Estimation of genetic parameters of fertility traits in Chinese Holstein cattle

The objective of this study was to estimate genetic parameters for fertility traits in Chinese Holstein heifers and cows. Data of 20 169 animals with 42 106 records over a period of 10 yr (2001-2010) were collected from Sanyuan Lvhe Dairy Cattle Center in Beijing, China. Traits included age at first service (AFS), number of services (NS), days from calving to first service (CTFS), days open (DO), and calving interval (CI). Genetic parameters were estimated with multiple-trait animal model using the DMU software. Heritability estimates for AFS, NS, CTFS, DO and CI were 0.100+/-0.012, 0.040+/-0.017, 0.034+/-0.011, 0.053+/-0.019 and 0.056+/-0.014, respectively. Genetic correlations between traits observed ranged from -0.13 to 0.99. Genetic correlations between AFS with NS, CTFS, DO and CI were -0.31, 0.15, -0.13 and -0.15, respectively. Calving interval was strongly correlated with NS, CTFS and DO (0.49-0.99), and DO showed strong correlation with NS and CTFS (0.49 and 0.58, respectively). The genetic correlation between CTFS and NS was negative moderate (-0.25). Results were in range with previous literature estimates and can be used in Chinese Holstein genetic evaluation for fertility traits.