Sustainable anaerobic rumen methane and carbon dioxide productions from prickly pear cactus flour by organic acid salts addition

Abstract

Ruminal fermentation is accompanied by production of methane (CH4) and carbon dioxide (CO2) which are greenhouses making the Earth warmer. Therefore, the sustainable production of CH4 and CO2 as well as fermentation kinetics when corn grain (CG) was replaced with prickly pear cactus flour (PC) was investigated. Besides, the effect of different levels of organic acid salts (OAS) was studied. Three total mixed rations used as substrates were prepared where CG was replaced with PC at three levels (/kg): 0 g (Control), 75 g (PC75) or 150 g (PC150). The OAS was used at three levels: 0, 5 and 10 mg/g dry matter (DM) of substrates. Asymptotic gas (GP), CH4, and CO2 productions as well as lag time had linear responses (P < 0.05) as PC level increased in the ration. Fractional rate of GP (P ¼ 0.007), GP, organic matter degradability, short chain fatty acid, and microbial biomass production (P < 0.001) were increased with increasing level of PC. Fermentation pH (P < 0.001), and DM degradability (P ¼ 0.0448) were linearly decreased as the PC level increased in the rations. Ration OAS interaction did not affect fermentation kinetics, GP, CH4 production and fermentation parameters. Prickly pear cactus flour at 150 g/kg DM inclusion level in ruminant ration has the potential to replace 60% of corn grain with enhanced fermentation and biodegradation efficiency in vitro; however, it increased CH4 production, which cannot be an environmental friendly way of feeding livestock.