Efeitos da realocação na qualidade de silagens de milho inoculadas

Abstract

Corn silage is a roughage widely used in ruminant diets, as it has a high concentration of digestible nutrients and the plant has characteristics that favor conservation through silage. However, it can be easily unstable when exposed to air, which makes this step critical in relocating these silages. Thus, it is extremely important that strategies to reduce deterioration during reallocation are defined. Therefore, the objective was to determine the effect of the time of exposure to air and the inoculation with strains of heterofermentative bacteria combined or not with homofermentative strains, on losses, fermentative characteristics and the nutritional value of reallocated corn silages. For that, it was proposed to conduct two experimental tests in a completely randomized design. The first study was conducted in a 4 × 6 factorial arrangement, with four replications. The factors studied were: microbial inoculant (without inoculant; Lactobacillus plantarum (DSM3676; DSM3677) + Lactobacillus buchneri (DSM13573), Lactobacillus plantarum + Propionibacterium acidipropionici and Lactobacillus buchneri (DSM13573) and real time; 36; 48 and 60 hours of exposure to air before relocation). It was observed that after 120 days of fermentation, the silages treated with microbial inoculant showed a better fermentation profile, less yeast population and less dry matter losses. After 60h of relocation, all silages had a high temperature (> 30 ° C), which indicates that after this period the silages were entering a more advanced deterioration process. However, the changes that occurred up to 60h of reallocation did not reflect an increase in the pH of the silages, indicating that the silages were not completely deteriorated. During the relocation, silages treated with L. buchneri had better control in the development of yeasts, and after the second fermentation process these silages had higher quality and were more unstable than the others, regardless of the time of relocation. In the second study, the effects of relocating corn silage inoculated or not, with L. buchneri (LB) or in combination with L. plantarum (LBLP), were tested on aerobic stability, apparent digestibility and lamb performance. The treatments were the diets: corn silage without non-relocated inoculant (SISR); corn silage without inoculant relocated after 24h of aerobic exposure (SIR); corn silage with LB relocated after 24h of aerobic exposure (LBR); and corn silage with LBLP relocated after 24h of aerobic exposure (LBLPR). It was observed that silages with LBLPR had greater aerobic stability than silages SISR, SIR and LBR. In the metabolism test, it was observed that there was no difference in diet intake and digestibility, regardless of the silage used and, consequently, there was no effect on the lambs nitrogen balance. In the performance test, the SISR silage showed a higher consumption of neutral detergent fiber (NDF), due to the greater amount of NDF and less non-fibrous carbohydrates contained in this silage when compared to the SIR, LBR and LBLPR silages. However, none of the silages affected feed conversion, daily weight gain and ingestive behavior of the lambs. It is concluded that LBLPR silages are more stable in an aerobic environment, decreasing the daily amount of deteriorated silage discarded. Silages relocated within 24 hours of exposure to air containing or not microbial inoculants do not affect the digestibility and performance of lambs.