The present investigation was conducted to evaluate the effects of Escherichia coli against the ruminal microflora fermentation activities in the mitigation of CH4 and CO2 production as well as ruminal fermentation kinetics by substituting dietary corn grain with prickly pear cactus (PC) flour. Three total mixed PC rations were prepared (/kg DM): 0 g (Control), 75 g (PC75), and 150 g (PC150). Besides, E. coli was supplemented at four different levels (dose): 0, 10, 20, and 40 mg/g DM of substrates. The in vitro rumen GP, CH4, and CO2 were estimated to be affected due to various doses of E. coli up to 72 h of incubation. Asymptotic GP, fractional rate of GP, and lag time were influenced significantly (P < .05) in the presence of ration. However, E. coli doses showed minor impact on the rate of GP as well as lag time. The asymptotic CH4 production was decreased linearly (P = .005) at the ration PC150. E. coli doses reduced the asymptotic CH4 production at 10 and 20 mg/g DM. The asymptotic CO2 production was linearly (P < .001) decreased by different levels of PC. The cubic (P = .023) effect of E. coli doses as well as significant (P = .002) ration × E. coli doses impact were reported on asymptotic CO2 production. The fractional rate of GP was quadratically (P < .05) influenced by PC and E. coli doses. The rations, dose, and rations × E. coli dose interaction had no influence (P > .05) on lag time. In a nutshell, PC flour inclusion in diet has the potentiality to replace the existing conventional feedstuffs for ruminant. Most importantly, revealing the first report, PC flours along with E. coli supplementation at varied doses mitigated the ruminal biogases production. This was as consequence to the antimicrobial impacts of E. coli against ruminal microflora, and that could certainly be a promising approach in order to improve ruminant's diet constituents.
Keywords: Biogases; E. coli; Fermentation; Prickly pear cactus; Ruminal microflora.
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