The effect of straw meal on the crude protein and amino acid metabolism and the digestibility of crude nutrients in broiler breeding hens. 3. Digestibility of amino acids

In two experiments with colostomized broiler hens the influence of a straw meal supplement on the apparent digestibility of the amino acids of the ration and the 15N labelled basic amino acids in wheat was studied. In experiment 1 the animals received 120 g mixed feed plus 0, 20, 30 and 40 g straw meal per animal and day. The digestibility of the amino acids decreased on average from 86% to 83%, 80% and 79% with the growing straw intake. In contrast to the control variant, 20 g straw meal intake resulted in a significant decrease of digestibility for lysine, histidine, glycine, tyrosine, phenylalanine, cystine and methionine. 30 and 40 g straw meal reduced significantly the digestibility of all amino acids with the exception of arginine. The amino acid composition of the crude protein in faeces changed only very slightly due to the straw supplement. In experiment 2 15N labelled wheat was a component of the ration. Of the 15N labelled amino acids lysine, histidine and arginine, 88, 90 and 95% were apparently digested. The adaptation of the animals to straw meal intake did not change the digestibility of the amino acids.