Parasitic management of the cord of destete in a natural field

I Alternate grazing with cattle in a surface basalt area

Abstract

A total of 450 Australian Merino lambs with a mean age of 4 months were exposed from december through june to two management strategies. The conventional weaning-dosification strategy on infected pastures with gastrointestinal nematodes was studied together with the strategy of weaning-dosification on pastures with low levels of contamination obtained through alternate previous grazing with bovines older than two years. Two wide spectrum anthelmintics (ABZ and IVM) and one of reduced spectrum with residual strength (CLT) were used in both groups of lambs. Weight increase and evolution parameters were measured every 28 days and the elimination of eggs from feaces every 14 days. It was also established on 8 monthly basis for each group the relative parasitary composition of gastrointestinal nematodes. The use of safe pastures, obtained by alternate grazing, was successful in the obtention of low infestation rates up to at least three months post-weaning of lambs. In comparison with the traditional strategy, it was possible to maximize the effect of the wide spectrum drug, without great influence on the relative composition of the parasitary population of the sheepfold. The flexibility shown by alternate grazing with bovines, allowed the production of safe grazings in a farm whera a relation ovine/bovine of 7.5/1 is normally used.