Does it matter when we commingle?

Looking back, I ponder long-ago Christmas gatherings at Grandma’s house. A dozen cousins from across the country gathered for a week-long visit. Every year, the herd of young cousins commingled and … a new bug was introduced to the family.

Bethany M. Johnston

The flu would start with one cousin, who would quickly be quarantined to the spare bedroom. But within a few days, the entire fleet of kids were hugging buckets and sipping 7-Up.

Lucky for us, the flu passed quickly from the kids to the adults. We spent the rest of the holiday playing, fighting and thundering through Grandma’s house while our parents took sick.

A loose definition of commingling in the cattle world refers to the practice of mixing animals from differing origins. Think of your cow herd. Are you introducing “cousins” that could potentially make your entire herd sick? Can the timing of commingling influence your herd health?

Simply put, herd health can be broken into two categories: preventing the disease from entering your herd (biosecurity) and controlling the disease after it has entered your herd (biocontainment). Commingling fits into both sides of the equation. When and how long to wait to mix cattle depends on the animals coming into (or off of) your ranch, the stage of the production cycle the herd is in and other factors.

Weaned calves

Most producers have shipped calves off the ranch, but others purchased weaned animals and brought them onto the ranch. How those calves were handled could have a big impact on their health.

Think about the stress those calves are going through. “Mom is gone. I’m all alone. I can’t find my old water tank. Another shot – ahhh! These pellets taste funny …” And that is before they take their first trailer ride to a new home.

The “cousins at Christmastime” becomes the “cousins at weaning time” scenario when bunches of pairs from different pastures are brought together to wean. Research is also showing that, from an “immunity to disease” perspective, these animals are often not the same, even though they may have been born at the same time with the whole herd located on one ranch.

For calves shipped off the ranch, research shows differences in the health of calves shipped to feedlots based on their respective weaning systems. The groups included freshly weaned home-raised and preconditioned calves, purchased high-risk calves and home-raised calves that are preconditioned and weaned for 45 days at the ranch prior to shipping.

The calves weaned at the ranch for 45 days had lower death loss at the feedlot and improved health and performance than the other groups. Preconditioning also had an effect on health, as preconditioned calves that were commingled had fewer negative effects when compared to commingled calves that were weaned and immediately shipped to a feedyard.

Replacement heifers

Replacement animals are essential. Without replacement heifers, your herd will shrivel away. If you raise your own replacement heifers, they should have a sound vaccination program.

They will eventually be exposed to bulls, the cow herd and other animals, so part of the plan becomes minimizing the effects of eventual commingling.

Gather as much history about the heifers’ history as possible. What did their vaccination program look like? Do the heifers come from a “clean” herd? Were virgin bulls used to breed heifers? Have the heifers been tested for BVD as a PI carrier?

Germs flow both ways when commingling on-farm and off-farm heifers. That is, on-farm and off-farm heifers are just as likely to suffer health effects. Rule of thumb: Isolate new purchases for three to four weeks. If the heifers become sick during this time, doctor and isolate for another three to four weeks.

It is a good idea to avoid commingling outside animals also during late gestation to avoid risk for late-term reproductive losses. Avoid commingling during calving, as this can increase your risk for calf diarrhea. Calve purchased pregnant heifers separately from on-farm animals and test the newborn calves for BVD PI status.

Calves hitting the ground

Scours can be a deadly and frustrating battle in baby calves. Dr. David Smith developed the “Sandhills Calving System” to control the spread of calf diarrhea. The Sandhills Calving System achieves two goals: separate calves by age to prevent pathogen transmission from older to younger calves and scheduled pasture moves of pregnant cows to clean calving pastures.

The older calves are the main spreaders of scours to the younger calves, so the Sandhills Calving System segregates the calves by age. Instead of one calving lot you pair out of, the calves are born in smaller pastures, and then the heavies are moved.

Every week, the pairs stay in the pasture, and the pregnant cows are moved to a new calving pasture. By controlling the commingling of young and old calves, many operations have nearly eliminated scours from their herds.

The neighbors

In a perfect world, my cattle would stay on my side of the fence, and your cattle would stay on your side of the fence. However, we probably both have had to take the neighbor’s cattle out of our pasture or go looking for a bull that was missing from our herd.

Commingling is not always a planned event. The goals of a good vaccination program, in part, are to control at least some of the health risk when unplanned events occur. Visit with your veterinarian if you have concerns about potential diseases from sources outside your herd.

Commingling presents one of the major health risks in the beef industry. While much more than the timing of commingling goes into a herd health plan, knowing the best time to commingle can be beneficial to keeping disease out of your herd.

Don’t let that persistently infected cousin ruin Christmas break in your cow herd.