RUMINANT DIGESTION IN VITRO AS AFFECTED BY INOCULUM DONOR, COLLECTION DAY, AND FERMENTATION TIME

Abstract

A two-stage in vitro digestibility technique was used to study variations in the viability of the rumen microflora among nine sheep on three different days. Interactions between the two stages of the technique were studied from the effect of microbial fermentation time on the digestibility of cellulose, noncellulosic organic matter, and organic matter in alfalfa hay and wheat straw. Small sporadic differences among animals were less significant than those between days. The differences were generally smaller than those observed in in vivo digestibility determinations with sheep. Interactions between sheep and days were suggested to result from the consumption of water at varying intervals prior to the collection of rumen liquor, giving rise to inocula of various dilutions.Most of the digested noncellulosic organic matter fraction in alfalfa was digestible by the acid–pepsin fermentation, whereas very little of the same fraction in wheat straw was digestible by acid–pepsin, the remainder being digested at a very slow rate by the microbial fermentation. The cellulose in alfalfa was digested quicker than that in straw but the final amount of digested cellulose was greater in the straw.