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Effect of Weaning Age of Dairy Calves Fed a Conventional or More Optimum Milk Replacer Program
The Professional Animal Scientist 25 (2009):619–624
©2009 American Registry of Professional Animal Scientists
Effect of Weaning Age of Dairy Calves Fed a Conventional or More Optimum Milk Replacer Program T. M. Hill,1 H. G. Bateman II, J. M. Aldrich, PAS, and R. L. Schlotterbeck Akey, Nutrition and Research Center, Lewisburg, OH 45338
ABSTRACT Comparisons of different weaning ages of calves fed high-protein, high-feedingrate milk replacer (MR) programs have not been reported in the literature. Thus, the objectives of these trials were to compare the performance of calves fed either a conventional MR [0.454 kg of a 22% CP, 20% fat (as fed) MR powder daily; MR A] or a more optimum MR [0.681 kg of a 26% CP, 17% fat (as fed) MR powder daily; MR B] and weaning them at either 28 or 42 d. Trial 1 evaluated the weaning age of calves fed MR A or B. Trial 2 compared the weaning age of calves fed MR B. Holstein calves were fed an 18% CP starter and fresh water ad libitum throughout the 56-d trials. In trial 1, calves fed MR B had 50% greater ADG, consumed 24% more starter, were 13% more efficient, and had 68% more hip width change than calves fed MR A (P < 0.05). Calves weaned at 28 d consumed 36% more starter than calves weaned at d 42 (P < 0.05). In trial 2, calves weaned at 28 d consumed 25% more starter than calves weaned on d 42 (P < 0.05). Weaning age did not affect BW gain by 56 d in either trial. A metaanalysis of published data using MR B revealed that weaning age did not change 1
Corresponding author: [email protected].
ADG through d 56, but calves weaned at 28 d consumed more starter and had a lower feed efficiency than calves weaned at 42 d. Key words: calf, weaning age, milk replacer
INTRODUCTION Weaning age, with specific emphasis on early weaning (approximately 4 wk of age or less), to reduce feed and labor costs has received attention in research units for decades (Owen and Larson, 1982; Kehoe et al., 2007). However, the most recent US survey (USDA, 2002) reported the average weaning age of calves is 8.4 wk of age. There is a renewed interest in feeding more milk or milk replacer (MR) to calves (Diaz et al., 2001). However, this may be counterproductive to early weaning. When more milk or MR has been fed, weaning age has been at 6 wk of age or older, and a weaning and postweaning slump in growth has occurred (Bar-Peled et al., 1997; Jasper and Weary, 2002; Cowles et al., 2006; Hill et al., 2006a), which appears to be a function of reduced starter intake, feed efficiency, and digestion (Strzetelski et al., 2001; Jasper and Weary, 2002; Cowles et
al., 2006; Hill et al., 2006a; Terre et al., 2007). However, a program was developed recently to overcome this problem in calves weaned at 42 d of age (Hill et al., 2006b), in which a specifically formulated 26% CP, 17% fat MR was fed at only 0.681 kg powder/d (greater rates were unsuccessful; Hill et al., 2007b). However, this program has not been evaluated in calves weaned earlier than 42 d of age. Likewise, other research on early weaning calves fed high rates of milk or MR does not appear available in peer-reviewed form. The objectives of these trials were to compare the performance of calves fed daily a 22% CP, 20% fat MR fed at 0.454 kg powder (as fed) with a 26% CP, 17% fat MR fed at 0.681 kg powder (as fed) while being weaned at either 28 or 42 d. The hypothesis was that the calves fed the greater amount of MR would not perform as well as calves fed the lesser amount of MR because of difficulties with transitioning from MR to starter feed.
MATERIALS AND METHODS Trial 1 Calves were fed 1 of 2 MR in a 56-d trial. Milk replacer powder A was
620 22% CP and 20% fat (as fed) and was fed to calves at 0.454 kg powder/d (as fed), reconstituted to 0.12 kg/L. It was formulated based on the NRC (2001) calf submodel to be balanced in CP and energy at thermoneutral temperatures and to contain all whey protein and animal fat sources. Milk replacer powder B was 26% CP and 17% fat (as fed) and was fed to calves at 0.681 kg powder/d (as fed), reconstituted to 0.148 kg/L. It was formulated based on published research showing increased calf ADG without reduced starter intake compared with a conventional MR in a 42-d weaning program (Hill et al., 2006b). The NRC (2001) calf submodel predicted energy-limiting ADG of 42-kg BW calves at thermoneutral temperatures to be 0.21 kg/d with MR A and 0.53 kg/d with MR B. Protein-limited ADG were predicted to be 0.27 kg/d with MR A and 0.55 kg/d with MR B. Formulas of the MR are shown in Table 1. For a 42-d weaning, the MR for each program was halved into a.m.
Hill et al.
and p.m. feedings for 39 d, followed by only an a.m. feeding for d 40 to 42. For 28-d weaning, the MR for each program was halved into a.m. and p.m. feedings for 25 d, followed by only an a.m. feeding for d 26 to 28. This resulted in 4 treatments of MR management. The starter was a complete pellet (Table 2). All calves received ad libitum fresh water and starter beginning on arrival. Approximately 110% of the estimated feeds needed were manufactured at one time. Samples of manufactured feeds were collected from every other bag (22.7 kg) of feed at the time of manufacture. Composites of the MR were analyzed (AOAC, 2000) before the animal phase of the trial for DM (oven method 930.15), CP (Keldahl method 988.05), fat (alkaline treatment with Roese-Gottlieb method 932.06), ash (muffle furnace method 923.03), Ca, and P (dry ashing, acid digestion, analysis by inductively coupled plasma spectrometry, method 985.01). A composite of the starter
Table 1. Ingredient composition and assayed nutrients in milk replacers (MR) Trial 1 Item Ingredient, % (as fed) Whey (12% CP) Dry fat (7% CP, 60% fat) Whey protein concentrate (78% CP) Lecithin based emulsifier Mineral-vitamin premix Decoquinate premix1 (0.5%) Flow agent Flavor Dry fat (12% CP, 26% fat) dl-Met l-Lys Nutrient, % of DM DM Protein Fat Ash Ca P ME,2 Mcal/kg 1
Alpharma Inc. (Fort Lee, NJ).
2
Calculated using NRC (2001) equations.
