Abstract：
There are no studies regarding the estimation of genetic parameters and genetic trends for reproductive traits and somatic cells in goats. Their knowledge allows optimization of selection schemes. The objective of this study was to estimate genetic parameters and genetic and phenotypic trends for age at first kidding (AFK), kidding interval (KIN) and somatic cell score (SCS). Analyses were conducted within and across seven US goat breeds, namely, Nubian (NU), Alpine (AL), LaMancha (LM), Toggenburg (TO), Saanen (SA), Nigerian Dwarf (ND) and Oberhasli (OB), and a set of all of these breeds (AB). The restricted maximum likelihood methodology and trivariate animal models were used. Genetic and phenotypic trends were estimated using regression models. The average and standard deviation of AFK, KIN and SCS for AB were 573.6 ± 178.5 days, 418.8 ± 125.5 days and 4.67 ± 2.23 Log2, respectively. The heritabilities (h2) and standard errors of AFK, KIN and SCS for AB were 0.28 ± 0.02, 0.04 ± 0.02 and 0.22 ± 0.01, respectively. The h2 ranged from 0.15 (SA) to 0.37 (NU) for AFK, from 0.04 (AB) to 0.10 (AL) for KIN, and from 0.11 (TO) to 0.26 (LM and ND) for SCS. Genetic correlations between AFK and KIN and between AFK and SCS for AB were positive and weak (0.07 and 0.12, respectively) but significant (P < 0.01). Genetic correlations between SCS and KIN were significant (P < 0.01) for all the breeds and ranged from -0.15 (NU) to 0.44 (AL). Genetic correlations between AFK and SCS in the NU and AL breeds were similar (approximately 0.21). A positive genetic trend was found for KIN in the SA breed, which caused an increase in the number of days between consecutive kiddings. The genetic trend of SCS for the NU, AL and ND breeds was negative and decreased annually, which is beneficial for producers. These first results show the intensity and direction of some favorable/unfavorable relationships between AFK or KIN and SCS Log2 in some U.S. goat genetic groups.
摘要：
没有关于山羊繁殖性状和体细胞的遗传参数和遗传趋势估计的研究。他们的知识允许优化选择方案。这项研究的目的是估计遗传参数和遗传和表型趋势的年龄在第一次开玩笑（AFK），开玩笑间隔（KIN）和体细胞评分（SCS）。分析是在七个美国山羊品种内进行的，即,努比亚（NU），高山(AL),拉曼查（LM），Toggenburg(TO),Saanen(SA),尼日利亚矮人（ND）和奥伯哈斯利（OB），和一组所有这些品种（AB）。使用限制性最大似然方法和三变量动物模型。使用回归模型估计遗传和表型趋势。AFK的平均值和标准偏差，AB的KIN和SCS为573.6±178.5天，分别为418.8±125.5天和4.67±2.23Log2。AFK的遗传力(h2)和标准误差，AB的KIN和SCS分别为0.28±0.02、0.04±0.02和0.22±0.01。AFK的h2范围为0.15（SA）至0.37（NU），KIN从0.04(AB)到0.10(AL)，SCS从0.11(TO)到0.26(LM和ND)。AB的AFK与KIN之间以及AFK与SCS之间的遗传相关性分别为正相关和弱相关（分别为0.07和0.12），但显着（P<0.01）。所有品种的SCS和KIN之间的遗传相关性均显着（P<0.01），范围为-0.15（NU）至0.44（AL）。NU和AL品种中AFK和SCS之间的遗传相关性相似（约0.21）。在SA品种中发现了KIN的正遗传趋势，这导致了连续开玩笑之间的天数增加。NUSCS的遗传趋势，AL和ND品种呈阴性，逐年减少，这对生产者是有利的。这些第一个结果显示了某些美国山羊遗传群体中AFK或KIN与SCSLog2之间的一些有利/不利关系的强度和方向。
