Dietary interaction of phosphorus with sodium from either chloride or bicarbonate affects laying hen performance

Experimental diets consisting of two levels of total phosphorus (.30 and .75%) and three different treatments of supplemental sodium (.35% NaCl, 1.40% NaCl, and .35% NaCl plus 1.50% NaHCO3) were fed in a 2 X 3 factorial arrangement to laying hens for 16 weeks. The latter two treatments of sodium were designed to supply the same level of sodium (.55%) from different chemical forms. Hens fed .30% phosphorus laid significantly (P less than .01) less eggs than those fed .75% phosphorus. A highly significant (P less than .01) interaction was found between phosphorus and sodium treatments. The high level of sodium from either chloride or bicarbonate decreased egg production at the lower level of phosphorus and increased it when the higher level of phosphorus was fed. Sodium bicarbonate affected egg production more strongly than sodium chloride did. There were no significant treatment effects on egg weight and egg shell weight. Addition of sodium bicarbonate to the low phosphorus diet significantly (P less than .05) decreased feed consumption of the hen. Supplemental sodium bicarbonate with either level of dietary phosphorus significantly (P less than .05) increased percent nitrogen retention of the hen, but excessive sodium chloride did not.