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 …

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.