哺乳期发生腹泻和肺炎对荷斯坦奶牛寿命和生产性能的影响OA北大核心

To investigate the effects of diarrhea and pneumonia during pre-weaning on the longevity and subsequent productivity of Holstein cows,this study utilized the culling records from a large-scale commercial dairy farm between 2012 and 2022.Based on the disease records during pre-weaning period,cows were categorized into four groups:H group(healthy group),D group(diarrhea group),P group(pneumonia group),and D+P group(diarrhea+pneumonia group).After cleaning the raw data,an analysis of variance was used to compare the effects of the diseases on cows'survival days,age at first insemination,age at first calving,and 305-day milk yield of the first lactation.The Kaplan-Meier method was used to analyze the survival probabilities of cows in each group,and the Cox proportional hazards regression model was used to analyze the culling risk within 400 days for each group.The results showed that compared to the H group,the survival days and survival probabilities of cows in the D,P,and D+P groups were significantly reduced(P＜0.01),and the culling risk within 400 days was significantly increased(P＜0.01).However,there were no significant differences in the age at first insemination,age at first calving,and 305-day milk yield of the first lactation(P＞0.05).The findings indicate that diarrhea and pneumonia during pre-weaning negatively affect cow longevity but do not negatively impact reproductive performance and milk yield in first lactation.