Uma nova abordagem para identificar e controlar a deterioração aeróbia de silagens de milho estocadas em silos trincheira

Abstract

Aiming to identify and control the aerobic deterioration of corn silage two trialswere carried out. In the first study, the aim was to evaluate the silage pH as a method to identify the aerobic deterioration of corn silage under field conditions. For that, a dpH index was created, which is the difference between the pH of the sample collected at the top at 200 mm depth and the pH collected at 200 mm depth in the center of the silo (reference pH). The dpHwas positively correlated with the microbial counts (yeast and molds) and with the silage temperature, and negatively correlated with the lactic acid concentration. When the dpH of the silages was ≥ 0.25, 72.4% of the silages also had a yeast count ≥ 5 log cfu / g, 69.0% of the silages had a molds count ≥ 2 log cfu / g and 86.2% of the silages presented dTref40 ≥ 5°C. The data from this research showed that dpHcan be used as an index associated with aerobic deterioration, as it is related to the activity of yeasts and molds and with increasing silage temperature during the deterioration process. The dpH ≥ 0.25 shows that aerobic deterioration is occurring and thusgood management practices during the unloading silage should be adopted. In the second study, the aim was to find an unloading rate that considers silage density to control aerobic deterioration of corn silage stored in bunker silos. The feed-out rate proposed in this study was based on daily silage consumption per silo face area (kg/m2/day). In the silos where the feed-out rate was greater than 280 kg/m2/day the silage located at the top was similar to the center, in relation to the yeast and mold count, which maintained a good microbial quality of the silage throughout the silo face. Furthermore, when the feed-out rate was greater than 280 kg/m2/day, no signs of aerobic deterioration were observed in the silages, such as yeast count ≥ 5 log cfu/g, mold count ≥ 2 log cfu/g, dTref40 ≥ 5 °C and dpH ≥ 0.25. Therefore, the silage feed-out rate greater than 280 kg/m2/day was effective in controlling the aerobic deterioration in corn silages stored in bunker silos.