Separation of autosomal and sex-linked direct additive genetic effects has significant role in sheep breeding programs. Hence, this study was conducted to determine the genetic parameters of autosomal and sex-linked effects for growth traits of Zandi sheep. The data set used in this study contained 7571 Zandi lambs, descendent of 220 sires and 1481 dams, which were collected from Zandi sheep breeding Station at Khojir, Tehran, Iran from 1992 to 2011. The fixed effects included of year (20 classes), season (winter and spring), sex (male or female), birth type (single or twin), and the age of dam (seven classes, 2-8 years old). The data were analyzed using REML methodology by WOMBAT software. In the most appropriate fitted model, based on Akaike's information criterion (AIC) and Bayesian information criterion (BIC), the values of direct autosomal heritabilities of birth weight (BW), kleiber ratio at weaning (KR), 6-month weight (6MW), and 9-month weight (9MW) were 0.12 ± 0.03, 0.29 ± 0.05, 0.14 ± 0.04, and 0.15 ± 0.04, respectively. Furthermore, weaning weight (WW), average daily gain from birth to weaning (ADG), and 12-month weight (12 MW) showed the values of 0.19 ± 0.03 and 0.22 ± 0.03, 0.13 ± 0.05 and 0.15 ± 0.03, and 0.15 ± 0.05 and 0.18 ± 0.05, respectively. Based on the best models through all traits, estimates of the direct sex-linked heritability ranged from 0.0 (WW, ADG, KR, and 6MW) to 0.02 ± 0.03 (12MW). The average of autosomal and sex-linked breeding values (BVs) of body growth traits except KR (for autosomal) and 9MW and 12MW (for sex-linked) were greater than zero. The Pearson's/Spearman's correlation coefficients varied between 0.344 and 0.599/0.30 and 0.61 for autosomal and sex-linked BVs. Direct autosomal and sex-linked additive correlations for growth traits were ranged from - 0.02 (BW-KR) to 0.98 (WW-ADG) and 0.04 (KR-9 MW) to 0.99 (WW-ADG), respectively. Our results revealed that the genetic parameters related to growth traits in Zandi sheep could be more useful in selection strategies.

中文翻译：

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伊朗赞迪羊的生长特性的常染色体和性别相关的（共）方差成分和遗传参数。

常染色体和性别相关的直接加性遗传效应的分离在绵羊育种计划中具有重要作用。因此，这项研究是为了确定赞迪羊生长性状的常染色体和性别相关效应的遗传参数。本研究使用的数据集包含1992年至2011年从伊朗德黑兰Khojir的Zandi绵羊繁育站收集的7571头Zandi羔羊，后代220头公母和1481个水坝。季节（冬季和春季），性别（男性或女性），出生类型（单身或双胞胎）和水坝年龄（七节课，2-8岁）。通过WOMBAT软件使用REML方法分析数据。在最合适的拟合模型中，基于Akaike信息标准（AIC）和贝叶斯信息标准（BIC），出生体重（BW），断奶时的颈肌比率（KR），6个月体重（6MW）和9个月体重（9MW）的直接常染色体遗传性值为0.12±0.03、0.29±0.05、0.14±0.04，和0.15±0.04分别。此外，断奶体重（WW），从出生到断奶的平均日增重（ADG）和12个月体重（12 MW）的值分别为0.19±0.03和0.22±0.03、0.13±0.05和0.15±0.03和0.15分别为±0.05和0.18±0.05。根据所有性状的最佳模型，对与性别相关的直接遗传力的估计范围为0.0（WW，ADG，KR和6MW）至0.02±0.03（12MW）。除KR（常染色体）和9MW和12MW（对于性别相关）外，身体生长性状的常染色体和性别相关繁殖值（BV）的平均值均大于零。皮尔逊/斯皮尔曼的相关系数在0之间变化。常染色体和性相关的BV分别为344和0.599 / 0.30和0.61。生长特性的直接常染色体和性别相关的加性相关性分别为-0.02（BW-KR）至0.98（WW-ADG）和0.04（KR-9 MW）至0.99（WW-ADG）。我们的结果表明，与赞迪绵羊生长性状相关的遗传参数在选择策略中可能更有用。