Effect of storage condition on bone breaking strength and bone ash in laying hens at different stages in production cycles.

This study was conducted to determine the effects of refrigeration and frozen storage on tibia breaking strength (kg/g) and tibia ash (%) in bones obtained from hens of different ages. A total of 75 Single Comb White Leghorn hens were divided into three equal groups according to age (72, 80, and 92 wk of age). Both tibias of each hen were harvested and immediately defleshed. The tibias from each hen were randomly assigned to either 1 d of refrigeration or 7 d of frozen storage. Tibia breaking strengths were determined using an Instron Universal Testing Machine with 50-kg-load cell at 50-kg-load range with a crosshead speed of 50 mm/min. Tibia ash weights were determined by ashing for 24 h at 615 degrees C. Bone breaking strength in 72 wk of age hens was significantly (P < 0.05) higher in refrigerated tibias (2.48 kg/g) than those in frozen storage (1.75 kg/g). However, there was no difference (P > 0.05) for bone ash (percentage of tibia ash) in all three groups between refrigerated storage (72 wk: 38.840%, 80 wk: 46.40%, 92 wk: 46.99%) and frozen storage (72 wk: 39.12%, 80 wk: 44.88%, 92 wk: 45.35%). This study indicated that frozen storage only influenced assessment of bone strength in 72-wk-old laying hens but could be used for sample storage of bones from older hens.