Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2008
Publication Date: 8/1/2008
Citation: Hill, S.R., Knowlton, K.F., Daniels, K.M., James, R.E., Pearson, R.E., Capuco, A.V., Akers, R.M. 2008. Effects of Milk Replacer Composition on Growth, Body Composition, and Nutrient Excretion in Pre-weaned Holstein Heifers. Journal of Dairy Science. 91(8):3145-3155. Interpretive Summary: We evaluated growth, nutrient utilization, and body composition in calves fed diets varying in protein and fat content. Calves fed a standard milk replacer ate more grain than calves fed more nutrient-dense diets, but had poorest gain and greatest feces excretion. Addition of protein to standard milk replacer improved calf growth and nutrient retention, but few additional benefits were observed with added fat. Finally, our data on nutrient manure excretion indicate that current regulations for concentrated animal feeding operations (CAFO) are more stringent for calf growers than for producers with lactating cows.
Technical Abstract: Twenty-four newborn Holstein heifer calves were fed one of 4 diets: CON (20% CP, 21% fat milk replacer (MR), fed at 441 g/d); HPLF (28% CP, 20% fat MR, fed at 951 g/d); HPHF (27% CP, 28% fat MR fed at 951 g/d); and HPHF+ (27% CP, 28% fat MR fed at 1431 g/d). Calves were obtained from a commercial dairy. Upon arrival at the research farm, calves were fed CON for two feedings. On d 3, treatments were imposed and calf starter (20% CP, 1.43% fat), comprised of ground corn (44.4%), 48% CP soybean meal (44.4%), cottonseed hulls (11.2%), and molasses (1.0%), was offered free choice. Body weight and body size measures were taken weekly. Calves were harvested at 63 d to evaluate body composition. Preplanned contrasts were used to compare CON to all, HPLF to HPHF, and HPHF to HPHF+. Calves fed CON consumed more starter than those fed other treatment diets but their total DMI and apparent DM digestibility were lowest. Fecal output was highest in calves fed CON while urine output and urine nitrogen (N) excretion were lowest. Nitrogen intake and urine N excretion were higher for calves fed HPHF+ compared to HPHF, but were not affected by fat content (HPHF vs. HPLF). Retention (g/d) of N and phosphorus (P) were higher in calves fed all nutrient-dense diets compared to those fed CON, but were not improved by increasing fat in the milk replacer (HPLF vs. HPHF) or by increasing the amount fed. Addition of fat to the milk replacer (HPLF vs. HPHF) increased EBW fat percentage and fat gain, and decreased body length and ash gain. Increasing the volume fed (HPHF vs. HPHF+) increased growth rate and empty body weight, but HPHF+ calves were not taller or longer and their carcasses contained more fat. Clear improvements in growth and nutrient retention were observed with more nutrient-dense diets, but most of the improvements were seen with the increased protein intake relative to the control milk replacer; adding fat to the high protein replacer did not further improve lean tissue gain.