Lameness, due to injury or disease in the foot or leg, is considered to be one of the most important welfare problems facing dairy cattle today. Lame dairy cows may experience pain and discomfort; disturbed resting, feeding and social patterns; reduced fertility; lowered milk yields; and an increased likelihood of being culled.

The majority of lameness cases are due to disease in the hoof, with the hind hooves being most commonly affected. On any given day lameness affects around a quarter of milking cows in the UK. Given that the UK has getting on for 2 million cows, close on half a million cows may be suffering from lameness at any one time. It is generally accepted that over the course of a year more than half the herd will experience lameness. It has also been observed that virtually all cows' hooves show either past or present damage on inspection of cull dairy cows at slaughter.

The average dairy herd loses about 1p per litre annually from lameness due to lower milk yields, treatments and higher culling costs. That doesn't sound much, but it adds up to a hefty £15,000 a year or so for a typical herd of 200 cows. or around £250m a year for the UK industry.

Lameness and limb injuries do not always result in an obviously sick cow and the effect on production can be subtle, often going undetected. Additionally, a number of studies have shown that farmers may significantly underrate lameness and delay treating lame animals - so early detection is key.

Every cow has its own normal walking pattern. When it becomes lame, there are subtle changes in the way it walks. It could put the sore foot down more slowly or put less weight on that foot, or pick that foot up more quickly than usual. A system which could automatically detect early signs of lameness from changes in an individual cow's normal gait pattern and alert the herdsman would be a huge benefit to dairy farmers.

To that end, research was carried out using force plates - plates containing sensors which measure a range of forces when an animal walks across them- to analyse their gait. Over a two-year period data was collected automatically from a series of force plates at the exit from a milking parlour that provided data on over 500,000 individual foot strikes from which a wealth of information could be extracted.

Other researchers have tried to develop a detection system using 3-dimensional (3D) depth video data to analyse the animal's gait from the height variations in the hip joint during walking. The cows are recorded using an overhead 3D depth camera as they walk freely in single file after the milking session.

Despite a lot of effort, the quest for an affordable, automated detection system remains work in progress.

Prevention is undoubtedly the best approach to lameness. That involves ensuring that all farm roads and tracks that cows walk on as they make their way to and from their twice-a-day milking are well maintained. Sharp stones and uneven surfaces hidden by mud take their toll on cows' feet. Concrete floors in the cowsheds and yards should also be well-maintained and regularly scraped clean. Clean and dry conditions underfoot is a major protective factor for hooves, reducing the amount of lameness due to foul-in-the-foot, inter-digital growths and digital dermatitis. Taking steps to improve foot hygiene and introducing foot disinfection by foot bathing can be an extremely effective and rapid way of improving foot health.

Progress has been made in reducing lameness by training farmers how to regularly examine, trim and pair cows' hooves. That involves putting the cows in a special catching crate, or "crush" as we call it, located at the end of a narrow passage or "race". There they are securely held by the neck so that their feet can be safely examined and pared.

Now SRUC, Scotland's Rural College, is to lead a new £1 million scientific research project, funded by the Biotechnology and Biological Research Council, to generate a deep understanding of the reasons dairy cows become lame. The three-year, multi-institutional project is being run in collaboration with the University of Liverpool, and the Royal Veterinary College, University of London.

Professor Georgios Banos of SRUC, who is heading up the project, said: "Among cows raised in the same environment, some become lame while others do not. Understanding the reasons behind this will help us develop targeted preventative practices contributing to enhanced animal welfare and farm profitability."