Effects of the carbohydrate and protein compositions in the milk replacer on the growth performance and gastrointestinal development of the Holstein calves from 35–70 days of age

Abstract

The study was designed to determine whether carbohydrate and protein compositions in milk replacer (MR) could influence growth performance, incidence of diarrhea, serum metabolites, and gastrointestinal development in Holstein calves from 35 to 70 days of age. Forty Holstein calves (d 28; 25 female calves, 56.14 ± 2.24 kg body weight; 15 male calves, 58.93 ± 3.41 kg body weight) were randomly assigned to 4 MR treatments and 1 control treatment (5 female calves and 3 male calves per treatment). The MR treatments represented a 2 × 2 factorial arrangement of carbohydrate composition (L1, the ratio of glucose to lactose was 0.03; L2, the ratio of starch and glucose to lactose was 0.25) and protein composition (the ratio of a combination of wheat protein and soybean protein to whey proteins was 0.87 in WP1 and 1.87 in WP2). Calves were fed whole milk (WM) in the control treatment. The transition period of MR was from d 28 to d 34, and then calves received 12 L/d of liquid feed from d 35 to d 50. The transition period of weaning was from d 51 to d 60. Calves were weaned at d 60 and female calves remained until d 70. Nine male calves from the L1WP2, L2WP2, and WM treatments (n = 3/treatment) were selected at weaning for slaughter. There were no differences in growth performance among MR treatments. The starter intake was affected by the interaction of L × day (P < 0.01). There were differences in weaning withers height with carbohydrate composition (P = 0.047) and final body length with protein composition (P = 0.03). The WP2-fed calves had a lower incidence of diarrhea than those fed WP1 (P = 0.01). The L2WP2 treatment had a superior rumen papillae length than other treatments (P < 0.01). The L1WP2 treatment had a higher ileum villus length than other treatments (P = 0.01). Overall, during the period from d 35 to d 70, the partial substitution of lactose with starch plus glucose in MR benefits in the developments of rumen and pre-weaning withers height; the partial replacement of whey proteins with plant proteins in MR improved the development of post-weaning body length. Moreover, the combined plant proteins, starch, and glucose for inclusion in MR had no significant negative impact on the development of the small intestine of the calves.