The effect of pre-natal nutrition and type of birth and rearing of lambs on vigour, temperature and weight at birth, and weight and survival at weaning
Moore, R.W.; Millar, C.M.; Lynch, P.R.
Proceedings of the New Zealand Society of Animal Production 46: 259-262
1986
Document Number: 624742
230 five-yr-old New Zealand Romney ewes were synchronized with progestogen intravaginal sponges and injected with dexamethasone 142 or 143 days after the median mating day of the 1st and 2nd cycles of oestrus. 71% of the lambs were born 30-50 h after injection. The ewes were offered 2 pasture allowances for the last 6 wk of pregnancy (approx. 6 and 1 kg dry matter per ewe per day). Lambs were scored for vigour (1-10) and probed for rectal temp., and ewe lambs were cross-fostered as soon as possible after birth in order to obtain a 24 factorial design incorporating birth type (single and twin), rearing types (single and twin), prenatal nutrition of dam (high and low allowance), and prenatal nutrition of foster dam (high and low allowance). Lambs born from high-allowance ewes had higher rectal temp. at birth than those born from low-allowance ewes, and ewe lambs had higher rectal temp. than ram lambs. Single-born lambs had higher vigour scores than those born as multiples. Increasing vigour was associated with increasing birth weight for all lambs, but increasing temp. was associated with increasing birth weight only for ram lambs. There were no effects of prenatal nutrition on lamb growth either through the dam or foster dam. The effect of birth type on lamb live weight was significant to 9 wk of age, whereas the effect of rearing type was significant to 33 wk. There were no significant birth type x rearing type interactions at any age.