Effects of two different rearing protocols for Holstein bull calves in the first 3weeks of life on health status, metabolism and subsequent performance

The aim of this study was to investigate the impact of weight gain of calves within the first 3weeks of life on health status and subsequent performance. Holstein bull calves were reared either intensively (IR; individual hutches and ad libitum milk feeding for the first 3weeks of life; n=24), or according to the established protocol [ER; 4l milk/day in hutches during week 1 and 720g/day milk replacer (MR) from day 8 to 21 in a group pen; n=24]. Water, hay and concentrates were freely available to all calves. From week 4, calves of both groups were housed together in a group pen and fed 720g MR/day; step-down weaning was performed between week 5 and 10. Key metabolic blood parameters were analysed on day 2, 12, 21 and 70 of life. After weaning, all animals were fed concentrates and corn silage until slaughter at an age of 8months. Within the first 3weeks, average daily weight gain was threefold higher in IR calves in relation to ER calves (1.28 vs. 0.38kg/day, p<0.001). Neither incidence nor duration of scouring differed significantly between groups. Starter intake (week 4-10) was higher in IR calves in relation to ER calves (49.7 vs. 38.0kg/calf, p=0.006). Serum glucose, urea, albumin and insulin were higher at an age of 21days in IR calves in relation to ER calves; no differences were obvious at an age of 70days. Plasma GH and IGF-I concentrations revealed an uncoupling of the somatotropic axis in ER calves within the first 3weeks of life. At slaughter, body weight of IR calves tended to be higher than that of the ER calves (320 vs. 309kg, p=0.07). In conclusion, intensive feeding and individual housing during the first 3weeks of life had positive long-term effects on subsequent performance.