Proteolysis and rumen degradability of alfalfa silages preserved with a microbial inoculant, spent sulfite liquor, formic acid or formaldehyde

The efficacy of biological additives and direct acidifiers on the preservation and extent of proteolysis in unwilted alfalfa silage was investigated using a 2 × 3 × 5 factorial design. Alfalfa, harvested as unwilted second-cut (21% dry matter (DM)) and third-cut (17% DM) material was ensiled untreated or treated with formic acid (0.4%) or a microbial inoculant (Ecosyl: ICI Biologicals, Mississauga, ON), with or without formaldehyde (0.2%) or three levels of spent sulfite liquor (SSL) (0.25, 0.50 and 0.75%) in laboratory silos for 90 d. Addition of direct acidifiers (formic acid with or without formaldehyde or SSL) reduced pH and enhanced levels of water-soluble carbohydrates (WSC) and lactic acid. Proteolysis of unwilted second- and third-cut silage as measured by soluble nitrogen (N), nonprotein N (NPN) and ammonia N (NH3-N) concentration was reduced (P   0.05...