Barth Neto A.,Federal University of Paraná |
Barth Neto A.,Federal University of Rio Grande do Sul |
Savian J.V.,Federal University of Rio Grande do Sul |
Schons R.M.T.,Federal University of Rio Grande do Sul |
And 5 more authors.
European Journal of Agronomy | Year: 2014
We evaluated the re-establishment of an Italian ryegrass pasture by self-seeding on a no-till integrated crop-livestock systems (ICLS) in the southern region of Brazil. This work is part of a long-term experimental protocol initiated in 2003. We tested the effects of various management practices, such as summer crop systems (soybean vs. maize-soybean rotation), stocking methods (continuous vs. rotational) and grazing intensities (low vs. moderate), on Italian ryegrass pasture establishment. In addition, we tested resilience of the system by testing pasture's ability to re-establish following a year without seed head production. The experiment consisted in the rotation, on the same area, of Italian ryegrass pasture grazed by sheep during the winter and up to the end of the grass production cycle, and soybean or soybean-maize grain crops rotation cultivated during the summer. The pasture established itself by self-seeding since 2005. Data were collected in 2011 and 2012 stocking season. The soybean summer crop, continuous stocking and low grazing intensity, all positively affected the production of reproductive tillers in 2011. Grazing intensity in 2011 strongly influenced early vegetative tiller densities (before crop harvest) in 2012. However, none of the grazing intensity or the stocking method treatments affected herbage mass at the end of pasture establishment in 2011 or 2012. On the other hand, the soybean summer crop positively affected pasture establishment, both in term of tiller densities and herbage mass at the end of pasture establishment. The removal of all seed heads in 2011 (preventing seed production) resulted in the total failure of pasture establishment in 2012. Overall, Italian ryegrass establishment by self-seeding relies on the annual replacement of the soil seed bank. This experiment demonstrated that under various stocking methods, moderate grazing intensity and maize or soybean summer crop, Italian ryegrass pasture establishment by self-seeding remains successful even when the stocking periods extended up to the end of the grass production cycle. Self-seeding with moderate grazing intensity ensures successful pasture establishment, reduces labour and costs and allows to increase the stocking period and so animal live weight gain over the grazing season. © 2013 Elsevier B.V.
University of Kansas Medical Center and National Institute For Agriculture Research | Date: 2011-07-18
The present invention is directed to a DNA vaccine for immunization against HIV. The invention comprises a DNA molecule that has a sequence encoding a plurality of viral proteins capable of stimulating an immune response against HIV. The DNA molecule is rendered safe for use as a vaccine by the disruption of genes encoding reverse transcriptase, integrase, and Vif. The DNA molecule is further rendered safe by at least a partial deletion of the 3 LTR.