Do Hoof Lesions Affect Heat Detection?

A cow’s activity climbs about 24 hours before ovulation. Heat detection systems identify these changes in cow activity and alert farmers. CowManager, in particular, monitors “high-activity” behavior in cows. Figure 1 is an example of the high-activity data collected for a cow within our herd. This cow’s activity began rising on July 26, 2018, and peaked on July 27, 2018. She was bred on July 27.

The size of hoof lesions did not affect cow high-activity behavior. However, cows with active lesions spent 42 minutes less per day being highly active than cows with digressing lesions as shown in Figure 2.

When looking at individual cows, we noticed that cows were 2 to 8 percent less highly active when they had an active hoof lesion rather than a digressing lesion. It is interesting to note that hoof lesions did not affect cow lying behavior.

Rumination in Cows

Lame cows often have reduced rumination, so we expected cows with active hoof lesions to have lower rumination. This was not the case. Lesion size or healing status did not affect cow rumination behavior. Cows with swollen feet, however, did reduce their rumination behavior, but it depended on ear temperature. As shown in Figure 3, cows with lower ear temperatures and a swollen foot spent the most time ruminating. In cows with a swollen foot, rumination fell as ear temperature rose. The rule of thumb is that as ear temperature climbs, body temperature falls. We didn’t see any difference in rumination between cows with no lesions and cows with lesions.

What is the heat detection rate on your dairy? What is the prevalence of lameness on your farm? We know that these two rates are closely related. A lame cow will spend more time lying down and less time being active. That scenario makes heat detection rather tricky. If lameness causes these behavioral differences, then we would expect hoof lesions to cause similar effects.

As prey animals, cows tend to exhibit signs of pain only when it becomes severe. It is easier for us to identify cows with severe lame- ness than cows with mild lameness. This means that hoof lesions from digital dermatitis may be undetected until cows show signs of lameness. Could these unnoticed hoof lesions become an underlying cause of missed heats?

Preferred methods of heat detection vary across the United States, but some of the most common methods are visual observation and tail chalk or paint. Advanced technologies such as pedometers and heat detection systems are also gaining popularity. One of these technologies is the CowManager system. This system uses ear tag sensors to transmit data from each cow to a router. The data can then be viewed on a computer or smartphone. Most systems record each cow’s behavioral patterns and alert the farmer if any abnormal patterns occur.

Hoof health

A little over two years ago, a group of farmers asked me to answer two questions related to hoof health:

1. Do hoof lesions affect cow activity and rumination behavior?
2. Can hoof lesions affect heat detection?

My research team and I recently completed a study that aimed at answering those questions. We conducted this two-year-long study at the Washington State University’s Knott Dairy Center in Pullman, Wash. The dairy milks, on average, 170 Holstein cows twice a day. We use the CowManager system on our dairy for heat detection and health monitoring. I hope that by sharing what we learned over the last two years, managing hoof lesions and heat detection will become easier on your dairy.

Hoof Health Evaluations

Most digital dermatitis lesions are located on the rear feet, as opposed to the front feet of cattle. We evaluated the rear feet of all lactating cows in the milking parlor once a month over the course of the two-year-long study.

Upon entering the parlor, each cow’s rear feet were sprayed with water. We documented the presence, size, and healing status of all hoof lesions. We also noted any swollen feet. Healing status was defined as either active or digressing/regressing. Lesion size on rear feet was classified as small (< ¼ inch), medium (¼ inch to ½ inch), or large (> ½ inch).

What Does it All Mean?

We learned that heat detection systems provide useful data on cow behavioral patterns that we can use to identify cows with health concerns, including hoof lesions. Our team also learned that cows with active hoof lesions spend 42 fewer minutes a day being highly active than cows with digressing lesions. This means that the presence of active lesions could make it more difficult for us to heat detect, whether we use visual observations or heat detection systems.

Cows with swollen feet may reduce their rumination by as much as 2 hours per day, depending on ear temperature. The relationship between ear temperature and rumination is one that we will be taking a closer look at in future studies. We were surprised to learn that lesion size did not affect cow activity or rumination behavior. One of the major recommendations from this study is to take the time to spray off rear feet in the parlor; it’s one of the easiest ways to evaluate hoof health on a regular basis.