Effect of non-genetic factors on age at first freezing and age at first use in Murrah bulls

摘要

In present investigation, the effect of non -genetic factors on age at first freezing and age at first use in Murrah breeding bullshas been studied. The data on reproduction traits of 57 Murrah bulls under NDRI (National Dairy Research Institute) centre belonging to 14 sets of Network Project on Buffalo Improvement at ICAR-NDRI, Karnal (Haryana), India during 20 years (1993-2013) were analysed using fixed linear model. The data were classified into various sub-classes for season of freezing and use, period of freezing and use, parity, stages of lactation and age groups of buffalo for age at first freezing and age at first use of Murrah breeding bulls. The average age at first freezing and use of Murrah bulls was estimated as 3.46 +/- 0.08 years and 4.05 +/- 0.13 years with the coefficient of variation of 14.43 % and 12.27%. The overall least-squares means for age at first freezing of Murrah bulls was estimated as 3.38 +/- 0.01 years. Period and season of freezing had significant effect (P<0.01) on age at first freezing. The overall least-squares means for age at first use was estimated as 3.96 +/- 0.03 years in Murrah breeding bulls. Period (P<0.01) and season (P<0.05) of use of bulls had significant effect on age at first use of breeding bulls.