Dietary starch source influences in growing goats: the intestinal losses of endogenous nitrogen and amino acids.

Four goats (20 (SD 2.5) kg) fitted with ruminal, duodenal and ileal cannulae were used in a 4 x 4 Latin square design to estimate the effects of a dietary starch source on the duodenal and ileal flows of endogenous N (EN) and endogenous amino acids (EAA) in growing goats. Goats were fed total mixed rations containing four starch sources (mainly from maize (MR), wheat (WR), paddy (PR) and sorghum (SR) treatments). There were no significant (P>0.05) effects of the dietary starch source on the intestinal flows of EN and EAA. The duodenal flows of EN were 2.40, 2.39, 2.18 and 1.56 g/d for the MR, WR, PR and SR treatments, respectively, as determined by the difference method, and the duodenal flows of EAA were 10.76, 11.29, 10.95 and 10.96 g/d by estimation with the amino acid profile method. The flows of EN and EAA at the ileum were 1.17, 1.12, 1.01, 0.70 and 4.87, 4.95, 4.94, 4.99 g/d, respectively, as estimated by the water-soluble method. The average intestinal reabsorption of EN and EAA was 57.5 %, and the endogenous Leu by the MR treatment was significantly (P < 0.05) lower than that of the other three treatments. The present results indicate that losses of endogenous protein in the intestine were not affected by the dietary starch source.