Phenotypic Correlation between Growth and Reproductive Traits in Crossbred Layer Chickens

Aims: To study the phenotypic correlation between growth and reproductive traits in layer chicken. Place and Duration of Study: This study was carried out in Poultry Research Farm, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, India, between 2019-2021. Methodology: In this study, 450 crossbred layer chickens were selected from three distinct genetic groups: Desi Cross 1, Desi Cross 2, and Punjab Red at the Poultry Research Farm of the Directorate of Livestock Farms at Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana. Data collection occurred between 2020 and 2021, focusing on several economically important traits. These included body weight at sexual maturity (BWSM; g), age at sexual maturity (ASM; days), weight of the first egg (FEW; g), egg production at the 40th weeks and 52nd weeks (EP; number) and egg weight at the 40th weeks and 52nd weeks (EW; g). Additionally, weekly body weights were recorded from day 0th to the 20th and 40th weeks (BW; g). Results: The highest coefficient of variation (CV; %) for body weight was observed at the 4th week, while the lowest CV was recorded at the 0th week. Among reproductive traits, the average age at sexual maturity (ASM) was 165.61 ± 0.81 days, with a CV of 14.05%. The egg production at the 40th and 52nd weeks displayed the greatest variability, whereas egg weight at these weeks showed relatively low variation. The first egg weight exhibited moderate variability, with a CV of 13.29%. Meanwhile, the body weight at sexual maturity had a CV of 19.97%, reflecting a moderate level of variation for this trait. The phenotypic correlations among these traits were estimated using the WOMBAT software. The analysis revealed highly significant phenotypic correlations between body weight at 1st week and egg production at 40th week, as well as first egg weight. Similarly, significant correlations were observed between body weight at 2nd weeks and egg weight at 40th weeks, body weight at 3rd weeks and first egg weight, body weight at 10th weeks and egg production at 52nd weeks, and body weight at 14th weeks and egg weight at 40th weeks. Conclusion: Overall, the present study suggests that while body weight traits demonstrate relative consistency in growth patterns, reproductive traits, particularly egg production, show greater variability and thus offer more opportunities for genetic improvement. Selective breeding efforts should be focused on reducing variability in key traits such as EP40 and EP52 to enhance overall productivity in layer chickens. Moreover, this study highlights the significant phenotypic relationships between growth and reproductive traits in layer chicken populations.