Effects of weaning age and milk feeding frequency on dairy calf growth, health and rumen parameters

Livestock Science 110 (2007) 267 – 272 www.elsevier.com/locate/livsci

Effects of weaning age and milk feeding frequency on dairy calf growth, health and rumen parameters ☆ S.I. Kehoe, C.D. Dechow, A.J. Heinrichs ⁎ Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, United States Received 18 April 2006; received in revised form 3 November 2006; accepted 10 November 2006

Abstract Various methods can be used to feed dairy calves that may influence calf performance and these include changing frequency of feeding or age at weaning. Two trials were conducted to determine effects of feeding frequency and weaning age on calf growth, health and rumen development, where 124 Holstein heifer and bull calves were weaned at 3, 4, 5 or 6 weeks of age. During Trial 1, milk replacer (12.5% DM; 22% CP, 15.6% fat) was fed at 10% BW twice per day until 1 week prior to weaning when intake was reduced to 5% BW. During Trial 2 calves were fed at 10% BW in two feedings until 14 days, then at 10% BW once daily until 1 week prior to weaning when milk replacer was reduced to 5% BW. Blood glucose and urea nitrogen, BW 4 h post-feeding, heart girth, hip height, and withers height 4 h post-feeding were obtained weekly. Growth and structural measurements were similar for all treatments up to 8 weeks of age in both trials. Blood constituents and health observations were not different between trials. Similar growth and performance between treatments in both trials through 8 weeks of age indicate that calf performance is not affected by weaning early and feeding once daily. © 2007 Elsevier B.V. All rights reserved. Keywords: Calf growth; Feeding frequency; Weaning

1. Introduction Weaning calves as early as 3 to 5 weeks from milk or milk replacer saves labor, time and feed costs (Owen and Larson, 1982). However, in the United States, dairy calves are commonly fed milk twice daily and average weaning age is 8.4 weeks (USDA, 2002). ☆ This research is a component of NC-1119; Management Systems to Improve the Economic and Environmental Sustainability of Dairy Enterprises. ⁎ Corresponding author. 324 Henning Building, University Park, PA 16802, United States. Tel.: +1 814 863 3916; fax: +1 814 865 7442. E-mail address: [email protected] (A.J. Heinrichs).

1871-1413/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2006.11.007

Calves are able to utilize VFA prior to weaning at 3 weeks of age, thereby allowing earlier weaning (Martin et al., 1959) than is often accomplished on dairy farms. Calves having early access to solid feed and weaned as early as 4 weeks of age increased starter feed intake as well as plasma VFA, indicating successful adaptation to weaning (Quigley et al., 1991). Other work reported adequate rumen bacterial populations starting at 3 weeks of age, resulting in higher ruminal metabolic activity when compared with conventionally weaned calves (Anderson et al., 1987). Winter (1985) weaned calves at 3, 5, and 7 weeks of age and reported no differences in average daily gain (ADG) and dry matter intake (DMI) pre and post-weaning. Other research showed calves

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weaned earlier were not different from calves weaned conventionally in feed intake, ADG and feed efficiency (FE); however, early weaning reduced feed and labor costs (Winter, 1985). An alternative method to improve calf management is feeding milk replacer once daily. For example, calves may be fed twice daily from birth until 10 to 14 days of age, then both feedings consolidated into one feeding. Feed intake and FE were similar between calves fed once or twice daily. Feeding once daily also reduced labor spent on feeding calves by 30% (Galton and Brakel, 1976). In another study, no differences were detected in withers height and heart girth between calves fed once or twice daily (Willett et al., 1969). Although the use of once daily feeding and early weaning result in similar calf performance compared to conventional strategies, little research has incorporated both options into one management system. Therefore, the objective of these studies was to determine the effect of different weaning ages and 2 milk replacer feeding strategies on rumen, blood, growth, and health parameters.

Research has shown no differences in growth and health of calves weaned at 6 or 8 weeks of age; therefore, 6 week weaning age was chosen as an upper limit (Appleman and Owen, 1974). For Trial 1, 34 heifer and 30 bull calves (16 calves/ treatment) were fed at 5% of birth BW in the morning and 5% of birth BW in the afternoon from birth until 1 week prior to their respective weaning age; during the final week, milk replacer was fed at 5% of birth BW for the morning feeding only. For Trial 2 which began immediately after Trial 1, 36 heifer and 24 bull calves (15 calves/ treatment) were fed at 5% of birth BW in the morning and 5% of birth BW in the afternoon from birth until 14 days of age. Beginning on day 15, calves were fed 10% of birth BW in the morning until 1 week prior to their respective weaning age, at which time milk replacer was reduced to 5% of birth BW fed in the morning. Both trials shared one common treatment (treatment 3) where calves were fed exactly the same format. All experimental procedures were approved by the Pennsylvania State University Animal Care and Use Committee.

