1. Performances of two broiler strains grown in cages at two different stocking rates to 8 weeks of age were compared.
2. High stocking rate (18 birds/m2) adversely affected weight and food conversion efficiency. Performance of females was more sensitive to stocking rate than that of males. Stocking rate x strain interactions in weight and food conversion efficiency at 8 weeks were highly significant.
3. Carcass dissection showed a marked difference between males and females.
4. Stocking rate merits further attention in respect of strain and sex.