Comparison of reproductive performance of Seminal-Holstein cows with Holstein in Golestan province

The aim of this study were carried out to compare reproduction performance of pure Holstein and crossbreds of Holestein-Simmental (50H:50S and 25H:75S) that kept in one farm located in Golstan Province. Reproductive parameters including age of first insemination, age of first calving, gestation length, open days, calving interval and calf birth weight were studied. The Pure Holstein and Holestein- Simmental (50H:50S and 25H:75S) were not different for age at first insemination and age at first calving. The open days had significant influence on Pure breed Holstein and Holestein- Simmental (50H:50S) during the first and third lactation. In this study, the calving distance between pure Holstein breeds and Holstein-Seminal crossbred was significant with a ratio of 50H:50S in the first and second lactation (p<0.05). Calf birth weight in pure Holstein breed (41.228 and 43.787 Kg) were more than Holestein- Simmental crossbred (50H:50S), (40.32 and 41.107 Kg) during the first and second lactation and that was in Holestein- Simmental crossbred (50H:50S), (40.32 Kg) more than Holestein- Simmental crossbred (25H:75S), (36.6 Kg) but there was no significant difference between them. The results of this study indicate that the reproductive performance of Holestein- Simmental crossbred for open days and calving interval and the age of the first inoculation of Seminal-Holstein crossbred with a ratio of 25H:75S were better than Pure Holstein.