2. Materials and methods

2.2. Feed nutrient composition

2.1. Animals, housing, and diet

Composition of calf starter used throughout the study and milk replacer used for both trials is presented in Table 1. Milk replacer and calf starter samples were taken twice monthly and stored at − 20 °C until further

Holstein heifer and bull calves from the Pennsylvania State University dairy herd were separated from their dams 0.5 to 1 h after birth and housed in 1.2- × 2.4-m individual pens in a naturally and mechanically ventilated barn bedded with wood shavings. Nose to nose contact was eliminated by pen arrangement. All calves received 4 L of colostrum within 6 h of birth followed by 4 feedings (over 2 days) of transition milk before feeding of milk replacer. Calves were assigned to treatments at birth in a randomized complete block design and maintained on the study until 8 weeks of age. Milk replacer fed was 22% CP (all milk protein), 15% fat (lard; Akey, Inc., Lewisburg, OH), and contained no additional additives or medication and was mixed at 12.5% DM for feeding. Fresh calf starter feed (Purina Mills, Camp Hill, PA; textured starter with rolled corn, rolled oats and a protein/supplemented pellet) was offered ad libitum and intake was recorded daily. Water was offered free choice daily. Calves were kept in individual pens from birth until 1 week after weaning when they were moved to a group pen (4 × 5 m2) with a maximum of 5 animals per pen and group fed through 8 weeks of age. Treatments consisted of weaning calves at 3, 4, 5 or 6 weeks of age (treatments 3, 4, 5 and 6). Although average weaning is 8.4 weeks of age, 30% of US farms wean at 6 weeks or less (USDA, 2002).

Table 1 Composition of calf starter and milk replacer used for weaning age and feeding frequency experiments a Item

Calf starter b

SE

Milk replacer

SE

Crude protein, % Fat, % c Acid detergent fiber, % Neutral detergent fiber, % Ash, % Non-fiber carbohydrate, % d Calcium, % Phosphorus, % Magnesium, % Potassium, % Sodium, % Manganese, ppm Zinc, ppm Copper, ppm Vitamin A, IU/kgc Vitamin D, IU/kgc Vitamin E, IU/kgc

22.75 1.71 6.70 14.50 10.25 49.53 1.25 0.61 0.27 1.28 1.37 87.50 116.75 26.25 6,600 2,200 22

1.53 . 0.14 0.98 0.82 1.49 0.04 0.03 0.02 0.05 0.05 12.89 19.31 1.5 . . .

22.79 15.64 . . 7.48 . 0.81 0.63 0.10 1.69 0.69 0.42 0.53 0.11 35,140 7,780 151

0.05 1.11 . . 0.04 . 0.01 0.03 0.01 0.19 0.05 0.03 0.01 0.02 198 311 0

a b c d

All values are expressed on a DM basis. Purina Mills, Inc., Camp Hill, PA. Starter values based on manufacturer's tag. Calculated.

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analysis. Samples were dried at 55 °C in a forced air oven and ground (1-mm screen; Wiley mill, Arthur A. Thomas Co., Philadelphia, PA). Starter grain samples were analyzed for moisture (AOAC, 1990), CP (Leco FP528 Nitrogen Combustion Analyzer; Leco, St. Joseph, MI) soluble CP (Krishnamoorthy et al., 1982), NDF, ADF, (Van Soest et al., 1991), and crude fat (AOAC, 2000) using a Tecator Soxtec System HT 1043 Extraction unit (Tecator, Foss NA, Eden Prairie, MN). Ash and mineral content were determined (AOAC, 2000) utilizing a Perkin-Elmer 3300 XL ICP (PerkinElmer, Shelton, CT). 2.3. Fecal scoring and experimental measurements Health scores were assigned daily on each calf to evaluate scours, respiration and general appearance (Lesmeister and Heinrichs, 2004). Blood urea nitrogen (BUN) and glucose were determined weekly, starting at 1 week of age. Blood was obtained 4 h after a.m. milk feeding from the jugular vein, utilizing evacuated tubes containing sodium heparin, and immediately centrifuged for 15 min at 1500 ×g. Plasma was stored at − 20 °C until further analysis. Samples were analyzed for BUN using Stanbio Urea Nitrogen Kit 580 (Stanbio Laboratory, San Antonio, TX) and plasma glucose using Sigma Glucose Kit 510 (Sigma Chemical Co., St. Louis, MO). Growth measures including heart girth, hip height, body weight, and withers height were measured weekly four hour post morning feeding for all animals in both trials. 2.4. Rumen tissue sampling and body composition After completion of Trial 2, 12 bull calves were euthanized at 8 weeks of age by captive bolt stunning and exsanguination. Rumen tissue samples were collected and digestive tracts weighed. Papillae width (PW), papillae length (PL) and rumen wall thickness (RWT) were analyzed according to Lesmeister et al. (2004). A 9–10–11 rib section was excised from the left half of the carcass and deboned. After grinding, moisture was determined by drying in a laboratory oven at 60 °C. Kjeldahl procedure (AOAC, 2000) was used to determine N, and lipid was determined using the Goldfisch apparatus (AOAC, 1990). Samples were then heated in a muffler furnace at 600 °C to determine ash (AOAC, 1990). 2.5. Statistical analysis Blood, rumen, growth and health observations were analyzed using repeated measures analysis and the

