Modificações na estrutura vertical de pastos de capim-xaraés sob lotação intermitente por bovinos

Abstract

RESUMOO objetivo deste trabalho foi avaliar os efeitos dos índices de área foliar residual (IAFr), dos anos de avaliação e dos ciclos de pastejo sobre as modificações na estrutura vertical do dossle, bem como a proporção de componentes morfológicos de pastos capim-xaraés submetidos a intensidades de pastejo, durante dois verões. O experimento foi conduzido na Faculdade de Ciências Agrárias e Veterinária da Unesp, Câmpus de Jaboticabal, SP, e as intensidades de pastejos foram definidas por IAFr: 0,8; 1,3; 1,8 e 2,3. Quando o dossel interceptou 95% da luz incidente, os animais foram colocados no piquete para o pastejo e permaneceram até o IAFr alvo ser alcançado. Os pastejos foram realizados por vacas da raça Holandesa (Bos taurus taurus L.) não lactantes, com peso corporal médio de 450kg±50kg, utilizando-se a técnica de mob-stocking. Foram avaliadas a proporção de componentes morfológicos dos pastos e a estrutura vertical do dossel pelo aparelho de ponto inclinado. Índices de área foliar residual de 1,3 a 1,8 são os que melhores respostas apresentam em relação à estrutura vertical do dossel e à proporção dos componentes morfológicos de pastos de capim-xaraés submetidos a intensidades de pastejo.

Anatomical, morphogenic and structural characteristics of Xaraés palisade grass under grazing

“…The management of pastures at a lower grazing intensity provided stem elongation and consequently an increase in the stem proportion as well as accumulation of older ungrazed leaves (Euclides et al 2019) due to the higher rLAI used, which might have increased the proportion of sclerenchyma (Table 1). Studies conducted by Galzerano et al (2015) demonstrated alterations in leaf:stem ratio and in the proportion of dead material in Xaraés palisadegrass pastures managed under different grazing intensities. Galzerano et al (2013) also evaluated the effects of rLAI on the morphogenetic traits of Xaraés palisadegrass under grazing and determined a quadratic effect of rLAI on the final leaf length in one of the grazing cycles.…”

“…The rLAI values were chosen based on previous experiments conducted by the research group in pastures of Tifton 85 (Cynodon spp.) (Silva et al 2013;Costa et al 2015;Silva et al 2016a;Silva et al 2019) and Xaraés palisadegrass (Raposo et al 2014;Galzerano et al 2015) in order to cover an amplitude that represented different grazing intensities. The rLAI was monitored during the grazing period through measurements taken in each paddock, and once the rLAI was achieved, animals were moved to another paddock where the pasture had intercepted 95% of light (LI) during the regrowth period.…”

“…Coupled with information on the leaf anatomy and morphogenetic characteristics, studies involving light interception by the sward and residual leaf area index as predictors of frequency and grazing intensity respectively, have demonstrated the importance of these variables regard to the growth of plants and responses to defoliation. Regrowth ability, in addition help to define the best moment for the insertion and removal of animals into and from pastures under intermittent grazing (Galzerano et al 2013;Galzerano et al 2015;Silva et al 2016a;Silva et al 2016b;Silva et al 2019). Thus, we need to understand how the grazing intensity in intermittent grazing can change the morphogenesis and leaf anatomy of grasses in order to interfere in the degradability of tissues in the animals' rumen.…”

The water footprint of beef cattle in the amazon region, Brazil

“…Continuous stocking is adopted in the area. It consists of giving the herd unrestricted and uninterrupted access to the entire pasture throughout the grazing season (GALZERANO et al, 2013).…”