BACKGROUND: Two factorial studies compared enzymic and
in sacco methods to estimate degradation of ruminant foods. Enzyme degradation (
in vitro = enzyme) was determined from the release of leucine‐equivalent amino acid (LA) crude protein (CP) from sunflower meal (SF), maize gluten meal (MG), distillers' dark grain (DG) and field beans (FB) after their separate incubations with
Streptomyces griseus enzyme for 0–24 h.
In sacco crude protein (CP) degradation of these foods was estimated during washing (0 h) and rumen incubations in fistulated cows for 2–24 h. The LA data were expressed as g LA per either kg of CP (LACP) or acid‐hydrolysable LA (HLA) of each food and compared with
in sacco data. RESULTS: These methods showed comparable degradation with time (
P < 0.01). The
in sacco and HLA were greater than LACP for all foods except MG where
in sacco value was either lower or equal to LACP depending upon the incubation time (
P > 0.05 or
P < 0.05). Conversely, HLA was significantly (
P < 0.01) greater than LACP from 2 h onwards. At 0 h,
in sacco values were significantly greater than those of enzyme for SF, DG and FB (
P < 0.05) but not for MG. The foods differed significantly for degradation constants (
a,
b,
c) in each method (
P < 0.05). CONCLUSIONS: Despite variations between
in sacco and enzyme estimates for different foods, the relationships between these estimates suggest that the HLA enzyme method has the potential to estimate food degradation. Copyright © 2007 Society of Chemical Industry
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