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mixed procedure of SAS 8.2 (2001). Calf was used as the random effect. The statistical model used for analysis was:

Y ijkl ¼ μ þ T i þ W j þ Lk þ ðTWÞij þ ðTLÞik þ ðWLÞjk þ ðTWLÞijk þ calfl þ eijkl ; where:

Yijk μ Ti

dependant variables, overall mean, fixed effect of treatment i, where i = 3, 4, 5 or 6 weeks at weaning, Wj repeated measure of week j, Lk fixed effect of trial k, (TW)ij effect of treatment by week interaction, (TL)ik effect of treatment by trial interaction, (WL)jk effect of week by trial interaction, (TWL)ijk effect of treatment by week by trial interaction, calfl random effect of calf l, eijkl residual. Differences between least squares means were further investigated only if the model was significant (P b 0.05). The model used to measure rumen measurements also included overall starter feed intake as a covariate. Individual daily feed intake was measured until 1 week post-weaning when calves were moved from individual pens into group pens. Thereafter group average feed intake was used. Due to differences in physical structure of the rumen and body metabolism, it would be illogical to compare older weaning ages with younger weaning ages. Therefore, blood and rumen measurements for treatments were compared across trials but not within trials. Initial measurements of growth from birth through 2 weeks of age were compared by treatment within trials and between trials. No significant differences were detected; therefore initial growth measurements were not used as covariates in their respective analyses. Sex was not different in any models and therefore not used. Treatment 3 was the same in both trials. Calves were fed twice daily until 14 days of age and then switched to once daily for 1 week, whereas in Trial 1 other treatments continued twice daily feeding and in Trial 2 other treatments began once daily feeding at 10% BW. Therefore, treatment 3 may be used as a measure of repeatability between trials.

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3. Results and discussion 3.1. Feed intake Starter feed intake pre- and post-weaning was higher in Trial 2 than Trial 1 for treatments 4, 5 and 6. Overall starter feed intake (weeks 1 to 8) was higher between trials for treatments 5 and 6 (Table 2). Treatment 3 feed intake was not different between trials, indicating that trial differences and time had little effect; therefore, higher feed intake for treatments 4, 5 and 6 may be attributed to feeding once daily. Feed efficiency and growth were not different, although FE was numerically higher during pre-weaning for Trial 1 compared to Trial 2.

Due to low intake of starter before weaning, the majority of treatment 3 calves were hand fed starter during the week of gradual weaning to assist them in increasing starter intake and prepare them for weaning; this was done during both trials. Winter (1978) concluded that calves weaned before 3 weeks of age may have trouble adapting to dry feed and have lower FE than calves weaned at 5 weeks of age. Other research has shown no differences in feed intake between calves fed once (Ackerman et al., 1969) or twice daily (Galton and Brakel, 1976; Van Horn et al., 1976). 3.2. Growth measurements Treatment least squares means for heart girth, hip height, body weight, and withers height were not different

Table 2 Least squares means of growth parameters and feed intake at 8 weeks of age for calves in weaning age and feeding frequency experiments Weaning age a

3

Trial

1

4 2

5

1

2

1

6 2

1

2 SEM b

Variable Weight, kg Initial Final, 8 weeks ADG, kg/day Pre-weaning Post-weaning Weeks 1–8

