Department of Animal Science, College of Agriculture, Shiraz University, Shiraz, Iran
The effects of a microbial inoculant (containing propionic and lactic acid bacteria) and formic acid on chemical composition, ruminal degradability of dry matter (DM) and nutrient digestibility of corn silage were examined. Whole-plant corn was ensiled for 60 days in plastic polyethylene bags, and three treatments were compared, 1: control (no additive), 2: Propionibacterium acidipropionici plus Lactobacillus plantarum at 3 × 1010 cfu/g of fresh forage, and 3: formic acid (98%) at 2.41/t fresh forage. The silages were subjected to chemical analysis, DM degradability and nutrients digestibility in sheep. At the end of ensiling period, treatment 3 had significantly higher (P<0.05) content of crude protein (CP), lactic acid, total acids, DM recovery and pH values than other treatments. Treatment 2 had the lowest pH value, the highest level of propionic acid, and the lowest level of butyric and total acids (P<0.05). No traces of ethanol were detected for neither of silages. CP digestibility was higher (P<0.05) for treatment 1 compared with others, while ether extract (EE) digestibility was higher (P<0.05) for treatments 1 and 3 compared with treatment 2. Effective DM degradability was higher for treatment 3. All silages went under rapid fermentation and were wellpreserved and treatment 2 was more stable after opening. The degree of improvement in fermentation using microbial inoculant was lower than formic acid but expected to improve the aerobic stability by inhibition of yeast activity, especially in warm climates.