Sodium chloride concentration in drinking water and eggshell quality

Two experiments with White Leghorn hens (36 and 49 wk old, respectively) were conducted to examine the effects of varying NaCl concentrations provided through drinking water upon eggshell quality. Experiments were of 6 and 5 wk duration, respectively. Seven replicate pens of five individually caged hens received each water treatment. Treatments were the same in both studies and consisted of low-Na (9 ppm) tap water supplemented with 0, 200, 400, 600, or 800 ppm NaCl. Solutions were prepared weekly. All eggs produced were examined visually for shell defects, and egg weight and specific gravity were determined. In the second experiment, eggs from 2 consecutive d were also broken out each week for Haugh Unit determinations. In both studies, hen-day egg production, daily feed and water intake, egg weight, and body weight change over the experimental period were not influenced by any level of waterborne NaCl. Haugh Units were also not affected in Experiment 2. In contrast to other literature reports, visually determined shell defects and egg specific gravity were not adversely affected by NaCl supplementation of layer drinking water.