Identification of Cow-related Health Disorders Affecting the Culling in Torbat-e Jam Dairy Farms

An experiment was conducted to assess characterization of cow-related health disorders affecting the culling in Torbat-e Jam dairy farms. In total, the data of 5874 lactating cows have been used in this study (1997 to 2017). The logistic regression was applied to investigate the associations between the response variable, the risk of culling, and predictor variables including the parity, calving ease, birth type, calving season, and age at the first calving. The risk of culling increased with parity and twinning (P< 0.001). The odds ratio (OR) of a cow leaving the herd were 1, 1.17, 1.35, 2.06, 2.95 and 3.55 for parities 1 to 6, respectively, 1 and 1.14 for twinning. The OR increased with increasing in calving difficulty score (P< 0.001). The OR were 1, 1.21, 1.26 and 2.30 for calving difficulty score 1 to 4, respectively. Calving in hot season increased the risk of culling (P< 0.001). The OR were 1, 1.59, 1.46 and 1.06 for spring, summer, fall and winter respectively. Cows that calved first at about 24 months of age had a lower risk of culling (P< 0.001). These findings help farmers reduce their involuntary culling rates in dairy herds by improving the management of dairy cows in Torbat-e Jam.