Influence of strain and production cycle on egg quality traits of two Nigerian indigenous chicken strains
Records obtained from purebred normal feather and naked neck Nigerian indigenous chicken strains were used to assess the influence of strain and production cycle on external and internal egg quality traits. The assessment commenced from first lay to 120 days of lay, classified into four production cycles (PC): PC1 (1-30 days of lays), PC2 (31-60 days of lays), PC3 (61-90 days of lays), and PC4 (91-120 days of lays). Mean egg weight, length and breadthwere 4.34%heavier, 2.10%longer and 1.72%wider in the normal feather than in the naked neck (p<0.05). No disparity due to strain effect was found in egg shape index. Eggshells from the two strains had similar weight but varied in thickness with shells from the naked neck being 0.02mmthicker than those from the normal feather (p<0.05). Eggs fromthe normal feather were 7.13, 5.76, 5.00, 7.10 and 8.11% superior in albumen weight, yolk height, albumen height, yolk index, and albumen index, respectively compared to its naked neck counterpart (p<0.05). Production cycle significantly influenced all external egg quality studied. An increase of 16.21% in egg weight was obtained by PC4. Egg length and breadth increased consistently with each subsequent PC (p<0.05) whereas egg shape index decreased with PC(p<0.05).Higher values were recorded for yolk weight, yolk and albumen length and width in each subsequent production cycle. Haugh unit, yolk and albumen height had best values at PC2. Our findings indicate that strain type and production cycle highly influenced egg quality traits of Nigerian indigenous chickens with the normal feather showing superiority. Furthermore, the best internal quality was obtained at PC2 (31-60 days of lay). Our findings could be useful in choosing selection criterion traits in breeding plans for the development of different layer lines of normal feather and naked neck.