Iodinated Casein Supplementation of Laying Hen Diets Containing Various Levels of Sulfur Amino Acids

Two experiments, each of ten months duration, were conducted to determine the effects of iodinated casein supplementation upon the performance of egg-type hens receiving various levels of sulfur amino acids. Eight replicate groups of five individually caged hens were assigned to each dietary treatment. Dietary treatments consisted of sulfur amino acid levels of 0.355 and 0.412 percent in experiments 1 and 2, and an additional level of 0.592 percent in experiment 2. All of these diets were fed with and without the addition of 220 mg. of iodinated casein per kilogram of diet. Iodinated casein supplementation resulted in significant reductions of hen-day egg production for diets containing 0.412 and 0.355 percent sulfur amino acids in experiments 1 and 2, respectively. In experiment 1 iodinated casein significantly decreased the feed efficiency and significantly increased the daily feed intake of birds receiving 0.355 percent sulfur amino acids. Diets of experiment 2 containing 0.355 and 0.412 percent sulfur amino acids and iodinated casein were associated with significant feed efficiency decreases as compared to comparable control diets, and the lower amino acid level resulted in a significant reduction of feed intake when iodinated casein was included. Although the performance of birds receiving the 0.592 percent sulfur amino acid diet of experiment 2 was not significantly reduced by the addition of iodinated casein, numerical depressions due to supplementation were evident. Egg weights were not significantly affected in either experiment. Body weights were significantly reduced only in experiment 2 with the diet containing 0.355 percent sulfur amino acids.