عملكرد گاوهاي نر هلشتاين وارداتي براي صفات توليدي در شرايط مختلف آب و هوايي ايران

The performance of imported Holstein bulls for production traits in different climates of Iran

67873 first lactation records of Holstein cattle were used to compare the performance of imported bull in different climates of Iran for milk and fat traits. Data were collected by the Iranian Animal Breeding Center from 1995 to 2001. Heritability estimated using REML method and derivative - free algorithm for milk yield and fat yield ranged from 0.16 to 0.25 and 0.06 to 0.24, respectively. Genetic correlations among regions ranged from 0.76 to 0.99 for milk yield and 0.46 to 0.99 for fat yield, respectively. In conclusion, different genetic parameters, low correlation between some regionsʹ and reran king of bull indicated that genotype by environment interaction may be present.