Balancing production and reproduction traits in frieswal cattle: a multivariate approach

This study aimed to estimate breeding values, selection differentials, and response to selection for production and reproduction traits in Frieswal cattle. Data on 1,163 progeny records sired by 69 sires over nine years were collected and analyzed using Average Information Restricted Maximum Likelihood (AI-REML) and principal component analysis (PCA). The traits included age at sexual maturity (ASM), age at first calving (AFC), gestation period (GP), first calving interval (FCI), number of services per conception (NSPC), first dry period (FDP), first service period (FSP), test day peak milk yield (TDPY), first lactation 305-days milk yield (FL305-DMY), fat percentage (FP), and first lactation length (FLL). The response to selection and selection differential for the top 10 individuals showed that FL305-DMY had the highest selection differential (1,726.26 kg) and response to selection (611.10 kg). PCA revealed four principal components that explained 79.90% of the total variance, with PC1 associated with fertility-related traits (FLL, FCI, and FSP), PC2 with sexual maturity (ASM and AFC), PC3 with milk production traits (TDPY and FL305-DMY), and PC4 with milk composition traits (FP and FDP). Although hindered by non-digitized data and complex trait relationships, the study contributes to understanding genetic variability, informs breeding programs, and demonstrates the application of PCA in animal breeding, ultimately enhancing dairy production efficiency. The findings suggest that a multi-trait selection index is essential for achieving sustainable genetic improvement in dairy herds. By considering both production and reproduction traits, breeders can make informed decisions to improve the overall efficiency and sustainability of dairy production.