Effects of two tannin extracts at different doses in interaction with a green or dry forage substrate on in vitro rumen fermentation and biohydrogenation

Extensive ruminant farming systems often face fluctuating pasture availability, resulting in two periods with very different forage quality. Tannins are natural bioactive compounds able to modify ruminants’ digestive metabolism thanks their properties. To evaluate a differential effect of tannins feeding situations, according the availability along year, an vitro rumen incubation trial was performed. Buffered sheep content incubated substrates, vetch (VP) and hay (VH), presence tannin extracts, from quebracho (QUE) mixture chestnut (MIX). Each extract tested at 0, 15 30 g tannin/kg DM. The gas production determined 3.5 24 h fermentation. After anaerobic conditions, volatile fatty acids (VFA), ammonia (FA) were analysed. Interesting significative two-way interactions extracts observed some fermentation parameters. Adding MIX VH treatment resulted higher depression (P < 0.050) iso-VFA proportions, compared QUE supplementation, while no differences VP treatment. more effective than reducing acetate/propionate ratio when supplemented However, showed increase CO2/CH4 after g/kg, exerted similar effects on biohydrogenation. Tannin decreased rumenic/linoleic acid iso-FA proportions only added These results demonstrate that modulating associated hay-based diet. Also, protecting proteins ruminal degradation, key point grazing periods. Therefore, extensive husbandry could benefit strategies for using dietary season availability.