Cage Density and Frozen Storage Effect on Bone Strength of Broilers

Abstract

Three trials were conducted to determine the effect of cage density on the breaking strengths of humeri and tibiae from broilers. Cockerels were reared on the floor at 900 cm.2 per bird and in cages at 400, 600, and 900 cm.2 per bird from 0 to 8 weeks. The breaking strengths of humeri and tibiae from floor-reared broilers were in all trials numerically greater than those from cage-reared broilers. In two trials, the difference in breaking strengths of humeri was significant (P < 0.01, 23.70 kg. and 22.56 kg. for floor-reared broilers vs. 7.33 to 10.38 kg. and 13.46 to 16.45 kg. for cage-reared broilers at the three densities). In one trial, the difference in breaking strengths of tibiae was significant (P < 0.05, 21.16 kg. for floor-reared broilers vs. 14.04 kg. for broilers reared in cages at a density of 400 cm.2 per bird). When data from the three trials were combined, density had no significant effect on the breaking strengths of either humeri or tibiae within the cage treatments.The effect of frozen storage on bone strength was determined by comparing bones dried immediately with others frozen and stored for 2 weeks before drying and breaking. Freezing significantly (P < 0.01) reduced breaking strengths of tibiae (61.1%) and humeri (60.9%). When data from the three trials were combined, the reduction in breaking strengths from freezing did not alter the significance of the experimental results.