In vitro fermentation patterns and methane production of sainfoin (Onobrychis viciifolia Scop.) hay with different condensed tannin contents.

Sainfoin (Onobrychis viciifolia Scop.) is a perennial legume recently reappraised for some positive charac- teristics leading to highly satisfactory animal perfor- mance. Sainfoin’s characteristics may be partly explained by the presence of moderate levels of condensed tannins (CTs) able to protect dietary protein from microbial degradation in the rumen. Decreased CH4 emissions have been reported for ruminants consuming CT-containing forage. The aim of this study was to evaluate the effects of CT content on the in vitro fermentation characteristics and kinetics and methane production of four samples of O. viciifolia cut at different phenological stages. Sainfoin hays and one sample of alfalfa hay were incubated at 39C in anaerobiosis using the in vitro gas production technique. The chemical composition, tannin content and fermentation charac- teristics and kinetics of sainfoin samples were signifi- cantly affected by phenological stage. After 48 h, the CH4 production in sainfoin hays showed a tendency to increase with the advancement of phenological stage [from 38Æ6 to 49 Æ8 mL g )1 of degraded organic matter (OM)]. The best period to cut sainfoin for hay making is between early and late flowering, when the forage combines high OM digestibility, low CH4 production and more efficient microbial fermentation.