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Parasitic helminth infection in young cattle raised on silvopasture and open-pasture in Southeastern Brazil |
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| Authors: | R M A de Mendonca R C Leite A M Q Lana J O Costa G Toth |
| Institution: | 1. Department of Animal Production, Veterinary School, Universidade Federal de Minas Gerais, PO Box 567, Av Antonio Carlos 6627, Belo Horizonte, MG, 30123-970, Brazil 2. Department of Preventive Veterinary Medicine, Escola de Veterinária, Universidade Federal de Minas Gerais, PO Box 567, Av Antonio Carlos 6627, Belo Horizonte, MG, 30123-970, Brazil 3. School of Forest Resources & Conservation, University of Florida, Gainesville, FL, USA |
| Abstract: | More than 95 % of Brazil’s beef production occurs in pastures where parasitic helminths are a serious problem, potentially inhibiting an average annual weight gain of 8 kg per young animal. Current pharmaceutical treatments for parasitic infestation are expensive (estimated to cost Brazil 370 million U.S. dollars per year) and sometimes inefficient due to rapid adaptation of worms to new drugs. The presence of trees in pastures (silvopasture) has proven to be environmentally beneficial, but may favor multiplication of parasites and cause higher infestation rates compared to traditional pastures. This study in Southeastern Brazil compared the weight gains of crossbred Holstein and Gir (Zebu) bovines, 8–24 months of age, under two different grazing systems: open (tree-less) pasture, and silvopasture (primarily “Sucupiras Brancas” at 156 trees ha?1). Despite the favorable environment for helminths, silvopasture did not increase the worm egg count per gram of animal feces and did not create overall weight or weight gain patterns different from those of animals grazing on the open pasture. The experiment took place from August 2008 to February 2009, encapsulating the transition from the dry to rainy season; a period when worm infection rates are highest, causing the greatest impact in animal development. The significance of this period aside, the results must be taken as indicative due to the short time frame and the extraneous challenges of climate variation, individual immune system resistance development, and natural helminth predator growth conditions. |
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