Evaluation of holstein bulls widely used for artificial insemination of cows at aydin province

In this study, milk yield characteristics and reproductive performance of Holstein Friesian cows obtained from imported semen were evaluated. The effects of environmental factors on the investigated traits were also determined. In this research, the following characteristics were studied as milk yield trait; duration of lactation period, lactation milk yield, 305 day milk yield and duration of dry period. Calving interval, number of inseminations per conception, service period, gestation period, age at first insemination and age at first calving were also studied as reproductive traits.Data were collected from daughters of 26 sires at different dairy farms from 13 district of Aydin province in Turkey. Least-squares means for duration of lactation period, lactation milk yield, 305 day milk yield and duration of dry period were 347 day, 7103 litre, 6348 litre and 59 day, respectively. The cows raised in Aydin which evaluated for milk yield performance had high average milk yield results in condition of Turkey.Least-squares means for reproductive traits inluding calving interval, number of inseminations per conception, service period, gestation period, age at first inseminations and first calving, were found as 412 day, 1.48, 101 day, 277 day, 577 day (~19.2 month) and 854 day (~28.5 month), respectirely.Sire x district interaction were found significant (P<0.05 or P<0.01) for lactation and 305 day milk yield, number of inseminations per conception, service period, age at first inseminations and first calving, while not significant (P>0.05) for duration of lactation periods, duration of dry periods, calving interval and gestation length. On the other hand, year x season interaction was not significant for milk yield traits and reproductive traits except duration of dry period and gestation length.The highest breeding value for milk yield were reported from international evaluations for A bull among the 25 sires widely used in Aydin. However, the rank of this sire accordiry to breedy values of his daughter abtained in Aydın was 11. The ranking of sires for breeding values of milk yield obtained from international evaluation do not agree with local ranking as a result of genotype by environment interactions.The results obtained from this study can be used for planning of herd management in farms of Holstein cattle at Aydin province.