Tannins are known for their ability to modify digestion and reduce CH4 emissions in ruminants. Novel forages able to tolerate water deficits often contain low-to-moderate levels of dietary tannins. The aim of the study was to compare the effect of tannic acid (hydrolysable tannin, HT) and Tannivin (quebracho, condensed tannins, CTs) added to a total mixed ration at a concentration of 2.5% on rumen fermentation over time using in vitro methods. The substrates were incubated with buffered rumen fluid at 39 °C for 0, 3, 6, 12, 24, and 48 h to study dry matter (DM) degradability, tannin disappearance, utilizable protein (uCP), and rumen fermentation parameters. In parallel, gas production was measured using the ANKOM-RF Gas Production System. Gas composition was determined after 24 and 48 h of incubation. DM degradability was influenced by the incubation time (p < 0.001), reaching approximately 50% after 48 h, with a similar course of degradability for both tannin types. Tannin disappearance was significantly influenced by the type of tannins and the incubation time (both p < 0.001), reaching 50% in HTs and 39% in CTs within the first 6 h of fermentation. Production of individual and total VFA and uCP increased during incubation (p < 0.001) but were not influenced by the tannin type. However, the formation of uCP was relatively stable over time. Ammonia-N production increased during the first 12 h of fermentation with both tannin types and the increase continued with HTs (p < 0.001). Gas and methane production increased during fermentation and the increase was more substantial in HTs (p < 0.001). Our results suggest that at moderate concentrations, tannins mainly affect protein metabolism, with a minor effect on rumen fermentation.
Křížová et al. (Tue,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: