Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/31/1999
Publication Date: N/A
Citation: Interpretive Summary: Bone weakness is a common production problem associated with the rapid growth of young broiler chickens. This is a serious problem in poultry production because it can lead to crippled birds that are not fit for human consumption. We have done studies to try to determine what makes bones stronger in chickens. Our work has shown that the chemical nature of collagen ( a type of protein) is related to bone strength. This work will help as we try to develop methods to assure that chickens can be raised in a manner to greatly reduce or even eliminate losses due to bone strength problems.
Technical Abstract: Leg and Skeletal problems are major poultry health and welfare issues. To understand the basis of bone strength, we compared the serum chemistry, bone histology, the composition and the biomechanical properties of tibial bones from 7 and 72-week-old male and female chickens. The biomechanical properties: density, ash, collagen, proteoglycan; were measured and pyridinium crosslink content of diaphyseal bones were measured. The collagen content was reduced and the proteoglycan content increased in 72 wk- old hens. The bone strength measured using load at break and Young's modulus were significantly higher in older birds. The presence of extensive medullary bones in females did not increase bone breaking strength in females though it reduced strain and increased modulus of elasticity indicative of increased stiffness of bones. Hypophosphatemia in older birds did not influence the ash content, which was similar between groups except that the older females had an approximately 10% higher ash content (p<0.01) than younger birds. The hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), and collagenase-extractable fluorescence content of bone matrix from older birds were higher. The bone matrix from older birds showed increased susceptibility to collagenase. The changes in the breaking strengths of bones from all groups showed better correlation with the content of pyridinium crosslinks and fluorescence. These results suggest that increase in bone strength is associated to an increase in bone collagen cross link content.