The prediction of the digestibility of silages using cellulase

The use of the Jones and Hayward 1 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 Hayward 1 ) 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 Terry 2 (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 Hayward 1 technique is then as good a predictor of DOMD% as the Tilley and Terry 2 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.