Effect of nutrition during pregnancy on birth weight and lamb survival in Fec B Booroola×South Australian Merino ewes

Abstract

The potential of nutritional manipulation during mid and late pregnancy to improve birth weight and reproductive efficiency in high fecundity (Fec B Fec +) Merino ewes was examined. Four treatment groups were allocated in each of 3 years (1987–1989); two groups were given either low (L) or high (H) nutrition during mid pregnancy (Days 50–100 post mating) and one group from each of the mid pregnancy treatments were provided with a high protein diet 1–2 weeks prior to term. Differential feeding during mid pregnancy resulted in treatment groups varying by 7.5 kg and 5.0 kg liveweight at Day 100 and Day 135 of pregnancy, respectively. Birth weight was not significantly improved by either increased nutrition during mid pregnancy or an increased proportion of dietary protein fed in late pregnancy. In addition, neither nutrition during mid pregnancy nor late pregnancy significantly influenced lamb survival between birth and 2 weeks and 2–6 weeks of age. Increased ewe mortality in the latter 2 years (1988, 1989) was associated with a high level of nutrition during mid pregnancy.