The impact of Stomoxys calcitrans populations on cattle in a feedlot near Heidelberg, Gauteng, South Africa

Abstract

The stable fly (Diptera: Muscidae), Stomoxys calcitrans, is a widespread economically important pest of livestock at confined production facilities such as dairies and feedlots. Stable flies are haematophagous insects that frequently feed on the forelegs of cattle. Stable flies can cause significant production losses and are of severe animal health and welfare concerns. The present study evaluated the impact of stable fly populations on cattle. In order to achieve this aim, the following were investigated: (1) the temporal and spatial distribution of stable flies; (2) stable fly density on cattle in sprayed and unsprayed pens as sampled with traps and counted on cattle forelegs; (3) impact of stable flies on the feed intake of cattle; (4) impact of stable flies on the weight gain performance of cattle. Knowledge gathered during this study was used as recommendations for an integrated fly management programme. The seasonal abundance of stable flies was monitored from 24 October 2013 to 3 December 2014 with Nzi tsetse type traps. The diurnal and seasonal distribution of stable flies was investigated. Stable fly populations in vegetation have been observed to follow peak feeding periods on cattle. A fairly good correlation between stable flies collected from traps and the number of stable flies counted on cattle forelegs, confirmed the use of trap collection rates in accurately predicting the degree of stable fly feeding and irritation on cattle. Feed intake were related to the various levels of stable fly pressures and feed management practices. Statistically significant differences observed, were identified as having a little practical impact on meat production, specifically for the Karan Beef environment. This indicates little need of routine chemical control. Continuous monitoring of stable fly populations remains necessary to identify abnormal seasonal increases in fly populations. The results of this study have important implications for the development of an integrated fly management program.