One option that stockers and backgrounders have in their toolbox is antibiotic metaphylaxis on arrival. Metaphylaxis is like a deluxe power tool—it does a great job but costs a lot of money. So before we inject several thousand dollars into purchased cattle, it is important to realize what metaphylaxis actually accomplishes and which groups of cattle might need this treatment.
Anyone who has used arrival metaphylaxis will tell you that some cattle will need another treatment. This is because in every pen there are some calves that will recover from pneumonia without treatment, some that will respond to the arrival treatment and some that will not respond to the arrival treatment. Our problem is we just don’t know which animals will respond which way.
However, that doesn’t mean we operate without some data. When we look at multiple pens, we can discover how effective our treatments can be. For example, research done for FDA approval for injectable antibiotics shows that we have to treat five calves on arrival to keep from treating one calf later. (Apley, Virginia VMA, “Antibiotic Differences in Cattle,” 2018). With an average cost of $20.14 per head for a 500-pound calf, this means we spend $100.70 on that one calf.
Our question then is will we get our money’s worth? We all recognize that highly comingled and stressed cattle need metaphylaxis. We also know that short-haul, low-stress cattle do not. But what about the groups in between, that have some level of stress and some degree of comingling?
While not perfectly predictive, we can look at some indictors to decide if metaphylaxis is a good idea or unnecessary.
Get a history
Having a history on the calves is key to deciding to use metaphylaxis or not. Even if you don’t have a history in the form of vaccination or weaning records, that is still historical information—it says that the owner didn’t think his or her preconditioning practices were enough of a selling point to be worth advertising. These calves are probably worth treating.
For known histories, look for length of time weaned. Calves weaned 45 days and from the same ranch are usually lower risk. However, just because they are "one-ranch" calves doesn’t guarantee they are not comingled. Calves gathered from eight geographically separate pastures and weaned on the truck are comingled similar to calves from eight different ranches.
If you get your cattle from the same source every year and they usually don’t require metaphylaxis, there are a couple red flags that may cause you to use it this year. If you are sent fewer cattle than years past or the calves are coming in lighter and rougher looking, this is a sign that the health on these calves will not be up to the level you had in the past. Here, arrival treatment may be indicated.
We know that shrink is indicative of the stress calves went through before arriving to your operation. A good, quick test to try is to weigh at least ten calves off the truck. If you have a shrink of greater than 10%, it is much more likely you will have major disease issues in that group of calves. Treat them on arrival, give them the most comfortable new home pen or pasture you possibly can (stress tubs are a great asset in this case) and be ready to pull heavily.
Your environmental impact
Your labor situation can have a distinct impact on whether or not you utilize arrival metaphylaxis. In an outbreak, can you and your crew stay on top of pulling and treating? And does this change throughout the year? If you can, not using metaphylaxis will incur a significant cost savings.
Where you receive calves also makes a difference as to how likely it will be to require metaphylaxis. Calves that go into a grass trap will be more spread out and less apt to be sick than those that go into a dirt pen. This can influence your decision to use metaphylaxis or not. However, take extra care to control flies, as calves bunched together to swat flies lose the space advantage that comes with pasture.
Using metaphylaxis on moderate-risk calves is decided on a case-by-case basis. Taking the sum of the positive and negative indicators for health outlined in this article functions as a guide to making the best-informed decision. If you are unsure of what to do, involve your veterinarian both before the cattle arrive and upon arrival.