The effects of the strains and age on the production and economic performances of three commercial strains of chicks (Isa Brown, Harco and Lohman) were evaluated in humid tropical area, in Southern of Benin. A total of 180 female day-old chicks of the three strains Isa Brown, Harco and Lohman were bought from Belgium and distributed in 3 groups. They were raised under ambient temperature of 32°C, feed ad libitum during 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: 1243.17 g; Isa Brown: 1176.83 g and Lohman: 1142.32 g) were influenced by the strain. The interaction between age and strain was significant (P < 0.05) onlive weight, feed intake, feed efficiency and feed cost but not on feed efficiency (P> 0.05) the. On the wholes, age influenced many zoo - economic parameters, and the strain only affect the live weight during growth of pullets.

Keyword: Age, Performances, pullet, Strain, Sud-Benin.