A comparison of methods for determining the digestibility of rations for sheep

Abstract

The dry matter digestibilities (DMDs) of three sheep rations, namely hay, hay and pelleted concentrates and the pellets only were determined in vivo, by an in vitro technique and four modifications to it, and by using a summative equation. The in vivo DMDs were 57.2,63.2 and 71 .1 per cent for the hay, hay and pellets, and pellets respectively. The basic in vitro two stage technique over-estimated these by 5.1, 4.8 and 6.5 units respectively. The DMDs of the modifications to the basic in vitro technique did not differ from those resulting from the basic procedure except in one instance where the in vitro DMD of hay (57.9) was significantly lower (P < 0.01). The summative equation gave values that were 3.5, 2.5 and 3.7 units greater than the in vivo DMDs.