Low concentrations of protein- and fiber-bound proanthocyanidins in sainfoin (Onobrychis viciifolia) are stable across accessions, growth stages and drought conditions.

Proanthocyanidins (PAs) in forages may be present in either soluble (S-PA) or non-extractable (NE-PA) form. Despite potential benefits of the NE-PA in ruminant nutrition, few studies have analyzed NE-PA in forages. This study examined the impact of a range of conditions on S-PA, as well as protein- and fiber-bound PA (the NE-PA fractions) in sainfoin (Onobrychis viciifolia). Thus, five sainfoin accessions in either generative or vegetative stage were subjected to drought for 18 weeks and sampled repeatedly for PA analysis. Drought stressed plants increased S-PAs on average by 59% across all accessions yet only in the vegetative stage. In contrast, NE-PA concentrations were generally lower (on average 15% of the total PAs) and unaffected by drought. Thus, for sainfoin, the low and stable concentration of NE-PAs across accessions, growth stages and drought conditions should have a low, predictable impact on the future sainfoin analyses and feeding studies.