DISTRIBUI O DE LARVAS DE NEMATóDEOS GASTRINTESTINAIS DE OVINOS EM PASTAGENS DE INVERNO

The aim of this work was to study the dynamics of nematode larvae of sheep on winter pasture species. A completely randomized design was used. The treatments were composed by two different dry matter offers of each forage species (black oat 5% and 12%; ryegrass 10% and 20%). A total of 28 Suffolk female lambs were used. Pasture was taken every fifteen days and samples were separated into superior and inferior fractions and sent for counting and identification of parasite larvae. Lambs were evaluated each fifteen days for parasitological evaluations. Ryegrass (104.53 L/g MS) presented higher (p<0.05) contamination by helminth larvae per dry matter gram (L/g MS) than black oat forage (24.6 L/g MS). A linear increase in the amount of helminth larvae per gram of dry matter in the superior part of the plant was observed in black oat with lower dry matter content. The animals maintained in different dry matter offers of ryegrass and black oat did not present difference (p>0.05) in the worm burden. Otherwise a trend of linear increase in the number of fecal egg count was observed in the treatment with black oat with lower dry matter content. Sheep rearing in high stocking rates leads to parasitic infection of animals and environment contamination by pathogenic helminth larvae.