A validation study of the FAMACHA ß system for clinical evaluation of anaemia due to Haemonchus contortus was conducted on two commercial sheep farms in the summer rainfall region of South Africa. In this region, the Haemonchus season lasts from October to April. On Farm 1 the system was tested over a period of five successive years in consecutive sets of young stud Merino replacement rams and ewes examined at intervals of 3-5 weeks over each Haemonchus season, under routine farming conditions. When FAMACHA ß scores of 3, 4, and 5 and haematocrit values of 22%, 19%, and 15% were separately considered to be anaemic, sensitivity on Farm 1 ranged from a maximum of 83% for a haematocrit cut-off of 15%, to 40% for a haematocrit cut-off of 22%. Sensitivity increased to 93% when FAMACHA ß scores of 2, 3, 4, and 5 were considered anaemic at a cut-off value of 19%, but the positive predictive value decreased to 0.43, indicating that many non-anaemic animals would be treated. The analysis indicated a high level of classification bias on Farm 1, with the animals consistently being classified one FAMACHA ß category lower (i.e. less anaemic) than reality. On Farm 2 the test was conducted over two successive years in yearling rams evaluated at weekly to fortnightly intervals during each worm season. Every ram judged to be in FAMACHA ß category 4 or 5 was bled for haematocrit determination, and it was only dewormed with effective anthelmintics if the haematocrit was 15% or lower. When FAMACHA ß scores of 3, 4, and 5 and haematocrit values of 22% and 19% were separately considered to be anaemic on Farm 2, sensitivity ranged from 64% for a haematocrit cut-off of 22%, to 80% for a cut-off of 19%.For identical haematocrit cut-off values and proportions of the sampled flock considered to be diseased as for Farm 1, sensitivity was always higher for Farm 2. On the other hand, further analysis of the data indicated that the magnitude of the error on Farm 1 was very consistent on average over the entire trial period.The results of this study indicate that (i) persons introduced to the system should not only be trained, but also be evaluated for accuracy of application; (ii) the sensitivity of the FAMACHA ß diagnostic system should ideally be evaluated at shorter intervals to avoid production losses due to failure to detect anaemic animals which may be at risk of death; (iii) that calibration of the FAMACHA ß scoring is essential per individual evaluator, and (iv) that animals should be examined at weekly intervals during periods of the highest worm challenge. Please cite this article in press as: Reynecke, D.P., et al., Validation of the FAMACHA ß eye colour chart using sensitivity/ specificity analysis on two South African sheep farms.

This article is the first of a series aimed at developing specific decision-support software for on-farm optimisation of sustainable integrated management of haemonchosis.It contains a concept framework for such a system for use by farmers and/or their advisors but, as reported in the series, only the first steps have been taken on the road to achieving this goal.Anthelmintic resistance has reached such levels of prevalence and intensity that recently it evoked the comment that for small ruminants the final phase of resistance was being entered, without effective chemotherapeutic agents on some farms with which to control worms at a level commensurate with profitable animal production. In addition, in the case of cattle, a recent survey in New Zealand showed 92% of worm populations to be resistant to at least one anthelmintic group.Ironically, new technology, such as the FAMACHA © system which was devised for sustainable management of haemonchosis, is at present being adopted relatively slowly by the majority of farmers and it is suggested that an important reason for this is the It is emphasised that, in order not to repeat the mistakes of the past, such an automated support system should ideally be developed urgently in a attempt to engineer greater sustainability of any unrelated new anthelmintics which may reach the market.