Effect of nutrition during pregnancy on fetal growth and survival in FecB Booroola X South Australian Merino ewes

The effect of nutritional manipulation during mid and late pregnancy on fetal growth and survival in high fecundity (FecB Fec+) Merino ewes was examined. A total of 4 treatment groups was utilized in each of 3 years (1987, 1988 and 1989); and 2 groups were given low nutrition during mid pregnancy while 2 groups received high nutrition during this period. One group from each of these treatments subsequently received a high protein diet 1 to 2 weeks prior to term. Differential feeding during mid pregnancy resulted in the high and low treatment groups varying by 7.5 and 5.0 kg liveweight at Days 100 and 135 of pregnancy, respectively. Fetal survival was not improved by variation in nutritional intake during mid pregnancy (P 0.05) and neither were placental and fetal growth (P 0.05), as indicated by observations on cotyledon diameter and fetal head width, respectively. However, fetal survival during late pregnancy was reduced by a high level of nutrition during both mid and late pregnancy (P 0.05)