Dr. Robert Tremblay
In 2005, a researcher at Guelph investigated injuries to cows in over 300 tie-stall barns in Ontario. She looked at barn-related injuries that most people recognize like neck abrasions and hair loss and open wounds on hocks. She recorded information on docked tails, which is something that is not related to housing. She also documented cows with broken tails. Hock and neck injuries are usually the result of barn design and stall maintenance. Tail docking is a purposeful (and controversial) management choice that is no longer permitted under proAction. Fractured or broken tails are likely neither.
Not long ago, researchers in New Zealand investigated how much force it takes to fracture a cow’s tail. The idea was to help determine whether cows might fracture their tail themselves just through their interactions with the barn environment – in other words, by accident. They did find that the amount of force needed was quite different from cow to cow. They only tested 5 tails, but this is quite a wide difference of the force required to break a tail. Those tails that they used in the study had been harvested from mature cows immediately after slaughter. The researchers concluded that it took enough force to break a tail that it was unlikely to happen to very many cows as the result of an accident in the barn – tail fractures are almost exclusively caused by people.
In the US, the animal care program, FARM which stands for Farmers Assuring Responsible Management, is in its fourth edition. The fourth edition includes broken tails amongst the things that must be measured when a farm’s dairy cows are evaluated. The other animal-based measures include body condition score, hock lesions, knee lesions and lameness. FARM 4.0 requires that 95% of cows must not have broken tails.
The 1999 edition of the Canadian Code of Practice for dairy does not mention broken tails but it mentions and discourages ‘tail twisting’ several times. The Code is currently under revision. The animal care component of proAction is somewhat based on the code and like the code does not place emphasis on evaluating cows for broken tails.
The Guelph research may not reflect the current situation in Ontario but their findings on broken tails are interesting. They found that most herds (62%) had no cows with broken tails. Another 19% would fall under the limit defined by the FARM program; so a total of 81% of the 317 herds they evaluated would have an ‘acceptable’ number of cows with broken tails.
The research team separated out the remaining 19% of farms based on the percentage of cows with broken tails in the herd. Eleven percent of herds (34 herds) had 5-10% of their cows with broken tails. Another 3% of herds (11 herds) had 11-15% of their cows with broken tails. The remaining 5% of herds (17 herds) had more than 15% of their cows with broken tails. The researchers did not report just how many broken tails they found in the herd with the most broken tails.
If you examine that research data carefully, you find that more than a quarter of the herds that exceeded the acceptable 5% in the FARM program were actually more than 3 times above the acceptable level.
If the older data reflects what happens today, then it could be interpreted to mean that most herds have no or few cows with broken tails but the herds that do have cows with broken tails have quite a few cows with broken tails.
That made me wonder if farmers notice how many of their cows have broken tails. Being aware of the number of broken tails might be good information to know, especially if more than one person routinely works with the cows. Could many cows with broken tails or an increase in the number of broken tails point out that there is a need to reevaluate animal handling practices or to identify if there are housing or milking system issues that create situations where cows are reluctant to move?