Effect of Varying Levels of Phosphorus and Live Yeast Culture in Caged Layer Diets

Abstract Dietary levels of .31, .36, .41, .46, .51, .56, and .61% total phosphorus (TP) were incorporated into seven corn-soy diets to determine the minimum TP requirement of caged laying hens. Each diet was fed to six lots of 20 hens each for a test period of 308 days. Egg production, feed efficiency, feed consumption, egg weight, and egg breaking strength were the performance criteria. Egg breaking strength was significantly higher while the other performance measures were significantly inferior for hens receiving the .31 TP diet as compared to those hens receiving the other diets. Performance measures of hens receiving diets with TP levels ranging from .41 to .61% were not significantly different. Although hens receiving the .36% TP diet performed significantly better than those receiving diets containing .31% TP, their performance was not satisfactory when compared with performance of hens fed diets containing higher levels of phosphorus. In a second experiment, dietary levels of 0, .25, and .50% live yeast culture (LYC) were fed in combination with TP levels of .40 and .60% to individually caged hens for nine test periods of 28 days each. Each of the test diets was fed to three lots of 12 hens each. Performance criteria in this experiment were the same as those used in the first experiment. Hen responses to the six test diets did not differ significantly for any performance criterion, except for egg breaking strength, which was significantly higher for eggs produced by hens fed diets containing .40% TP level. Results obtained from these studies indicate that under similar experimental conditions the minimum dietary TP requirement of caged laying hens is approximately .40%. No beneficial effect of LYC on hens’ performance was obtained when fed at .25 or .50% of the diet.