The metabolisabie protein system (AFRC, 1992) requires the measurement of the dynamics of the degradation of protein in the rumen. However the recommended method, using fistulated animals, is slow, expensive and may be considered unacceptable by many in terms of animal welfare. The objective of this work was to develop an in vitro technique for the routine assessment of feed protein degradability.

A 101 vessel fitted with an automatic stirrer was filled with modified van Soest media and rumen liquor (pooled from two sheep) and maintained under anaerobic conditions at 39.5°C. Small artificial fibre bags (4.5x3cm, pore size 54 micro-m ±4) were filled with 0.4g of soya bean meal and incubated in the vessel for 3,6,10 and 24 hours using 3 replicates at each time. Bags were washed in running cold water for 30 mins immediately after removal. Four replicates of 3g samples in large Dacron bags (10x7cm, pore size 55 micro-m ±22) were also incubated in sacco in fistulated yearling wethers using a 4x4 Latin square design to assess the base line degradability. In sacco bags were rinsed and frozen after removal and washed in a domestic washing machine at the end of the experiment.