Effect of early weaning one lamb in a triplet lamb rearing system

Abstract

ABSTRACTThirty-seven Cambridge (C) and Suffolk (S) × C ewes and their lambs were housed and penned individually in family groups for 35 days post partum and then grazed on pasture until the lambs reached slaughter weight. Lambs were reared as twins (TR-TW). The lambs weaned at 35 days were artificially reared and formed the TR-AR group.Dry matter intake of the complete diet and hay offered ad libitum during the housing period was unaffected by rearing type. TR-TR and TR-TW ewes produced more milk at 10 days than TW-TW ewes, 4·4 and 4·2 v. 3·6 (s.e.d. 0·257) kg/day. From 35 days onwards the decline in milk yield tended o t be greater in the TW-TW and TR-TW ewes which also gained more condition than TR-TR ewes, 0·33 and 0·37 v. 0·01 (s.e.d. 0·139) of a score.TW-TW lambs grew faster than TR-TW and TR-TR lambs during the housed period, 336 v. 295 and 292 (s.e.d. 9·8) g/day but after 35 days TR-TW, TR-AR and TW-TW lambs had similar growth rates, 348, 350, and 348 (s.e.d. 14·2) g/day respectively whereas TR-TR lambs grew less quickly at 310 g/day. Forty-two male lambs were slaughtered. TR-AR lambs had a higher killing-out proportion and carcass fat content than naturally reared animals. In the latter group carcass fat content was negatively related to time reared as triplets and the kidney knob and channel fat weight was significantly lower in the TR-TR group. Crossbred lambs grew faster, had a higher killing-out proportion and greater weight of m. longissimus dorsi and m. psoas major in the half carcass.It is concluded that weaning one lamb at 35 days provides a suitable alternative system for rearing triplets and that it is possible to produce good quality carcasses with some desirable reduction in fat content from lambs reared as triplets throughout their life.