Perfil fermentativo da silagem de pornunça (Manihot spp.)

Abstract

In the Northeastern Semiarid region, forage conservation has been highlighted as a strategy to ensure a regular food supply, and pornunça (stem-fed silage) has emerged as a promising forage alternative. This study aimed to evaluate the dynamics of the fermentation profile of pornunça silage as a function of fermentation time and to determine its effects on aerobic stability. Samples from two batches (150 and 60 days) were collected from 40 kg laminated bag silos. The crop was grown with poultry manure fertilizer, spacing 1.2 x 0.5 m, and harvested at 120 cm with a 2 cm shredding process. In the laboratory, the samples were ground for dry matter and crude protein analysis. An aqueous extract was prepared from 25 g of fresh silage sample and added to 225 mL of saline solution to measure pH. Microbial populations (lactic acid bacteria, yeasts, and filamentous fungi) were quantified, and an aerobic stability test was conducted for 96 hours at 25°C with continuous temperature recording. A completely randomized design with two treatments (SIL1 = 150 days and SIL2 = 60 days) and five replicates was used. Means were compared using the F test (5%). It was observed that the fermentation time significantly influenced (P<0.05) the composition and fermentation profile: the silage with 150 days had a higher dry matter content (306.4g/kg) in relation to the silage with 60 days of fermentation (221.8g/kg), while the crude protein was higher at 60 days than at 150 days, presenting values, respectively, of 129.3g/kg and 59.0g/kg; the pH of the 150-day silage was obtained within the desirable range with averages of 3.82, while the 60-day silage was below this range, presenting values of 3.47; the greatest aerobic stability was obtained by the silage with 150 days of fermentation, totaling 32.49h, while the silage with the shortest time was only 14.23h. Microbial counts did not differ statistically (P>0.05), with mean values of 6.3, 0.66, and 3.72, respectively, in silage with 150 days of fermentation (SIL1) and 6.81, 1.98, and 5.87 in silage with 60 days of fermentation (SIL2). Because it presents a set of quality indicators, such as pH within the recommended range, greater aerobic stability, and reduced numerical counts of mold and yeast, it is noteworthy that silage with longer fermentation time (SIL1) is the most suitable option for use in animal feed. It is concluded that the 150-day fermentation time provides better nutritional value and aerobic stability than 60 days of fermentation of pornunça silage.