Integrated and biological control of parasites in organic and conventionalproduction systems

Organic and other non-intensive animal production systems are of growing im portance in several countries worldwide. In contrast to conventional farms, parasite control on organic farms is affected by several of the prescribed changes in management e.g. access to the outdoors in the summer and in mos t countries, a ban on preventive medication, including use of anti-parasiti cides. Organic animal production relies heavily on grazing, and pasture or soil related parasites are thus of major importance. Several studies in nor thern temperate climate have indicated that outdoor production of pigs, pri marily sows, and laying hens results in heavier and more prevalent helminth infections compared to conventional intensive production under indoor cond itions. In organic dairy cattle, parasitic gastroenteritis in heifers may b e more prevalent. In a short to medium term perspective, integrated control may combine grazing management with biological control using nematophagous micro-fungi, selected crops like tanniferous plants and on conventional fa rms, limited use of anti-parasiticides. At present, the non-chemotherapeuti c control of pasture related infections is based mainly on grazing manageme nt strategies. Preventive strategies, where young, previously unexposed sto ck, are turned out on parasite-free pastures, can be used for grazing first season dairy heifers and in all-in-all-out poultry production. Evasive str ategies aim at avoiding disease producing infections of a contaminated area by moving to a clean area and may be relevant for ruminants and pigs. In c attle, effective control of nematodes can be achieved by repeated moves of the herd or alternate grazing with other species. High stocking rates seem to be an important risk factor. In pig production, the effect of paddock ro tation on parasite infections is largely unknown and studies are warranted. Control of nematodes by larvae-trapping fungi, or perhaps in the future by egg-destroying fungi, looks promising for ruminants and certain monogastri c animals but delivery systems and practical dosing regimes integrated with grazing management have to be developed. In conclusion, good prospects are expected for acceptable parasite control without a heavy reliance on anti- parasiticides through integration of the above mentioned procedures but fut ure studies are needed to confirm their efficacy under practical fanning co nditions. (C) 1999 Elsevier Science B.V. All rights reserved.