Association of Some Physiological Factors and Milk Performance in Chinese Holstein

In an effort to determine the effect of physiological factors on milk production, a total of 13889 lactation records for 10544 Chinese Holstein cows from 2005-2011 year were collected for association analysis. Physiological information included age at first calving (AFC), milk peak day (MPD), calving interval (CI), calving season (CS) and parity (P). After the statistical comparison, it was concluded that all factors can significantly affect the level of 305-d milk production (p<0.05) with the exception of age at first calving. In addition, our data suggested that the 2nd and 3rd parity, calving in winter, reaching the milk peak at 60-80 day postpartum, calving for the first time at the age of 24-27 month and a 360-390 day calving interval are optimum for best milk performance in dairy cattle.