Department of Animal Science, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
J Anim Breed Genet. 2023 Mar;140(2):198-206. doi: 10.1111/jbg.12753. Epub 2022 Dec 30.
The objectives of this study were to assess the autosomal and sex-linked genetic inheritance of growth traits and identify the effective dosage compensation on the Z chromosome in Mazandaran native chickens. The data included body weights at hatching (BW0), 8 weeks (BW8) and 12 weeks (BW12) of age, related to the first 21 generations of selection, were collected from Mazandaran native chicken breeding centre. The fixed effects included sex of birds in two classes, hatch in five classes and generation in 21 classes. The inverse of the sex-linked additive genetic relationship matrix was constructed using nadiv package in R considering different models for dosage compensation on the Z chromosome. The setup inversed matrix was then supplied externally to WOMBAT using the GIN option. Twelve univariate animal models separating participation of autosomal additive genetic, sex-linked additive genetic and maternal effects (both genetic and permanent environment effects) with considering the five different dosage compensation methods for models with sex-linked effects were analysed by WOMBAT software. BW0 was not affected by sex-linked additive genetic effects. For BW8 and BW12 the model which included autosomal, sex-linked direct additive and maternal effects with no global dosage compensation for the Z chromosome was the most appropriate model. Autosomal heritability estimates were 0.05 ± 0.02, 0.10 ± 0.01 and 0.11 ± 0.01, for BW0, BW8 and BW12, respectively. For BW8 and BW12, sex-linked heritability estimates were 0.07 and 0.27, respectively. Spearman rank correlation coefficient between autosomal and sex-linked breeding values were 0.45 and 0.12 for BW8 and BW12, respectively. Spearman rank correlation coefficient between autosomal and sex-linked breeding values were 0.45 and 0.12 for BW8 and BW12, respectively. The autosomal direct additive genetic correlations between all traits were positive. The estimate of direct sex-linked additive genetic correlation between BW8 and BW12 was high (0.88). Also, maternal genetic correlations were 0.53, 0.54 and 0.91 between BW0-BW8, BW0-BW12 and BW8-BW12, respectively. Given the importance of Z-linked genes for BW8 and BW12, it is recommended that Z-linked effects be separated from autosomal effects in order to increase the accuracy of genetic evaluation of birds for these traits.
本研究旨在评估生长性状的常染色体和性连锁遗传，并确定马赞达兰本地鸡 Z 染色体上有效剂量补偿。数据包括来自马赞达兰本地鸡繁殖中心的 21 个世代选择中与孵化时（BW0）、8 周龄（BW8）和 12 周龄（BW12）体重相关的体况。固定效应包括两类鸟类的性别、五类孵化和 21 类世代。考虑到 Z 染色体上剂量补偿的不同模型，使用 R 中的 nadiv 包构建了性连锁加性遗传关系矩阵的逆矩阵。然后使用 GIN 选项将设置的逆矩阵外部提供给 WOMBAT。通过 WOMBAT 软件分析了 12 个单变量动物模型，这些模型分别分离了常染色体加性遗传、性连锁加性遗传和母体效应（遗传和永久环境效应）的参与，并考虑了 5 种不同的性连锁效应模型的剂量补偿方法。BW0 不受性连锁加性遗传效应的影响。对于 BW8 和 BW12，最适合的模型是包括常染色体、性连锁直接加性和母体效应的模型，而不对 Z 染色体进行全局剂量补偿。BW0、BW8 和 BW12 的常染色体遗传力估计值分别为 0.05 ± 0.02、0.10 ± 0.01 和 0.11 ± 0.01。对于 BW8 和 BW12，性连锁遗传力估计值分别为 0.07 和 0.27。BW8 和 BW12 的常染色体和性连锁育种值之间的斯皮尔曼等级相关系数分别为 0.45 和 0.12。BW8 和 BW12 的常染色体直接加性遗传相关性之间的斯皮尔曼等级相关系数分别为 0.45 和 0.12。所有性状之间的常染色体直接加性遗传相关性均为正相关。BW8 和 BW12 之间直接性连锁加性遗传相关性的估计值较高（0.88）。此外，BW0-BW8、BW0-BW12 和 BW8-BW12 之间的母体遗传相关性分别为 0.53、0.54 和 0.91。鉴于 Z 连锁基因对 BW8 和 BW12 的重要性，建议将 Z 连锁效应与常染色体效应分开，以提高这些性状的鸟类遗传评估的准确性。
