Produção animal e vegetal em pastagem nativa manejada sob diferentes ofertas de forragem por bovinos

Abstract

Neste trabalho avaliou-se a influência de diferentes ofertas de forragem e suas combinações ao longo do ano sobre a dinâmica do crescimento da pastagem e o desempenho animal. O experimento foi conduzido em área de pastagem natural com novilhas de sobreano mantidas em pastejo contínuo com taxa de lotação variável. Os tratamentos foram ofertas de forragem fixas ao longo do ano: 4; 8; 12 e 16kg de matéria seca 100kg de peso vivo-1 por dia e combinações de 8 na primavera e 12 no outono-inverno-verão (8-12%); 12 na primavera e 8 no outono-inverno-verão (12-8%); 16 na primavera e 12 no outono-inverno-verão (16-12%), constituindo um delineamento experimental de blocos casualizados com duas repetições. A produção de forragem e o ganho de peso animal foram medidos na estação de crescimento de 2007-2008. Os resultados comprovaram que o uso de oferta de forragem muito baixa, como 4%, prejudica o desempenho animal individual e por área. O manejo combinado de ofertas 8-12% promoveu aumento de 35% no desempenho individual (0,345kg animal-1) aumento de 20% na produção por área (209kg ha-1 de PV) em comparação ao manejo 12% ao longo do ano.

Beef heifers performance in natural grassland under continuous and rotational grazing in the autumn-winter

“…Our results had SR greater than other experiments in natural grassland of RS with FA of 12% (MEZZALIRA et al, 2012;PINTO et al, 2008). However, in our results, the FAr was based in the FM8 and LBMt (considering the percentage contribution of each stracta), differently to the experiments previously mentioned.…”

“…bite mass). MEZZALIRA et al (2012) worked with FA protocols obtained value of 1398kg DM ha -1 and 7.9cm for FMa and HLS, respectively, in the FA of 12% with positive animal performance in the autumn-winter period. However, in this experiment, with FMa and HLS similar to the previous experiment, the animal performance was negative during the autumn-winter period, using the sward height of the lower stracta as one of the criteria to adjust the stocking rate.…”

“…However, some studies demonstrate the potential of these grasslands for rearing beef heifers (SOARES et al, 2005;MEZZALIRA et al, 2012) and, after that, breeding this category. Besides, to promote a higher livestock production efficiency is necessary to breed heifers until 24 months old due to her capacity of increasing the genetic progress of the herd, weight and number of calves for sale (BERETTA et al, 2001).…”

Temporary grazing exclusion promotes rapid recovery of species richness and productivity in a long‐term overgrazed Campos grassland

“…The only anthropic intervention in the experimental units was the management of grazing intensity via adjustments of forage allowance, so there was no fertilization, irrigation, fire, or mowing. The severe grazing intensity treatment has evolved into an overgrazed pasture during years previous to our experiment, while the moderate grazing intensity was the best treatment in terms of forage productivity and animal performance in the same interval (Soares et al ; Mezzalira et al ). Grassland managed by severe grazing intensity showed several indications of degradation in both soil properties (decreased soil water infiltration, porosity, aggregation, and organic matter content, while increased soil bulk density) (Bertol et al ; Conte et al ) and plant diversity (decreased Shannon Weaver diversity index) (Carvalho et al ; Pinto ) compared to moderate grazing intensity.…”

“…In this article, we studied the effect of two different periods of grazing exclusions in paddocks managed for 27 years under intensive or moderate grazing intensities. Previous studies in this experimental site showed great benefits of moderate grazing intensities on both forage and animal production (Soares et al ; Mezzalira et al ). We hypothesized that moderate grazing intensities can act as a structuring factor of species assemblages, which in turn could facilitate the coexistence of a high number of species.…”