Lameness is probably the disease that has most implications for sheep farmers, not alone in terms of animal welfare and the economic losses that the disease can incur but also in terms of the labour requirements for its control and prevention. It was identified by sheep producers as one of the principal problems in flock management requiring further investigation into prevention and treatment practices (Technology Evaluation and Transfer Project, Progress Report, March 2002). The bactericidal effects of hydrated lime (Calcium Hydroxide) have been known for many years e.g. whitewashing of farm buildings. In more recent years it is used frequently as a floor dressing to disinfect livestock buildings such as cattle cubicle sheds and in sheep and pig units. Hydrated lime is used in sheep sheds to prevent and reduce the spread of infectious diseases such as footrot in ewes and the spread of contagious scouring in lambs during the lambing season. Despite its widespread use there is little quantifiable evidence on the efficacy of hydrated lime for the control of these sheep diseases. The purpose of this study was to evaluate the use of hydrated lime for the control of lameness in housed ewes over the winter period. Five sheep farmers located in County Wicklow undertook to treat a proportion of the flock by spreading hydrated lime periodically along the area where the ewes generally stand to feed. It was envisaged that liming would be carried out just prior to bedding the pens. A total of 652 ewes were in pens treated with lime and 518 were in untreated pens. All the ewes were fed silage and bedded on straw. The number of lame sheep in treated and untreated pens were recorded at the start and at least once weekly during the study. The frequency of application and the quantity of lime to be applied at each application were at the discretion of the individual farmer and details of both were recorded by the farmer. Each farmer was also afforded an opportunity to record comments and experiences associated with using hydrated lime. The project commenced in January / February 2002 and on average extended over a 47 day period ranging from 41-61 days on the individual farms. Statistical analysis of the results was performed using procedures for categorical data. While the overall incidence of lameness at the start averaged 7.7% there was a wide variation among flocks, ranging from 2 to 15%. These incidence levels are similar to those recorded in the lameness investigation undertaken as part of the Technology Evaluation and Transfer (TET) project. The scale of the problem can be gauged from the fact that while there is no acceptable level of lameness, a high prevalence can be defined as where 5% or more of the flock is affected. The effects of applying hydrated lime on the incidences of lameness are shown in Figure 1. The incidence of lameness decreased over time for ewes in the limed pens and increased steadily for ewes in the unlimed pens. After 6 to 7 weeks the incidences of lameness was significantly (P<0.01) lower among ewes in the lime-treated pens (5.2%) than among ewes in the untreated pens (12.8%). The present study was confined to a 6-7 week period but many flocks in Ireland are inwintered for a 10-12 week period and in such situations the application of hydrated lime may have an even more pronounced effect. The frequency of lime application varied from every 2 to 7 days on the individual farms. The quantity of hydrated lime applied averaged 28.3kg per 100 ewes per week (varied among farms from 12.6 to 52.2kg). It is suggested that 25-30kg per 100 ewes per week would be a reasonable recommendation. The most notable comment made by farmers was that sheep tended to cough after applying the lime but this was transient and lasted for about 10 minutes. In the same regard, it is recommended that farmers use the necessary protective clothing (overalls, eye/face protection, gloves) and maximise ventilation within the shed when spreading hydrated lime. There was a 7.7% incidence of lameness in housed ewes during January/February. The incidence of lameness in housed ewes on straw bedding was reduced by 7.6 percentage points over a 6-7 week period where hydrated lime was spread at least once a week along the inside of the feed barrier pre-bedding. On the basis of these results hydrated lime is a cost effective and labour saving method of reducing lameness in housed ewes. However, it would still be necessary to continue with a routine footcare programme based on paring and footbathing to achieve overall control of lameness. Once the disease is at a low level, the application of lime will contain its spread. Acknowledgement: Sincere thanks to the participating farmers for their interest and record keeping; to JP Hanrahan, Teagasc Research Centre, Athenry for statistical analysis and comments and to Andrew Kinsella, Teagasc Specialist Advisory Service.