CONTROLLING INTERNAL PARASITES IN GRAZING RUMINANTS WITHOUT RECOURSE TO ANTHELMINTICS - APPROACHES, EXPERIENCES AND PROSPECTS

Interest in ways of raising stock without using anthelmintics has been stimulated by the desire for intensive grazing systems to adopt more sustainable methods of internal parasite control and by potential prem iums for ''organic'' produce. This requires grazing management systems which are practicable and achieve levels of parasite control sufficie nt to meet realistic production objectives. This paper will summarise 3 years experience of lamb and cattle production without a recourse to anthelmintics on 2 production systems: a mixed cropping, lamb finishi ng, and cattle rearing unit and an all grass, mixed-stock, hill countr y unit in which all non-replacement lambs are sold at weaning. On both units parasite control was almost entirely dependent on integrated gr azing management of sheep and cattle and strict systems of grazing man agement had to be rigidly applied. Acceptable productivity could be mo re readily achieved in sheep than cattle. Rams selected for resistance to nematodes were also used in both sheep flocks. Their influence on lamb production was equivocal. There is a need for more information on factors influencing parasite epidemiology and for consideration of st rategies other than alternate grazing. The impact of pasture species o n parasite epidemiology needs to be clarified. Current research indica tes substantial differences between grasses in terms of parasite burde ns acquired and production losses suffered by lambs grazing them. Graz ing management may need to vary with pasture species. Also, specialty forage crops, particularly those containing condensed tannins (i.e. He dysarum coronarium, Lotus pedunculatus and Lotus corniculatus) hold sp ecial promise as a means of countering parasite-induced production los ses and dagginess. Using biological control of free-living larval stag es and vaccination, may in the long term, also prove useful. Developin g effective and acceptable systems for raising stock without using ant helmintics presents a considerable challenge, to parasitologists, as w ell as to plant breeders, agronomists, and farming systems researchers . Copyright (C) 1996 Australian Society for Parasitology. Published by Elsevier Science Ltd.