Genetic parameters and direct and maternal effects for important traits in late‐feathering Qingyuan partridge hens in China

Abstract

Qingyuan partridge chicken is an important indigenous chicken in China. In its breeding schemes, chickens are usually selected at the age of 105‐day‐old for five traits, including body weight (BW), shank length (SL), shank girth (SG), comb height (CH) and feather maturity (FM). At present, genetic parameters of the aforementioned traits have still not been studied in Qingyuan partridge chickens. The objectives of this study were the following: (1) to investigate whether the optimal statistical models of these traits need to consider maternal genetic and permanent environmental effects in late‐feathering Qingyuan partridge hens, and (2) to estimate genetic parameters for these traits based on the optimal models. The numbers of records for BW, SL, SG, CH and FM were 13,721, 13,671, 13,670, 13,669 and 13,672, respectively. Variance components were estimated using average information‐restricted maximum likelihood method, and the optimal model was determined based on Bayesian information criterion. More specifically, the optimal model for BW considered maternal genetic and permanent environmental effects in addition to direct additive genetic effect; SL, SG and FM considered direct and maternal genetic effects; and CH considered direct and maternal genetic effects, and the covariance between them. The direct heritabilities of these traits estimated using the optimal models were 0.21 ± 0.04, 0.30 ± 0.05, 0.40 ± 0.05, 0.59 ± 0.09 and 0.09 ± 0.04, respectively; the maternal heritabilities were 0.01 ± 0.04, 0.05 ± 0.05, 0.04 ± 0.05, 0.09 ± 0.09 and 0.03 ± 0.04, respectively. Maternal genetic effect evidently played an important part in FM and maternal heritability accounted for 30 per cent of total heritability. Furthermore, the direct and maternal genetic effects for CH were estimated to be negatively and moderately correlated (−0.51 ± 0.11). For all traits, neglecting existent maternal effects biased the estimation of direct heritability. Therefore, to implement optimum breeding strategies for improvement of these traits in Qingyuan partridge hens, maternal effects should be taken into consideration.

Estimation of genetic parameters for important traits using a multi‐trait model in late‐feathering Qingyuan partridge hens in China

“…Based on the multi‐trait models, we estimated the direct heritability and total heritability. Estimates of direct heritabilities based on the model including only direct additive genetic effects (Table 2) were higher than those based on the model also including maternal additive genetic effects (Table 3), which was consistent with the findings of our previous study (Kang et al, 2020). Because the maternal additive effects were significant for all five traits, it is better to include them in models for analysing these traits.…”

“…Therefore, we also used a model, model 2, that included both direct additive genetic effects and maternal additive genetic effects. Because we previously found that the optimal model for BW included maternal genetic and maternal permanent environmental effects in addition to the direct additive genetic effect (Kang et al, 2020), we tested a third model, model 3, that additionally included the permanent environmental effect for BW. The specific models were as follows:where y is the vector of phenotypic measurements for the five aforementioned traits, is the population mean, b is the vector of fixed effects (herd‐year‐season and cage), a is the vector of direct additive genetic effects, m is the vector of maternal additive genetic effects, p is the vector of permanent environmental effects for BW, e is the vector of residuals, and X , , and are the corresponding incidence matrices.…”

“…Model 1 was an animal model in which random effects included the direct additive genetic effect in addition to the residuals. Our previous study demonstrated that neglecting maternal additive genetic effects biased the estimation of direct heritabilities for all five traits (Kang et al, 2020). Therefore, we also used a model, model 2, that included both direct additive genetic effects and maternal additive genetic effects.…”

“…Therefore, we also used a model, model 2, that included both direct additive genetic effects and maternal additive genetic effects. Because we previously found that the optimal model for BW included maternal genetic and maternal permanent environmental effects in addition to the direct additive genetic effect (Kang et al, 2020), we tested a third model, model 3, that additionally included the permanent environmental effect for BW. The specific models were as follows:…”

“…Genetic parameter estimation of important economic traits such as these is a fundamental component of animal breeding improvement programmes. A large number of studies have already estimated the heritability of these traits, especially BW (Chu et al, 2020; Kang et al, 2020; Norris & Ngambi, 2006). However, very little work has been done in the estimation of genetic correlations.…”