Moioli B M, Pilla A M
Institute for Animal Production, Rome, Italy.
J Dairy Sci. 1994 Feb;77(2):609-15. doi: 10.3168/jds.S0022-0302(94)76990-3.
Two traits were compared as breeding objectives for the selection of dairy sheep: the total milk produced during 1 yr and the production over the first 70 d in milk. Both traits are proposed for sheep breeds that have more than one lambing per year and, consequently, highly variable lactation length. Breeding values for both traits were obtained with an animal model including flock-year-season of lambing and age class as fixed effects and additive genetic and permanent environmental as random effects. A total of 12,759 ewes and 547 rams of the Masses breed of sheep were evaluated for both traits, which were built up from a total of 31,170 lactations of 11,106 ewes. Average annual production was 161.8 kg; average length of lactation was 146.9 d/yr, and average partial lactation production from d 31 to 100 after lambing was 90.9 kg. Estimated breeding values ranged from -54.8 to 74.5 kg of milk for annual production and from -26.2 to 33.1 kg of milk for partial lactation production. Correlation of the estimated breeding values for the two traits was 67.4%. Annual genetic trend from 1980 to 1988 was .48 kg of milk for annual production and .07 kg of milk for 70 d lactation production.
一年产奶总量和产奶前70天的产量。这两个性状适用于每年产羔不止一次、因此泌乳期长度变化很大的绵羊品种。利用动物模型获得了这两个性状的育种值，该模型将产羔的羊群年份季节和年龄组作为固定效应，将加性遗传效应和永久环境效应作为随机效应。对共计11,106只母羊的31,170次泌乳所产生的共计12,759只母羊和547只公羊的马塞斯品种绵羊进行了这两个性状的评估。年平均产量为161.8千克；平均泌乳期为146.9天/年，产羔后第31天至100天的平均部分泌乳产量为90.9千克。年总产奶量的估计育种值范围为-54.8至74.5千克，部分泌乳产量的估计育种值范围为-26.2至33.1千克。这两个性状的估计育种值之间的相关性为67.4%。1980年至1988年的年度遗传趋势是，年总产奶量为每年0.48千克奶，70天泌乳产量为每年0.07千克奶。
