Heterogeneity in a communal cattle-farming system in a zone endemic for foot and mouth disease in South Africa

Abstract

In South Africa, communal livestock farming is predominant in the foot and mouth disease control zone adjacent to the Greater Kruger National Park (KNP), where infected African buffaloes are common.During routine veterinary inspections of cattle in this area, a large amount of production and demographic parameters were being recorded. These data were collated for a five-year period (2003)(2004)(2005)(2006)(2007) in three study sites to better understand the temporal dynamics and spatial heterogeneity in this system. A decreasing gradient from South to North with respect to both human and cattle population densities was observed. Rainfall and human population density alone could explain 71% of the variation in cattle density. Northern and central sites showed an overall decrease in total cattle numbers (15.1 and 2.9%, respectively), whereas a 28.6% increase was recorded in the South. The number of cattle owners in relation to cattle numbers remained stable during the study period. Only 4.0% of households in the South own cattle, compared to 13.7 and 12.7% in the North and Centre. The overall annual calving rate was 23.8%. Annual mortality rates ranged from 2.4 to 3.2%. Low calf mortality (2.1%) was recorded in the North compared to the South (11.6%). Annual off-take in the form of slaughter averaged 0.2, 11.7, and 11.0% in the North, Central and South sites, respectively. These figures provide valuable baseline data and demonstrate considerable spatial heterogeneity in cattle demography and production at this wildlife-livestock interface, which should be taken into consideration when performing disease risk assessments or designing disease control systems. IntroductionA large area next to the Kruger National Park (KNP) and its adjoining private and provincial nature reserves (APNR) in South Africa, is used for communal farming of both livestock and crops. Although the World Animal Health Organisation (OIE) considers South Africa to be free from the foot and mouth disease (FMD) in areas where vaccination is practised, the KNP and APNR are endemic for FMD (Brückner et al., 2002;Vosloo et al., 2002;Scoones et al., 2010), and this is due to the presence of the reservoir host of the disease, the African buffalo (Syncerus caffer) (Vosloo et al., 2006). To this end, a fence was erected around the KNP in the 1960s (Joubert, 2007;Scoones et al., 2010), and compulsory, weekly cattle inspections and bi-to tri-annual vaccination against FMD takes place at government livestock inspection points (IPs) within the area directly adjacent to the infected zone (the so-called protection zone with vaccination). Livestock in the remainder of the protection zone (protection zone without vaccinaCorrespondence: Ockert Louis van Schalkwyk, Office of the State