45.1 73.1

42.5 72.8

44.3 74.5

42.8 74.2

41.1 71.6

41.7 77.2

43.8 74.1

43.2 79.2

1.7 2.2

0.15 0.73 0.50

0.12 0.81 0.54

0.31 0.75 0.53

0.31 0.81 0.58

0.37 0.87 0.55

0.59 0.88 0.69

0.46 0.88 0.56

0.55 0.98 0.65

0.09 0.09 0.07

Heart girth, cm Initial Final ADG, cm/day

80.0 93.7 0.66

79.3 94.2 0.71

80.5 93.7 0.47

80.0 93.9 0.49

79.8 94.2 0.41

78.2 96.3 0.52

80.8 96.0 0.36

78.9 94.9 0.38

1.25 3.1 0.05

Hip height, cm Initial Final ADG, cm/day

79.8 88.1 0.39

80.8 88.9 0.39

81.3 87.9 0.24

80.3 89.2 0.32

81.0 89.2 0.23

75.2 91.2 0.46

81.5 89.7 0.19

80.5 91.7 0.32

2.4 1.5 0.04

Withers height, cm Initial Final ADG, cm/day

75.9 82.6 0.32

76.5 85.1 0.41

76.9 83.1 0.22

76.9 85.1 0.29

77.2 84.6 0.21

77.9 86.1 0.23

77.2 85.1 0.19

75.9 86.1 0.24

1.1 1.1 0.04

Starter intake, DM kg/day Pre-weaning 0.27 Post-weaning 1.06

0.27 1.19

0.32 c 1.14 c

0.53d 1.50d

0.41 c 1.37 c

0.73d 1.94d

0.49 c 1.72 c

0.98d 2.43d

0.07 0.08

Milk replacer intake, DM kg/day Pre-weaning 0.45 FE e (pre-weaning) 4.80

0.41 5.67

0.46 2.52

0.43 3.09

0.44 2.29

0.45 3.39

0.48 2.11

0.46 2.62

0.02 1.50

a

Milk replacer was administered differently in each experiment. SEM are listed as the higher value of trial 1 or trial 2 SEM. c, d Different postscripts indicate differences (P b 0.05) between trials within the same treatment (eg., treatment 4 in trial 2 is significantly higher in starter intake pre-weaning than treatment 4 in trial 1). e FE = Feed efficiency expressed as kg DM of milk replacer and starter intake: kg of gain. b

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Table 3 Least squares means of blood and health parameters for calves in weaning age and feeding frequency experiments Weaning age

3

Trial Variable

1

Fecal scoreb,c Respiratory scoreb,c Appearance scoreb,c BUN (mg/dl) d Glucose (mg/dl) d

1.15 1.01 1.04 12.68 76.90

a b c d

4 2

1

5 2

1

6 2

1

2 SEM a

1.14 1.01 1.09 14.31 84.28

1.65 1.00 1.04 11.05 79.60

1.69 1.00 1.12 12.11 69.79

1.54 1.02 1.03 9.98 81.75

1.63 1.00 1.00 12.31 80.90

1.48 1.02 1.04 9.66 77.03

1.58 1.01 1.04 11.82 92.41

0.08 0.01 0.03 0.64 6.41

SEM are listed as the higher value of trial 1 or trial 2 SEM. Scored on a scale of 1 to 5 as described by Lesmeister et al. (2004). Lower numbers indicate more normal calf health. Health scores are least squares means from birth through one week post-weaning. Blood parameters are least squares means of treatment at week of weaning.

between trials (Table 2). This is in agreement with other researchers who reported no differences in growth postweaning between calves fed once or twice daily and calves weaned at different ages (Wood et al., 1971; Galton and Brakel, 1976). Other research reported lower BW in calves fed once daily when weaned at 4 weeks compared to calves weaned at 6 and 12 weeks. These differences did not extend to 12 and 28 weeks, but FE post-weaning was lower than calves weaned at a later age (Wickes et al., 1972). Average daily gain was not different between trials (Table 2). Growth and ADG were typical for calves fed 0.5 kg/day milk replacer (NRC, 2001) and results reflect this level of feeding. 3.3. Blood constituents and health Least squares means of BUN and glucose were not different between treatments (Table 3). Least squares means for fecal, respiratory and general appearance scores between treatments were not different (Table 3). This finding is supported by others who detected no differences in fecal scores or days scouring in calves fed once daily compared with calves fed twice daily (Owens and Stake, 1971; Leaver and Yarrow, 1972; Stiles et al., 1974). During once daily feeding, milk replacer volume was doubled but DM concentration remained constant. Jenny et al. (1982) reported a linear increase in scours as DM concentration of milk replacer was increased and concluded that nutritional scours was caused by increased concentration of DM and not volume of milk replacer, which relates with the current trial where the volume of milk replacer and not concentration was increased. 3.4. Rumen development and body composition Rumen PL, PW and RWT were not different between treatments. Least squares means for treatments 3, 4, 5 and

