Genetic analysis of dairy cattle performance under extensive, semi-intensive and intensive production systems under tropical climate in Kenya

Genetic parameters for milk and fertility traits of dairy cattle managed under extensive, semi intensive and intensive production systems in Kenya were estimated. Univariate and bivariate analyses were used to estimate genetic parameters for 305 days milk yield, lactation length, age at first calving, and calving interval. The heritability estimates for milk yield were moderate to high and ranged from 0.17 to 0.34. Estimated heritability for calving interval was low under all three production systems. Moderate to high heritability was estimated for lactation length and age at first calving. All the estimates varied among the production systems. Genetic correlation estimates among milk yield and fertility traits were negative. Production system specific parameters are essential to achieve optimum genetic gain under the three production systems in Kenya.