In this research, records of milk yield, mastitis occurrence and teats hyperkeratosis of 453 Holstein cows from a large herd with calving dates from December 2012 to December 2014 was used to estimate genetic and environmental correlations between milk yield, mastitis and hyperkeratosis. The highest and the lowest number of mastitis occurrence were in winter (January to March) and spring (April to June), respectively. Also, the highest and the lowest averages of days in milk at the time of mastitis occurrence were observed in winter and spring, respectively (162.53 vs. 29.67 days). The total number of mastitis occurrence was 151 times and in average a sick cow was infected 1.649 times. Obtained results showed low heritabilities for measures of mastitis... |