Trial 2
MR A
MR B
MR
48.7 27.0 19.0 2.0 1.2 1.0 0.9 0.2 0.0 0.0 0.0
45.8 21.0 23.0 2.6 1.1 0.7 0.9 0.2 4.0 0.4 0.3
45.8 21.0 23.0 2.6 1.1 0.7 0.9 0.2 4.0 0.4 0.3
96.4 23.1 21.0 6.66 0.82 0.64 4.8
96.2 27.2 17.7 5.99 0.77 0.60 4.8
96.5 27.0 17.8 5.62 0.81 0.63 4.8
was analyzed for DM, CP, ash, Ca, and P. Holstein bull calves (n = 48) were received in the late afternoon from multiple dairy farms at less than 7 d of age after a 10-h transit and immediately were fed 0.227 kg of electrolyte and nutrient powder (Critical Care, Akey, Lewisburg, OH) reconstituted to 1.8 L with warm water. The following a.m. feeding consisted of 0.284 kg (as fed) powder of MR B reconstituted to 1.8 L with warm water. The day after arrival, at approximately noon, the calves were weighed, measured with a caliper for hip widths, scored for body condition, and after sampling blood intravenously for serum protein via a refractometer (ATAGO US Inc., Bellevue, WA), they were randomly assigned to treatment (d 0, initial measurement). Calf BW was measured weekly at approximately noon. Hip widths and BCS were measured every 14 d. Calf BCS was based on a 1 to 5 system using 0.25 unit increments, with 1 being emaciated and 5 being obese (Wildman et al., 1982). Scores were based on changes around the vertical and transverse processes of the spine as palpated by one experienced technician, and ranged from 1.5 to 3.5. Fecal scores were assigned daily based on a 1 to 5 system (1 being normal, thick in consistency; 2 being normal but less thick; 3 being abnormally thin but not watery; 4 being watery; 5 being watery with abnormal coloring). Vaccines and medical treatments were based on the recommendations of a veterinarian and are described in Hill et al. (2006a). Calves were housed in a curtainsided, naturally ventilated barn with no added heat in 1.2 × 2.4 m pens bedded with straw. This trial was conducted from May through July. Based on hourly measurements, the average temperature in the barn was 21°C, with a range of 8 to 31°C. All animals were cared for by acceptable practices as described in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999).
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The data were analyzed as a completely randomized design in a 2 × 2 factorial arrangement. Factors were MR and weaning age. The analysis was performed using the GLM procedure (SAS Institute Inc., Cary, NC), using a mixed model as repeated measures with an autoregressive type 1 covariance structure. Data reported are least squares means. The experimental unit was the calf.
Trial 2 Calves were fed one MR in a 56-d trial. The MR powder was 26% CP and 17% fat and was fed to calves at 0.681 kg/d (as-fed basis) reconstituted to 0.148 kg/L. This MR was the same as MR B in trial 1 (Table 1). Weaning management was the same as in trial 1. The starter was a textured feed (Table 2). All calves received ad libitum fresh water and starter beginning on arrival. Feeds were manufactured and analyzed as in trial 1. Holstein bull calves (n = 48) were received at approximately noon from one dairy farms at 2 to 5 d of age after a 3.5-h transit. Their first MR was fed at the p.m. feeding. The day after arrival at approximately noon, the calves were weighed, measured with a caliper for hip widths, and scored for BCS, and then blood was sampled intravenously for serum protein via a refractometer (ATAGO US Inc.); they were then randomly assigned to treatment (d 0, initial measurement). Measurements were as described in trial 1. Calves were housed a curtain-sided, naturally ventilated barn with no added heat in 1.2 × 2.4 m pens bedded with straw. This trial was conducted September to November. Based on hourly measurements, the average temperature in the barn was 11°C, with a range in temperature of −7 to 29°C. All animals were cared for by acceptable practices as described in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999). The data were analyzed as a completely randomized design. The analy-
sis was performed using the GLM procedure as in trial 1.
Meta-analysis Results from 14 treatment means using 438 calves were compiled and used in a meta-analysis to better estimate the impact of weaning age on ADG, starter intake, and feed efficiency. The data for this analysis were taken from published trials conducted by our research group. All data were collected from Holstein calves initially 2 to 3 d old. All calves were used in trials with nondirect comparisons of feeding a similar 26% CP and 17% fat MR at 0.681 kg/d and weaned at either 28 or 42 d. Treatment means for ADG, starter intake, and feed efficiency were used in a mixed model. The model contained a term for the fixed effect of weaning age and the random effect of trial.
RESULTS AND DISCUSSION No calves died or were removed from either trial. All medical treatments were due to scouring. Initial measurements did not differ (P > 0.05) among treatments (Tables 3 and 4). All calves weaned on their designed weaning dates without complications. In trial 1, there were no interactions of the main effects (MR and weaning age) over the 56-d trial. Calves fed MR B had 50% greater ADG, consumed 24% more starter, were 13% more efficient, and had 68% more hip width change than calves fed MR A (P < 0.05). Calves weaned at 28 d consumed 36% more starter than calves weaned on d 42 (P < 0.05). Other measures did not differ between the weaning ages of 28 or 42 d. In trial 2, calves weaned at 28 d consumed 25% more starter than calves weaned on d 42 (P < 0.05) over the 56-d trial. Other measures did not differ between weaning ages of 28 or 42 d. Greenwood et al. (1997) weaned calves based on starter intakes of 10, 15, or 20 g/kg of initial BW, which resulted in weaning ages of 32, 43, or
Table 2. Ingredient composition and assayed nutrients in starters Item Ingredient, % (as fed) Corn Soybean meal Wheat middlings Minerals and vitamins Molasses Animal fat Pellet binder Decoquinate3 (0.5%) Oats Decoquinate3 (6%) Nutrient, % of DM DM Protein Fat Ash Ca P ME,4 Mcal/kg 1
Trial 11 Trial 2
53.90 24.30 14.00 2.80
37.00 7.802 23.702 2.802
2.50 1.00 1.00 0.50
3.00 0.352 0.302 0.00
0.00 0.00
25.00 0.052
87.4 20.9 3.8 6.4 0.93 0.66 3.1
87.9 20.6 3.7 6.1 0.94 0.71 3.1
Starter was a complete pellet.
These ingredients were pelleted as the supplement within the textured starter.
2
3
Alpharma Inc. (Fort Lee, NJ).
Calculated using NRC (2001) equations.
4
45 d, respectively, and similar BW gains up to 20 wk of age among all 3 groups. Calves weaned at 10 g of starter/kg initial BW consumed the most starter from 0 to 8 wk. Quigley et al. (1991) weaned calves from milk (1.8 kg/d per head) at either 28 or 56 d of age. They reported no differences in rate of BW gain because of weaning age, and calves weaned at 28 d consumed more starter but similar total amounts of DM over the 98-d trial. Hill et al. (2007a) weaned calves at 28 d from a 20% CP and 20% fat MR powder and reported them to have similar ADG, more starter intake, and lower feed efficiency from 0 to 56 d than calves weaned at 42 d. Owen and Larson (1982) reported statistically similar but numerically lower ADG during the first 8 wk of
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Table 3. Summary of 0- to 56-d performance from feeding a 22% CP and 20% fat milk replacer (MR) at 0.454 kg powder/d (as fed; MR A) or a 26% CP and 17% fat MR at 0.681 kg powder/d (as fed; MR B) and weaning at 28 or 42 d in trial 1 28-d weaning
42-d weaning
Main effect P-value
Item
MR A
MR B
MR A
MR B
SEM
MR
Weaning day
Calves, n Initial serum protein, mg/dL Initial BW, kg Final BW, kg ADG, kg/d Starter DMI, kg/d MR DMI, kg/d Feed efficiency2 Fecal score3 Abnormal fecal score days, n Initial hip width, cm Hip width change, cm Initial BCS4 BCS change Predicted ADG,5 kg/d Energy-limited Protein-limited
12 5.3 39.1 61.4 0.397 0.595 0.207 0.495 1.4 8.7 17.5 2.5 2.1 0.4
12 5.2 39.0 70.2 0.558 0.750 0.310 0.526 1.5 9.1 17.7 3.6 2.2 0.6
12 5.3 39.1 59.8 0.370 0.444 0.317 0.487 1.4 9.3 17.4 2.2 2.1 0.4
12 5.3 39.1 72.7 0.600 0.545 0.474 0.589 1.4 8.7 17 4.3 2.1 0.7
— 0.2 1.1 1.9 0.03 0.074 — 0.021 0.04 1.0 0.45 0.29 0.08 0.1
— <0.93 <0.80 <0.02 <0.01 <0.01 — <0.02 <0.93 <0.56 <0.95 <0.02 <0.99 <0.09
— <0.87 <0.29 <0.44 <0.89 <0.01 — <0.11 <0.85 <0.74 <0.76 <0.98 <0.96 <0.68
0.30 0.39
0.57 0.61
0.34 0.40
0.63 0.67
— —
— —
— —
1
There were no interactions of main effects in this trial.
