and feed intake. J. Dairy Sci. 59:924. 28 Warner, R. G., W. P. Flatt, and J. K. Loosli. 1956. Dietary factors influencing t h e development of the r u m i n a n t stomach. J. Agric. Food Chem. 4:788.