The Importance Of Weaning And Castration

By W. Mark Hilton, DVM, Purdue University School of Veterinary Medicine

Recent research findings by Edouard Timsit, a University of Calgary DVM, point a finger of responsibility for bovine respiratory disease (BRD) right back at the sick feeder calf. Using DNA typing, his studies show that the most common and destructive bacteria involved in the BRD complex (BRDC) - Mannheimia haemolytica - are mostly not spread from calf to calf during BRD outbreaks occurring at feedlots.

No, this bacterium seems to attack the calf's lungs after some stressful event, and it's primarily the M. haemolytica bacteria that live in the upper respiratory tract as a part of the calf's "normal" bacterial flora that do the damage. After some stressors, the calf's immune system is unable to fight off the bacteria that have been residing in the calf's nasopharyngeal area for months.

According to preliminary research by Jared Taylor at Oklahoma State University, Pasteurella multocida, another bacterial pathogen in BRDC, seems to be similarly opportunistic.

Both researchers contend that BRD due to M. haemolytica andP. multocida may not really be contagious. The stress on the calf's immune system, along with these bacteria that normally inhabit the upper respiratory system, could be all it takes to trigger a BRD event. While research is ongoing, the initial findings point more to the sick calf itself and less to the pen mates.

I'm not downplaying stressful events like commingling cattle and long truck rides, as we also know that the viruses that play a role in many BRDC cases, along with Mycoplasma bovis, are spread mostly from calf to calf in an outbreak. But what is the biggest stressor? I think the consensus would be weaning.

Most studies corroborate this finding, and most feedlot operators would concur. A calf weaned for 30 days (45 days is better) is much more tolerant to thrive in the feedlot environment than a calf that is unweaned.

Vaccinating the calf before moving is also important, but the work by Timsit and Taylor shows that if we add too many stressors, the bacteria will travel to the lungs and likely cause disease. With weaning being the biggest stressor, we need to have no other stressors that day, or opportunistic bacteria will likely storm down the trachea and set up shop, ready to cause disease.

Another health and welfare issue is selling bull calves. Castration at the backgrounding lot is too late. Walk those spring-born calves through the chute now and cut them.

I often hear that farmers and ranchers are the nation's original champions of animal welfare, and I believe it. But, if you're not weaning and castrating your calves before you sell them, you can't wear the animal welfare ribbon.

We've all heard someone say, "I can't wean calves before I sell them. I don't have the facilities or feed."

• If you don't have facilities, use the two-step weaning program in which you apply an anti-nursing device to the nose of the calf for five days, and then wean with a single electric wire between the cows and calves.

• If you have no feed, then wean the calves when you still have some grass and save the best patch for the weanlings.

I tell my students that "can't never did anything," and they figure out a way to get the task accomplished.

The bottom line is, we can do better. We can reduce morbidity and mortality, and enhance animal welfare. If you're not weaning and castrating calves before selling them, then figure out a way to get the task accomplished.

Ask a neighbor who weans before selling how he does it. Ask your herd health veterinarian or Extension beef specialist for help. They likely have helped others with similar concerns, and most love that part of their job.

Again, we can do better, and your calves deserve better.

Source:osu.edu