The condensed tannins in sainfoin can improve fermentation and reduce the degradation of alfalfa protein when the two forages are ensiled together, say researchers at Agriculture and Agri-Food Canada.
They harvested both at prebud stage, mixed them together at various alfalfa-to-sainfoin ratios and ensiled them for 74 days. Half of each mixture was sprayed with polyethylene glycol to deactivate the condensed tannins.
Increasing proportions of sainfoin in the mixtures increased lactic-acid and volatile-fatty-acid levels, and reduced silage pH, they report. The addition of polyethylene glycol didn’t affect silage pH, but increased lactic-acid levels. It also resulted in progressively higher non-protein nitrogen and ammonia levels as the sainfoin proportion increased.