RESUMEN
BACKGROUND: Copper (Cu) is an essential microelement to the health and proper functioning of metabolic processes in animals, but the particular function of Cu in fermentation processes and the formation of methane (CH4 ) in the rumen have been poorly analyzed. The innovative aspect of this study was to investigate the effects of high doses of Cu as copper sulfate on in vitro ruminal degradation, fermentation patterns, and CH4 production. RESULTS: There was a decrease (P < 0.04) on in vitro dry matter (DM) and organic matter degradability from 60 to 100 µg Cu/g DM. Ammonia concentration decreased drastically with increasing Cu levels (linear effect, P < 0.01). Total bacteria and volatile fatty acids (quadratic effect, P < 0.02) were reduced with 80 and 100 µg Cu/g DM. Methane production (milliliters per gram digestible organic matter) was decreased when dosages of Cu were increased (linear effect, P < 0.003). CONCLUSION: Overall, the addition of increasing levels of Cu to 40 µg Cu/g DM did not have an adverse impact on ruminal bacteria growth and decreased CH4 production, without affecting the ruminal kinetics. © 2018 Society of Chemical Industry.