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Effect of dietary energy source replacement in calf milk replacer fed ad libitum on voluntary feed intake and performance in dairy calves.

J. Echeverry-Munera

Abstract:

143
Effect of dietary energy source replacement in calf milk replacer fed ad libitum on voluntary feed intake and performance in dairy calves.
J. Echeverry-Munera*1,2, L. Leal2, J. Wilms2, H. Berends2, M. A. Steele1, J. Martin-Tereso2. 1University of Guelph Guelph, ON, Canada, 2Trouw Nutrition Amersfoort, the Netherlands.

Compared with whole milk, most commercial calf milk replacers (MR) deliver relatively high levels of lactose (42—45 vs. 35% inclusion), low levels of fat (18—20 vs. 30%), and protein levels that are rather comparable (~23%), resulting in lower energy density and energy to protein ratio of the diet. Thus, the study objective was to determine the effect of exchanging lactose by fat in MR on voluntary feed intake and growth performance. Thirty-two Holstein bull calves (2.1 � 0.16 d of age, 46.4 � 0.77 kg BW) were assigned to 1 of 16 blocks based on arrival date and serum IgG. Within each block, calves were randomly assigned to 1 of 2 treatments: High lactose MR (HL, 18% fat; n = 16), or high fat MR (HF, 24% fat; n = 16). Lactose was exchanged by fat on a wt/wt basis, resulting in a different energy content. The experiment was divided into 3 phases: Pre-weaning (P1; 0—35 d), weaning (P2; 36—63 d) and post-weaning (P3; 64—84 d). In P1, calves were initially housed in individual pens and fed their respective MR ad libitum through teat buckets and water through plain bucket. After 2 weeks, calves were group-housed (8 calves/ pen; 4 blocks) and fed ad libitum MR, starter feed, chopped wheat straw, and water via automated feeders. During P2, calves were gradually weaned until d-63. Measurements included intakes and BW. Data was analyzed by PROC MIXED in SAS accounting for the fixed effects of treatment, time, and their interaction, as well as the random effect of block. Measurements over time entered the model as repeated measures. Increasing fat content at the expense of lactose decreased MR intake during P1 by 15% (HL = 8.8; HF = 7.6 L/d), whereas total starter intake was not affected by MR composition (HL = 1.8; HF = 1.7 kg/d). Average daily gain (ADG) was higher for HL calves during P1 (0.837 vs. 0.729 g/d); however, no differences were found during P2 or P3. Final BW (d-84) did not differ between treatments. In conclusion, calves fed ad libitum seem to regulate their MR intake based on energy content of the diet, without significant effects on solid feed intake and overall BW.

Keywords: milk replacer, lactose, fat.

Biography: I was born and raised on a mixed farm in Medellin, Colombia. At a young age, I developed an interest in horses and dairy cattle. At the age of 14, I moved to Canada and attended the University of Alberta, Edmonton, from where I received my B.Sc. in 2019. During my B.Sc. I spent 4 months at Wageningen University, the Netherlands taking courses, and doing collaborative work with Trouw Nutrition. Currently, I am a M.Sc. student at the University of Guelph, under Dr. Michael Steele supervision and continue doing collaborative research with Trouw Nutrition in the Netherlands.