The Retention of Nutrients by Chicks Fed Rye Diets Supplemented with Amino Acids and Penicillin

Abstract

Two experiments were conducted to establish some of the factors that affect rye utilization in chicks fed rye diets. In the first experiment, rye diets were supplemented with one or more of the calculated first three limiting amino acids. In the second experiment, rye and wheat diets were supplemented with a mixture of essential amino acids and/or penicillin in order to study the relationship between chick performance and nutrient retention. In both experiments, the grain served as the sole protein source. The results indicated that several amino acids were limiting in rye, or that the availability of the constituent amino acids was reduced by some component in rye. Supplementation with a mixture of essential amino acids elicited a greater improvement (P<.01) in weight gain (372 vs. 135%) and efficiency of feed utilization (71 vs. 56%) in chicks fed wheat compared to those fed rye diets. Supplementation with penicillin in contrast elicited greater improvements in weight gain (68 vs. 5%) and efficiency of feed utilization (37 vs. 8%) in rye as compared to wheat-fed birds. Retention data showed that the values for dry matter (60 vs. 75%), ether extract (27 vs. 71%), phosphorus (14 vs. 21%), nitrogen (20 vs. 39%), total amino acids (65 vs. 82%) and all the individual amino acids were considerably lower (P<.01) in the unsupplemented rye diets than in the unsupplemented wheat diets. Supplementation of the rye diets with amino acids increased the retention of these amino acids only, and not those contributed by the rye portion. Penicillin supplementation enhanced the retention of nutrients, especially amino acids, more markedly in the rye than in the wheat diets. These results would suggest that rye contains factor(s) which depress(es) the retention by the chick of certain nutrients, particularly protein and fat.