Rumen degradability and intestinal indigestibility of individual amino acids in corn gluten meal, canola meal and fish meal determined in situ

Corn gluten meal (CGM), canola meal (CM), and two types of fish meal (FM) were examined in situ for rumen degradability (RD) and true intestinal indigestibility (TU) of crude protein (CP) and individual amino acids (AA). Results indicate that RD of CP can be used to predict RD of total AA (TAA) for CGM and CM, and probably FM. Differences in RD among AA were observed within all feedstuffs studied. The extent of the differences was larger with the highly rumen degradable CM than with the more resistant CGM and FM. In general, RD of individual AA was feed dependent. The exception was Tyr that had a significantly lower RD than TAA for all three feedstuffs. The TU of CP was a good predictor of intestinal AA indigestibility. In general, the variation in TU among AA was small within feeds. The exception was FM with a high ash fraction, where Gly and Pro had substantial higher TU than the other AA.