Composição botânica, morfológica e bromatológica de pasto nativo em campo de altitude no Rio Grande do Sul

Abstract

Native pastures have great importance for the sustainability of livestock farming in the South of Brazil, being the main forage resource used. However, these pastures have received less attention from governments compared to other agricultural areas, resulting in a number of degradation consequences, such as landscape fragmentation, loss of biodiversity, soil erosion, biological invasion, and others. The purpose of this study was evaluate the botanical composition, bromatological quality and dry matter accumulation rate of native pasture, located in a farm at São José dos Ausentes, RS. The collections were carried out every twenty days, beginning in January 2018 and ending in March of the same year, before animals incoming in the area and after seven days, in the moment of their exit, at random on picket. After the samples were collected, 50% were analyzed for the botanical composition in relation to the family and species and the remaining 50% for the bromatological analysis, where the determinations of Dry Matter (DM), Mineral Matter MM), Crude Protein (PB), Ethereal Extract (EE), Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) in the Laboratory of Bromatology and Animal Nutrition of the Federal University of Fronteira Sul (UFFS) Campus Erechim- RS. In addition, the dry matter accumulation rate and forage availability per hectare were determined through the Accumulation Rate Equation. The species identified in the native pasture were: Pycreus polystachyos (Rottb.) P. Beauv, Axonopus siccus (Nees) Kuhlm, Paspalum scrobiculatum L., Fimbristylis miliaceae (L.) Vahl, Setaria parviflora (Poir.) Kerguélen, Paspalum pumilum Nees, Desmodium tortuosum (Sw.) DC., Baccharis trimera (Less.) DC., Perezia squarrosa (Vahl) Less, Calea phyllolepis Baker, Bulbostylis sphaerocephala and Pteridium arachnoideum (Kaulf.) Maxon. The levels of MS, MM, PB, EE, NDF and FDA were 93.24; 0.07; 7.32; 2.32; 33.76 and 20.09%, respectively. The daily dry matter accumulation rate ranged from 1597 to 3596 kg / ha and forage availability averaged 2596.5 kg DM / ha \ day. It is concluded that due to the results of the bromatological parameters and the values of forage availability and dry matter accumulation rate found, native pasture needs improvement mechanisms to obtain higher yields.