Many times, herd owners and herd managers are so accustomed to seeing cows with abnormal gaits that they do not fully appreciate the level of lameness that really exists in their herds.
In either situation, the impact of lameness on a dairy's bottom line can be very significant! Despite the fact that the cost of treating lame cows may at times appear to be the biggest economic cost of lameness, it is often quite negligible in the overall scheme of things. Lameness is associated with a decrease in milk production and impaired reproductive performance, and can increase the probability of a cow being culled. Estimates are that a case of lameness is associated with $300- $400 in costs and lost revenue. The loss of milk production associated with 'subclinical' lameness has also been documented (see "Locomotion scoring" below). Lameness is also an animal welfare issue that must be addressed by the industry.
In order to recognize and deal effectively with any problem within a herd, it must first be clearly defined. Well-developed systems exist for measuring and recording udder health and reproductive status of dairy cows. Useful tools for monitoring these quality and performance indicators on a regular basis have been developed and implemented by producers and veterinarians. Until recently however there has not been a systematic method to measure and record lameness events and foot health status on dairy farms. Fortunately, there are now some tools available which can help veterinarians and producers define, record, and monitor these important parameters.
Locomotion scoring (LS) is one method to routinely monitor the overall lameness condition of a herd. The 1 to 5 point system, which has been quite well described (for example, Zinpro's Dairy Cattle Locomotion Scoring), is akin to monthly DHI somatic cell counts used to monitor udder health. If the whole herd, or specific groups (pens) of cows, are scored at 30 or 60 day intervals, the veterinarian and herd owner will be able to keep abreast of the overall health of the animals' feet and legs. The scoring could be done by the veterinarian, a veterinary technician, or an employee at the farm.
Following a few simple guidelines will ensure consistent, comparable results. The cows should be evaluated on a level surface that provides at least a reasonable amount of traction. They should not be rushed or placed under duress while being scored since this will affect their gait. Animals that are scored on pasture will, overall, have slightly lower scores than if they are scored on a concrete floor. For this reason it is highly desirable to LS the cows under the same conditions every time. Ideally, the same one or two individuals should routinely assign scores within a herd so as to minimize the inter-assessor variation. A paper form, or electronic spreadsheet, available on the this site can be used to record and summarize the locomotion scores.
The results of locomotion scoring a group(s) or herd should be kept so that trends can be monitored over time. Although some seasonal variation can be expected, the overall trend should be one of improvement if the intervention strategies have been effective at addressing a lameness problem. Herd scores can also be compared to 'target' values, although the validity of these targets has not been critically evaluated. In general, no more than 5-10% of a group or herd should have an LS of 4 or 5 (and all of those should be receiving treatment!). Seventy-five to 80% of the animals should score a 1 or 2.
Locomotion scoring can also be used to select cows for further evaluation. Cows that are scored a 4 or 5 must be examined and treated as soon as possible for ethical, if not production, reasons. (Hopefully these cows are found within a day or two of becoming lame -- not just at 60 day intervals!) Score 3 cows should also be a high priority for evaluation. If a competent veterinarian or hoof trimmer is not immediately available to attend to these animals, a farm employee familiar with the basics of hoof care should examine the animal and administer appropriate treatment. If time permits, score 2 cows should also be examined by the hoof trimmer (in addition to the regularly scheduled "maintenance trims"), since early intervention may reduce the severity, duration, and impact of the condition which is causing the animal to walk abnormally.
Although many herds could benefit from identifying and treating lame cows more expediently, most do have a procedure in place for dealing with clinically lame cows. Therefore, keeping and analyzing records of the conditions found when treating lame cows (as well as pathology found on "maintenance trims") will allow the veterinarian to determine the common causes for lameness, and to make informed decisions about the most effective interventions to minimize further problems in the herd. There are a few different 'paper' systems available and at least one electronic system.
One such electronic record-keeping system is found in PocketDairy®, which is the hand-held computer companion to PCDart®. Basic reports can be generated which summarize the records and permit regular monitoring of the herd hoof health history. 'Paper' record-keeping systems, although not widely available, do exist. One such system (based on the recommendations of the American Association of Bovine Practitioners' Lameness Committee) is available at the Penn State Animal Health and Welfare website, and many trimmers use their own system of record-keeping. Veterinarians are strongly encouraged to work with all of the people providing hoof care on the farm in order to standardize the collection of this information. Collating and summarizing these data will be helpful in solving and preventing lameness problems in the herd.
Not many veterinarians are experienced and competent hoof trimmers. However, the training and expertise that they have in anatomy, physiology, medicine and other areas should provide them with a solid basis for leading the development, implementation, and monitoring of a hoof health program on dairy farms. This will involve working collaboratively and proactively with the hoof trimmer, the herd owner/manager, key farm employees, and other consultants such as the nutritionist. If veterinarians do not take the lead in implementing a comprehensive system on dairy farms, it may not be done at all - to the detriment of the reproductive performance, milk production, and welfare of the animals - or it may be done by other consultants or advisors.
See part 2:
Lameness in Dairy Herds - Part 2: Sorting Out Common Causes