l The Use of an Artificial Rumen to Assess Low Quality

. ABSTRACT The results of two fermentalion experimenls conducted n'ith an artifcial rumen ( rumen simulation technique-Rusitec ) are reported. The frst experiment compared the fermentation chsracleristics of a medium quolity hiy with those of untreated or urea-ammonia lrealed rice straw. (Jreo-ommonio treatment increased the digestibility, Volatile Fatty Acid production and microbial dry matter outpul compared wilh untreated strav'. while the dry matter disappearance conlinued almosl al the same rate up to 72h u'ith urea supplemented straw, it leuelled of after 48h in the case of ammoniated srraw. The second experiment examined the efects of leoel of feecting and diferent roughage: concentrate ratios onfermentation character' - istics of urea-ammonio trealed rice strqw. The output of VFA increosed x'ith the inirease in feed intake and the level of concentrate in the diet. This n'as also accompaiUa q a steady decline in the acetate:propionate ratio. The ratio of v FA production : methane production was slightly lawer for the high straw' diets compared with in vivo oalues reported for good quality hay' Ho*.euer, inueasing the quality of the ouerall diet by increasing the proportion of conceitrate tended to increase this ratio to accepted ualues. ' it ts clear that although Rusitec rs an in vitro technique it hqs aduantages ouer other in vitro lechniques as it can prouide much more information on runten ferntentation characteristics of a given feed. It is concluded that Rusitei is a taluqble rechnique for eualuatingfbrous residues ond testing nev' tliets hefore undertaking large-scale animal experimenls'