Genetic Parameters and Genome-Wide Association Analysis of Reproductive and Calving Traits in Jersey Cattle

Abstract

Simple Summary Reproductive performance is important for the efficiency and sustainability of dairy cattle production. However, the genetic factors affecting reproduction may differ between young heifers and adult cows. In this study, we analyzed reproductive and calving records from Jersey cattle to investigate how genetics influences reproductive performance in heifers and multiparous cows. Age at first service and age at first calving showed a greater genetic contribution than most reproductive traits, suggesting that these traits may respond more effectively to genetic selection. By examining genetic differences across the genome, we also identified several regions associated with age at first calving, number of services in heifers, calving interval, and dam-associated genetic variation in calving ease. Several genes in these regions may be involved in reproductive processes, cell signaling, transport, and development. These findings improve our understanding of reproduction in Jersey cattle and may help support breeding strategies aimed at improving reproductive efficiency.