The “BIG FIVE” – A South African perspective on sustainable holistic internal parasite management in sheep and goats

Abstract

Because we became an unintended world leader in the development of multiple anthelmintic resistance, South Africa has had to find, embrace and implement more sustainable and holistic methods of managing helminths in sheep. The problem has been to wean farmers off a heavy reliance on anthelmintics and to use a wide array of measures that require more management, in the face of inertia and attempts by some unscrupulous drug purveyors to block the needed changes. Packaging the available and proven measures into five practical sections helps to make the change more palatable and attractive to farmers. These sections are termed “The Big Five” and consist of firstly, host resistance and resilience: in the past we have concentrated too much on anthelmintic resistance (AR) and not enough on SR (sheep resistance). The motto must be “Stop Selecting Sissy Sheep!” To achieve this we can apply selection of rams by faecal egg counts (FEC) or FAMACHA, culling of ewes based on targeted selective treatment (TST) results, good nutrition, especially protein and trace elements needed to support immunity, enough exposure to worms for immunity to develop, and control of other diseases. Secondly, reducing parasite load: since the outcome of parasitosis is largely determined by numbers, this needs ongoing attention. This can be achieved by reducing the length of stay in a pasture, reducing the grazing pressure if this is not possible, increasing the time of absence from a pasture, especially at danger times, alternation with non-susceptible grazing species where possible, avoiding worm “hot spots” like grassed pens and leaking water troughs. Thirdly, evaluate pasture factors: the farmer and advisor have to consider the height (length) of grazing as it affects its risk for parasite transfer, the type (pasture species) as it will influence risk, the pasture slope affecting run-off and thus the suitability for larval survival, and the aspect (direction facing) should also be used to assess risk. Fourth, monitoring the situation: farm situations can be assessed by regular (monthly or bimonthly) pooled flock FECs, AR assessments using FEC reduction tests (FECRTs) or other measures, measures using TST like the 5 POINT CHECK, a weather watch to predict conditions favourable for larval development (rain, humidity, temperature) and grazing monitoring to assess developing dangers. Fifth, optimise drugs to be used: drug usage must be rationalised and minimised. Implement TST and TT (targeted treatment); read the label, follow instructions and check the spectrum covered; weigh the sheep, set dose according to the heaviest in the group and check the gun for accuracy and repeatability; target the most vulnerable (lambs and lactating or heavily pregnant ewes) for special attention; do not buy on cost alone and do not formulate (mix) own farm mixtures. By emphasising the “Big Five” we can encourage and enable farmers to implement four or more items in each section, and thus minimise the long-term effects of internal parasites on farm profitability. This approach has assisted with getting farmers to use sustainable, holistic internal parasite management (SHIPM) in sheep flocks. A reminder in the form of a poster to be hung on the wall of the farm office will help encourage continuous implementation.