VN May 2023

Vetnuus | May 2023 14 grazers and browsers, based on movement from nutritionally exhausted to fresh, rested pastures. Overstocking played a role, but the consensus of evidence available from research conducted by pasture scientists is that the most important determinant of veld condition and change is how the grazing of the veld is managed. Veld management requires the separation of veld into camps. This requires effective fencing, which is expensive, especially in arid areas with large camps, and only began when predator control, stock theft, and disease management made fencing essential. That, in turn, necessitates separate water supplies and other facilities, so the central question became the number of camps needed. The most successful management systems apply short-duration, high-intensity grazing followed by an effective growing season rest period. Multispecies grazing and veld burning may be used, and farmers must be ready to change stocking rates. These principles result in veld improvement, higher carrying capacities and higher profitability. Predation has been a problem facing livestock owners from the earliest times. Originally the solutions used were to kraal (corral) livestock overnight and keep them under the close protection of herders during the day. Firearms led to the progressive elimination of large predators from most livestock farming areas, but this transferred the problem to smaller carnivores, particularly the black-backed Jackal and the Caracal. These proved much more wily, adaptive, and resilient and survived decades of predator control. Some farmers have now adopted non-lethal predator management measures that preserve the balance of ecology. Currently, besides legislation and stock theft police units, farmers are encouraged to report all cases, permanently identify their animals as required by law, take extra precautions, and invest in stock movement sensors to detect untoward activity that may indicate theft. Drones are also being used for this purpose. In some circumstances, farmers have been forced to return to nightly kraaling and daily shepherds. The marketing of wool can be problematic, especially when embargoes are imposed on wool imports due to disease outbreaks, even when the wool poses no disease threat to the importing country. Another potential trading obstacle is the perception amongst consumers of unsatisfactory sheep welfare practices. This is counteracted by strict guidelines set out by Cape Wools in their Sustainable Cape Wool Standard and by mandatory Mules-free Certification. Sheep diseases in South Africa include those encountered elsewhere in the world, as well as important diseases and problems that are largely or totally confined to Africa, including an array of toxic plants. In most cases, these plants become a problem due to faulty grazing management practices. Good veld management is the key to limiting losses from toxic plants. Apart from the globally widespread problem of sheep scab, several tick species cause health problems, including direct damage, disease transmission and toxicity. These are best controlled by holistic, integrated programmes and not exclusive reliance on ectoparasiticides. Blowfly strikes constitute a major challenge. However, breeding for plain-bodied animals (with very little skin pleating) that are not susceptible to strike has allowed South Africa to discontinue and prohibit the controversial Mules Operation. Haemonchus contortus is by far the most dangerous internal parasite, and misuse of anthelmintics has resulted in severe and widespread drug resistance. The situation has been counter- balanced by implementing integrated management that includes pasture management, breeding resistant and resilient sheep, monitoring worm infection, and targeted selective treatment. Three unique, infectious diseases are encountered: the most important is Blue Tongue which can cause severe losses. The availability of a trivalent vaccine containing the most virulent and important strains renders Blue Tongue a minor problem, provided the vaccine is used correctly. Rift Valley Fever only becomes a widespread and severe problem duringyears of higher rainfall suited to theproliferationof thevector, mosquitoes. Since these years are irregular and unpredictable, farmers often fail to vaccinate. The vaccine is very effective if used correctly. Heartwater affects cattle and goats as well as sheep. This complicates control measures that may include the control of the vector tick as well as vaccination. A promising new vaccine is under development, while the existing ‘vaccine’ has many limitations. Very few sheep farms are based on intensive artificial pastures and whole mixed rations. In contrast, most wool sheep are either part of mixed farming that may include crops and cattle or are based almost exclusively on natural pastures. Since over 65% of South Africa is regarded as arid or semi-arid and 85% unsuited to arable farming, these areas are best suited to utilisation by ruminants. Wool exports were a turning point in South Africa’s economic history, influencing trade growth and harbours and railways development. Wool sheep farming based on the Spanish Merino continues to form a cornerstone of the livestock industry in South African agriculture. v Continuous systematic assessment of veld condition is needed Theft is another long-standing intractable problem of livestock farming. Wool farming in South Africa created stable incomes and started a commercial farming economy. Article