Effects of Sodium Plus Potassium to Chloride Ratio in Practical-Type Diets on Blood Gas Levels in Three Strains of White Leghorn Hens and the Relationship Between Acid-Base Balance and Egg Shell Strength ,

Abstract

A 3 × 6 factorial experiment involving three strains of Single Comb White Leghorn hens and six dietary ratios of sodium plus potassium to chloride ((Na + K)/C1) of .40, .91, 1.92, 2.83, 4.04, and 7.69 was done with 108 individually caged hens. The six corn-soybean meal-brewers’ dried grains diets included comparisons among low and high levels of sodium and chloride. Feed and distilled water were provided ad libitum from 403 to 487 days of age. Egg and shell measurements were taken on eggs laid between 479 and 483 days. At the completion of the experiment, blood pH and gases (pCO2, pO2) and plasma Na, K, Cl, Ca, P, and Mg were measured for each hen. Blood bicarbonate was calculated from the pH and pCO2 values. Much of the variation in blood gas levels and 485-day body weight could be attributed to the effects of the .40 diet. The effects of dietary sodium and chloride levels appeared independent of each other with decreasing levels of sodium and increasing levels of chloride reducing blood pH, pCO2, and bicarbonate; these ions had the reverse effect on plasma K. Significant differences in feed intake, feed efficiency, and egg production were apparently due to extremely poor performance of birds fed the .40 diet. Differences among strains were significant for feed intake, productivity, egg and shell weight, percent shell, shell weight per unit surface area, and egg specific gravity but were not significant for blood gas and plasma inorganic ion levels, nondestructive deformation, compression fracture force, and interior quality. Increasing dietary chloride levels significantly reduced deformation and fracture force. There were few dietary (Na + K)/Cl ratio × strain interactions. Partial correlation coefficients indicated very weak relationships (r = −.19 to .14) between blood pH or bicarbonate and specific gravity, deformation, or fracture force. The results of this experiment indicate that although the acid-base balance of laying hens was influenced by the (Na + K)/Cl ratio of the diet, there was no relationship between acid-base balance and egg shell strength.