Effect of Maternal Under-nutrition during Late Pregnancy on Lamb Birth Weight

This study investigated the effects of maternal undernutrition during late pregnancy on lamb birth weight. 45 Mongolian ewes, synchronized for oestrus and then mated, were divided into four groups and offered 0.86 MJME/kgw'°. ?5 d" (control group; CG : ad libitum access to feed), 0.44 MJME/kgw -0.75 d -1 (Restricted Group 3; R3), 0.33 MJME/kgw -0.75 d -1 (Restricted Group 2; R2) and 0.20 MJME/kgw 0.75 d -1 (Restricted Group 1; Rl) respectively during late pregnancy (90-150 days). During restriction, maternal net body weight loss, insulin and NEFA concentrations and lamb birth weight were measured. The results indicated that loss of maternal body weight in R3, R2 and Rl was 4.42, 7.23, 11.13 kg respectively, which was significantly (p<0.01) higher than that in CG (0.93 kg). Insulin concentrations of the ewes in Rl, R2 and R3 were lower and were significantly different (p<0.05) between restricted groups and CG at 124 d of pregnancy. NEFA concentrations in all groups tended to decrease from 90d of gestation to parturition and in Rl were significantly (p<0.05) lower than in CG at 124 d of gestation. Lamb birth weight in Rl was significantly lower than in R2, R3 and CG (p<0.05). In conclusion, with decreasing supply of maternal nutrition, the retardation of fetal growth became worse. When the plane of nutrition was below 0.33 MJME/kgw -0.75 d -1 , significant effects of maternal undernutrition on lamb birth weight were observed.