Esmaeili Mohammad, Gholizadeh Mohsen, Hafezian Hasan, Farhadi Ayoub
Department of Animal Science, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
J Anim Breed Genet. 2024 Jul;141(4):465-472. doi: 10.1111/jbg.12855. Epub 2024 Feb 3.
Body weight is an economically important trait in poultry that shows sexual dimorphism (SD). In the present study, variation in SD in Mazandaran native chickens was investigated in terms of the (Co) variance components and genetic parameters of body weight between males and females. Studied traits were body weights at hatch (BW1), 8 weeks (BW8) and 12 weeks of age (BW12). Also, for weight at sexual maturity (WSM) covariance components were only estimated in females. Cross-sex direct and maternal correlations were also estimated for studied traits except for WSM. For this purpose, a deep 21-generation pedigree and body weight data (57,576 BW1, 72,925 BW8, 62,727 BW12 and, 42,496 WSM) were used. Evaluation of SD of body weight was performed using six bivariate animal models with and without considering the genetic and permanent maternal environmental effects under the restricted maximum likelihood method in WOMBAT software. Model with direct additive genetic effects and maternal genetic effects without covariance between them was identified as the best model for BW1 and BW8. The Model including direct additive genetic effects and permanent maternal environmental effects was the best model for BW12 and WSM. Direct heritability (h) estimates for BW1, BW8 and, BW12 were, respectively, 0.05 ± 0.013, 0.17 ± 0.02 and, 0.25 ± 0.03 in males and, 0.05 ± 0.012, 0.15 ± 0.01 and 0.21 ± 0.01 in females. Also, the direct heritability of WSM based on univariate analysis in females was estimated to be 0.40 ± 0.01. Maternal heritability ( ) varied from 0.39 ± 0.01 (BW1) to 0.04 ± 0.009 (BW8) in males, and 0.36 ± 0.10 (BW1) to 0.04 ± 0.006 (BW8) in females. The correlation between direct genetic effects between males and females for BW1 was not significantly different from one. The direct genetic correlation between the two sexes for BW8 and BW12 was significantly different from 1 concluding that these traits are dimorphic in terms of direct genetic effects and therefore independent selection in both sexes is possible.
体重是家禽中一个具有经济重要性的性状，表现出性别二态性（SD）。在本研究中，从体重的（协）方差分量以及雄性和雌性之间体重的遗传参数方面，对马赞德兰本地鸡的性别二态性变异进行了研究。所研究的性状为出雏时体重（BW1）、8周龄体重（BW8）和12周龄体重（BW12）。此外，对于性成熟时体重（WSM），仅在雌性中估计了协方差分量。除WSM外，还对所研究性状的跨性别直接和母体相关性进行了估计。为此，使用了一个深度为21代的系谱和体重数据（57576个BW1、72925个BW8、62727个BW12和42496个WSM）。在WOMBAT软件中，采用限制最大似然法，使用六个双变量动物模型，在考虑和不考虑遗传和永久性母体环境效应的情况下，对体重的性别二态性进行了评估。对于BW1和BW8，具有直接加性遗传效应和母体遗传效应且它们之间无协方差的模型被确定为最佳模型。对于BW12和WSM，包含直接加性遗传效应和永久性母体环境效应的模型是最佳模型。雄性BW1、BW8和BW12的直接遗传力（h）估计值分别为0.05±0.013、0.17±0.02和0.25±0.03，雌性分别为0.05±0.012、0.15±0.01和0.21±0.01。此外，基于单变量分析，雌性WSM的直接遗传力估计为0.40±0.01。母体遗传力（ ）在雄性中从0.39±0.01（BW1）到0.04±0.009（BW8）不等，在雌性中从0.36±0.10（BW1）到0.04±0.006（BW8）不等。BW1的雄性和雌性之间直接遗传效应的相关性与1无显著差异。BW8和BW12的两性之间直接遗传相关性显著不同于1，这表明这些性状在直接遗传效应方面是二态的，因此在两性中进行独立选择是可能的。
