Available phosphorus in poultry. 1. Effect of phosphorus levels on the performance of laying hens and their egg quality, hatchability, bone analysis and strength in relation to calcium and phosphorus in blood plasma.

For 6 months 432 medium heavy laying hens were given diets which supplied 0.16, 0.20, 0.40, 0.60, 0.80 or 1.00% available phosphorus. Egg production was greatest by hens given 0.20 or 0.40% P and least by those given 0.16%. Feed intake did not differ among groups. Heaviest eggs, 62.2 g, were laid by hens given 1.00% P. Shell quality, determined from shell percentage, shell thickness and shell index, decreased as P in the diet increased. Hatchability, yolk and white indices of eggs and calcium, P and ash in tibiae of chicks one day old did not differ among groups. Ca in blood of hens did not differ among groups but inorganic P in plasma increased with increasing P in the diet. Ash, Ca and P in tibiae and breaking strength of tibiae of hens increased with increasing P in the diet. (Abstract retrieved from CAB Abstracts by CABI’s permission)