The effects of body condition score and nutrition of triplet-bearing ewes in late pregnancy

At day 128 (P128) of pregnancy, triplet-bearing Romney ewes were allocated to either a 'Control' or 'ad-libitum' ('Adlib') nutritional regimen until P142. Both nutritional regimens included ewes of body condition score (BCS): 2.0, 2.5 and 3.0. During the nutritional period the post grazing masses were 807.9 ± 58.5 and 1254 ± 61.1 kg DM/ha for the Control and Adlib regimens respectively. At P142 Control ewes had lighter (P < 0.05) live weight and lower (P < 0.05), condition score and backfat depths than Adlib ewes. Neither ewe nutritional regimen nor BCS affected (P > 0.05) lamb live weight or indices of colostrum uptake. There was no effect (P > 0.05) of ewe nutritional regimen on lamb survival. Lambs born to BCS2.5 ewes had lower survival (P < 0.05) than BCS3.0 lambs and BCS3.0 lambs tended (P = 0.09) to have greater survival than BCS2.0 lambs. BCS3.0 ewes weaned a greater total weight of lamb (P < 0.05) than BCS2.5 ewes. There were no (P < 0.05) interactions between ewe nutritional regimen and BCS for any of the lamb traits measured. In conclusion, the data indicates triplet-bearing ewes can be managed under controlled grazing conditions with post grazing masses of approximately 800 kg DM/ha to day 142 of pregnancy without affecting lamb performance. The present study also suggests farmers should aim to have their triplet-bearing ewes at a body condition score of 3.0 prior to late pregnancy to achieve higher levels of performance.