2
Gain divided by DMI from MR plus starter.
Fecal scoring system: 1 = normal, thick in consistency; 2 = normal but less thick; 3 = abnormally thin but not watery; 4 = watery; 5 = watery with abnormal coloring. Abnormal fecal scores were days with scores >2.
3
4
Using 1 to 5 system, with 1 = emaciated and 5 = obese.
Predicted using NRC (2001) based on the average trial temperature of 21°C, 50 kg BW, and the average MR and starter intakes of the treatments listed in the table.
5
age for calves weaned at 21 vs. 42 d; however, ADG at subsequent ages and first-lactation milk yield were virtually identical. These results from other trials and the current 2 trials are all consistent with calves being of similar BW by approximately 56 d of age regardless of weaning age, whereas earlier weaning results in more starter intake. The calf submodel in NRC (2001) was used to predict energy- and protein-limited ADG based the average trial temperatures, average MR intake and composition, average starter intake and composition, and a 50-kg BW in trial 1 and a 60-kg BW in trial 2. In both trials, energy-limited ADG was lower than protein-limited ADG. In trial 1, differences in predicted and observed ADG between MR were similar, with the model predicting a greater difference in ADG than was
observed. Predicted ADG was greater for calves weaned at 42 versus 28 d in both trials. Calves in trial 1 fed MR B, the 26% CP and 17% fat MR, appeared to have greater ADG (0.579 vs. 0.517 kg/d) than calves in trial 2. Calves in trial 1 had initially lower BW (39.1 vs. 45.5 kg), had greater serum protein concentrations (5.3 vs. 4.8 mg/dL), and were in greater average environmental temperatures (21 vs. 11°C) than calves in trial 2. The MR were fed at a fixed rate, not as a percentage of BW; thus, the lighter BW calves in trial 1 were consuming more energy above maintenance than calves in trial 2, and this intake relative to maintenance requirements may explain the apparent difference. Comparison of the predicted ADG using the calf submodel in NRC (2001) shows the same apparent difference
of calves in trial 2 having greater predicted ADG than calves in trial 1. Calves in trial 2 were much healthier than calves in trial 1, as evidenced by their lower number of abnormal fecal score days (0.2 vs. 8.9 d). The opposite tendency of calves in trial 1 to have a lower average fecal score (1.4 vs. 2.1) than calves in trial 2 is confusing and possibly misleading because calves in trial 2 had almost no days of a score 1. Both fecal scores of 1 and 2 were considered normal but different, and a fecal score of 3, 4, or 5 was considered abnormal. Comparison of results between in trials 1 and 2 could be misleading because of these various trial effects of BW, health status, environmental temperatures, and other unknown issues. No other direct comparisons of weaning age of high-protein, highfeeding-rate MR could be found in
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Table 4. Summary of 0- to 56-d performance from feeding a 26% CP and 17% fat milk replacer (MR) at 0.681 kg powder/d (as fed) and weaning at 28 or 42 d in trial 2 Item
28-d weaning 42-d weaning
Calves, n Initial serum protein, mg/dL Initial wt, kg Final wt, kg ADG, kg/d Starter DMI, kg/d MR DMI, kg/d Feed efficiency1 Fecal score2 Abnormal fecal score days, n Initial hip width, cm Hip width change, cm Initial BCS3 BCS change Predicted ADG,4 kg/d Energy-limited Protein-limited 1
SEM
P-value
24 4.8 45.6 73.8 0.503 0.773 0.308 0.465 2.0 0.2 18.7 3.9 2.3 0.3
24 4.7 45.4 75.2 0.531 0.615 0.475 0.487 2.1 0.2 19.0 3.9 2.4 0.3
— 0.1 1.2 2.3 0.022 0.046 — 0.022 0.01 0.01 0.1 0.01 0.02 0.01
— <0.90 <0.77 <0.71 <0.37 <0.003 — <0.36 <0.44 <0.84 <0.09 <0.31 <0.12 <0.34
0.41 0.61
0.50 0.69
— —
— —
Gain divided by DMI from MR plus starter.
Fecal scoring system: 1 = normal, thick in consistency; 2 = normal but less thick; 3 = abnormally thin but not watery; 4 = watery; 5 = watery with abnormal coloring. Abnormal fecal scores were days with scores >2.
2
3
Using a 1 to 5 system with 1 = emaciated and 5 = obese.
Predicted using NRC (2001) based on the average trial temperature of 11°C, 60 kg BW, and the average MR and starter intakes of the treatments listed in table.
4
the literature. In Table 5, treatment means from 438 calves are shown from nondirect comparisons of feeding a 26% CP and 17% fat MR at 0.681 kg/d and weaning at either 28 or 42 d. All these means were published data from our research unit. Other data of this type were not found in the literature. These data were subjected to a meta-analysis and, similar to the current trials, the mean ADG from 0 to 56 d of calves weaned at 28 d was not different (P < 0.12), but numerically was 9% less than the mean of calves weaned at 42 d. In addition, similar to trials 1 and 2, the mean starter intake was greater (P < 0.01) in calves weaned at 28 compared with those weaned at 42 d, and feed efficiency of calves weaned at 28 d was less (P < 0.01) than that of calves weaned at 42 d. Regardless of treatment or trial, all calves were weaned at their assigned weaning date without issues of poor starter intake, slumps in ADG postweaning, or health challenges. In contrast to previous trials in which additional milk or MR was fed that
Table 5. Summary and meta-analysis of 0- to 56-d ADG, starter intake, and feed efficiency in 438 calves fed a 26% CP and 17% fat milk replacer at 0.681 kg powder/d (as fed) and weaned at either 28 or 42 d1 Reference Hill et al. (2007a) Hill et al. (2007a) Hill et al. (2007c) Hill et al. (2008) Hill et al. (2008) Hill et al. (2008) Hill et al. (2008) Hill et al. (2006b) Hill et al. (2007a) Hill et al. (2007a) Hill et al. (2007b) Hill et al. (2007b) Hill et al. (2007b) Hill et al. (2007c) 7-trial average 7-trial average SEM P-value
Trial in reference
Weaning day
Calves, n
ADG, kg/d
Starter DMI, kg/d
Feed efficiency2
5 6 2 1 2 3 4 3 3 4 1 2 3 3 — — — —
28 28 28 28 28 28 28 42 42 42 42 42 42 42 28 42 — —
48 48 32 24 16 32 48 12 50 48 16 24 24 16 248 190 — —
0.550 0.556 0.644 0.677 0.602 0.605 0.724 0.688 0.783 0.593 0.727 0.593 0.714 0.697 0.623 0.685 0.025 <0.12
0.813 0.797 0.842 0.896 0.882 0.894 1.118 0.715 0.760 0.556 0.742 0.555 0.719 0.704 0.892 0.679 0.040 <0.01
0.491 0.503 0.560 0.563 0.506 0.503 0.508 0.578 0.634 0.575 0.597 0.576 0.598 0.591 0.519 0.593 0.026 <0.01
1
These results are not from direct comparisons of weaning age and represent different environmental and calf conditions.
