Interaction of Dietary Phosphorus and Sodium Chloride Levels on Blood Phosphorus and Egg Production of Hens

Abstract

A 3 × 3 factorial arrangement of experimental diets consisting of three levels of total phosphorus (.30, .75, and 1.40%) and three levels of added sodium chloride (0, .35, and 1.40%) were fed to laying hens 16 months of age of Babcock B-300 strain. Most of the hens fed no added salt stopped laying within 2 weeks from the start of the experiment. Although there were no significant differences in egg production among hens fed three different phosphorus levels and between hens fed .35 and 1.40% added salt for 3 weeks, a significant (P<.05) interaction was found between dietary phosphorus and salt level on the third week of egg production. Generally, hens fed a high level of salt required a higher level of phosphorus in the diet, and those fed a low level of salt required a lower level of phosphorus for maximum production.Increasing dietary phosphorus resulted in elevated serum phosphorus levels in hens both immediately following oviposition and at 15 hr after oviposition on the second day of the experiment. Although there was no significant phosphorus × salt interaction on serum phosphorus, a significant (P<.05) interaction between dietary phosphorus and time of bleeding was found. Immediately following oviposition serum phosphorus was significantly (P<.01) higher in hens receiving .75% dietary phosphorus compared to those receiving .30%, but the difference between hens fed .75 and 1.40% phosphorus was not significant. At 15 hr after oviposition a numerical increase in serum phosphorus was observed in hens fed dietary phosphorus levels from .30 to .75% and when higher dietary levels of phosphorus were fed there was a significant (P<.01) increase in serum phosphorus. The interaction between dietary salt and time was not significant.