Avaliação de silagem mistas de sorgo e palma forrageira

Abstract

The objective was to identify the optimal level of inclusion of forage cactus in sorghum silages. Forage sorghum (Sorghum bicolor) cv. BRS Ponta Negra and forage cactus (Nopalea cochenillifera) cultivar Miúda. Sorghum was harvested at approximately 100 days and the forage cactus had been harvested after two years of regrowth. The design used was completely randomized with five treatments and four replications. The treatments were the levels of inclusion of palm in sorghum silage (0, 25, 50, 75 and 100% based on natural matter). The chemical composition, microbial profile, fermentation profile, silage losses and aerobic stability of the silages were evaluated. Analysis of variance and regression was performed with the SISVAR statistical program. Lactic acid bacteria (BAL) had a quadratic effect, while molds had a decreasing linear effect (P<0.05). Yeasts showed no difference between the evaluated treatments (P>0.05). Regarding the fermentation profile, pH and water-soluble carbohydrates did not show a significant effect, regardless of the level of palm added. The ammonia nitrogen content showed a linear increase as palm was added to the silages. Dry matter recovery was higher at the 25 and 50% levels, decreasing significantly at the 100% palm level. The aerobic stability of the silages linearly increased as a function of the higher levels of palm, where from the 50% level there was no break in stability. There was a difference in the chemical composition of the silages, as the DM, CP and NDF content showed a linear decreasing effect, while EE and CNF showed a linear increase as more palm was included. The sorghum silages with 50% palm inclusion showed the best balance between the evaluated characteristics, resulting in qualitative and quantitative improvements.