Correlation between Behavior and Milk Yield of Dairy Cows

The objective of this study was to evaluate correlation between four behaviors (lying, standing, feeding and drinking) of daily cows and milk yield using principal component regression method. For each behavior, daily occupied time, daily frequency, daily occupied time for a single behavior, and percentage of cows with each behavior to all cows were investigated for 7 d in the middle of each month. The results showed that both the lying time and lying percentage were higher than other three behaviors. During whole year, the lying, standing, feeding and drinking time were 735.5, 347.6, 232.6 and 18.3 min per day, respectively and the percentages were 57.9, 25.1, 14.9 and 2.1%, respectively. Additionally, four behaviors demonstrated their seasonal characteristic. The low lying time and low lying frequency occurred in winter months, averaged 644.1, 724.3, 686.0 min and 8.4, 13.3, 8.0 times per day; low feeding time and low feeding frequency occurred in summer months, averaged 309.7, 315.7, 335.4 min and 12.0, 11.0, 16.3 times per day. The drinking time and drinking percentage were highest in summer months, averaged 23.8, 25.0, 24.2 min and 3.9, 4.8, 2.4% per day. On the other hand, a significant negative correlation was observed between the standing time and feeding time or feeding percentage (P<0.05). Besides, the milk yield of dairy cows was significantly positively correlated with the lying time (P<0.05, r = 0.686) or feeding frequency (P<0.05, r = 0.595) during a whole year. Based on our investigated data, two regression equations, between the milk yield and time distribution of the four behaviors, and between the milk yield and behaviors percentage, were also established, suggesting the lying time had a crucial effect on milk yield. Therefore, the results would provide important information for improving milk performance for daily cows. (C) 2019 Friends Science Publishers