Response of laying hens to choline when fed practical diets devoid of supplemental sulfur amino acids

Two experiments were conducted with White Leghorn laying hens. In both experiments, a corn-soybean meal basal diet was used, and hens were housed individually in cages in open-type houses. In Experiment 1, the basal diet contained no supplemental choline, inorganic sulfate, or sulfur amino acids and was supplemented with 0 or 660 mg choline/kg, and 0 and .1% K2SO4, or K2Mg(SO4)2. In Experiment 2, the basal diet contained .1% reagent grade K2SO4. Four diets were formulated to contain 0, 110, 220, and 440 mg choline/kg, respectively. A fifth diet was formulated to contain 440 mg choline/kg and .15% DL-methionine. In Experiment 1, a significant increase in egg production resulted from supplementing the diet with 660 mg choline/kg in the absence of supplemental inorganic sulfate and sulfur amino acids. Only a numerical increase in egg production resulted from adding inorganic sulfate alone or in combination with choline. Addition of choline and inorganic sulfate in combination resulted in an increase in egg weight. In Experiment 2, 220 mg of supplemental choline/kg, or 114 mg choline intake/bird/day, resulted in maximum egg production and feed efficiency. However, maximum egg size was obtained only when supplemental DL-methionine and choline were present. The results obtained in this study indicate that laying hens will respond to supplemental choline in practical situations when diets are deficient in total sulfur amino acids, and daily sulfur amino acid intake is insufficient to meet the animal's requirement. For maximum egg size, adequate sulfur amino acids must be present in the diet, because supplementing choline alone will not maximize egg size.