Caracterização da vegetação espontânea, atividade biológica de taninos condensados e seletividade de ovinos em pastagens nativas

• Autor(a) principal: OLIVEIRA, Osniel Faria de
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6966
• topic: Vegetação nativa; Planta forrageira; Atividade biológica; Tanino condensado; Valor nutritivo; CIENCIAS AGRARIAS::ZOOTECNIA

Forages undergo structural and qualitative changes as the climate, soil changes and forage allowance influence intake and animal performance. The selection of plants by animals are usually influenced by forage allowance. This study aimed to evaluate the vegetation structure, nutritive value and the biological activity of condensed tannins (CT) from forage plants under grazing and in different rangeland sites of Pernambuco State, as well as selectivity index of sheep in manipulated Caatinga. The experiment I was carried out in eight sites of Pernambuco, gathering natural plants during the rainy season of 2013 and 2014. In this trial were evaluated the botanical composition (BC), bare soil (BS) and plant height, as well as forages nutritive value including crude protein (CP), neutral detergent fiber (NDF) and acid (ADF), lignin (ADL), mineral matter (MM), ether extract (EE), digestibility (IVDMD), carbon/nitrogen ratio (C/N), phosphorus (P) and CT. I also estimated methane suppression (CH4), inhibition of larval migration (LMI), molecular weight (Mw) and Procyanidin:Prodelfinidin ratio (PC:PD). Grasses and legumes comprised 22.2 and 33.0% of BC, respectively. The BS was greater in Sertão (31.8%) than Agreste (14.2%) and Zona da Mata (10.8%). The herbaceous height was lower in Sertão (29 cm) than Agreste (69 cm) and Zona da Mata (104 cm). However, woody plants were greater in Sertão (160 cm) than Agreste (145 cm) and Zona da Mata (105 cm). The plants showed variation in nutritional value, averaging 198 g CP kg%1, 497 g NDF kg%1, 270 g ADF kg%1, 113 g ADL kg%1, 35 g EE kg%1, 458 g CT kg%1, 16.4 C:N, and 715 g IVDMD kg%1. The suppression of CH4 was greater (#≤0.05) in Sertão plants (5.5 mM) than Agreste (6.1 mM) and Zona da Mata (8.4 mM), with plants collected in Flores during 2013 and Pesqueira in 2014 with greater (#≤0.05) CH4 suppression, 2.8 and 2.5 mM, respectively. Plants CT were effective in LMI averaging 21.3 ± 9.3%, Flores had greater (#≤0.05) LMI (33.4%) in 2013 and Sertânia (35.7%) in 2014. The PC:PD was 74:26, greater (#≤0.05) in plants collected from Flores (100:0), Serra Talhada (93:7) and Pesqueira (85:15). Bezerros was the only site with lower PC:PD (48:52). The Mw in Sertão plants (1476 Da) was also greater (#≤0.05) than Agreste (1333 Da) and Zona da Mata (1099 Da), highlighting plants from Serra Talhada (1719 Da) and Sertânia (1753 Da). In the experiment II, sheep were submitted to four forage allowances [2.0, 2.5, 3.0 and 3.5 kg of dry matter (DM)/kg body weight (BW)], in Caatinga thinned, with mororó. The nutritive value and CT bioactivity from mororó were evaluated, as well as the selectivity index from BC of pasture and sheep diet, analyzed via microhistological examination of feaces. The BC of the pasture was influenced (#≤0.05) by forage allowance and year. In general, grasses contributed more (#≤0.05) to the pasture. In 2013, as forage allowance decreased, grasses increased (#≤0.05) their presence, while legumes decreased, and the reverse ocurring in 2014. Overall, the sheep consumed great proportion of dicots in all treatments. Grasses were selected 49.8% more (#≤0.05) in 2014 while dicots were more selected in 2013. The Mw and PC:PD ratio were 1158 Da and 95:5, respectively. The chemical composition of mororó shows potential for ruminant nutrition because it had up to 17.5 g CP kg%1 and its CT (0.3 to 167.1 g kg%1) can suppress CH4 (4.5 to 10.7 mM) and reduce larval motility (from 3.0 to 28.5%). Thus, the structural and qualitative characterization was diverse, in different physiographic zones with plants of forage potential that have adequate nutritional value and effective biological activity via CT. Different forage allowances levels in Caatinga promotes changes in BC of pasture as a result of sheep diet change. Mororó show promising nutritional value for ruminants, as well as effective biological activity of CT. Depending on the purpose for which mororó is used, whether as forage or as an environmental tool, forage allowance can be manipulated at different levels.