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Portela J.N.,Instituto Federal Of Educacao | Pedreira C.G.S.,University of Sao Paulo | Braga G.J.,Polo Regional Of Desenvolvimento Tecnologico Dos Agronegocios Do Centro Oeste
Pesquisa Agropecuaria Brasileira | Year: 2011

The objective of this work was to assess the effects of grazing intensities and defoliation frequencies on the demography and density of signalgrass (Urochloa decumbens syn. Brachiaria decumbens) tillers under intermittent stocking. Two grazing intensities (5 and 10 cm after-grazing stubble height) and two defoliation frequencies (rest periods determined by 95 or 100% of light interception, LI) were evaluated, from August 2007 to August 2008. It was used the completely randomized design, in factorial arrangement with four replicates. Tiller densities and appearance and survival rates of basal (TDb, ARb, SRb, respectively) and aerial+basal tillers (TDab, ARab, SRab) were evaluated. The highest ARb and ARab, in the autumn, were observed in pastures defoliated at 10 cm. Nevertheless, in the late spring and in the summer, the 5 cm intensity resulted in higher rates, which promoted higher TDb. The SRb was higher in the summer for pastures managed at 10 cm. The pasture grazing management that promotes the highest TDab, ARab and SRab, during periods of fast pasture growth, is the combination of 10 cm grazing intensity and 95% LI of defoliation frequecy.


Herling V.R.,University of Sao Paulo | Pedreira C.G.S.,University of Sao Paulo | De C. Luz P.H.,University of Sao Paulo | Braga G.J.,Polo Regional Of Desenvolvimento Tecnologico Dos Agronegocios Do Centro Oeste | And 3 more authors.
Journal of Agricultural Science | Year: 2011

Herbage allowance (HA) impacts performance of grazing cattle as well as sward structure and herbage yield. The objective of the current study was to compare average daily gain (ADG) of Nellore steers on Marandu palisadegrass (Brachiaria brizantha (Hochst ex A. Rich.) Stapf. cv. Marandu) pastures in response to HA. Treatments were applied as 5, 10, 15 and 20 kg dry matter (DM) per 100 kg live weight (LW) per day HA5, HA10, HA 15 and HA20), in rotationally stocked pastures under a 35-day grazing cycle (28 days of rest and 7 days of grazing). The trial was carried out in Pirassununga, Brazil, during two summer seasons in 2003 and 2004, each divided into four grazing cycles. Individual animal (250 kg yearling steers) gain increased with HA up to HA15 (mean=0•69 kg/head per day) during each of four grazing cycles per year. The 2-year gain per area was greater for HA5 and HA10 than for HA15 and HA20 and average stocking rate was 9•6, 6•7, 5•4 and 4•6 head/ha for HA5 to HA20, respectively. In addition to the effects of HA on ADG, changes in sward structure, especially sward height, help to explain variation in daily gain in both years. The HA 10 treatment provides higher gain per area without excessively reducing individual animal performance, and thus may be the level of choice for optimizing animal output in pasture-only systems. © 2011 Cambridge University Press.

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