The utilization of non-protein nitrogen in the bovine rumen. 5. The isolation and nutritive value of a preparation of dried rumen bacteria

Abstract

Rumen liquid (130 1.) was incubated at 39[degree] for 4 hr. in 57 batches of 2-3 1., each with 1% maltose and 0.05% urea, and the bacterial sludge separated by centrifugation in a Sharpies centrifuge. The sludge was dried by successive treatments with ethanol and ether. The dried prepn. (461 g., of which 7.5% was moisture) contained on a dry weight basis 44.4% protein and 7.1% ash. Its analysis is compared with corresponding figures for fodder yeast and linseed cake. It was calculated that about 58% of the bacterial protein was present in the liquid as it was removed from the rumen. The remaining 42% was synthesized during incubation. The prepn. did not appear to be contaminated with feeding-stuff or feeding-stuffs protein to any significant degree. The biological value and the true digestibility of the prepn. determined using 12 young female rats were 88.3 and 73.2, respectively.