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Genetic analysis of egg production and allied characters in two long term selected strains of white Leghorn

The genetic parameters like population mean and genetic and phenotypic correlations were analyzed from IWN and IWP strains of White Leghorn, which were selectively bred for egg production for 23 generations. The traits analyzed were hen housed egg number up to 40 (EN40) and 64 (EN64) weeks of age, age at first egg (AFE), body weights at 16 (BW16), 40 (BW40) and 64 (BW64) weeks of age and egg weights at 28 (EW28), 40 (EW40) and 64 (EN64) weeks of age in 23rd selected generation (S23). The mean values for different traits in IWN and IWP strains respectively were 110.67 and 105.64 eggs for EN40, 248.27 and 234.46 eggs for EN64, 154.24 and 152.65 days for AFE, 1064.48 and 1024.67g for BW16, 1560.47 and 1587.34g for BW40, 1547.13 and 1628.28g for BW64, 51.12 and 50.37g for EW28, 54.54 and 55.04g for EW40 and 59.46 and 60.38g for EW64. Moderate to high heritability estimates were recorded for EN40 (0.284), EN64 (0.182), AFE (0.349), BW16 (0.488), BW40 (0.388), BW64 (0.284), EW28 (0.375) EW40 (0.447) and EW64 (0.390) in IWN strain. Barring AFE which exhibited low magnitude (0.090), other traits like EN40 (0.239), EN64 (0.220), BW16 (0.318), BW40 (0.285), BW64 (0.242), EW28 (0.460) EW40 (0.491) and EW64 (0.505) showed moderate to high magnitude of heritability in IWP strain. Estimated genetic correlations of EN64, the primary trait of selection with other related traits viz., EN40, AFE, BW16, BW40, BW64, EW28, EW40 and EW64 were 0.824, -0.497, -0.234, -0.070, -0.094, -0.293, -0.455 and - 0.274 respectively for IWN strain and the corresponding figures for IWP strain were 0.944, -0.516, -0.030, -0.061, -0.092, 0.006, -0.073 and 0.0. From the heritability estimates for egg number it can be conclude that the good amount of additive genetic variance for egg production can exist in White Leghorn populations undergoing selection for long period for more than 20 generations. | Genetic analysis of egg production and allied characters in two long term selected strains of white Leghorn