Abstract
The occurrence and intensity of helminth infections were evaluated in sheep from pastures shared with cattle. In 2015 and 2016, young male sheep acquired in Santana do Livramento, Rio Grande do Sul, Brazil, were finished in integrated crop-livestock system. We selected the 12 sheep that showed the highest number of nematode eggs per gram of faeces to search for worms in the gastrointestinal tract. Haemonchus contortus and Trichostrongylus colubriformis were the major parasites. H. contortus presented mean intensities of 1,159 and 257 worms in 2015 and 2016, respectively. T. colubriformis displayed mean intensities of 4,149 and 2,427 worms in 2015 and 2016, respectively. Of the 127 male specimens of Haemonchus spp. analysed by Polymerase Chain Reaction (PCR), 125 were H. contortus, one Haemonchus placei and one hybrid. Other species detected were Cooperia punctata , Cooperia pectinata, Cooperia spatulata, Cooperia curticei, Ostertagia ostertagi, Teladorsagia circumcincta , Trichostrongylus axei, Nematodirus spathiger , and Trichuris ovis. Twenty lambs presented cysts of Taenia hydatigena in the liver and mesentery. One lamb presented Coenurus cerebralis, the larval stage of Taenia multiceps, in the brain. In conclusion, sheep from pasture shared with cattle presented a high diversity of nematode species. H. contortus and H. placei co-infection occur with consequent hybridization.
Highlights
Rio Grande do Sul State (RS) has the largest sheep population in Brazil, with an estimated 3,957,275 head (IBGE, 2015)
In 2015 and 2016, young male sheep acquired in Santana do Livramento, Rio Grande do Sul, Brazil, were finished in integrated crop-livestock system
In 2015 and 2016, young sheep were purchased in Santana do Livramento, which is located in the southern half of RS State, to be finished in an integrated crop-livestock system (ICL) in Botucatu, São Paulo State, Brazil, where they rotationally grazed paddocks for a total of 72 days
Summary
Rio Grande do Sul State (RS) has the largest sheep population in Brazil, with an estimated 3,957,275 head (IBGE, 2015). In this State, most sheep are raised by continuous grazing on grassland vegetation (native pasture) that is usually shared with cattle in the biome of the Pampa, located in the southern half of RS. Grass-dominated vegetation types prevail, with many herb, shrub, and tree let species co-occurring within the grass matrix (OVERBECK et al, 2007). In this environment, sheep production faces gastrointestinal nematode (GIN) infections, which are a significant cause of productivity losses and mortality. This problem has become worse due to the widespread emergence of nematode populations with resistance to anthelmintics (ECHEVARRIA et al, 1996)
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