Odds ratio of dystocia in Holstein cows in Iraq

Firas Al-Samarai

The objective of this research was to determine the effect of some factors on dystocia in Holstein cows. The analysis consist of 19090 records of parturitions belonged to 3181 cows from 1990 to 2004 in the Nasr Dairy Cattle Station in Iraq. A logistic regression model was used to predict dystocia. The model included effects of year of birth, season (winter or other seasons), parity (first or later), birth weight (kg), and sex of calf. Results revealed that odds of dystocia decreased by 5% per year. Calves born in the winter have higher risk of dystocia by 27% than calves born in the other seasons. Male calves associated with dystocia were greater than female calves by 39%. First parity cows had a 2.04 times higher risk of dystocia than cows in later parities. Odds of dystocia increased with increasing birth weight by 16%/kg. It was concluded that dystocia was affected by all the factors under consideration.