Longitudinal growth of leg and wing bones of chickens reared in cages and on the floor.

The histomorphometry of proximal growth plate and rate of longitudinal growth was estimated in tibia and humerus of chickens reared in the cages and on the floor, during 0, 2, 4, 6 and 8 weeks of age. The floor vs. the cage area was 3:1. All chicks were fed ad libitum standard broilers mixture: starter (0-4 weeks) with 0.9% Ca; 0.7% P and grower (4-8 weeks) with 0.8% Ca; 0.5% P. The rearing system showed no significant effect on macroscopy estimated tibia and humerus growth in length, just as in case of bone's proximal growth plate microscopy of floor reared chickens. However, our results suggested that wing bones are more affected by the housing system than that of leg bones. The proliferative zone, hypertrophic zone and total growth plate of the humerus in cage reared birds were significantly higher than in those reared on the floor.