Effects of calving season,lactation days,and parity on dairy cow production performance in Tianjin

LI Shuangshuang; CHEN Lili; YANG Sheng; MA Yi; HAN Bo; WANG Yang

doi:10.13557/j.cnki.issn1002-2813.2025.14.019

Abstract：The experiment aimed to investigate the effects of calving season,lactation days,and parity on the dairy cow performance in Tianjin.A total of 132 541 Dairy Herd Improvement(DHI)records from three large-scale dairy farms in Tianjin,covering the period from December 2022 to November 2024,were statistically analyzed.The results showed that cows calving in the spring exhibited the highest milk yield,while cows calving in the autumn had the highest milk fat percentage,fat-to-protein ratio,persistency and within herd index(WHI).Milk yield peaked during lactation days 31 to 100,while urea nitrogen and WHI were the highest between 101 to 200 days,but the milk fat percentage,fat-to-protein ratio,and somatic cell count were the lowest during this period.Cows in their third lactation had the highest milk fat percentage and milk protein percentage,while cows in their seventh lactation had the highest fat-to-protein ratio and somatic cell count.The correlation analysis results of different calving seasons,lactation days and parity showed that milk yield was significantly negatively correlated with milk fat percentage,milk protein percentage,fat-to-protein ratio and somatic cell count(P＜0.05),and significantly positively correlated with persistency and WHI(P＜0.05).Milk fat percentage showed a significant positive correlation with milk protein percentage and fat-to-protein ratio(P＜0.05).The study indicates that the production performance of dairy cows in Tianjin is significantly influenced by the calving season,lactation days,and the parity.In the future,the proportion of the second to fifth parity cows giving birth in autumn could be increased,and the feed formula could be optimized to enhance the production performance of dairy cows.At the same time,measures should be taken to improve the insulation of the cowshed in winter to increase the milk production of dairy cows giving birth in winter and reduce the risk of mastitis in dairy cows.