Birth weight, liveweight gain in early life, and subsequent gain in sheep and cattle

Abstract

The relationships between birth weight, liveweight gain in early life, and subsequent gain of cattle and sheep grazing improved pastures were studied.

In both species the correlations between liveweights at each age were highly significant.

For female lambs, but not for males, birth weight was significantly correlated with the subsequent liveweight gain to 3 weeks, and this gain was significantly correlated with the subsequent gain to 17 weeks of age. These sex differences could be explained by the more variable growth rates of the female lambs. Ewe milk production and lamb milk intakes from birth to 3 weeks of age were significantly correlated with the liveweight gain over that period, but not with the subsequent gain.

In cattle the correlation between birth weight and the liveweight gain to 6 weeks of age was non-significant. Gain from birth to 6 weeks was significantly correlated with gain between 6 and 36 weeks of age (weaning), but not with gain between 36 and 89 weeks (slaughter). The correlations between the gains, birth or 6 weeks to weaning, with the subsequent gains to slaughter were highly significant.