Native or local chicken breeds play an important role in the rural sector and small households in developing countries, as well as provide a reservoir of potentially useful genetics for commercial strains. Standardisation and classification of the available native chicken populations based on morphological appearance, coupled with genetic diversity are necessary to conserve them for genetic improvement strategies. Most of the studies conducted on Saudi native chickens to evaluate their productive performance usually ignore the genetic origin and purity of the breed. Despite most native chickens having poor productivity, people in Saudi Arabia traditionally raise these chickens for their preferred eggs and ornamented appearance. The majority of such native chickens are maintained in rural communities and household poultry farms however, some native chickens with genes such as naked neck (Na), frizzle (F) and crest (Cr) are kept by poultry fanciers in small populations. These genotypes exhibit better performance under hot environmental conditions, a trait that may be useful in commercial strains. Six Saudi native chicken populations have been recognised and characterised. Their morphological characteristics, plumage appearance and productive performance have extensively been studied and documented in the current review.

Major marker genes are believed to confer not only adaptability to the tropical climate, but also resistance to diseases. During the last two decades, many investigations have observed that naked neck and frizzle genes have favourable effects on immunocompetence in chickens raised under high ambient temperatures. As a result, several tropical countries have introduced these genes in breeding programs to improve both the productive performance and survival rate of chickens.

High ambient temperatures in tropical and subtropical regions adversely affect the growth and egg productive performance of both broiler and laying chickens. Relative humidity and ventilation rate influences bird's performance, particularly when they are reared in open sided poultry houses. Genetic approaches that aid in reducing or altering the extent of plumage cover has, as a result, been adopted in many hot regions. Fortunately, there are some major and marker genes can reduce the deleterious effects of heat stress, naked neck (Na) and frizzle (F) genes being the most notable ones. The bulk of relevant literature has shown that their favourable effects on growth and laying performance are well established. Therefore, the naked neck and frizzle genes can be a viable alternative for broiler and layer production particularly, in the tropical countries where summer temperatures are very high.

The genetic basis and dominance relationships of the Naked neck gene and its geographical distribution in local populations is described. The effects on growth, feed efficiency, body composition and meat yield of broilers and the effects on egg laying and egg traits, reproduction and liveability in broiler breeding and laying birds are reviewed. On the whole, the results are encouraging for the future use of these genotypes at high ambient temperatures, either for meat or egg production. The results revealed that the autosomal Naked neck (Na) gene reduces feather mass by about 20% in heterozygous (Ndna) and by about 40% in homozygous (Na/Na) birds. The reduction in feather mass improves heat dissipation through the naked area, leading to a relatively higher tolerance to heat and a higher productivity under high ambient temperatures. It is concluded that heterozygous Naked neck broilers gain about 3% more weight than their normally feathered siblings under commercial conditions during the spring and summer months, and that this advantage is almost tripled at a constant high ambient temperature of about 32°C. Thus, the higher the capacity of broilers to gain weight, the more they benefit from the reduction in plumage as a result of the Naked neck gene.