Effect of the Naked Neck Gene (Na) on marketability, carcass traits, haematological and serum biochemical indices of cockerels

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A research comprising of two phases; a survey and an experimental work was conducted: the survey comprised mainly of interviewing market women and supplying birds to them for sale in order to find answers to questions related to marketability or otherwise of the naked neck, frizzled- naked neck and normal feathered cockerels whiles the experiment was carried out to evaluate the effect of the three genotypes namely: (i) NanaFf, (ii) Nanaff and (iii) nanaff on carcass characteristics, haematological/ serum biochemical parameters and marketability of cockerels. The birds used were the fourth generation (F4) offspring of crosses between local heterozygous naked neck (Nana) and heterozygous frizzled (Ff) males and hybrid commercial Lohmann females. Three hundred (300) eleven-week old crossbred cockerels (hundred each of the three genotypic groups) were randomly housed in fifteen (15) opensided deep litter pens with twenty (20) cockerels in each pen in a Completely Randomized Design for nine weeks and their haematological/ serum biochemical indices and carcass characteristics evaluated. The birds were provided with grower mash ad lib throughout the experimental period. Blood was taken from 3 birds from each genotypic group when the birds were 18 and 20 weeks old. At the end of the trial, 15 cockerels from each of the three genotypic groups were randomly selected and slaughtered to determine the carcass parameters. Burgers were prepared from the breast muscle of the carcass for sensory evaluation. The results from the survey indicated that majority (91.7%) of the respondents admitted they would readily accept to sell the naked neck cockerels. Also, at almost all the sales points the Nanaff was first to be sold out followed by the nanaff feathered with the NanaFf being the last both before and during the major seasons‟ sales. On the other hand, the results from the experiment indicated that except for total cholesterol, spleen and neck weight, there was no significant genotypic effect (p>0.05) on haematological, serum biochemical and carcass parameters measured. The nanaff genotype birds had significantly higher (p<0.05) cholesterol levels than both Nanaff and NanaFf genotype birds, both of which did not differ significantly. The Nanaff had significantly (p<0.05) higher spleen and neck weight than both the nanaff and NanaFf. The latter two did not differ significantly (p>0.05). Also, haematological and serum biochemical assays of all the birds were within normal range. The results from the sensory evaluation indicated that the burgers from nanaff and NanaFf birds had significantly (p<0.05) lower acceptability levels than those from the Nanaff birds. In conclusion, the naked neck gene had a positive effect on cockerel meat and cockerel marketability.
A thesis submitted to the Department of Animal Science, Faculty of Agriculture, College of Agriculture and Natural Resources, in partial fulfilment of the requirements for the degree of Master of Philosophy,