Study of reproductive indexes of dairy herds in Northwest of Iran and its comparison with existing standards

Background: Reproductive performance has declined in dairy herds over the last few decades associated with changes in management practices, housing, and milk production. The present study was carried out to evaluate reproductive performance and reproductive disorders of Holstein dairy cows in Northwest of Iran.Methods: Data from farms were retrieved by using reproductive management files. In this study, 5118 dairy cows’ records were used to evaluate reproductive performance (open days, calving interval and gestation length) and reproductive disorders (retained placenta and dystocia) during consequent seven years. SAS 9.2 Software was used for data analysis.Result: The means of open days, calving interval and gestation length were 109±61.98, 387±62.33 and 277±7.85 respectively. Season of calving, 305-day milk production, calving status and status of placenta had a significant effect on open days and calving interval (PConclusion: In conclusion, similar to an existing trend in modern dairy herds of Northern America and Western Europe, high milk production had an adverse effect on reproductive performance and disorders in dairy herds of Northwest of Iran.

کلیدواژه ها:

Dairy cattle ، Dystocia ، Open days ، Parturition ، Reproduction ، Retained placenta ، Calving interval