In 2 experiments ewe milk production, lamb water turnover, and lamb growth were measured during early lactation in Romney, Dorset, and crossbred sheep at pasture. Water turnover began to exceed milk production during Weeks 2-4 of lactation in single lambs reared by crossbred and Dorset ewes and in twins reared by Dorsets. In contrast, lambs suckling Romney ewes appeared to face a milk deficit during the first 3 weeks of lactation, particularly twins, when up to 34% of their food intake was from herbage. Despite large differences between ewe breeds in milk production, differences in lamb water turnover and growth rate were small. For ewes rearing twin lambs, Dorsets produced 58% more milk than Romneys but their lambs had only 19% greater average water turnover and were 15% heavier at 3 1 /2 weeks-of-age. Within breeds, rearing status markedly affected milk production but not water turnover. Water turnover was more closely related to final lamb liveweight for single lambs (r2 = 0.35 to 0.74) than was milk production (r2 = 0.34 to 0.62). Logarithmic regressions (pooled within breeds) showed a close association between lamb body water space and liveweight (r 2 = 0.72 to 0.96). Breed relationships between ewe milk production and the consumption of milk and herbage by lambs are discussed in relation to the comparatively small differences among breeds in final lamb liveweight.