The effects of quantity and distribution of milk substitute on the performance and carcass measurements of artificially reared lambs

Abstract

SUMMARYTwenty-seven groups of Finnish Landrace × Dorset Horn lambs each of 2 castrated males and 2 females were offered daily quantities of 180, 248 or 343 g of milk substitute dry matter (DM) for 21, 29 or 40 days. Concentrate pellets were available ad libitum and from 22 days of age 150 g of hay per week was offered. When the mean live weight of a group reached 35 kg two castrates and one female from each group were slaughtered and the carcasses appraised.The growth rate and daily concentrate intake of lambs from 48 days of age until slaughter (reported -in this paper) were not affected by previous treatment, but lambs weaned at 40 days had a higher food conversion efficiency in this period (0·266 kg gain/kg feed DM) than those weaned at 21 days (0·244) or 29 days (0·232).Delaying weaning from 21 to 29 and 40 days reduced overall concentrate DM intake from birth to slaughter (from 88·15 to 81·09 and 73·39 kg) but increased growth rate (261, 276 and 288 g/day) and the conversion of total DM consumed to live weight (0·300, 0·311 and 0·350 kg/kg). Increasing the daily allowance of milk substitute from 180 to 248 and 343 g/day also reduced total concentrate intake (84·18, 80·74 and 77·71 kg). Growth rate and food conversion efficiency tended to increase and concentrate DM intake to decrease when the same total quantity of milk substitute was given over a longer period. Castrated males grew faster than females (290 v. 260 g/day).Weaning age generally had a greater effect than daily allowance of milk substitute on carcass measurements. Fat in the carcass tended to increase with increasing weaning age and significant interactions between daily allowance of milk substitute and weaning age were found for some carcass measurements.