Abstract

The relationship between lamb growth rate and ewe milk yield was examined using 213 ewe-lamb sets in 6 experiments. Factors included ewe breed, lamb rearing status, herbage allowance, lambing date and season. Lamb growth and ewe milk production were greater for twin- than single- lamb groups, for Dorset than Romney ewe breeds and for late than early lambing dates. Ewe live weight showed the reverse trend. Regression parameters indicated lamb growth rate was generally more dependent on milk supply during the first 6 than during 12 weeks of lactation. The exception was Romney ewes with low milk production rearing twin lambs. Comparisons among groups of regression coefficients and nominal ordinates (i.e. growth rate at low milk yield) showed that twin lambs were proportionately more dependent on pasture for growth than singles as were lambs reared by Romney compared with Dorset ewes. Similarly, a high herbage allowance, good seasonal pasture growth and a late lambing date caused a greater contribution of pasture to lamb growth. However, among groups there was much variability in the relationship and generally lamb live-weight gain was a poor indicating of ewe milk yield (approx. r

KT, Jagusch, MM Gray, KS MacLean, NR Towers, di ME Menna, and WH McMillan

Proceedings of the New Zealand Society of Animal Production, Volume 46, , 251-254, 1986