Produção e qualidade de forragem de cultivares de Panicum maximum implantados no semiárido brasleiro

Abstract

The objective was to evaluate the rate of forage accumulation and the quality of six cultivars of Panicum maximum in the Brazilian semiarid region. The experiment was conducted at the Federal University of Rio Grande do Norte - UFRN. The treatments were six cultivars of Panicum maximum: Aruana, Massai, Mombaça, BRS Tamani, Tanzânia and BRS Zuri. The design was randomized blocks in a split plot scheme with four replications. The studied variables were: forage accumulation rate (RFA), dry matter (DM), ashes for the determination of organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), protodioscin, in vitro digestibility of dry matter (IVDMD), in vitro digestibility of organic matter (IVOMD), in vitro digestibility of crude protein (IVCPD), in vitro digestibility of neutral detergent fiber (IVNDFD), in vitro digestibility of acid detergent fiber (IVADFD), cumulative gas production in vitro and thermoanalysis. The highest RFA were observed in cv. Zuri in the rainy season and for cv. Tamani in the establishment period (86,9 and 47,0 Kg/ha/day of DM, respectively), the lowest RFA was observed in cv. Aruana (13,4 Kg/ha/day of DM) in the dry period. The highest levels of CP were found in cv. Tamani during the transition period, cv. Zuri in the dry period and cv. Tanzânia in the rainy period (128,2; 116,7 and 95,0 g/Kg of DM, respectively), and the lowest in cv. Massai (61,5 g/Kg of DM). The highest levels of NDF were found in cv. Zuri (827,5 g/kg of DM) in the period of establishment and in the cvs. Massai, Mombaça, Tamani and Tanzânia (766,0; 746,5; 762,0 and 750,7 g/Kg of DM, respectively) in the rainy season, and the lowest in the cv. Aruana (644,5 g/Kg of DM) in the transition period. The highest amount of protodioscin was observed in cv. Aruana is the lowest in cv. Tamani, both in the transition period (1,14 and 93,0 g/Kg of DM, respectively). The highest IVDMD was observed in cv. Aruana in the transition and rainy periods (826,0 and 810,0 g/Kg of DM respectively). For the cumulative production of gas in vitro there was only the effect of cultivar, being observed the highest value in cv. Aruana and the lowest for cv. Mombaça (Y=20,48 and 13,85 mL/100 mg of incubated DM, respectively). The thermal profile of Panicum maximum cultivars was similar. The cv. Aruana has a low rate of forage accumulation in semi-arid conditions, however the quality of the forage is superior to the others, in contrast to cv. Mombaça suffered losses in quality and high rate of forage accumulation. The cultivars of Panicum maximum are indicated for use in animal production systems in the Brazilian semiarid, as they present forage accumulation and quality that meet the nutritional requirements of ruminants.