Divergence effects between dietary Acacia and Quebracho tannin extracts on nutrient utilization, performance, and methane emission of ruminants: A meta‐analysis

Extracts of Acacia and Quebracho have been used as a feed additive in ruminantdiets; the effects, however, have been varied. This study used a meta-analysisapproach to evaluate the use of those extracts on nutrient utilization, performance,and methane production of ruminants. A database was developed from 37 publishedpapers comprising 152 dietary treatments. The result showed that a higher concen-tration of tannins was associated with a decrease (p < 0.05) in nutrient intake anddigestibility. An increasing tannin concentration was negatively correlated withammonia, acetic acid, and the ratio of acetic to propionic acid. Methane productiondecreased (p < 0.01) with the increasing tannin concentration. Nitrogen (N) balanceparameters were not affected by the tannin concentrations, but fecal N excretionincreased (p < 0.01) as the tannin concentration increased. The relationshipsbetween the Acacia and Quebracho and the changes in organic matter intake, milkfat concentration, butyric acid, valeric acid, and methane production were signifi-cantly different. In conclusion, it is possible to use both condensed tannins(CT) extracts as a methane emission mitigation without impairing the ruminant per-formance. Furthermore, the Quebracho showed more pronounced to decrease rumi-nal protein degradation and lower methane emission than the Acacia.