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

Abstract

Milk yields and milk composition of three-year-old Romney, Corriedale, 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 express.ed 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). l.amb 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 rates for a 0-12 week lactation period were significantly higher (P < 0.01) than the 0.53 lb/day growth rate of the Merino lambs. Highly significant correlations were obtained in all breeds between milk yields and lamb growth rates in the first six weeks of lactation. Merino lambs were less efficient (P < 0.01) in converting milk to live weight gain than their Romney or Corriedale counterparts.The regression of Merino growth rate and weaning weight on birth weight was highly significant. The regression of weaning weight on birth weight in the Romneys and Corriedales was significant (P < 0.05), although no growth rate relationship was evident.Ewe live weight, ante partum, was not related to milk yields in any breed.

Performance of sheep on New Zealand hill country

“…As expected, the Merino showed the lowest growth of all the breeds. This confirmed the work of Scales ( 1968) in a growth study up to 12 weeks of ! "\ge.…”

Relationships between Ewe Milk Production and Composition and Preweaning Lamb Weight Gain

“…Our results are in agreement with those obtained by , Slen et al (1963) and Moore (1966) that there was little improvement in the relationship between milk intake and growth rate when MP was expressed in terms of components rather than whole milk. Scales (1968), however, reported a highly significant correlation between fat intake and lamb growth in Romney lambs but not in Corriedales and Merinos.…”

“…The We publish these equations and associated r 2 values, however, to aid investigators who might wish to estimate milk production, which is costly and difficult to measure, from lamb weight gain, which is much easier to measure. (1955), Barnicoat et al ( , 1956d, , Munro (1962), Slen et al (1963), Folman et al (1966a, 1966b, Moore (1966), Peart (1967, Scales (1968), Butterworth et al (1968, Robinson et al (1969), Acharya andBawa (1971), Geenty and and Peart et al (1975) that ewe milk production is the most important variable influencing lamb weight gain in the early stages of lactation but that the effect of milk production tends to decline as lambs become more dependent upon the intake of forage or grain. With MP in the model for single lambs, the regression coefficient of total lactation G on PMP was large and positive.…”

Effects of hogget oestrus and the lambing and milking of hoggets on the subsequent milk composition and yields of 2‐year‐old Dorset ewes

“…data). Other workers have also found no relationship between milk yields and liveweight in mature ewes (Scales 1968;McGloughlin & Crowley 1971;Stern et al 1978;Geenty 1980). Where a relationship between milk yield and liveweight has been found, there was often a confounding of ewe age and liveweight (Mason & Dassat 1954).…”