Genetic analysis of first lactation persistency and milk production traits in graded Murrah buffaloes.

The 435 fi rst lactation records of Murrah buffaloes that were maintained at GADVASU dairy farm over a period of 31 years from 1981-2011 were studied. The heritability estimates of persistency, 305-day milk yield, total milk yield, peak yield and lactation length were 0.19±0.08, 0.29±0.18, 0.23±0.18, 0.48±0.17 and 0.21±0.15, respectively in the fi rst lactation. Genetic correlations between persistency and 305-day milk yield, total lactation yield, peak yield and lactation length were 0.41±0.12, 0.51±0.11, -0.24±0.14 and 0.49±0.11 while the phenotypic correlations were 0.292, 0.354, -0.202 and 0.373, respectively. Genetic correlations between 305-day milk yield and total lactation yield, peak yield and lactation length were 0.94±0.02, 0.66±0.08 and 0.53±0.11 while the phenotypic correlations were 0.92, 0.684 and 0.529, respectively. Genetic correlation between peak yield and lactation length was 0.18±0.15 while the phenotypic correlation was 0.24.