Ileal digestibility of amino acids and estimates of endogenous amino acid losses in pigs fed wheat, triticale, rye, barley, maize and sorghum

Abstract

Forty-three batches of cereals (10 of wheat, 10 of triticale, 5 of barley, 5 of rye, 7 of maize and 6 of sorghum) were analysed and studied for their nitrogen (N) and amino acid (AA) ileal digestibility. Each batch was tested on four castrated male pigs, weighing between 30 and 90 kg, and fitted with an end-to-end ilco-rectal anastomosis. Ileal true digestibility (TD) of AA was calculated by correcting ileal apparent digestibility (AD) for basal endogenous AA losses, measured by means of a protein-free diet. Ileal real digestibility (RD) of AA was calculated by correcting AD for total endogenous AA losses, estimated by a multiple regression model. TD of N and most AA decreased (P<0.001) from wheat, triticale and maize, to barley and sorghum and to rye (90.3, 88.7, 89.9, 85.4, 83.7 and 80.1%, respectively, for the sum of all AA). Estimates of endogenous N losses decreased (P < 0.001) from triticale, sorghum and wheat, to maize, barley and rye (on average 3.10, 2.93,2.63,2.43,2.27 and 2.16 g N-kg-1 DM ingested, respectively). Barley excluded, there was a trend toward increasing endogenous AA losses with increasing dietary acid detergent fibre (ADF) concentration (r = 0.57, P < 0.001). Barley caused low endogenous N losses relative to its ADF concentration.