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

SIMPLE SUMMARY: There is rising interest globally in reducing the use of antibiotics in livestock feeding regimens. Phytogenic feed additives have been evaluated for their potential use to replace compounds such as ionophores in finishing cattle diets. The effects of saponin-containing extracts from Yucca schidigera (YSE) on ruminal fermentation, average daily gain, and feed efficiency appear to be similar to monensin; however, YSE is not approved for the control or prevention of coccidiosis in cattle. Therefore, the objectives of this study were to evaluate sources and levels of anti-coccidial compounds and saponins, individually or in combination, on in vitro and in vivo ruminal fermentation and CH(4) production. In summary, the combination of decoquinate with YSE did not influence in vivo CH(4) production but tended to increase ruminal propionate proportion. Monensin inclusion decreased in vitro CH(4) production and the acetate:propionate. Increasing saponin inclusion increased the propionate proportion in vitro but was not accompanied by a reduction in CH(4) production. ABSTRACT: Four experiments were conducted to evaluate sources of anti-coccidial compounds and phytogenic saponin extracts on in vitro and in vivo ruminal fermentation and CH(4) 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 Yucca schidigera 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, Quillaja saponaria extract) and levels were evaluated for effects on in vitro ruminal fermentation and CH(4) production. DCQ + YSE supplementation did not influence (p ≥ 0.24) in vivo respiratory gas consumption/production, in situ DM degradation, or liquid passage kinetics. Ruminal propionate proportion tended to increase (p = 0.09) with DCQ + YSE. Monensin decreased (p ≤ 0.04) in vitro acetate:propionate and CH(4) production; saponin supplementation linearly increased (p < 0.01) propionate proportion but did not influence (p ≥ 0.38) in vitro CH(4) production. Saponins and non-antibiotic anti-coccidials did not influence in vitro or in vivo CH(4) production with finishing diets.