Next to reproductive failure and mastitis, lameness is the major reason for culling cows. And a significant proportion of poor fertility also is caused by lameness. This is true in both North America and Europe. Lameness costs are significant. In the US, the economic cost of a lame cow caused by a sole ulcer is estimated to be around $600. Direct costs include the hoof trimmer and the veterinarian; indirect costs include reduced milk production, culling/replacement costs, reduced fertility and time required to manage lame cows. Lameness is also the dairy industry’s most visible welfare issue.
The role of genetics
Although feeding and management have the most important short-term impact on hoof health, the role of genetics, although a longer-term influence, cannot be overlooked. Sweden has promoted breeding for healthy cows, maintaining high production for several decades. In 2006, a breeding value for claw health based on data recorded by hoof trimmers started to be included in the health profile. Because lameness has a positive genetic correlation with milk and protein yield, breeding for increased milk and protein yield affect claw health negatively, unless resistance is included in the selection criteria.
Research at the Swedish Agricultural University has shown that the genetic relationship between feet and leg type traits and claw disorders does not correlate for most traits in Swedish Holstein or Swedish Red cattle. Thus, indirect selection for better claw health using type trait data was not found possible. This conclusion is supported by studies in Germany and the Netherlands. The following traits were included in the Swedish research: rear leg side view, rear leg rear view, hock quality, bone structure and foot angle.
Since the heritability of the combined type traits from feet and legs is relatively low, locomotion score was suggested as an alternative indicator for developing claw disorders at a later stage in life. However, locomotion score is subject to significant error.
Recent research from the Swedish breeding association, Viking Genetics, on 108 Swedish bulls born in 1999-2001 also found that there was no genetic correlation between the overall breeding values for ‘feet and legs’ type traits and longevity.
A large number of Swedish hoof trimmers record the claw disorders of every cow in the herd at maintenance claw trimming; almost 20,000 cows are scored monthly. This data is used to compute an estimated breeding value for claw health and is reported 6 months after the first total merit index. Only the 4 most common claw disorders in Sweden are included in the breeding value: (inter)digital dermatitis, heel horn erosion, sole hemorrhage and sole ulcer. Sole ulcer counts for 50% of the breeding value, because of its high economic and welfare value.
The systems works in a direct way: a bull will get a lower breeding value for claw health if his daughters have more claw disorders. There is a large variation in claw health between the bulls, which means that the claw health trait can improve through selection. Although the heritability for claw disorders is rather low in comparison with milk production, it is higher than for other diseases such as mastitis. The heritability is sufficient to justify breeding for better claw health. Research by Viking Genetics shows that there is a clear correlation between the claw health breeding value and longevity. Thus, breeding for better claw health increases cow longevity.
Recording claw lesion data takes extra time and engagement. But, when done by the hoof trimmers, it only takes around 15 seconds per cow. The advantages of keeping records of claw disorders are obvious. After every claw trimming, the farmer has a great deal of additional information that can be used for management decisions. For example, many claw problems are related to inadequate fibre in the diet. Improving this could reduce the incidence of sole hemorrhage at the next claw trimming. Summarized national data is also posted on the internet so the farmer can see if lameness and claw disorders fluctuate across seasons and year and individual farm statistics can be compared with national figures.
source: Hoof Health Connection, the newsletter of the (North American) Hoof Trimmers Association, Inc., March 2009