2
Gain divided by DMI from milk replacer plus starter.
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Hill et al.
showed a weaning or postweaning slump (Bar-Peled et al., 1997; Jasper and Weary, 2002; Cowles et al., 2006; Hill et al., 2006a), none occurred in this study. Results in trials 1 and 2 were consistent with meta-analysis of the literature (Table 5) using the same 26% CP and 17% fat MR powder fed at 0.681 kg powder daily in calves weaned at 28 or 42 d of age. The only trial to report management issues with early weaning was Kehoe et al. (2007), who compared weaning at 3, 4, 5, and 6 wk of age. They reported that calves weaned at 3 wk of age required more attention to stimulate starter intake than calves weaned at the older ages. Producers and advisors can use these results to predict costs per calf and per unit of BW gain between 28- and 42-d weaning programs. The cost per kilogram of BW gain should be lower even with a modest potential BW loss from weaning at d 28 versus d 42 with a 26% CP and 17% fat MR powder because of the higher cost of MR powder compared with starter. Additionally, they can apply labor differences and costs. For example, one estimate of labor costs for the preweaned calf is $1.35 daily (Gabler et al., 2007). Thus, a reduction of 14 d of labor is $18.95/calf. Labor savings alone might justify weaning early in this type of MR program. However, these results should not be extrapolated to MR programs feeding more than 0.681 kg/d of MR powder because early weaning research results have not been reported for those MR programs.
IMPLICATIONS Calves fed either a conventional MR [0.454 kg of a 22% CP, 20% fat (as fed) MR powder daily] or a more optimal growth MR [0.681 kg of a 26% CP, 17% fat (as fed) MR powder daily] had similar ADG from 0 to 56 d when weaned at either 28 or 42 d. With each MR, starter intake was greater when calves were weaned at
28 d compared with 42 d. A metaanalysis of feeding 0.681 kg of a 26% CP and 17% fat (as fed) MR powder daily and weaning at 28 versus 42 d of age yielded no differences in BW at 56 d of age. Calves fed 0.681 kg of the 26% CP and 17% fat MR gained 51% more BW, consumed 24% more starter, were 33% more efficient, and gained 59% more hip width than calves fed 0.454 kg of the 20% CP and 20% fat MR over the 56-d trial.
LITERATURE CITED AOAC. 2000. Official Methods of Analysis. Vol. 1. 17th ed. Assoc. Off. Anal. Chem., Arlington, VA. Bar-Peled, U., B. Robinzon, E. Maltz, H. Tagari, Y. Folman, I. Bruckental, H. Voet, H. Gacitua, and A. R. Lehrer. 1997. Increased weight gain and effects on production parameters of Holstein heifer calves that were allowed to suckle from birth to six weeks of age. J. Dairy Sci. 80:2523. Cowles, K. E., R. A. White, N. L. Whitehouse, and P. S. Erickson. 2006. Growth characteristics of calves fed an intensified milk replacer regimen with additional lactoferrin. J. Dairy Sci. 89:4835. Diaz, M. C., M. E. Van Amburg, J. M. Smith, J. M. Kelsey, and E. L. Hutten. 2001. Composition of growth of Holstein calves fed milk replacer from birth to 105-kilogram body weight. J. Dairy Sci. 84:830. FASS. 1999. Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. 1st rev. ed. Fed. Anim. Sci. Soc., Savoy, IL. Gabler, M. T., P. R. Tozer, A. J. Heinrichs, and T. Beck. 2007. Cost of Raising Replacement Dairy Heifers. http://www.das.psu.edu/ research-extension/dairy/nutrition/xls/coststo-raise-replacement-heifers.xls Accessed June 15, 2009. Greenwood, R. H., J. L. Morrill, and E. C. Titgermeyer. 1997. Using dry feed intake as a percentage of initial body weight as a weaning criterion. J. Dairy Sci. 80:2542. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2006a. Effects of feeding calves different rates and protein concentrations of twenty percent fat milk replacers on growth during the neonatal period. Prof. Anim. Sci. 22:252. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2006b. Effects of feeding rate and concentrations of protein
and fat of milk replacers fed to neonatal calves. Prof. Anim. Sci. 22:374. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2007a. Protein concentration for starters fed to transported neonatal calves. Prof. Anim. Sci. 23:123. Hill, T. M., H. G. Bateman II, J. M. Aldrich, and R. L. Schlotterbeck. 2007b. Effects of feeding rate of high protein milk replacers. Prof. Anim. Sci. 23:649. Hill, T. M., H. G. Bateman II, J. M. Aldrich, and R. L. Schlotterbeck. 2007c. Effects of feeding rate of milk replacers and bedding material for calves in a cold, naturally ventilated nursery. Prof. Anim. Sci. 23:656. Hill, T. M., H. G. Bateman, II, J. M. Aldrich, R. L. Schlotterbeck, and K. G. Tanan. 2008. Determination of the optimal amino acid concentration in milk replacers for calves less than five weeks of age. J. Dairy Sci. 91:2433. Jasper, J., and D. M. Weary. 2002. Effects of ad libitum milk intake on dairy calves. J. Dairy Sci. 85:3054. Kehoe, S. I., C. D. Dechow, and A. J. Heinrichs. 2007. Effects of weaning age and milk feeding frequency on dairy calf growth, health and rumen parameters. Livest. Sci. 110:267. NRC. 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Press, Washington, DC. Owen, F. G., and L. L. Larson. 1982. A simplified liquid feeding program for calves. J. Dairy Sci. 65:1350. Quigley, J. D., III, L. A. Caldwell, G. D. Sinks, and R. N. Heitmann. 1991. Changes in blood glucose, nonesterified fatty acids, and ketones in response to weaning and feed intake in young calves. J. Dairy Sci. 74:250. Strzetelski, J., B. Niwinska, J. Kowalezyk, and A. Jurkiewiez. 2001. Effect of milk replacer feeding frequency and level of concentrate intake and rearing performance of calves. J. Anim. Feed Sci. 10:413. Terre, M., M. Devant, and A. Bach. 2007. Effect of level of milk replacer fed to Holstein calves on performance during the preweaning period and starter digestibility at weaning. Livest. Sci. 110:82. USDA. 2002. Part I: Reference of dairy health and management in the United States, 2002. USDA, Anim. Plant Health Inspect. Serv., Vet. Serv., Centers for Epidemiol. Anim. Health, Natl. Anim. Health Monit. Sys., Fort Collins, CO. Wildman, E. E., G. M. Jones, P. E. Wagner, R. L. Boman, H. F. Trout Jr., and T. N. Lesch. 1982. A dairy cow body condition scoring system and its relationship to selected production characteristics. J. Dairy Sci. 65:495.
