A study of the chemical and microbial changes in whole-plant corn silage during exposure to air: Effects of stage of maturity, packing density, sealing technique, and a biological additive

In study one, whole-plant corn was harvested at three stages of maturity: M1 = 50% milkline (32% DM), M2 = 80% milkline (36% DM), and M3 = blacklayer (46% DM); and ensiled at three densities. Maturity 1 was ensiled at D1, 369; D2, 688, and D3, 957 kg of fresh matter (FM)/m3. Densities for M2 and M3 were: D1, 369; D2, 529, and D3, 688 kg FM/m 3. One-half of the silos for each M and D were sealed immediately after filling (S, sealed), and the other one-half of the silos were sealed 48 hours after filling (DS, delayed seal). Silos were opened after 150 days, and chemical and microbial compositions and aerobic stability of the silages determined. The M2,D1,S and M2,D3,DS silages were the first to show a rise in temperature (e.g., after 44 hours of exposure to air). The aerobic stability of all other silages was acceptable (e.g., 60+ hours elapsed before a rise in temperature). Aerobic deterioration of the silages was accompanied by an increase in temperature and pH, a decrease in lactic acid content, and an increase in the lactate-assimilating yeast (LAY) population.; In study two, whole-plant corn was harvested at 80% milkline (36% DM) and ensiled at 529 kg of FM/m3. One-half of the pre-ensiled forage was treated with a biological additive (A) (e.g., a mixture of bacteria and enzymes); the other one-half was the untreated control (C). One-half of the silos in the A and C groups were sealed immediately after filling (S); the other one-half were sealed 48 hours after filling (DS). Silos were opened after 150 days, and chemical and microbial compositions and aerobic stability of the silages determined. All silages were moderately stable during exposure to air. The C, DS silage was the first to show a rise in temperature (e.g., after 65 hours of exposure to air). The DS silages were 48 hours less stable than their S counterparts, and the A silages were 24 hours more stable than their C counterparts. Aerobic deterioration of the silages was characterized by chemical and microbial changes that were similar to those observed in study one.