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ThesisItem Open Access Estimation of first lactation milk yield on the basis of part lactation milk yield in Murrah buffaloes.(Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut- 250 110, (U.P.) INDIA, 2011) SANJAY KUMAR; Rajkumar; Y.P.Singh, D.S. Sahu, Ravindra KumarA total number of 222 performance records of murrah buffaloes progeny of 53 sires at the Central Institute For Research on Buffalo Hisar (Haryana), over a period of 16 years from 1986 to 2001 (years of first calving) were used to study the effect of seasons and years on cumulative part lactation milk yield. The genetic and non-genetic parameters of cumulative part lactation milk yield and first lactation production traits and to predict the 305 days milk yields on the basis of cumulative part lactation milk yield viz. The effect of seasons were found to be non-significant on cumulative part lactation milk yield as recorded by Khan and Johar (1988), Iype and Nagarcanker (1992) and Yadav et al. (2003). The effect of years on cumulative part lactation milk yields were found to be highly significant as reported by Khan and Johar (1988), Iype and Nagarcanker (1992) and Yadav et al. (2003). The heritability estimates for cumulative part lactation milk yield and for first lactation production traits were found in arrange of 0.074±0.052 (120 days milk production) and from 0.001±0.188 (first lactation milk yield) to 0.0420±0.288 (first service period), respectively. The heritability of cumulative part lactation milk yield in earlier stages have higher magnitude than middle and later stages of lactation and showed more additive genetic effect. Appannayar et al. (1995) also reported heritability estimates of the cumulative test-day milk yields in range of 0.15±0.17 to 0.39±0.28. The genetic and phenotypic correlations among cumulative part lactation milk yields were a ranged from 0.572±0.020 (between 30 days and 240 days milk yield) and from 0.502± 0.288 (between 30 and 240 days milk yield) to 0.999±0.002 (between 150 and 180 days milk yield), respectively. Dass (1995) and Geetha (2006) also reported the high positive and significant genetic and phenotypic correlations among the adjacent test day milk yield. The genetic and phenotypic correlations among first lactation production traits were ranged from 0.017±0.937 (between first calving and dry period) to 0.995±0.007 (between age at first calving and service period) and from -.080±0.991 (between age at first calving and dry period) and service period, respectively. The prediction of 305 days lactation milk yield on the basis of cumulative part lactation milk yield showed the higher value of R² (78.70%) for 240 days and lower value of R² (12.92%) for 30 days of cumulative part lactation milk yield. However, significant differences were not found for 30, 60, 90, 120, 150, 180, 210, 240 and 270 days of cumulative part lactation milk yield. The R² values indicate that the animals for milk yield can be selected earlier on the basis of 60, 120, 150, 180, 240 and 270 days of cumulative part lactation milk yield,