©2009 American Registry of Professional Animal Scientists
Effect of Weaning Age of Dairy Calves Fed a Conventional or More Optimum Milk Replacer Program T. M. Hill,1 H. G. Bateman II, J. M. Aldrich, PAS, and R. L. Schlotterbeck Akey, Nutrition and Research Center, Lewisburg, OH 45338
ABSTRACT Comparisons of different weaning ages of calves fed high-protein, high-feedingrate milk replacer (MR) programs have not been reported in the literature. Thus, the objectives of these trials were to compare the performance of calves fed either a conventional MR [0.454 kg of a 22% CP, 20% fat (as fed) MR powder daily; MR A] or a more optimum MR [0.681 kg of a 26% CP, 17% fat (as fed) MR powder daily; MR B] and weaning them at either 28 or 42 d. Trial 1 evaluated the weaning age of calves fed MR A or B. Trial 2 compared the weaning age of calves fed MR B. Holstein calves were fed an 18% CP starter and fresh water ad libitum throughout the 56-d trials. In trial 1, calves fed MR B had 50% greater ADG, consumed 24% more starter, were 13% more efficient, and had 68% more hip width change than calves fed MR A (P < 0.05). Calves weaned at 28 d consumed 36% more starter than calves weaned at d 42 (P < 0.05). In trial 2, calves weaned at 28 d consumed 25% more starter than calves weaned on d 42 (P < 0.05). Weaning age did not affect BW gain by 56 d in either trial. A metaanalysis of published data using MR B revealed that weaning age did not change 1
Corresponding author: [email protected].
ADG through d 56, but calves weaned at 28 d consumed more starter and had a lower feed efficiency than calves weaned at 42 d. Key words: calf, weaning age, milk replacer
INTRODUCTION Weaning age, with specific emphasis on early weaning (approximately 4 wk of age or less), to reduce feed and labor costs has received attention in research units for decades (Owen and Larson, 1982; Kehoe et al., 2007). However, the most recent US survey (USDA, 2002) reported the average weaning age of calves is 8.4 wk of age. There is a renewed interest in feeding more milk or milk replacer (MR) to calves (Diaz et al., 2001). However, this may be counterproductive to early weaning. When more milk or MR has been fed, weaning age has been at 6 wk of age or older, and a weaning and postweaning slump in growth has occurred (Bar-Peled et al., 1997; Jasper and Weary, 2002; Cowles et al., 2006; Hill et al., 2006a), which appears to be a function of reduced starter intake, feed efficiency, and digestion (Strzetelski et al., 2001; Jasper and Weary, 2002; Cowles et
al., 2006; Hill et al., 2006a; Terre et al., 2007). However, a program was developed recently to overcome this problem in calves weaned at 42 d of age (Hill et al., 2006b), in which a specifically formulated 26% CP, 17% fat MR was fed at only 0.681 kg powder/d (greater rates were unsuccessful; Hill et al., 2007b). However, this program has not been evaluated in calves weaned earlier than 42 d of age. Likewise, other research on early weaning calves fed high rates of milk or MR does not appear available in peer-reviewed form. The objectives of these trials were to compare the performance of calves fed daily a 22% CP, 20% fat MR fed at 0.454 kg powder (as fed) with a 26% CP, 17% fat MR fed at 0.681 kg powder (as fed) while being weaned at either 28 or 42 d. The hypothesis was that the calves fed the greater amount of MR would not perform as well as calves fed the lesser amount of MR because of difficulties with transitioning from MR to starter feed.
MATERIALS AND METHODS Trial 1 Calves were fed 1 of 2 MR in a 56-d trial. Milk replacer powder A was
620 22% CP and 20% fat (as fed) and was fed to calves at 0.454 kg powder/d (as fed), reconstituted to 0.12 kg/L. It was formulated based on the NRC (2001) calf submodel to be balanced in CP and energy at thermoneutral temperatures and to contain all whey protein and animal fat sources. Milk replacer powder B was 26% CP and 17% fat (as fed) and was fed to calves at 0.681 kg powder/d (as fed), reconstituted to 0.148 kg/L. It was formulated based on published research showing increased calf ADG without reduced starter intake compared with a conventional MR in a 42-d weaning program (Hill et al., 2006b). The NRC (2001) calf submodel predicted energy-limiting ADG of 42-kg BW calves at thermoneutral temperatures to be 0.21 kg/d with MR A and 0.53 kg/d with MR B. Protein-limited ADG were predicted to be 0.27 kg/d with MR A and 0.55 kg/d with MR B. Formulas of the MR are shown in Table 1. For a 42-d weaning, the MR for each program was halved into a.m.
Hill et al.
and p.m. feedings for 39 d, followed by only an a.m. feeding for d 40 to 42. For 28-d weaning, the MR for each program was halved into a.m. and p.m. feedings for 25 d, followed by only an a.m. feeding for d 26 to 28. This resulted in 4 treatments of MR management. The starter was a complete pellet (Table 2). All calves received ad libitum fresh water and starter beginning on arrival. Approximately 110% of the estimated feeds needed were manufactured at one time. Samples of manufactured feeds were collected from every other bag (22.7 kg) of feed at the time of manufacture. Composites of the MR were analyzed (AOAC, 2000) before the animal phase of the trial for DM (oven method 930.15), CP (Keldahl method 988.05), fat (alkaline treatment with Roese-Gottlieb method 932.06), ash (muffle furnace method 923.03), Ca, and P (dry ashing, acid digestion, analysis by inductively coupled plasma spectrometry, method 985.01). A composite of the starter
Table 1. Ingredient composition and assayed nutrients in milk replacers (MR) Trial 1 Item Ingredient, % (as fed) Whey (12% CP) Dry fat (7% CP, 60% fat) Whey protein concentrate (78% CP) Lecithin based emulsifier Mineral-vitamin premix Decoquinate premix1 (0.5%) Flow agent Flavor Dry fat (12% CP, 26% fat) dl-Met l-Lys Nutrient, % of DM DM Protein Fat Ash Ca P ME,2 Mcal/kg 1
Alpharma Inc. (Fort Lee, NJ).
2
Calculated using NRC (2001) equations.
