Selecting for sound feet - a neglected aspect of sheep breeding (Agnes Winter)
Agnes Winter, MRVCS Specialist in Sheep Health & Production
Foot care and treatment of lame sheep take up a huge amount of time in many flocks, but foot soundness and health is often a neglected aspect in selection of breeding stock. Yet most sheep keepers will be aware that, among their flock, there will be some sheep who never need foot paring and are never lame, and others whose feet are constantly overgrown or have repeated lameness episodes. But unless you have a very small flock and a very good memory you may not be able to accurately identify all these animals unless you have a good recording system in place. Remember too that the general health and nutritional status of an animal will be reflected in the quality of the horn of the feet - slight horizontal grooving of the hoof walls is often present reflecting changes in nutrition throughout the year. Severe under nutrition reduces the strength and quality of the horn in all claws and is reflected by noticeable horizontal grooves in the wall of all the hooves. Similarly, illness such as acute mastitis or a bad lambing will lead to deep grooves developing which may crack as the affected part of the wall moves downwards as horn growth continues.
So what should a healthy hoof look like? Horn grows at the rate of about 1mm per week (although this is very variable) and the rate of wear should be similar so that the claw remains the same size. Both claws should be of roughly equal size and shape, although the inner claw is often slightly larger than the outer. The wall should be smooth with no deep horizontal grooves or vertical cracks. The sole should be smooth and slightly concave with the wall slightly higher. Problems frequently encountered include long narrow curving outer claws, rotation of the claw causing the wall to grow excessively and curve under the sole, poor quality flaking sole horn, separation of part of the wall along the white line (the junction of the wall and sole), separation of the sole from the deeper sensitive structures (usually indicating footrot) and vertical cracks in the hoof wall which may reflect damage at the coronary band or a previous abscess under the wall.
Making sure breeding ewes and, particularly rams, have healthy feet without the defects described above is a good start to developing flocks which should require less time to be devoted to foot care in them and their offspring.
More on footcare, including an interview with Agnes, in our DVD 'Managing Your Flock for Peak Health', programme 2 in the series ' Sheep on Your Smallholding'.