Farm Table says:
Evaluation of risk factors and management options
What is the problem?
Foot abscess in sheep occurs only sporadically when wet environmental conditions prevent hooves from drying out for extended periods. Because of this irregular expression FA was considered as only a disease of medium economic importance in the most recent analysis of nationally important endemic sheep diseases.
However in the high altitude, high rainfall Tablelands region of NSW, FA has been shown, particularly during 2010, to cause ewe and lamb deaths and serious financial loss, particularly in heavy crossbred meat sheep.
What did the research involve?
Consequently, in 2011 MLA conducted a two part study designed to
- determine whether supplementing pre-lambing ewes with iodine would reduce the prevalence of foot abscess
- identify environmental and management risk factors associated with foot abscess expression amongst local producers
Given the sporadic nature of FA they proposed to conduct a simplified low cost opportunistic trial that could be applied at short notice should the environmental conditions arise for FA expression.
The risk factor investigation comprised a cross-sectional, observational study of 115 producers in the Tablelands region of NSW by telephonic interview
What were the key findings?
Because of the sudden onset of dry conditions during winter and early spring of 2011, and the consequent reduction in the prevalence of FA, they were unable to adequately test the value of supplementing pregnant ewes with iodine for reducing the impact of FA.
In the risk factor study, detrimental risk factors identified were moving sheep during lambing, having more than four months of wool growth at lambing, having any level of boggy areas within the paddock, a wet season, and having greater than 30% clover in the paddock.
A favourable risk factor was having shale/slate soils.
In terms of changed management producers should be prepared for an increased risk of FA when wet seasons are predicted, and where practical consider lambing in the autumn, not moving sheep during lambing, moving shearing to within four months before lambing, running pregnant ewes in a paddocks with no higher than 30% clover, or containing boggy areas.
At best producers should be prepared for an increased risk of foot abscess when wet seasons are predicted. By being more vigilant in these periods and making sure that the precursor condition, interdigital dermatitis (OID), is absent or controlled, they may be able to reduce losses.