Lasalocid-sulfur amino acid interrelationship in the chick

Several experiments were conducted with young healthy chicks to investigate the relationship between lasalocid and sulfur-containing amino acids (SAA). Chicks were housed in heated starter batteries in all experiments and were fed, in all but one trial, a completely purified crystalline amino acid diet. As previously determined in our laboratory with monensin, the quantitative requirement for SAA, expressed as a percent of the diet, was neither increased not decreased by 125 mg/kg dietary lasalocid. Unlike that observed with monensin, a consistent and striking SAA X lasalocid interaction was apparent. Hence, lasalocid elicited a marked gain and gain/feed response when added to diets severely deficient in SAA, but it resulted in a marked depression in chick performance when added to diets adequate in SAA. At moderate levels of SAA deficiency, such as those existing in practical corn-soybean meal broiler diets, 125 mg/kg lasalocid neither increased nor decreased rate and efficiency of weight gain. Indeed, no evidence of the SAA X lasalocid interaction was seen when lasalocid was provided in a typical corn-soybean meal chick starter diet.