ABSTRACT
Genetic parameters were estimated for egg production, egg quality, and eggshell colors in eight lineages of Brazilian laying hens. Age at first egg (AFE), total egg production up to the 45th week (PROD), egg weight (EW), albumen height (AH), yolk color (YC), the Haugh units (HU), eggshell strength (ESS), eggshell thickness (EST), yolk weight (YW), eggshell weight (ESW), and eggshell color (L*, a*, and b*) were measured in 2030 eggs obtained from 645 laying hens. Variance components were estimated from a mixed animal model, which included the fixed effects of contemporary groups, cage location, and hen line, and the additive genetic, permanent environmental, and residual as random effects. In general, heritabilities were low to moderate (h2 = 0.11 to 0.48). Genetic correlations among eggshell quality traits were moderate to high (0.36 and 0.69). High genetic correlations were obtained between the eggshell color traits [rg = -0.90 (L* and a*); rg = -0.64 (L* and b*); and rg = 0.65 (a* and b*)]. Results suggest that EW is strongly correlated with ESW, but the genetic correlations between EW and ESS and between EW and EST were low. Genetic correlations between L* and eggshell quality traits were low to moderate, suggesting that L* has little or no relation with external egg quality. However, genetic correlations between a* and b* values and eggshell quality traits were high. The genetic correlations between eggshell color and eggshell quality traits were low, suggesting that the eggshell color does not influence external egg quality. Genetic correlations between PROD and egg quality traits were negative and varied between -0.42 and -0.05. This antagonistic relationship emphasizes the importance of adopting breeding schemes that allow the simultaneous genetic progress of these traits by considering their genetic correlation and economic relevance, such as the selection index.
Subject(s)
Chickens , Cytochrome P-450 CYP2B1 , Animals , Female , Chickens/genetics , Brazil , Ovum , Egg Shell , EggsABSTRACT
The objective of this study was to determine the effects of eggshell color of guinea fowl (Numida meleagris) eggs on eggshell quality and hatchery results. The highest mean grey value (MGV), integrated density (ID), lightness (L*) and Hue angle (H*) values were obtained in eggs with lighter eggshell color. The effects of color difference (DE*) value levels on egg characteristics were evaluated. Eggshell color presented different (p < 0.01) MGV, ID, L*, redness (a*), yellowness (b*), H* and Chroma (C*) values. Eggs with lighter color presented thicker eggshells and lower egg weight loss on day 25 of incubation (p < 0.05) compared with intermediate and darker eggs. Eggshell color did not have any significant effect on fertility and hatchability (p > 0.05). In conclusion, under the conditions of the present study, eggshell color influenced eggshell thickness and weight loss, but not hatching parameters of guinea fowl eggs. Further studies on this subject should be carried out.(AU)
Subject(s)
Animals , Poultry Products/analysis , Chickens/physiology , Egg Shell/anatomy & histology , Color , Poultry/growth & development , Birth RateABSTRACT
The objective of this study was to determine the effects of eggshell color of guinea fowl (Numida meleagris) eggs on eggshell quality and hatchery results. The highest mean grey value (MGV), integrated density (ID), lightness (L*) and Hue angle (H*) values were obtained in eggs with lighter eggshell color. The effects of color difference (DE*) value levels on egg characteristics were evaluated. Eggshell color presented different (p 0.05). In conclusion, under the conditions of the present study, eggshell color influenced eggshell thickness and weight loss, but not hatching parameters of guinea fowl eggs. Further studies on this subject should be carried out.