0023-6152

AA00697606

20196

査読無

0023-6152

AA00697606

The objective of this study was to investigate the effects of environmental factors on reproductive traits of pure Brown Swiss cows reared under steppe climate conditions in the central Anatolia region of Turkey. In this study, 1502 reproductive records of Brown Swiss cows, which were reared in Ulaş State Farm, were analyzed. The least squares means for gestation period, calving interval, non–pregnant period, insemination number for cows, insemination number per conception for heifers at first insemination, first insemination age, and age at first calving were 287 days, 416 days, 128 days, 1.8 times, 1.6 times, 608 days, and 928 days, respectively. Calving times significantly affected the non–pregnant period, calving interval and gestation period (P<0.05). The calving intervals were significantly the longest in the 2nd calving time and the shortest in the 8th and 9th calving times (P<0.01). The birth season of heifers significantly affected first insemination age and age at first calving (P<0.01, P<0.001, respectively). For the calving season analysis, gestation period was the longest in autumn (P<0.01). The number of inseminations per conception for cows was significantly larger in spring and autumn than that in summer (P<0.01). The first calving ages were significantly earlier in autumn than in the other seasons (P<0.01). For analysis of insemination season, regarding insemination number per conception, first insemination age and first calving age, heifers in spring and summer were significantly larger than those in winter and autumn (P<0.01). These results suggested that 1) birth and insemination season affected first insemination age and first calving age, 2) Cows born in autumn and winter showed an earlier first insemination and first calving age than in spring and summer, and 3) the same trend would be observed for insemination season.