Abstract

The current study aimed to estimate (co)variance components and heritability for pre-weaning body weight traits and Kleiber ratio in Sangsari sheep. Data used in this research were collected over 30 years (1986–2016) at the breeding station of Sangsari sheep. Traits considered were birth weight (BW), weaning weight (WW), pre-weaning daily gain (PWDG), and Kleiber ratio (KR). Genetic parameters were estimated by the average information restricted maximum likelihood (AI-REML) procedure, using six animal models. The most suitable model was selected using the Akaike information criterion (AIC) for each trait. Direct heritability estimates for BW, WW, PWDG and KR were 0.30 $\pm$ 0.04, 0.20 $\pm$ 0.03, 0.15 $\pm$ 0.02, and 0.13 $\pm$ 0.05, respectively. Maternal heritability estimates varied from 0.06 $\pm$ 0.02 for PWDG to 0.12 $\pm$ 0.03 for BW. The maternal permanent environmental effects for the traits of KR, WW and PWDG account for about 7%, 9% and 12% of the phenotypic variance. The estimates of the direct genetic (${\mathrm{r}}_{\mathrm{a}}$) and maternal genetic (${\mathrm{r}}_{\mathrm{m}}$) correlations among pre-weaning growth traits were positive and ranged from 0.21 (BW-KR) to 0.98 (WW-PWDG) and 0.27 (WW-PWDG) to 0.48 (BW-WW), respectively. Therefore, to have an accurate genetic evaluation, maternal effects need to be considered in any program aimed at improving pre-weaning growth traits. In addition, due to the existence of genetic variation for early growth traits and generally positive and medium to high genetic correlations among them, it can be concluded that in the Sangsari breed of sheep, genetic progress for these traits is possible by selection.

• HIGHLIGHTS

• Genetic parameters (direct and maternal heritability) were estimated for the Sangsari breed of sheep.

• The low to moderate estimate of heritability for pre-weaning body weights and Kleiber ratio indicate that genetic improvement of these traits is possible by selection.

• Considerable genetic correlations among early body weights, pre-weaning daily weight gain, and Kleiber ratio in Sangsari sheep were estimated.

摘要

目前的研究旨在估计 Sangsari 绵羊断奶前体重性状和 Kleiber 比率的（协）方差分量和遗传力。本研究中使用的数据是在 Sangsari 羊的繁殖站收集了 30 多年（1986-2016）的数据。考虑的性状是出生体重 (BW)、断奶体重 (WW)、断奶前日增重 (PWDG) 和克莱伯比率 (KR)。使用六种动物模型，通过平均信息限制最大似然 (AI-REML) 程序估计遗传参数。使用 Akaike 信息准则 (AIC) 为每个性状选择最合适的模型。BW、WW、PWDG 和 KR 的直接遗传力估计值为 0.30 $\pm$ 0.04, 0.20 $\pm$ 0.03, 0.15 $\pm$ 0.02 和 0.13 $\pm$ 分别为 0.05。母体遗传力估计值从 0.06 不等 $\pm$ PWDG 为 0.02 至 0.12 $\pm$ BW 为 0.03。KR、WW和PWDG性状的母体永久环境效应约占表型变异的7%、​​9%和12%。直接遗传的估计（${\mathrm{r}}_{\mathrm{一种}}$) 和母系遗传 (${\mathrm{r}}_{\mathrm{米}}$) 断奶前生长性状之间的相关性呈正相关，范围分别为 0.21 (BW-KR) 至 0.98 (WW-PWDG) 和 0.27 (WW-PWDG) 至 0.48 (BW-WW)。因此，为了进行准确的遗传评估，任何旨在改善断奶前生长性状的计划都需要考虑母体效应。此外，由于早期生长性状存在遗传变异，并且它们之间通常呈正相关和中高遗传相关性，因此可以得出结论，在 Sangsari 绵羊品种中，这些性状的遗传进展是可能通过选择进行的。

• 强调

• 估计 Sangsari 绵羊品种的遗传参数（直接和母本遗传力）。

• 对断奶前体重和 Kleiber 比的遗传力的低到中等估计表明这些性状的遗传改良是可能的。

• 估计 Sangsari 羊的早期体重、断奶前每日增重和 Kleiber 比率之间存在相当大的遗传相关性。