AN INVITRO METHOD FOR PREDICTION OF THE DIGESTIBLE CRUDE PROTEIN-CONTENT IN PIG FEEDS

An in‐vitro method using commercially available enzymes for the prediction of the in‐vivo digestible crude protein content was developed and tested on seven feedstuffs and 16 diets for pigs. Fat‐extracted feed samples were consecutively incubated with pepsin at pH 1 and pancreatin at pH 6.8. From the nitrogen content of the feed sample and of the residue after incubation the in‐vitro digestibility of the crude protein was calculated. Using the linear regression of in‐vitro on in‐vivo digestible crude protein of samples obtained in feeding trials, the in‐vivo digestible crude protein content (DXPp) in g kg−1 dry matter could be predicted. For feedstuffs and diets the correlation was 0.99 and 0.95 and the residual standard deviation 17 and 6 g kg−1 dry matter, respectively. In a similar procedure the nitrogen solubilised during incubation with enzymes was analysed. The regression value was similar to that of the original procedure. However, this procedure was abandoned because it was more laborious. Copyright © 1990 John Wiley & Sons, Ltd