Metabolism of protein supplements studied by the rumen simulation technique (Rusitec)

Long-term experiments were made with the Rumen Simulation Technique (Rusitec) with hay diet and with three different protein supplements (casein, fish meal and soyabean meal). Soyabean meal made the greatest contribution to the output of end-products of fermentation and casein made the smallest contribution. The supplements did not have any marked effect on the metabolism of the basal diet of hay. The experiments showed that rumen microorganisms destroy a large proportion of protein (measured as total alpha-NH2 groups) and that this loss of protein was increased by supplementation with high protein compounds. The degradation of protein in soyabean meal and fish meal appeared to be considerably greater in the model system than the reported results of measurement in vivo and in situ.