6 were as follows: PL 2.62, 2.49, 2.24, and 2.42 ± 0.23 mm; PW 1.11, 1.09, 1.05, and 1.08 ± 0.08 mm; and RWT 2.20, 1.97, 2.12, and 2.07 ± 0.23 mm. Other researchers have reported greater lengths and widths of rumen papillae (Zitnan et al., 1999) and greater lengths and denser papillae (Stobo et al., 1966) in calves weaned at younger ages as compared to older ages. In previous studies, calves were slaughtered and rumen papillae were compared immediately after weaning whereas during the current trial, all calves were slaughtered at 8 weeks of age. This may indicate that differences seen by other researchers at the time of weaning may not continue postweaning. No differences were observed between treatments for composition of protein, fat, ash and moisture in the 9–10–11 rib section. Protein content was 17.96, 18.81, 18.27 and 19.14 ± 0.4% and fat content was 2.4, 2.0, 2.7 and 1.7 ± 0.4% for treatments 3, 4, 5 and 6, respectively. Ash content was 2.7, 2.6, 2.5 and 2.3 ± 0.2%, and moisture content was 77.4, 77.5, 76.8 and 76.9 ± 0.5% for treatments 3, 4, 5 and 6, respectively. Growing steers fed diets differing in protein and energy content have been reported to maintain similar body composition (Oltjen and Garrett, 1988), which may support the observed lack of changes in body composition of young calves weaned at different ages. 4. Conclusions Under management conditions and feeding rates of this experiment, calves weaned at 3 weeks required more attention during weaning to stimulate starter intake than calves weaned later. This may indicate that although calves weaned at 3 weeks successfully attain the same growth measurements and health scores as other calves at 8 weeks of age, they may require more initial attention than other treatments. Calves weaned at

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4, 5, and 6 weeks increased starter intake when the amount of milk replacer fed was halved, however, age at weaning had no effect on growth by 8 weeks of age. Feeding once vs. twice daily also had no effect on any of the items measured, indicating that the two management systems can be successful when combined or used independently. Management abilities, calf health and labor determine the best method to use for raising young calves on individual operations. Many management combinations are possible for producers; however, weaning calves as early as 4 weeks and once daily feeding can be used to save time and money by way of reduced labor with no apparent negative effects on calves through 8 weeks of age. References AOAC, 1990. Official Methods of Analysis.15th ed. Assoc. Off. Anal. Chem., Arlington, VA. AOAC, 2000. Official Methods of Analysis.17th ed. Assoc. Off. Anal. Chem., Gaithersburg, MD. Ackerman, R.A., Thomas, R.O., Thayne, W.V., Butcher, D.F., 1969. Effects of once-a-day feeding of milk replacer on body weight gain of dairy calves. J. Dairy Sci. 52, 1869–1872. Appleman, R.D., Owen, F.G., 1974. Breeding, housing, and feeding management. J. Dairy Sci. 58, 447–464. Anderson, K.L., Nagaraja, T.G., Morrill, J.L., Avery, T.B., Galitzer, S.J., Boyer, J.E., 1987. Ruminal microbial development in conventionally or early-weaned calves. J. Anim. Sci. 64, 1215–1226. Galton, D.M., Brakel, W.J., 1976. Influence of feeding milk replacer once versus twice daily on growth, organ measurements, and mineral content of tissues. J. Dairy Sci. 59, 944–948. Jenny, B.F., Van Dijk, H.J., Grimes, L.W., 1982. Performance of calves fed milk replacer once daily at various fluid intakes and dry matter concentrations. J. Dairy Sci. 65, 2345–2350. Krishnamoorthy, U., Muscato, T.V., Sniffen, C.J., Van Soest, P.J., 1982. Nitrogen fractions in selected feedstuffs. J. Dairy Sci. 65, 217–225. Leaver, J.D., Yarrow, N.H., 1972. Type and level of milk substitute offered once daily to calves. Anim. Prod. 14, 155–159. Lesmeister, K.E., Heinrichs, A.J., 2004. Effects of corn processing on growth characteristics, rumen development, and rumen parameters in neonatal dairy calves. J. Dairy Sci. 87, 3439–3450. Lesmeister, K.E., Tozer, P.R., Heinrichs, A.J., 2004. Development and analysis of a rumen tissue sampling procedure. J. Dairy Sci. 87, 1336–1344. Martin, W.G., Ramsey, H.A., Matrone, G., Wise, G.H., 1959. Responses of young calves to a diet containing salts of volatile fatty acids. J. Dairy Sci. 42, 1377–1386.

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