INFLUENCE OF PASTURE ALLOWANCE AN0 MASS DURING LATE PREGNANCY ON EWE AND LAMB PERFORMANCE

Abstract

For 6 weeks in late pregnancy groups of Coopworth ewes (53-55 kg) were grazed on a range of pasture allowances in each of 2 years (1978: 5 allowances, ranging from I .O to 7.0 kg DM/ewe/day; 1979: 6 allowances, ranging from 0.7 to 4.0 kg DM/ewe/day) on ryegrass-white clover pasture of2 contrasting pre-grazing herbage masses (I 145 and 2895 kg DM/ha in 1978; I100 and 2700 kg DM/ha in influenced by feeding level. After lambing, ewes grazed a common pasture allowance. There were no consistent carry-over effects of late pregnancy feeding of kg in 1978, and 55-70 kgin 1979. Those on the pasture with higher mass were 1-5 kg heavier at each allowance than those on the lower mass. In spite of the large differences in ewe body weight just prior to lambing there were no effects on ewe or lamb mortality, pregnancy toxaemia or bearings. Birth weights were not consistently influenced by feeding level. After lambing, ewes grazed a common pasture allowance. There were no consistent carry-over effects of late pregnancy feeding on milk production or lamb weaning weights. Fleece weights differed between extreme treatments by 0.3-0.5 kg. After lambing, ewes compensated in terms of live weight, These results demonstrate the great buffering capacity of 52-55 kgewes (6 weeks prepartum) under the conditions of these trials. The management implications are that under such circumstances strict rationing of pasture can continue right up until lambing, conserving pasture insitu for the much more important period immediately post-lambing.