Manipulation of fermentation dynamics of corn silage with selected additives and their effects on silage quality, digestibility and animal performance

Study 1. A laboratory-scale experiment with 75-kg steel drums was conducted using sorbic acid (SA), an amylase-sterilant (AS) or both (SA+AS) as silage additives for whole-plant corn, to determine type of fermentation and change in nutrient composition over time due to treatments. Addition of SA, AS or SA+AS increased concentrations of water-soluble carbohydrates (WSC) by 60.3, 17.4 or 50.1%, respectively. Treatment with SA inhibited formation of butyric acid, and lowered ammonia-N and ethanol concentrations in silage by 6.4 and 34.2% respectively (P< .02). Use of AS reduced butyric acid concentration, but increased ammonia-N and ethanol content in silage by 6.8 and 33.1%, respectively (P< .10).

Study 2. Using the aforementioned silages, a digestion and nitrogen balance trial and a rumen fermentation experiment measuring in-vitro gas production and microbial protein synthesis were conducted. In-vitro gas production was increased twofold in sheep fed SA- or AS-treated silages (P< .10). Microbial protein synthesis with SA, AS or SA+AS treatment was increased by 125, 133 (P< .10) and 61%, respectively. Digestibility and nitrogen utilization were not affected by treatments.

Study 3. A fermentation time study with 8-kg plastic buckets using α-amylase, α- and β-amylases or α-, β-amylases and sulfur-salts (AS) as silage additives, and a growth trial with beef heifers were conducted to identify the cause for increased animal performance with AS-treated silages. After 28 days of ensiling, all amylase-treated silages retained 41 to 60% higher concentrations of WSC (P< .10), and produced more lactic acid (P< .10) than untreated silage. Presence of fungi was reduced in two of the amylase-treated silages (1.10 to 1.17 log; P< .10). Dry matter recovery of amylase-treated corn silages was markedly increased (6.3 to 10.7%, P< .10). Beef heifers fed amylase-treated corn silages had 5.3 to 12.1% increased ADG. Results suggest that addition of SA and AS shows potential for improving silage quality, nutrient preservation and ultimately, animal productivity.