The effectiveness of using bulls with increased immune response in terms of milk yield, milk contents, and somatic cell count in Polish Holstein-Friesian cows

The dairy cattle industry has witnessed significant advancements in production traits, including milk yield, reproduction, and health, through decades of breeding efforts. Despite these improvements, cow health and milk hygiene remain essential. High Immune Response (HIR) technology identifies cattle with optimized immune responses, enabling the selection of bulls with high immune responses for breeding. Studies indicate that HIR-based breeding improves animal health without compromising production traits. This study aimed to assess the effectiveness of bulls with a high immune response (HIR) in improving milk yield, milk contents, and somatic cell count in the milk of Polish Holstein-Friesian cows. A total of 11,509 cows of the Polish Holstein-Friesian breed were used. Among those, 1,773 animals were the offspring of HIR bulls, including 926 first-generation offspring (called I50 group) and 847 second-generation offspring (I25 group). There were 9,736 animals unrelated to HIR bulls (I0 group). Selected production and functional traits were analyzed. The results show that cows with higher kinship to HIR bulls showed increased milk yield. However, their milk exhibited lower fat, protein, and casein content. A favorable impact of HIR bulls was demonstrated by the decrease in somatic cell count in their offspring’s milk compared to the milk of cows from the I0 group. This research contributes valuable insights into the potential benefits of using HIR bulls in dairy cattle breeding programs, emphasizing the importance of balancing production traits with health considerations.