Trial 2
MR A
MR B
MR
48.7 27.0 19.0 2.0 1.2 1.0 0.9 0.2 0.0 0.0 0.0
45.8 21.0 23.0 2.6 1.1 0.7 0.9 0.2 4.0 0.4 0.3
45.8 21.0 23.0 2.6 1.1 0.7 0.9 0.2 4.0 0.4 0.3
96.4 23.1 21.0 6.66 0.82 0.64 4.8
96.2 27.2 17.7 5.99 0.77 0.60 4.8
96.5 27.0 17.8 5.62 0.81 0.63 4.8
was analyzed for DM, CP, ash, Ca, and P. Holstein bull calves (n = 48) were received in the late afternoon from multiple dairy farms at less than 7 d of age after a 10-h transit and immediately were fed 0.227 kg of electrolyte and nutrient powder (Critical Care, Akey, Lewisburg, OH) reconstituted to 1.8 L with warm water. The following a.m. feeding consisted of 0.284 kg (as fed) powder of MR B reconstituted to 1.8 L with warm water. The day after arrival, at approximately noon, the calves were weighed, measured with a caliper for hip widths, scored for body condition, and after sampling blood intravenously for serum protein via a refractometer (ATAGO US Inc., Bellevue, WA), they were randomly assigned to treatment (d 0, initial measurement). Calf BW was measured weekly at approximately noon. Hip widths and BCS were measured every 14 d. Calf BCS was based on a 1 to 5 system using 0.25 unit increments, with 1 being emaciated and 5 being obese (Wildman et al., 1982). Scores were based on changes around the vertical and transverse processes of the spine as palpated by one experienced technician, and ranged from 1.5 to 3.5. Fecal scores were assigned daily based on a 1 to 5 system (1 being normal, thick in consistency; 2 being normal but less thick; 3 being abnormally thin but not watery; 4 being watery; 5 being watery with abnormal coloring). Vaccines and medical treatments were based on the recommendations of a veterinarian and are described in Hill et al. (2006a). Calves were housed in a curtainsided, naturally ventilated barn with no added heat in 1.2 × 2.4 m pens bedded with straw. This trial was conducted from May through July. Based on hourly measurements, the average temperature in the barn was 21°C, with a range of 8 to 31°C. All animals were cared for by acceptable practices as described in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999).
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The data were analyzed as a completely randomized design in a 2 × 2 factorial arrangement. Factors were MR and weaning age. The analysis was performed using the GLM procedure (SAS Institute Inc., Cary, NC), using a mixed model as repeated measures with an autoregressive type 1 covariance structure. Data reported are least squares means. The experimental unit was the calf.
Trial 2 Calves were fed one MR in a 56-d trial. The MR powder was 26% CP and 17% fat and was fed to calves at 0.681 kg/d (as-fed basis) reconstituted to 0.148 kg/L. This MR was the same as MR B in trial 1 (Table 1). Weaning management was the same as in trial 1. The starter was a textured feed (Table 2). All calves received ad libitum fresh water and starter beginning on arrival. Feeds were manufactured and analyzed as in trial 1. Holstein bull calves (n = 48) were received at approximately noon from one dairy farms at 2 to 5 d of age after a 3.5-h transit. Their first MR was fed at the p.m. feeding. The day after arrival at approximately noon, the calves were weighed, measured with a caliper for hip widths, and scored for BCS, and then blood was sampled intravenously for serum protein via a refractometer (ATAGO US Inc.); they were then randomly assigned to treatment (d 0, initial measurement). Measurements were as described in trial 1. Calves were housed a curtain-sided, naturally ventilated barn with no added heat in 1.2 × 2.4 m pens bedded with straw. This trial was conducted September to November. Based on hourly measurements, the average temperature in the barn was 11°C, with a range in temperature of −7 to 29°C. All animals were cared for by acceptable practices as described in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999). The data were analyzed as a completely randomized design. The analy-
sis was performed using the GLM procedure as in trial 1.
Meta-analysis Results from 14 treatment means using 438 calves were compiled and used in a meta-analysis to better estimate the impact of weaning age on ADG, starter intake, and feed efficiency. The data for this analysis were taken from published trials conducted by our research group. All data were collected from Holstein calves initially 2 to 3 d old. All calves were used in trials with nondirect comparisons of feeding a similar 26% CP and 17% fat MR at 0.681 kg/d and weaned at either 28 or 42 d. Treatment means for ADG, starter intake, and feed efficiency were used in a mixed model. The model contained a term for the fixed effect of weaning age and the random effect of trial.
RESULTS AND DISCUSSION No calves died or were removed from either trial. All medical treatments were due to scouring. Initial measurements did not differ (P > 0.05) among treatments (Tables 3 and 4). All calves weaned on their designed weaning dates without complications. In trial 1, there were no interactions of the main effects (MR and weaning age) over the 56-d trial. Calves fed MR B had 50% greater ADG, consumed 24% more starter, were 13% more efficient, and had 68% more hip width change than calves fed MR A (P < 0.05). Calves weaned at 28 d consumed 36% more starter than calves weaned on d 42 (P < 0.05). Other measures did not differ between the weaning ages of 28 or 42 d. In trial 2, calves weaned at 28 d consumed 25% more starter than calves weaned on d 42 (P < 0.05) over the 56-d trial. Other measures did not differ between weaning ages of 28 or 42 d. Greenwood et al. (1997) weaned calves based on starter intakes of 10, 15, or 20 g/kg of initial BW, which resulted in weaning ages of 32, 43, or
Table 2. Ingredient composition and assayed nutrients in starters Item Ingredient, % (as fed) Corn Soybean meal Wheat middlings Minerals and vitamins Molasses Animal fat Pellet binder Decoquinate3 (0.5%) Oats Decoquinate3 (6%) Nutrient, % of DM DM Protein Fat Ash Ca P ME,4 Mcal/kg 1
Trial 11 Trial 2
53.90 24.30 14.00 2.80
37.00 7.802 23.702 2.802
2.50 1.00 1.00 0.50
3.00 0.352 0.302 0.00
0.00 0.00
25.00 0.052
87.4 20.9 3.8 6.4 0.93 0.66 3.1
87.9 20.6 3.7 6.1 0.94 0.71 3.1
Starter was a complete pellet.
These ingredients were pelleted as the supplement within the textured starter.
2
3
Alpharma Inc. (Fort Lee, NJ).
Calculated using NRC (2001) equations.
4
45 d, respectively, and similar BW gains up to 20 wk of age among all 3 groups. Calves weaned at 10 g of starter/kg initial BW consumed the most starter from 0 to 8 wk. Quigley et al. (1991) weaned calves from milk (1.8 kg/d per head) at either 28 or 56 d of age. They reported no differences in rate of BW gain because of weaning age, and calves weaned at 28 d consumed more starter but similar total amounts of DM over the 98-d trial. Hill et al. (2007a) weaned calves at 28 d from a 20% CP and 20% fat MR powder and reported them to have similar ADG, more starter intake, and lower feed efficiency from 0 to 56 d than calves weaned at 42 d. Owen and Larson (1982) reported statistically similar but numerically lower ADG during the first 8 wk of
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Table 3. Summary of 0- to 56-d performance from feeding a 22% CP and 20% fat milk replacer (MR) at 0.454 kg powder/d (as fed; MR A) or a 26% CP and 17% fat MR at 0.681 kg powder/d (as fed; MR B) and weaning at 28 or 42 d in trial 1 28-d weaning
42-d weaning
Main effect P-value
Item
MR A
MR B
MR A
MR B
SEM
MR
Weaning day
Calves, n Initial serum protein, mg/dL Initial BW, kg Final BW, kg ADG, kg/d Starter DMI, kg/d MR DMI, kg/d Feed efficiency2 Fecal score3 Abnormal fecal score days, n Initial hip width, cm Hip width change, cm Initial BCS4 BCS change Predicted ADG,5 kg/d Energy-limited Protein-limited
12 5.3 39.1 61.4 0.397 0.595 0.207 0.495 1.4 8.7 17.5 2.5 2.1 0.4
12 5.2 39.0 70.2 0.558 0.750 0.310 0.526 1.5 9.1 17.7 3.6 2.2 0.6
12 5.3 39.1 59.8 0.370 0.444 0.317 0.487 1.4 9.3 17.4 2.2 2.1 0.4
12 5.3 39.1 72.7 0.600 0.545 0.474 0.589 1.4 8.7 17 4.3 2.1 0.7
— 0.2 1.1 1.9 0.03 0.074 — 0.021 0.04 1.0 0.45 0.29 0.08 0.1
— <0.93 <0.80 <0.02 <0.01 <0.01 — <0.02 <0.93 <0.56 <0.95 <0.02 <0.99 <0.09
— <0.87 <0.29 <0.44 <0.89 <0.01 — <0.11 <0.85 <0.74 <0.76 <0.98 <0.96 <0.68
0.30 0.39
0.57 0.61
0.34 0.40
0.63 0.67
— —
— —
— —
1
There were no interactions of main effects in this trial.
