Abstract: The objective of this study was to investigate the main factors of retention of the afterbirth of diary cow, datas of calving records form Xinjiang Hutubi dairy farm were collected and sorted out, the effects of calving season, parity, sex, and calf birth weight on retention of afterbirth of the diary cow were analyzed by SAS 8.1. Results showed that the effect of cows calving season on retained fetal membranes of cows was highly significant (P<0.01), incidence rate of retained fetal membranes of cows in winter was up to 40.72%; the effect of parity on retained fetal membranes of cows was highly significant (P<0.01), incidence rate of retained fetal membranes of cows was no less than 40% especially when the parity was more than 3. The effect of sex and calf birth weigh on retained fetal membranes of cows was not significant (P>0.05).

Key words: dairy cow; calving season; parity; sex; calf birth weight; retention of the afterbirth