A comparative study of the digestibility of soyabean and cottonseed meal amino acids in domestic chicks and muscovy ducklings

True digestibilities of amino acids derived from soyabean and cottonseed meal were measured in domestic chicks and muscovy ducklings. Endogenous amino acid losses were determined in animals fed on a protein-free diet. Similar endogenous losses were found in both species. Slight, but significantly different protein digestibilities, were observed with a basal diet. The digestibility of lysine and arginine derived from soyabean meal was slightly greater in ducklings. The digestibility of cottonseed meal leucine was slightly higher in chicks than in ducklings. These results suggest that, for practical purposes, digestibility values from the chicken are adequate for the formulation of duckling diets.