Influence of Anti-Coccidial Compounds and Phytogenic Saponin Extracts on In Vitro and In Vivo Ruminal Fermentation and Methane Production of Cattle

Four experiments were conducted to evaluate sources of anti-coccidial compounds and phytogenic saponin extracts on in vitro and in vivo ruminal fermentation and CH₄ production at multiple inclusion levels. In experiment 1, eight steers were fed either a finishing diet or a finishing diet supplemented with 0.5 mg/kg BW decoquinate (DCQ) and 3.33 mg/kg BW <i>Yucca schidigera</i> extract (YSE), and respiratory gas exchange was measured. In experiment 2, four ruminally-cannulated steers were fed the same treatments as experiment 1, and ruminal fermentation was evaluated. Anti-coccidial sources (experiment 3; monensin, DCQ, amprolium) and saponin sources (experiment 4; YSE, <i>Quillaja saponaria</i> extract) and levels were evaluated for effects on in vitro ruminal fermentation and CH₄ production. DCQ + YSE supplementation did not influence (<i>p</i> ≥ 0.24) in vivo respiratory gas consumption/production, in situ DM degradation, or liquid passage kinetics. Ruminal propionate proportion tended to increase (<i>p</i> = 0.09) with DCQ + YSE. Monensin decreased (<i>p</i> ≤ 0.04) in vitro acetate:propionate and CH₄ production; saponin supplementation linearly increased (<i>p</i> < 0.01) propionate proportion but did not influence (<i>p</i> ≥ 0.38) in vitro CH₄ production. Saponins and non-antibiotic anti-coccidials did not influence in vitro or in vivo CH₄ production with finishing diets.