Crop-livestock integration system as a method of control of pasture contamination by gastrintestinal nematodes of sheep

The rest period necessary for the decontamination of pasture by gastrointestinal nematodes of sheep can be used with agricultural crops. The objective of this study was to determine if after the implantation of the crop-livestock integration system (ICL) with a period of 300 days without animals, the pasture would be free of contamination by infective larvae (L3) of gastrointestinal nematodes of sheep. The area was used for the production of a mixed silage—maize (Zea mays), marandu palisade grass (Urochloa brizantha cv. Marandu) and pigeon pea (Cajanus cajan), and overseeding of black oats (Avena strigosa), with the grazing of sheep. This area was divided into four treatment subplots: ICL 1 (maize + marandu palisade grass + pigeon pea + black oats, sown in rows); ICL 2 (maize + marandu palisade grass + pigeon pea + black oats, sown by broadcasting); ICL 3 (maize + marandu palisade grass + black oats, sown in rows); and ICL 4 (maize + marandu palisade grass + black oats, sown by broadcasting). In order to verify the decontamination of the pasture, were used twelve tracer lambs (3 / treatment), male not castrated, Dorper x Santa Inês crossbred with 60 days of age, 25 kg of weight and worm free by Trichostrongylideos and Strongyloides infections. The animals grazed the area for 14 days from 6 a.m. to 4 p.m., and after that period they stayed another 14 days in collective pens, being slaughtered for recovery and identification of the parasites present in the abomasum and small and large intestines. Analysis of eggs per gram of faeces (EPG) and composite faecal cultures were done on days 0, 7 and 14 post-grazing. No eggs (EPG = zero) were detected in any of the faeces collections, nor were any larvae found in the composite faecal cultures. After slaughter, no adult worms were found in the abomasum, small and large intestine contents. It is concluded that the period of 300 days without animal presence was sufficient to descontaminate the pasture by infective larvae of gastrointestinal nematodes of sheep. (AU)