The prediction of the digestibility of silages using cellulase

The use of the Jones and Hayward1 two stage digestion technique for evaluating the digestibility of dried ground grass silages with digestible organic matter in the dry matter (in‐vivo DOMD%) values ranging from 54 to 72 was investigated. By grinding the samples through a 0.75 mm screen and increasing the concentration of cellulase the digestion time could be reduced from 48 h (Jones and Hayward1) to 24 h whilst maintaining a high degree of correlation with DOMD% (in‐vivo). A number of silages were analysed by this modified technique and by the Tilley and Terry2 (in‐vitro) technique. Comparing the DOMD% values from both determinations with the DOMD% (in‐vivo) values the correlation coefficient (r) in each case was 0.85 (with an r.s.d. of 2.3). The modified Jones and Hayward1 technique is then as good a predictor of DOMD% as the Tilley and Terry2 technique. The length of time and cost needed to predict DOMD% of silages has been reduced which is a distinct advantage when determinations are carried out on a routine basis for advisory purposes.