Avaliação da qualidade nutricional de Brachiaria spp. para uso em sistemas de produção no Nordeste brasileiro

Abstract

The objective was to evaluate five cultivars of Brachiaria spp. regarding production and nutritional quality for use in production systems in Northeast Brazil. The experiment was carried out in the experimental area of the Federal University of Rio Grande do Norte - UFRN, the design used was that of a parcel subdivided over time, with four replications and five treatments represented by five cultivars of Brachiaria s pp .: Marandu, Paiaguás, Piatã , Xaraés and Basilisk, evaluated in four periods in the first year of implementation. The analyzes were performed at the applied nutrition laboratory belonging to the Federal University of Mato Grosso do Sul Foundation in the period. From the collected samples, the rate of forage accumulation (TFA), dry matter content (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), Leaf blade and stem, in vitro dry matter digestibility (IVDDM), organic matter (IVDOM), crude protein (IVDCP), neutral detergent fiber (IVDNDF), acid detergent fiber (IVDADF), the kinetics of in vitro degradation, protodioscin concentration and thermogravimetric analysis (TG). The cultivars showed similar results for DM (351.2 g / kg), with the lowest values observed in the rainy season samples (255.7 g / kg). The cultivar Xaraés showed the highest TFA (54.1 kg / ha.day of DM) and the cultivar Paiaguás the lowest with 33.72 kg / ha.day of DM. The cultivar Basilisk presented the highest levels of CP (95.1 g / kg DM), followed by the cultivars Marandu and Paiaguás (86.5 g / kg DM and 86.0 g / kg DM, respectively). For all cultivars, the highest percentages of NDF (707.6 g / kg DM) and ADF (415.2 g / kg DM) were found in the rainy season. The cultivar Basilisk showed the highest digestibility in vitro of DM (825.5 g / kg DM), followed by the cultivar Paiaguás (759.5 g / kg DM). The protodioscin concentrations were influenced by the periods, the Basilisk cultivar showed the highest concentrations (5.54 and 5.13 g / kg DM) in the establishment and dry / water transition periods and the lowest (1.51 and 1.23 g / kg DM) in the dry and rainy periods. The cultivars Piatã and Xaraés showed the lowest concentrations of protodioscin, ranging from 0.94 to 2 g / kg DM. The Basilisk cultivar stands out from the other cultivars for its nutritional value and high digestibility even in periods of water deficit, being an option to compose production systems in the semiarid region. However, due to the higher concentrations of protodioscin, in production systems with small ruminants the cultivars Piatã and Xaraés are the best forage options, with low levels of protodioscin, excellent forage accumulation and leaf: stem ratio.