Genetic, Phenotypic and Environmental Trend for Milk Yield and Production Efficiency Traits in Gir Cattle
Nikhil S Dangar Pravin H Vataliya
Vol 7(9), 36-42
The first lactation records of 1450 Gir cattle progeny of 290 dams and 41 sires maintained over the period from 1987 to 2010 at Cattle Breeding Farm, Junagadh Agricultural University, Junagadh, Gujarat were used to estimate the phenotypic, genetic and environmental trends of traits viz. first lactation total milk yield (FLTMY), first lactation total milk yield per day of first calving interval (FLTMY/FCI), first lactation total milk yield per day of first lactation length (FLTMY/FLL). The phenotypic trends were estimated as: 90.70 ± 6.44 kg, 0.24 ± 0.01 kg and 0.32 ± 0.02 kg for FLTMY, FLTMY/FCI and FLTMY/FLL respectively. The genetic trends were compared by five methods as Smith method1 (SM1), Smith method 2(SM2), Powell and Freeman method 1 (PM1), Powell and Freeman method 2 (PM2) and BLUP. The annual genetic trends for FLTMY were found to be positive by SM1 (2.88 ± 39.58 kg), PM1 (2.21 ± 37.34 kg) and BLUP (9.17 ± 1.94 kg). The annual genetic trends for FLMY/FCI were positive by SM1 (0.43 ± 0.03 kg), SM2 (2.69 ± 0.03 kg), PM1 (0.38 ± 0.02 kg) and PM2 (2.06 ± 0.02kg) while negative by BLUP (-0.05 ± 0.01 kg). The annual genetic trends for FLMY/FLL were found to be positive by SM1 (0.51 ± 0.06 kg) and PM1 (0.45 ± 0.03 kg) methods while negative by SM2 (-2.37 ± 0.05 kg), PM2 (-1.79 ± 0.03 kg) and BLUP (-0.06 ± 0.01 kg). However, the estimates obtained by BLUP method had the lowest standard errors and were more reliable compared to other methods.
Keywords : Gir Cattle Genetic Trends Phenotypic Trends Environmental Trends
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