2
Gain divided by DMI from MR plus starter.
Fecal scoring system: 1 = normal, thick in consistency; 2 = normal but less thick; 3 = abnormally thin but not watery; 4 = watery; 5 = watery with abnormal coloring. Abnormal fecal scores were days with scores >2.
3
4
Using 1 to 5 system, with 1 = emaciated and 5 = obese.
Predicted using NRC (2001) based on the average trial temperature of 21°C, 50 kg BW, and the average MR and starter intakes of the treatments listed in the table.
5
age for calves weaned at 21 vs. 42 d; however, ADG at subsequent ages and first-lactation milk yield were virtually identical. These results from other trials and the current 2 trials are all consistent with calves being of similar BW by approximately 56 d of age regardless of weaning age, whereas earlier weaning results in more starter intake. The calf submodel in NRC (2001) was used to predict energy- and protein-limited ADG based the average trial temperatures, average MR intake and composition, average starter intake and composition, and a 50-kg BW in trial 1 and a 60-kg BW in trial 2. In both trials, energy-limited ADG was lower than protein-limited ADG. In trial 1, differences in predicted and observed ADG between MR were similar, with the model predicting a greater difference in ADG than was
observed. Predicted ADG was greater for calves weaned at 42 versus 28 d in both trials. Calves in trial 1 fed MR B, the 26% CP and 17% fat MR, appeared to have greater ADG (0.579 vs. 0.517 kg/d) than calves in trial 2. Calves in trial 1 had initially lower BW (39.1 vs. 45.5 kg), had greater serum protein concentrations (5.3 vs. 4.8 mg/dL), and were in greater average environmental temperatures (21 vs. 11°C) than calves in trial 2. The MR were fed at a fixed rate, not as a percentage of BW; thus, the lighter BW calves in trial 1 were consuming more energy above maintenance than calves in trial 2, and this intake relative to maintenance requirements may explain the apparent difference. Comparison of the predicted ADG using the calf submodel in NRC (2001) shows the same apparent difference
of calves in trial 2 having greater predicted ADG than calves in trial 1. Calves in trial 2 were much healthier than calves in trial 1, as evidenced by their lower number of abnormal fecal score days (0.2 vs. 8.9 d). The opposite tendency of calves in trial 1 to have a lower average fecal score (1.4 vs. 2.1) than calves in trial 2 is confusing and possibly misleading because calves in trial 2 had almost no days of a score 1. Both fecal scores of 1 and 2 were considered normal but different, and a fecal score of 3, 4, or 5 was considered abnormal. Comparison of results between in trials 1 and 2 could be misleading because of these various trial effects of BW, health status, environmental temperatures, and other unknown issues. No other direct comparisons of weaning age of high-protein, highfeeding-rate MR could be found in
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Table 4. Summary of 0- to 56-d performance from feeding a 26% CP and 17% fat milk replacer (MR) at 0.681 kg powder/d (as fed) and weaning at 28 or 42 d in trial 2 Item
28-d weaning 42-d weaning
Calves, n Initial serum protein, mg/dL Initial wt, kg Final wt, kg ADG, kg/d Starter DMI, kg/d MR DMI, kg/d Feed efficiency1 Fecal score2 Abnormal fecal score days, n Initial hip width, cm Hip width change, cm Initial BCS3 BCS change Predicted ADG,4 kg/d Energy-limited Protein-limited 1
SEM
P-value
24 4.8 45.6 73.8 0.503 0.773 0.308 0.465 2.0 0.2 18.7 3.9 2.3 0.3
24 4.7 45.4 75.2 0.531 0.615 0.475 0.487 2.1 0.2 19.0 3.9 2.4 0.3
— 0.1 1.2 2.3 0.022 0.046 — 0.022 0.01 0.01 0.1 0.01 0.02 0.01
— <0.90 <0.77 <0.71 <0.37 <0.003 — <0.36 <0.44 <0.84 <0.09 <0.31 <0.12 <0.34
0.41 0.61
0.50 0.69
— —
— —
Gain divided by DMI from MR plus starter.
Fecal scoring system: 1 = normal, thick in consistency; 2 = normal but less thick; 3 = abnormally thin but not watery; 4 = watery; 5 = watery with abnormal coloring. Abnormal fecal scores were days with scores >2.
2
3
Using a 1 to 5 system with 1 = emaciated and 5 = obese.
Predicted using NRC (2001) based on the average trial temperature of 11°C, 60 kg BW, and the average MR and starter intakes of the treatments listed in table.
4
the literature. In Table 5, treatment means from 438 calves are shown from nondirect comparisons of feeding a 26% CP and 17% fat MR at 0.681 kg/d and weaning at either 28 or 42 d. All these means were published data from our research unit. Other data of this type were not found in the literature. These data were subjected to a meta-analysis and, similar to the current trials, the mean ADG from 0 to 56 d of calves weaned at 28 d was not different (P < 0.12), but numerically was 9% less than the mean of calves weaned at 42 d. In addition, similar to trials 1 and 2, the mean starter intake was greater (P < 0.01) in calves weaned at 28 compared with those weaned at 42 d, and feed efficiency of calves weaned at 28 d was less (P < 0.01) than that of calves weaned at 42 d. Regardless of treatment or trial, all calves were weaned at their assigned weaning date without issues of poor starter intake, slumps in ADG postweaning, or health challenges. In contrast to previous trials in which additional milk or MR was fed that
Table 5. Summary and meta-analysis of 0- to 56-d ADG, starter intake, and feed efficiency in 438 calves fed a 26% CP and 17% fat milk replacer at 0.681 kg powder/d (as fed) and weaned at either 28 or 42 d1 Reference Hill et al. (2007a) Hill et al. (2007a) Hill et al. (2007c) Hill et al. (2008) Hill et al. (2008) Hill et al. (2008) Hill et al. (2008) Hill et al. (2006b) Hill et al. (2007a) Hill et al. (2007a) Hill et al. (2007b) Hill et al. (2007b) Hill et al. (2007b) Hill et al. (2007c) 7-trial average 7-trial average SEM P-value
Trial in reference
Weaning day
Calves, n
ADG, kg/d
Starter DMI, kg/d
Feed efficiency2
5 6 2 1 2 3 4 3 3 4 1 2 3 3 — — — —
28 28 28 28 28 28 28 42 42 42 42 42 42 42 28 42 — —
48 48 32 24 16 32 48 12 50 48 16 24 24 16 248 190 — —
0.550 0.556 0.644 0.677 0.602 0.605 0.724 0.688 0.783 0.593 0.727 0.593 0.714 0.697 0.623 0.685 0.025 <0.12
0.813 0.797 0.842 0.896 0.882 0.894 1.118 0.715 0.760 0.556 0.742 0.555 0.719 0.704 0.892 0.679 0.040 <0.01
0.491 0.503 0.560 0.563 0.506 0.503 0.508 0.578 0.634 0.575 0.597 0.576 0.598 0.591 0.519 0.593 0.026 <0.01
1
These results are not from direct comparisons of weaning age and represent different environmental and calf conditions.
