The effect of the naked neck (NA) and frizzling (F) genes on the fertility, hatchability, egg quality and pterylosis of locally developed commercial layer parent lines

The effect of the naked neck (Na) and frizzling (F) genes on the fertility and hatchability of eggs of 24 week- old locally developed layer parent lines (brown and white) were examined. Three feather genotypes were used, namely, the naked neck (Nanaff), frizzle (nanaFf) and the normal feathered birds (nanaff). A total of 3,196 eggs were set in the study. Fertility values in the naked neck (71.98%) and the frizzle birds (70.29%) were significantly higher (p<0.05) than those in the normal feathered bird (63.17%). Hatchability of eggs from the frizzle (76.81%) was significantly higher (p<0.05) than the 65.07% and 59.64% obtained for the naked neck and normal feathered birds respectively. The weights of the day-old chicks obtained from the different lines did not differ significantly (p>0.05). In the second phase of the study, 2,430 eggs were used to determine the effect of the feather genotypes on egg quality traits. There were no significant differences (p>0.05) among the three genotypes with respect to egg length, egg width, shell thickness and shape index. There was a significant difference (p<0.05) in egg weight between the naked neck and the normally feathered birds but no difference (p>0.05) was observed between Nanaff and nanaFf. The naked neck and frizzled birds laid eggs that had significantly higher (p<0.05) yolk weight compared to their normal feathered sibs. The Nanaff also produced eggs with significantly higher (p<0.05) diameters than eggs from their sibs while, the normal feathered birds showed a significantly higher (p<0.05) yolk index than the Nanaff and nanaFf genotypes. There was no significant (p>0.05) difference in yolk weight and yolk colour score among all three genotype. Average values for albumen diameter, albumen height, albumen index and Haugh unit were significantly higher (p<0.05) in eggs from Nanaff (naked neck) vii compared to the frizzle (nanaFf) and normal feathered (nanaff ) birds while there was no significant (p>0.05) difference in albumen weight for the three feather types. A study was also conducted on the feather pattern exhibited by birds with the naked neck and Frizzle genes compared to normal feathered birds. The pterylosis of the dorsal, ventral and lateral regions were evaluated as to the number of lines and follicle for each region. Twenty seven birds nine from each genotype naked neck, frizzle and normal feathered were slaughtered for the determination of the pterylosis of the three regions dorsal, ventral and lateral. The birds were de-feathered carefully to avoid damage to the skin. Lines and follicles in each tract were then counted and recorded for each genotype. The study showed that the numbers of lines and follicles of the three regions were significantly reduced (p<0.05) in the naked neck as compared to their frizzle and normal feathered counterparts. The frizzle and naked neck genes could be incorporated in layer parents in hot humid areas to improve performance in fertility, hatchability and some egg quality traits.

Source: KNUST