effect of concentrate: roughage ratio and the addition of kefir on the production characteristics of ruminant in vitro

The stability of the gut ecosystem, especially the rumen, is an important area of ​​research that has an impact on the use of feed additives and is associated with a number of diseases. the current study aimed to survey the effect of concentrate: roughage (c: r) ratio and the addition of kefir on the production characteristics of in vitro ruminant fermentation. in a 5x6 factorial order, six ratios of c: r (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100) and five doses of kefir (0, 0.8, 1.6, 2.4, and 3.2 ml) were used, respectively. gas production during incubation was estimated at 0-96 h. during inoculation, the rumen fluid was obtained at 0, 4, 8, 12, and 24 h of incubation. cumulative gas production, gpdm, gpom, and gpndf at 24 h was highest at the c: r ratio of 100:0 (67.82 ml, 75.92 ml/ 200 mg, 1979.15 ml/200 mg, and 11.11 ml/ 200 mg, respectively). the kefir addition improved the kinetics and gas production significantly. the highest in vitro dry matter and organic matter digestibility (ivdmd and ivomd) were obtained at the c: r ratio of 100:0 (9.26% and 182.2% higher than those in c: r ratio of 0:100, respectively). the increase of concentrate diet ratio improved the overall volatile fatty acids (tvfa). no interaction effect on the gas production was detected between the c: r ratio and kefir. the microorganism populations were influenced neither by the level of concentrate nor by the level of kefir. consequently, the high concentrate-to-roughage ratio and the addition of 1.6 ml kefir to the overall dietary substrate could promote rumen fermentation and feed digestibility without affecting microbe counts.