The effect of naked neck, frizzle and normal feather genotypes on laying performance and pterylosis of brown and white layer parents

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Three experiments were conducted in this study. In Experiment one, a study was conducted in the Afigya Sekyere and Ejura Districts, and Offinso Municipal of Ashanti Region with the aim of finding the laying performance of birds possessing various mutant genes in the population of indigenous chickens in the three areas. Questionnaires and interviews were used for the study. Twelve towns/villages (4 from each District) were sampled at random and 90 chicken keepers (30 from each area) who reared their birds under the extensive system of production were randomly selected from these towns/village. The average flock size of a keeper ranged between 22 and 25 in the ratio of 3 males: 9 females. The observed frequency of the normally feathered genotypes differed significantly (P<0.05) from that of the dominant genotypes. In terms of number of eggs laid per year per bird, the frizzled and the naked neck birds were significantly superior compared to the normally feathered birds. The number of eggs hatched in a year was significantly higher (p<0.05) for the frizzle birds than the normally feathered and naked neck birds. Disease resistance was also significantly higher (p<0.05) for the normally feathered birds than the naked neck birds but the naked neck birds did not differ significantly from the frizzle birds. Acceptability was significantly lower for the naked neck than the frizzle and normally feathered birds. Among the problems confronting the keepers were: small size of birds and eggs, theft, low acceptablilty of the Nanaff, annual Newcastle disease attack, lack of funds to maximize production, unavailability of improved breeds and predation. Multiplication, selection and usage of indigenous birds possessing naked neck and frizzle mutant genes in local chicken production coupled with improvement in housing, disease prevention and nutrition would improve productivity significantly. Experiment two was conducted to assess the effects of the naked neck (Nanaff), frizzle (nanaFf) and normal feathered (nanaff) genotypes, and also gold (s-) and silver (S-) plumage colours on the performance of local-exotic crossbred pullets. The pterylosis of the dorsal, ventral and lateral tracts of 27 of these birds were also assessed. Three hundred and sixty (360) pullets of 24 weeks of age were studied in a 3X2 factorial design for 40 weeks. There were 120 pullets within each of the three genotypic groups (Nanaff, nanaFf and nanaff); there were two plumage colours (s- and S-) with three replications in each plumage colour. There were 18 pens with 20 pullets in each pen. Nanaff pullets had significantly higher values (p<0.05) in hen-day egg production, feed intake, age at 50% production, body weight and hen-house egg production than their nanaFf and nanaff counterparts, but the nanaFf pullets were significantly superior (p<0.05) to the nanaff in terms of age at 50% production. Egg mass was not significantly different (p>0.05) in Nanaff and nanaFf pullets and were also not significantly different (p>0.05) between nanaFf and nanaff genotypes but were significantly better (p<0.05) in Nanaff than nanaff groups. No significant differences (P>0.05) were recorded among the genotypes in terms of FCR and egg weight. The S- pullets performed significantly better (p<0.05) in hen-day egg production, egg mass, hen-housed egg production and age at 50% production than their s- counterparts whilst no significant differences (p>0.05) were recorded between the two plumage colour genotypes in terms of egg weight, feed intake and body weight. The naked neck birds had the highest number of feather follicles in the dorsopelvic tract and no feathers in the dorsal cervical tract and cloacal circlet. The naked neck genotype and silver plumage colour improve egg laying performance in layer parents.
A dissertation submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of Master of Science degree in Animal Breeding and Genetics