Effects of Supplements during Pregnancy on Reproductive Performance and Wool Growth by Merino Ewes

During the last trimester of pregnancy single and twin-bearing ewes were fed chopped oat hay ad libitum and supplements (300 g/day) of cottonseed meal (CSM) (T1) or barley grain plus urea and sodium sulfate (Bar+N+S) (T2), or CSM and oat hay restricted to the level consumed by the T2 ewes (T3). T1 ewes consumed 47% more hay and approximately 13% more digestible organic matter than T2 ewes. T1 ewes had higher liveweight and condition score at parturition than T2 or T3 ewes, and birth weight of single lambs was also higher (P c 0.05). During lactation all ewes were fed oat hay ad libitum and 300 g CSM/day. Milk production at day 7 was lower for T2 (P c 0.05), but colostrum availability, milk production at days 14 and 21, and lamb growth were not affected by treatments during pregnancy. The lower birth weight of single lambs from ewes given treatments T2 and T3 appeared to be due principally to a lower roughage intake by these ewes during late pregnancy.