A CASE-CONTROL STUDY OF BLOWFLY STRIKE IN LAMBS

A case control study of the risk factors associated with blowfly strik e was conducted on 11 farms in the south west of England. For each cas e, three control lambs were randomly selected from the remainder of th e flock. Samples of blood, faeces and wool were taken from thee cases and controls, and measurements of weight, dag score (faecal soiling), fleece length, crimp frequency and tail length were made. Conditional logistic regression was used to examine the univariate and multivariat e relationships between the independent variables and the rate of blow fly strike. Case lambs had significantly higher dag scores and lower c rimp frequencies than their matched controls, although the association with crimp frequency was confounded by dag score. The relationship be tween blowfly strike and fleece length was also strongly confounded by dag scare. After stratifying by dag score, case lambs had shorter fle eces than their controls. Lambs with blowfly strike had significantly higher levels of blood copper and significantly lower levels of blood urea.