Lactation performances of Romney, Corriedale, and Merino ewes in a tussock grassland environment

摘要

Abstract Milk yields and milk composition of three-year-old Romney, Corrie-dale, and Merino ewes rearing single lambs in a tussock grassland environment were compared. Mating was synchronised in order to concentrate lambing. The interbreed differences in milk yields as measured by the oxytocin technique were small and non-significant. Yields expressed in ml/h for a 12 week lactation were: Romneys, 54.3; Corriedales, 56.8; and Merinos, 52.7. Diurnal fluctuations in milk yields were of the order of 8-10%. No significant differences between breeds were apparent. No breed differences in solids-not-fat percentages were evident, although Romney fat percentages in the second half of lactation were significantly higher than those of the Merinos (P < 0.01) and Corriedales (P < 0.05). Lamb growth was highly correlated to fat intake in the Romneys but not in the other breeds. The regression of growth rate on S.N.F. was significant (P < 0.01) for all breeds. The 0.59 lb/day Romney and 0.62 lb/day Corriedale growth ra...