Performance and health responses of dairy calves offered different milk replacer allowances

Eighty female Holstein calves (12±4.1 d of age and 42±4.3 kg of BW) were collected from different herds, brought to the study site, and blocked by age and assigned to either a 6 L/d maximum daily milk replacer (MR) allowance (LMR) or a maximum MR allowance of 8 L/d (HMR). Calves were kept in individual hutches until 52 d of age and then moved into pens, forming groups of 10. All calves had ad libitum access to a mash starter feed. Calves in both treatments received the MR distributed in 3 separate allotments between 1 wk after the beginning of the study and 52 d of age. Then, all calves were moved to group pens and preweaned by offering 2 L/calf of the same MR twice daily in a trough until the age of 59 d, when MR offer was further reduced to a single dose of 2 L until the age of 73 d, when all calves were completely weaned. Individual starter feed and MR consumption was recorded on a daily basis until 52 d of age, and on a group basis until weaning time. Body weight was measured at the beginning of the study and at 52 (preweaning), 73 (weaning), and 110, 160, and 228 d of age. Solid feed consumption (mean ± SE) was greater in LMR (821±42.1 g/d) than in HMR calves (462±42.1 g/d) between 42 d of age and 52 d (preweaning). As expected, as age increased, solid feed consumption increased, and LMR showed a more marked increase than HMR calves. Despite the greater solid feed intake of LMR calves, HMR grew faster than LMR calves until preweaning time, but from preweaning to weaning, LMR calves grew more than HMR calves (977 vs. 857±30.7 g/d, respectively; mean ± SE). No differences in feed efficiency were observed. While calves were individually housed, no differences were observed in the incidence of bovine respiratory disease or diarrhea between treatment groups. We concluded that, under the milk regimen, age range of calves, and weaning method used in the current study, before preweaning, HMR calves grow more than LMR calves, but between preweaning and weaning, LMR grow more than HMR calves, overcoming the difference in BW at preweaning. As a result, with the weaning scheme followed herein, providing more milk does not ensure greater performance; no differences are obtained in BW at weaning and at 228 d of life. Also, based on solid feed consumption patterns seen in this study, we determined that the optimum age to reduce MR allowances and foster solid feed intake is around 45 d of age.