Estimation of breeding value, genetic parameters and maternal effects of economic traits in rural male parent line chicken using pedigree relationships in an animal model

Breeding value (BV), genetic parameters and additive genetic, and maternal effects were evaluated on growth and production traits utilizing data from eight generations employing animal model in a rural male parent line (PD-6) chicken at ICAR-Directorate of Poultry Research, Hyderabad, India. The least squares means (LSM) for body weight (BW) and shank length (SL) up to 6 weeks of age varied significantly (p <= .01) among the generations and hatches. BW increased significantly (p <= .01) over the generations and decreased with the hatches. Sex also had a significant effect on BW and shank length except for BW at 0 day (BW0). LSM for BW (BW6) and Shank length (SL6) at 6 weeks of age were 598.84 +/- 0.79 g and 74.57 +/- 0.04 mm, respectively. Males recorded significantly (p <= .01) higher BWs and shank length. All the production traits were significantly (p <= .01) influenced by the generation effect. The overall LSM for age at sexual maturity (ASM), egg production at 40 weeks (EP40) and egg weight at 40 weeks (EW40) were 164.93 +/- 0.23 days, 74.66 +/- 0.40 eggs and 54.79 +/- 0.08 g, respectively. Model 3 with additive, maternal permanent environmental and residual effects was the appropriate model for BW2, BW4, BW6, SL4 and SL6, whereas Model 4 with maternal effects was the best for BW0. The heritability estimates for BW6 and SL6 were 0.22 +/- 0.02 and 0.18 +/- 0.02, respectively. Model 1 with additive direct and residual effects was the best appropriate model for all the production traits. The heritability estimates of EP40 and EW40 were 0.16 +/- 0.04 and 0.34 +/- 0.05, respectively. BW and shank length were highly correlated with significant (p <= .05) positive association from different components. The correlation coefficient from direct additive component between egg production and BW40 was negative, while it was positive with less magnitude between egg production and BW20. The egg production and egg weights had a negative association at different ages. BV of SL6, the primary trait of selection, was significant (p <= .05) across the generations and increased linearly with an average genetic gain of 1.05 mm per generation. BV of BW6 was also significant (p <= .05) and increased linearly as correlated response with an average genetic response of 22.34 g per generation. BV of EP40 showed an increasing trend with a genetic gain of 0.02 eggs per generation. The EW 40 also increased linearly with an average genetic gain of 0.06 g. The average inbreeding coefficient of the population was 0.015. The study concluded that the population was in ideal status with a linearly increasing trend of average BV with negligible inbreeding over the eight generations of selection.

Automated summary

The study evaluated breeding value, genetic parameters, and additive genetic and maternal effects on growth and production traits in a rural male parent line of chickens in India. Results showed significant variations in body weight and shank length among different generations and hatches, as well as a linear increasing trend in breeding values related to growth traits. Maternal effects and genetic factors were found to play important roles in the expression of production traits.