The effects of strain and age on production and economic performances of three commercial strains of chicken (Isa Brown, Harco and Lohman) were evaluated in a humid tropical area, in Southern Benin. A total of 180 female one day-old chicks of the three strains Isa Brown, Harco and Lohman were bought and distributed in 3 groups. They were raised under ambient temperature of 32°C, feed ad libitum and submitted to the same prophylaxis during 16 weeks. The feed intake, the feed efficiency and the feed cost were significantly influenced by age. The live weight at the end of the growth phase (Harco: 1243 g; Isa Brown: 1177 g and Lohman: 1142 g) were influenced by the strain. The interaction between age and strain was significant (P < 0.05) on live weight, feed intake, feed efficiency and feed cost but not on feed efficiency (P> 0.05). Overall, age influenced many parameters and the strain only affected the live weight at the end of growth period.

Key Word: Age, Performances, chicks, Strain, Benin