Dietary effects on bone quality and turnover, and Ca and P metabolism in chickens

The responses of skeletal health and blued calcium (Ca) and phosphorus (P) status to different dietary calcium and available P (avP) contents were exa mined in 2-week-old chickens. High avP content resulted in more inorganic P (P-i) and less ionised Ca (Ca2+) in the blood. Birds on low Ca and high av P diets showed a higher incidence of tibial dyschondroplasia and hypocalcae mic rickets and were therefore assumed to be hypocalcaemic. However the mol ar Ca:P ratio in bone was closer to the expected 1.67:1 in diets high in av P. No significant dietary mineral content effect was found on bone mineral content, or breaking strength, within the range of diets used. Results sugg est that variations in molar Ca:P ratios in bone have little effect on mech anical competence, and that diets for this strain should be higher in Ca, a nd could be lower in avP, than current recommendations. (C) Harcourt Publis hers Ltd.