Näsholm A, Danell O
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Anim Sci. 1996 Feb;74(2):329-39. doi: 10.2527/1996.742329x.
Genetic parameters were estimated for weights of lambs from birth to 1 d before slaughter and mature ewe weight (EMW) using REML procedures and single- and two-trait animal models. The data consisted of weight registrations from 5,001 animals descended from 131 sires, 788 dams, 48 maternal grandsires, and 530 maternal granddams in an experimental flock with Swedish finewool sheep. Direct heritabilities increased with lamb age from .07 for birth weight to .21 for weight before slaughter. Maternal heritabilities declined with age from .30 to .07. Direct-maternal genetic correlations were positive and increased with age from .11 for birth weight to .73 for weight before slaughter. For daily gain during shorter periods, direct heritability increased from .07 for the period from birth until 3 wk of age to .14 for the period from weaning until 1 d before slaughter. The values for maternal heritabilities were .16 and .03, respectively. The direct-maternal genetic correlations ranged from -.11 to .59. The direct heritability for EMW varied between analyses from .29 to .63. A nonsignificant maternal heritability of .22 was noted for EMW. Direct genetic correlations between EMW and various lamb weights varied between .36 to .85. Genetic correlations between direct effects on EMW and maternal effects on lamb weights varied between .39 and .53. Direct and maternal genetic correlations between the lamb weights were positive. The results showed that the maternal influence on lamb weights decreased with age. It was indicated that positive genetic relationships exist between ewe weight and maternal effects on lamb weight. Therefore, selection for larger lamb weights alone will not only increase ewe weights but also improve the maternal ability to the ewe.
采用REML程序以及单性状和双性状动物模型，对瑞典细毛羊实验群体中从出生到屠宰前1天的羔羊体重和成年母羊体重（EMW）的遗传参数进行了估计。数据包括来自131只父系、788只母系、48只外祖父和530只外祖母的5001只动物的体重记录。直接遗传力随羔羊年龄增长而增加，出生体重的直接遗传力为0.07，屠宰前体重的直接遗传力为0.21。母体遗传力随年龄从0.30下降到0.07。直接-母体遗传相关为正，且随年龄从出生体重的0.11增加到屠宰前体重的0.73。在较短时期的日增重方面，直接遗传力从出生至3周龄的0.07增加到断奶至屠宰前1天的0.14。母体遗传力值分别为0.16和0.03。直接-母体遗传相关范围为-0.11至0.59。EMW的直接遗传力在不同分析中从0.29到0.63不等。注意到EMW的母体遗传力为0.22，不显著。EMW与各种羔羊体重之间的直接遗传相关在0.36至0.85之间。对EMW的直接效应与对羔羊体重的母体效应之间的遗传相关在0.39至0.53之间。羔羊体重之间的直接和母体遗传相关为正。结果表明，母体对羔羊体重的影响随年龄下降。表明母羊体重与母体对羔羊体重的影响之间存在正遗传关系。因此，仅选择较大的羔羊体重不仅会增加母羊体重，还会提高母羊的母体能力。
