Avaliação de silagens de capim-elefante (Pennisetum purpureum Schum.) de diferentes portes em monocultivo ou consorciado com cunhã (Clitoria ternatea L.)

Abstract

The aim of this study was to evaluate the losses, aerobic stability and nutritive value of elephant grass (Pennisetum purpureum Schum.) genotypes of different sizes, in monoculture and intercropped with butterfly pea (Clitoria ternatea L.). The experiment was conducted at the Sugarcane experimental station of UFRPE (EECAC-UFRPE), in randomized complete blocks, under factorial arrangement (4 × 2) and four replications. Four elephantgrass clones (IRI-381 and Elephant B, tall, besides Taiwan A-146 2.37 and Mott, dwarf) were used in two cropping systems (monoculture and intercropping with butterfly pea) and harvested at 60 days of growth. Dry matter (DM), mineral matter (MM), organic matter (OM), crude protein (CP), neutral detergent insoluble fiber (NDF), acid detergent insoluble fiber (ADF), hemicellulose, lignin, acid detergent insoluble protein (PIDA), neutral detergent insoluble protein (PIDN) contents of the silages were evaluated. Moreover, in vitro dry matter digestibility (DIVMS), pH, soluble carbohydrates (CS) and ammoniac nitrogen (N-NH3) contents were analyzed too. In addition, gas (PG) and effluent (PE) losses, dry matter recovery (RMS), total digestible nutrients (TDN), fermentation coefficient (CF) and buffer capacity of forage were estimated. Data were analyzed with the aid of ExpDes 1.2.0 package, from free software R 3.0.3. Means were compared by Tukey test, at 5% probability. There was effect of culture system for CS and MS contents, on the other hand, genotype × culture system interaction for CP, NDF, ADF, PIDA and PIDN. Higher values of PIDA(11,38 g kg-1 da MS), PIDN (15,90 g kg-1 da MS) and CP (111,1 g kg-1 da MS ) were observed, as well as lower values of NDF (635,06 g kg-1 da MS) and AFD (420,4 g kg-1 da MS) and ADF in silages of the inter cropping. Higher RMS (87,33 %) was observed in Mott × butterfly pea mixture silage, as well as lower PE compared to exclusive Mott silage. Higher levels of CS (1,5 CSAr mg/g) were found in silages of the intercropping, and that made with Mott genotype. Lower DIVMS values occurred in silages mixed with butterfly pea, while the highest DIVMS (701,0 g kg-1 da MS) was observed in exclusive Taiwan A-146 2.37silage. The Mott and Taiwan A-146 2.37genotypes increase the nutritive value of elephant grass silages. The inclusion of legumes improves the grass silage fermentative characteristics, despite reducing the nutritional value. Considering all the variables studied, it’s suggested the confection of Mott silage mixed with butterfly pea.