Bayesian analysis of genetic parameters for early growth traits and humoral immune responses in Japanese quail

The aim of this study was to estimate genetic parameters of early growth performances and humoral immune responses (antibody titers against sheep red blood cells (SRBC) and Newcastle Disease Virus (NDV)) in Japanese quail. For this purpose, a total of 10,923 records of early growth traits including body weights (BW) at 0, 5, 10, 15 and 20 d old and body weight gain (BWG) between 0-5, 5-10, 10-15 and 15-20 days, and 2,314 records of humoral immune responses were used to estimate genetic parameters through multiple-trait Bayesian analyses. The estimates of heritability of BW and BWG traits were 0.14 to 0.28 and 0.08 to 0.10, respectively. The range of genetic and phenotypic correlations for BW traits varied from 0.63 to 0.98 and 0.17 to 0.89, respectively. Furthermore, estimates of genetic and phenotypic correlations for BWG traits at different ages were in the range of 0.46 to 0.86 and 0.12 to 0.46, respectively. Heritability estimates of total antibody titer (AbT), titer of immunoglobulin Y (IgY) and titer of immunoglobulin M (IgM) against SRBC were 0.21, 0.24 and 0.20, respectively, but h2 of antibody titer against NDV (AbNDV) was lower than those of estimated for SRBC antigen (h2 = 0.17). Genetic correlations between antibody titers against SRBC and NDV were similar (0.42 − 0.46). Genetic correlations were positive only for IgM with BW traits, however, estimates of genetic correlation between BW traits at different ages with AbT and IgY were negative and moderate (−0.30 to −0.66), and with AbNDV were negative and low (−0.13 to −0.25). Like BW traits, genetic and phenotypic correlations between AbT and IgY titers and BWG traits were negative and varied from −0.21 to −0.72, while genetic correlations of BWG traits with IgM and AbNDV titers were both positive (0.11 to 0.27 and 0.23 to 0.31, respectively). It is suggests that selection to improved BW and BWG traits may lead to decline of humoral immune responses in Japanese quail. However, improvement of BW and BWG traits and humoral immune responses would be possible through selection for IgM titers against SRBC due to its high and positive genetic correlation with growth traits.