The current study was outlined to investigate the influence of fecal inocula obtained from horses supplemented with Lactobacillus farciminis (L. farciminis) in diets constituting 50% oat straw on in vitro gas production (GP), methane (CH4), and carbon dioxide (CO2) productions as indicators of hindgut activity. The experiments were assessed on four Azteca horses ranging from 5 to 8 years of age, weighing 480±20.1 kg. The treatments comprised the in vitro incubation of fecal inocula with commercial product of L. farciminis at 0, 2, 4, and 6 mg/g dry matter (DM) of substrate. The fecal content mixed with the culture media were used to inoculate into the substrate containing a mixture of commercial concentrate and oat straw (1:1 DM). The subsequent incorporation of additives resulted into increased level of asymptotic GP, CH4, and CO2 productions (P0.05; quadric, P>0.05). A significant reduction in the fermentation pH range (linear, P=0.029) and higher metabolizable energy (ME) values (P=0.001) were obtained with the supplementation of L. farciminis in a dose dependent manner, whereas no impact of additives were reported on DMD (dry matter degraded) values (P>0.05). The in vitro GP, CH4, and CO2 productions were measured up to 48 h post incubation using standard methodology, and depicted
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higher responses. The additives at varied concentrations resulted in increased in vitro GP, CH4, and CO2 productions (linear, P≤0.001) from 6 to 48 h of incubation. In conclusion, the dose dependent addition of L. farciminis (2 to 6 mg/g DM of diet) found to be persuasive in terms of attaining amicable hindgut fermentation in order to digest fibrous forage by horses without any side effect
