The effect of the naked neck gene (Na) was assessed on growth parameters of the native chicken fed with two suboptimal rations (R1 and R2), and one optimal ration (R3) from 6 to 16 weeks of age. A total of 270 hens of 3 genetic types (homozygous (NaNa) naked neck, heterozygous (Nana) and normal type (nana) chicken) for three different feed rations including two sub-optimal rations (R1, R2) and one optimal ration (R3). Hence, 30 pullets per experimental unit for each genetic type receiving the same ration were used. The animals were subjected to the same experimental conditions except for the tested factor. The starter ration was served during the first six weeks then relayed by the experimental rations. A two-way ANOVA was used to test the main effects and interactions whereas the animal model was used for the estimates of the genotype and feed ration on the growth and related traits. Irrespective of the genotype, the highest growth parameter (p<0.05) was obtained with R3 with the lowest feed efficiency from 12 to 16 weeks. The mortality rate (MR) ranged from 3 to 9% cumulated at 6 and 8 weeks of age. The overdominance effect was confirmed for both the bodyweight (BW) and MR. The Na gene improved the weight gain from +1 to + 14 g from 10 to 16 weeks with optimal feed conditions against -6.67 to +4.33g with suboptimal feed. The more beneficial effect on FCR has been observed in homozygote NaNa with +1.07 to +1.27g and -0.43 to -1.63g for R3 and R1 respectively. This study confirms the importance of the Na gene as a good candidate to improve the growth rate and feed efficiency of native chickens. It also provides an effective protocol for the evaluation of major gene candidates for selection in low input production systems.
Hako Touko Blaise Arnaud and Yoniwo Shey Ndogmi
