The rational use of the native chicken genetic resource is seen a viable option for sustainably improving poultry meat production in Cameroon. This study aimed at assessing the potential of the Na gene for resilience under acute heat stress. The study was done in two trials. Firstly, a total of 180 young roosters reared in similar management conditions from the 1st to the 8th week of age were randomly distributed per genotype according to a 3 x 2 factorial design including two treatments (acute and moderate ambient temperatures) of 90 birds each and three genotypes (Na*Na, na*na and Na*na) of 30 birds per treatment. Treatments consisted of moderate and acute ambient temperatures of 25-27°C and 39 - 42°C respectively for 5 hours/day from 8 to 12 weeks of age. The genotypes within and between the treatments were compared for body weight (BW), average daily weight gain (ADG), water consumption (WC), feed consumption (FC), and feed conversion ratio (FCR). Results showed that the na*na and Na*na were statistically comparable but superior to the Na*Na genotype under moderate temperature. The three genotypes were significantly affected (P<0.05) by the heat stress. However, the Na*na was less affected and maintained the highest ADG and lowest FCR. For the second trial, 90 birds including 30 birds randomly sampled per genotype were compared for the feathering intensity and five carcass characteristics and giblets at 24-week-old. The results revealed an association of the “Na” gene with 21 to 50 % feather reduction in heterozygote and homozygote respectively whereas heterozygote naked neck had greater body and carcass weight as well as giblet and head weights (P<0.05). The animal model equation could clearly quantify the genotype effect. The phenotypic advantage evidenced for the Na gene is confirmed as an adaptation to heat stress whereas the significant superiority of heterozygote Na*na for most of the traits opens a window for the valorisation of potential overdominance effects for poultry breeding in hot climates.
Hako Touko Blaise Arnaud and Yoniwo Shey Ndogmi
