Abstract #M141

# M141
Effect of weaning program and milk feeding level on the solid feed intakes and growth of dairy calves.
S. D. Parsons*1, K. E. Leslie2, M. A. Steele1, D. L. Renaud2, T. J. DeVries1, 1Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada, 2Department of Population Medicine, University of Guelph, Guelph, ON, Canada.

The objective of this study was to investigate how gradual weaning programs affect feed intakes and growth of dairy calves during the milk-feeding (d 1–29), weaning (d 30–45) and post-weaning phases (d 46–59) when fed different levels of milk. 84 Holstein bull calves were housed individually and randomly assigned to 1 of 4 treatments in a factorial design: high level of milk (HIGH; 35 kg of 21:19 milk replacer over 45d) or a low level of milk (LOW; 25 kg of 21:19 milk replacer over 45d) and either a 2-step weaning program (2S) or a 4-step weaning program (4S). From d 30–45, the 2S calves had 2 reductions in their milk, while 4S calves had 4 reductions in their milk. All calves received no milk starting on d 46 and were monitored until d59. All calves had ad libitum water access starting on d 1, and a starter ration from d 5. Solid feed and milk intakes were recorded daily, and BW was measured on d 2, 30, 38, 46, 52 and 59. Data were summarized by phase and analyzed using repeated measures generalized linear mixed models. There was no interaction between milk level and weaning treatments for any outcome. On average, LOW calves consumed more feed than HIGH calves during the milk-feeding (0.5 vs. 0.3 kg/d; SE = 0.04; P < 0.01), and weaning (1.6 vs. 1.2 kg/d; SE = 0.08; P = 0.02) phase. HIGH and LOW calves consumed similar amounts of feed in the post-weaning phase (HIGH = 2.2kg/d, LOW = 2.4kg/d; SE = 0.14; P = 0.13). Growth rates did not vary between milk treatments during the milk-feeding (HIGH = 0.6kg/d, LOW = 0.5kg/d; SE = 0.03; P = 0.4) and post-weaning (HIGH = 0.8kg/d, LOW = 0.8kg/d, SE = 0.10; P = 0.6) phases. During weaning, on average, LOW calves tended to have higher growth than HIGH calves (0.9kg/d vs 0.8kg/d; SE = 0.05; P = 0.09). Feed intakes were similar for weaning treatments during the weaning (2S = 1.4kg/d, 4S = 1.4kg/d; SE = 0.09; P = 0.9) and post-weaning (2S = 2.3kg/d, 4S = 2.3kg/d; SE = 0.14; P = 0.92) phases. Growth did not vary by weaning treatment for the weaning (2S = 0.8kg/d, 4S = 0.8kg/d; SE = 0.05; P = 0.7) or post-weaning (2S = 0.7kg/d, 4S = 0.9kg/d; SE = 0.10; P = 0.2) phases. Overall, the results indicate that the milk feeding level may impact solid feed consumption and growth during the weaning phase, while the weaning treatments did not affect feed consumption or growth.

Key Words: dairy calf, weaning, growth