Evaluation of productive Performance of Crossbred Naked-Neck and Frizzle Chicken Genotypes

Two studies (survey and experimental work) were conducted to determine the frequency and incidence of naked-neck and frizzle genes existing in the indigenous chicken and to evaluate the performance of crossbred naked-neck and frizzle birds. In the first phase of the work a survey covering a three month period was conducted in six randomly selected districts in the Ashanti Region of Ghana. From the survey it was observed that the heat-tolerant genes, though dominant in nature, had very low frequencies of 0.03 and 0.05 for frizzle and naked-neck respectively. With regard to the experimental work, two studies (on-station and on-farm) were carried out to evaluate the egg production, growth and carcass characteristics of four crossbred naked-neck and frizzle genotypes, namely: (i) Na/naF/f, (ii) Na/naf/f (iii) na/naF/f and (iv) na/naf/f. These crossbred cockerels were generated from a reciprocal crossing between crossbred heterozygous naked-neck (50% indigenous naked-neck and 50% Lohman Brown) and frizzle (50% indigenous frizzle and 50% Lohman Brown) stocks. In the first on-station experimental study, one hundred and twenty (120), nine-week old crossbred cockerels (thirty each of the four genotypic groups) were randomly assigned to nine deep litter pens in a Completely Randomized Design for six weeks and their growth and carcass characteristics evaluated. The birds were provided with grower mash ad lib throughout the experimental period. At the end of the six-week trial, 3 cockerels from each of the four genotypic groups were randomly selected and slaughtered and their carcass parameters determined. The results indicated that there was no significant phenotype effect on initial body weights. iv However, the naked-neck frizzle phenotypes were significantly heavier at 14 weeks than the other phenotypes. The double heterozygous cockerels also gained significantly more weights than the other genotypes. The double heterozygous frizzled naked-necks (Na/naF/f) consumed significantly (P<0.05) more feed than the single heterozygous frizzles and naked necks (Na/na and F/f) and the normally feathered birds (na/naf/f). The double heterozygotes were significantly better converters of feed into meat than their single heterozygote and normally feathered counterparts. With respect to carcass yield characteristics, the double heterozygous cockerels had significantly (P<0.05) higher values in terms of percent leg yield, breast yield, thigh yield, dressed weight and dressing percentage. The second part of the on-station experimental work involved one hundred and twenty (120), eighteen-week old crossbred pullets (thirty each of the four genotypes) which were randomly assigned to a CRD experiment for a period of up to 60 weeks. The selected pullets were put in a partitioned deep-litter house, with 10 pullets in each compartment and provided with layer mash ad lib throughout the experimental period. The double and the single heterozygous pullets laid their first egg significantly (P<0.05) earlier than their fully feathered counterparts. The double heterozygotes produced significantly (P<0.05) more eggs (130) than the single heterozygotes (121 and 122) which also produced significantly more eggs than the normally feathered birds (113). Feed was more efficiently converted into eggs by the double heterozygous pullets than the other genotypes. There were no significant (P>0.05) differences among the genotypes in terms of eggshell thickness, albumen height, yolk height, Haugh unit and yolk v colour. Another on-farm study was carried out to compare egg production performance of the crossbred naked-neck and frizzle pullets and normally feathered local pullets under the semi-scavenging system. In this trial, 240, 10-week old randomly selected crossbred pullets (eighty each of naked-neck frizzle, naked-neck only and frizzle only) were distributed to some 10 selected farmers in the Ashanti Region of Ghana. The crossbred double and single heterozygous pullets were reared alongside the farmers’ own normally feathered local pullets that were of the same age as the crossbred pullets. Results on total eggs laid up to 60 weeks of age showed the crossbred pullets laying significantly (P<0.05) more eggs (105 eggs) than the local hens (78 eggs). There was a significant difference (P<0.05) between the crossbred pullets (181 days) and the local pullets (217 days) with respect to age at first lay. The crossbred layers produced eggs at a significantly (P<0.05) higher rate (43%) than the local layers (37%). Eggs laid by the crossbred layers were significantly (P<0.05) bigger than those laid by the local hens throughout the entire laying period. The farmers’ local pullets recorded significantly (P<0.05) lower deaths than the crossbred pullets, but between the crossbreed pullets (double and single heterozygotes), there were no significant differences. There was a genotype-environment interaction for rate of lay and mortality for the crossbred naked-neck and frizzle genotypes when the performance of the birds was compared under on-station and on-farm conditions. Estimates of heterosis showed that F2 offspring from the F X Na reciprocal cross were better than the offspring from the Na X F main cross in terms of body weights, egg weight and egg production parameters measured.

Source: KNUST