Twenty-four South African Mutton Merino ewe lambs were artificially reared in a 22-factorial experiment on 5 or 10 kg milk substitute to weaning at 25 or 30 days. From weaning until a minimum of 100 days of age and a minimum of 32 kg live weight, the lambs were individually fed ad lib. a meal mixture containing 16% crude protein, 72% total digestible nutrients and 9% crude fibre. During the milk substitute feeding period, both average daily gain (ADG) and food conversion ratio (FCR) were significantly greater in lambs fed 10 kg milk substitute (335 g and 1,08 vs. 228 g and 0,81 respectively; P <0,01), and ADG was significantly greater in lambs weaned at 25 days(297 vs. 265 g; P < 0,05). To reach 32 kg live weight, the lambs reared on 10 kg milk substitute took a mean of 92,0 days, consumed 65,9 kg meal and cost R7,23, while those reared on 5 kg took 106,4 days (when weaned at 25 days) or 111,0 days (when weaned at 30 days), consumed 85,4 kg meal and cost R6,29. Growth to 100 days of age was significantly affected by intake of milk substitute (P < 0,01), but not by weaning age; FCR (40-100 days) was not affected by treatments.