2
Gain divided by DMI from milk replacer plus starter.
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showed a weaning or postweaning slump (Bar-Peled et al., 1997; Jasper and Weary, 2002; Cowles et al., 2006; Hill et al., 2006a), none occurred in this study. Results in trials 1 and 2 were consistent with meta-analysis of the literature (Table 5) using the same 26% CP and 17% fat MR powder fed at 0.681 kg powder daily in calves weaned at 28 or 42 d of age. The only trial to report management issues with early weaning was Kehoe et al. (2007), who compared weaning at 3, 4, 5, and 6 wk of age. They reported that calves weaned at 3 wk of age required more attention to stimulate starter intake than calves weaned at the older ages. Producers and advisors can use these results to predict costs per calf and per unit of BW gain between 28- and 42-d weaning programs. The cost per kilogram of BW gain should be lower even with a modest potential BW loss from weaning at d 28 versus d 42 with a 26% CP and 17% fat MR powder because of the higher cost of MR powder compared with starter. Additionally, they can apply labor differences and costs. For example, one estimate of labor costs for the preweaned calf is $1.35 daily (Gabler et al., 2007). Thus, a reduction of 14 d of labor is $18.95/calf. Labor savings alone might justify weaning early in this type of MR program. However, these results should not be extrapolated to MR programs feeding more than 0.681 kg/d of MR powder because early weaning research results have not been reported for those MR programs.
IMPLICATIONS Calves fed either a conventional MR [0.454 kg of a 22% CP, 20% fat (as fed) MR powder daily] or a more optimal growth MR [0.681 kg of a 26% CP, 17% fat (as fed) MR powder daily] had similar ADG from 0 to 56 d when weaned at either 28 or 42 d. With each MR, starter intake was greater when calves were weaned at
28 d compared with 42 d. A metaanalysis of feeding 0.681 kg of a 26% CP and 17% fat (as fed) MR powder daily and weaning at 28 versus 42 d of age yielded no differences in BW at 56 d of age. Calves fed 0.681 kg of the 26% CP and 17% fat MR gained 51% more BW, consumed 24% more starter, were 33% more efficient, and gained 59% more hip width than calves fed 0.454 kg of the 20% CP and 20% fat MR over the 56-d trial.
LITERATURE CITED AOAC. 2000. Official Methods of Analysis. Vol. 1. 17th ed. Assoc. Off. Anal. Chem., Arlington, VA. Bar-Peled, U., B. Robinzon, E. Maltz, H. Tagari, Y. Folman, I. Bruckental, H. Voet, H. Gacitua, and A. R. Lehrer. 1997. Increased weight gain and effects on production parameters of Holstein heifer calves that were allowed to suckle from birth to six weeks of age. J. Dairy Sci. 80:2523. Cowles, K. E., R. A. White, N. L. Whitehouse, and P. S. Erickson. 2006. Growth characteristics of calves fed an intensified milk replacer regimen with additional lactoferrin. J. Dairy Sci. 89:4835. Diaz, M. C., M. E. Van Amburg, J. M. Smith, J. M. Kelsey, and E. L. Hutten. 2001. Composition of growth of Holstein calves fed milk replacer from birth to 105-kilogram body weight. J. Dairy Sci. 84:830. FASS. 1999. Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. 1st rev. ed. Fed. Anim. Sci. Soc., Savoy, IL. Gabler, M. T., P. R. Tozer, A. J. Heinrichs, and T. Beck. 2007. Cost of Raising Replacement Dairy Heifers. http://www.das.psu.edu/ research-extension/dairy/nutrition/xls/coststo-raise-replacement-heifers.xls Accessed June 15, 2009. Greenwood, R. H., J. L. Morrill, and E. C. Titgermeyer. 1997. Using dry feed intake as a percentage of initial body weight as a weaning criterion. J. Dairy Sci. 80:2542. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2006a. Effects of feeding calves different rates and protein concentrations of twenty percent fat milk replacers on growth during the neonatal period. Prof. Anim. Sci. 22:252. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2006b. Effects of feeding rate and concentrations of protein
and fat of milk replacers fed to neonatal calves. Prof. Anim. Sci. 22:374. Hill, T. M., J. M. Aldrich, R. L. Schlotterbeck, and H. G. Bateman II.. 2007a. Protein concentration for starters fed to transported neonatal calves. Prof. Anim. Sci. 23:123. Hill, T. M., H. G. Bateman II, J. M. Aldrich, and R. L. Schlotterbeck. 2007b. Effects of feeding rate of high protein milk replacers. Prof. Anim. Sci. 23:649. Hill, T. M., H. G. Bateman II, J. M. Aldrich, and R. L. Schlotterbeck. 2007c. Effects of feeding rate of milk replacers and bedding material for calves in a cold, naturally ventilated nursery. Prof. Anim. Sci. 23:656. Hill, T. M., H. G. Bateman, II, J. M. Aldrich, R. L. Schlotterbeck, and K. G. Tanan. 2008. Determination of the optimal amino acid concentration in milk replacers for calves less than five weeks of age. J. Dairy Sci. 91:2433. Jasper, J., and D. M. Weary. 2002. Effects of ad libitum milk intake on dairy calves. J. Dairy Sci. 85:3054. Kehoe, S. I., C. D. Dechow, and A. J. Heinrichs. 2007. Effects of weaning age and milk feeding frequency on dairy calf growth, health and rumen parameters. Livest. Sci. 110:267. NRC. 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Press, Washington, DC. Owen, F. G., and L. L. Larson. 1982. A simplified liquid feeding program for calves. J. Dairy Sci. 65:1350. Quigley, J. D., III, L. A. Caldwell, G. D. Sinks, and R. N. Heitmann. 1991. Changes in blood glucose, nonesterified fatty acids, and ketones in response to weaning and feed intake in young calves. J. Dairy Sci. 74:250. Strzetelski, J., B. Niwinska, J. Kowalezyk, and A. Jurkiewiez. 2001. Effect of milk replacer feeding frequency and level of concentrate intake and rearing performance of calves. J. Anim. Feed Sci. 10:413. Terre, M., M. Devant, and A. Bach. 2007. Effect of level of milk replacer fed to Holstein calves on performance during the preweaning period and starter digestibility at weaning. Livest. Sci. 110:82. USDA. 2002. Part I: Reference of dairy health and management in the United States, 2002. USDA, Anim. Plant Health Inspect. Serv., Vet. Serv., Centers for Epidemiol. Anim. Health, Natl. Anim. Health Monit. Sys., Fort Collins, CO. Wildman, E. E., G. M. Jones, P. E. Wagner, R. L. Boman, H. F. Trout Jr., and T. N. Lesch. 1982. A dairy cow body condition scoring system and its relationship to selected production characteristics. J. Dairy Sci. 65:495.