Abstract #158

# 158
Gradual weaning affects pre- and postweaning feed intake, growth, and gastrointestinal development in Holstein calves fed an elevated plane of nutrition during the pre-weaning stage.
Michael A. Steele*1,2, Leonel Leal3, Michelle Carson1, John H. Doelman1, John A. Metcalf1, 1Nutreco Canada AgResearch, Guelph, Ontario, Canada, 2University of Alberta, Edmonton, Alberta, Canada, 3Nutreco Research and Development, Boxmeer, the Netherlands.

The short and long-term benefits of feeding elevated quantities of milk have been recently been established and these feeding strategies have been implemented in many production systems worldwide. The objective of this study was to characterize the effect of abrupt and gradual weaning when calves are fed an elevated plane of nutrition (1.35 kg/d milk replacer) in a twice-daily feeding scheme. At total of 55 calves were randomly assigned to treatments of abrupt (0 d step-down) or gradual (12 d step-down) weaning at 48 d of life. Calves were housed and sampled in individual pens for the duration of the experiment. Milk, starter, straw and water intake was measured on a daily basis. Bodyweight was measured every 6 d until d 35 and every 3 d thereafter, while blood, rumen fluid and fecal matter was collected on d 35, 48 and 54 of the experiment. Although the growth rates of the step-down calves were lower from d 35 to weaning (0.48 ± 0.08 vs. 1.00 ± 0.10 kg/d; P < 0.01), the post-weaning average daily gain was greater compared with the abruptly weaned group (0.86 ± 0.12 vs. 0.15 ± 0.10 kg/d; P < 0.01). Total rumen volatile fatty acid concentration was greater in the step-down group compared with the abrupt group on the day of weaning on d 48 (76.84 ± 1.28 vs. 46.72 ± 0.78 mmol; P < 0.01). Fecal starch percentage was lower postweaning compared with the abruptly weaned calves on d 54 (2.97 ± 1.28 vs. 6.67 ± 1.22%; P < 0.05), whereas serum amyloid A concentration was not affected by weaning strategy. These results showcase the benefits of a step-down feeding scheme from an overall energy balance standpoint in twice daily feeding schemes, presumably due to the increased opportunities for the gut to adapt before weaning.

Key Words: calf, weaning, development