The chickens were supplemented with 15, 30 and 45 g feed/hen/day, determined by the existing production and feeding practice of the key rearers. RIR x Fay attained late sexual maturity (222 d vs 194.9 d) but produced more eggs of the best quality with the highest benefit cost ratio. The same crossbred showed the greatest resistance to diseases with heaviest weight at every bimonthly period of body weight measurement. None of the other breed/breed combinations were found to have a genetic potential as RIR x Fay (Sonali). Location did not have any effect on egg production and mortality, but in egg quality, in relation to shell thickness and yolk color. At the first bimonthly period of body weight measurement (two months after the age at sexual maturity) the location situated at the riverside areas showed significantly higher body weight (1305g vs 1193g). Egg quality was found to be better with the increased of age of the hens. Rate of lay/hd significantly increased with increased levels of supplemented feed. Highest level of supplementation (45g) was more beneficial in relation to egg production and egg weight. On the other hand levels of supplementation did not show any effect on body weight.

The present study showed that the breed effect was higher than that of the levels of supplementary feed and location. However, RIR x Fay (Sonali) crossbred has a higher potential for egg production, but required more supplementation to increase its potential. In order to improve the genetic potential of a breed combination it is important to improve the origin breed in the environment in which they have to produce. Therefore, a selection procedure to maintain the production potential of RIR and Fay should be adapted for better yield of RIR x Fay (Sonali). At the same time management, availability of scavenging feed and rate of supplementation are the important factors necessary to be improved.

The type of test presented in this thesis is an ever on going project as new breed combination/ hybrid will be available on the market all the time. It is very important to do this test in the environment in which the practical production takes place as a considerable Genotype x Environment is the general observations in many studies in which the scavenging management is one of the environmental sources. It is concluded that with the improved conditions RIR x Fay (Sonali) might be a potential in semi scavenging system of production and probably the best bid at the moment.