IN-VITRO FERMENTATION OF CELLULOSE, BEET PULP, CITRUS PULP, AND CITRUS PECTIN USING FECAL INOCULUM FROM CATS, DOGS, HORSES, HUMANS, AND PIGS AND RUMINAL FLUID FROM CATTLE

We evaluated the influence of gastrointestinal tract microflora from s everal species on fiber fermentation characteristics in vitro. Selecte d fibrous substrates (cellulose, beet pulp, citrus pulp, and citrus pe ctin) were incubated for 6, 12, 24, and 48 h with ruminal fluid from c attle or feces from dogs, cats, pigs, horses, or humans. When data wer e pooled across all substrates and fermentation times, OM. disappearan ce (29.4%) and acetate, propionate, butyrate, and total short-chain fa tty acid (SCFA) production (1.09, .41, .12, and 1.61 mmol/g of OM, res pectively) were lowest (P < .05), and lactate production (.23 mmol/g o f OM) was greatest (P < .05) for horse fecal microflora compared with samples from the other species. The greatest (P < .05) acetate product ion resulted when substrates were fermented by cat fecal microflora (2 .38 mmol/g of OM). The greatest (P < .05) propionate productions resul ted from pig fecal and cattle ruminal microflora (.88 and .83 mmol/g o f OM, respectively), and the greatest (P < .05) butyrate productions r esulted from human and pig fecal microflora (.39 and .40 mmol/g of OM, respectively). Total SCFA production was greatest (P < .05) for cat f ecal microflora (3.38 mmol/g of OM). When data were pooled across spec ies, substrate OM disappearance and SCFA production ranked from least to greatest in the following order: cellulose < beet pulp < citrus pul p < citrus pectin. The fermentability of different fibrous substrates by fecal or ruminal microflora from various species seems to be depend ent not only on the fermentative activity of the microbial population but on other factors as well, perhaps lag time and rate of digesta pas sage.