The Moos Room™

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Dr. Joe Armstrong: Welcome to The Moosroom, everybody. This is Dr. Joe Armstrong. I'm by myself, yet again. Life's just crazy and this is the way it worked out. Today, we're covering a feedlot topic. I guess it's not just a feedlot topic, but most often, it applies in the feedlot. We're talking about two things, a post-treatment interval and a post-metaphylactic interval. The basis for these things is to save money and use antibiotics more judiciously. What are we talking about here? Post-treatment interval, post-metaphylactic interval.
Let's first talk about metaphylaxis. What is it? Metaphylaxis is something that we do most often in a feedlot setting with high-risk calves. We have a group of calves or a cohort of calves that we know are high-risk for developing BRD or for breaking with BRD, Bovine Respiratory Disease. Now, how we determine high-risk and what groups are at risk or more at risk than others? That's a whole separate topic and something that we've covered briefly on this podcast before. We'll leave that for another day.
We're going to assume this group is high-risk for BRD. One of our options, in that case, is to treat that entire group metaphylactically, or taking that whole group and giving them an antibiotic in an attempt to reduce the incidence of morbidity and mortality associated with BRD. Now, often this comes up on labels of antibiotics where they are labeled for the control of BRD or certain pathogens associated with BRD. That's metaphylaxis. Now, treatment is much different. Metaphylaxis, we're making a decision on a big scale, a pen, a cohort, an entire source, whatever it is.
Treatment, we're looking for an individual animal. We're pulling that animal because we've noticed some clinical symptoms in the pen. We're evaluating that animal in the chute, and they're getting an individual treatment that's much different than metaphylaxis. Now, where these two crossover for today's purposes is in the post-metaphylactic and post-treatment interval. These terms post-treatment, post-metaphylactic intervals, what we're looking at is a period of time after the administration of an antibiotic or a treatment where that animal is not eligible to be pulled and treated again.
When we're looking at metaphylaxis, let's say I have a big group that comes in, I give them a long-acting antibiotic because I know they're high risk, I'm trying to decrease the incidence of BRD in this group. After that, I know there's an antibiotic on board. I know every animal is covered for a certain period of time, so I'm going to dictate to my pen riders people walking pens or whoever's doing the pulling, we are not going to pull animals for BRD because I know they're already covered for it, for a specific amount of time. Now, how long that is differs by drug, differs by risk category.
Truly, we don't have a ton of information about post-metaphylactic interval, or at least enough to recommend across the board, this is what you do. Post-treatment interval is exactly the same. All we're doing is pulling an animal, diagnosing them with BRD, giving them a treatment, and then I'm saying, "Hey, we need to trust the drug. We need to trust that we got the diagnosis right. Trust ourselves, trust the people pulling animals, and we're not going to pull that animal again for a specific amount of time." For post-treatment interval, we actually have more data than for post-metaphylactic interval, just because we've been doing this process of pulling and treating for a lot longer, and there's just more data available.
It differs of course, by drug. We're not going to get into a whole lot of specifics today of, "Hey, for this drug, it's this post-treatment interval and for this drug, it's this post-treatment interval." That's something to discuss with your veterinarian and whoever's helping you with protocols on your feedlot. Now, it doesn't just apply to feedlots either when we're talking post-treatment interval. That can be applied to just about anything, especially when we're talking about calves or even if we're on a dairy and we're talking about pneumonia on a dairy. If I've already treated that animal and I've given them an antibiotic, I'm going to trust it and let it work for a certain amount of time before I give more antibiotics.
Like I said, just a little bit ago, there's a lot of reasons to be doing this. One of them is to save money. We need to trust the first treatment, allow it to have a fair chance to work, and decide does that animal actually need more antibiotics or a different antibiotic or more treatment, or am I jumping the gun and giving something unnecessarily if I don't stick to my post-treatment interval or post-metaphlylactic interval? Additionally, especially when we're talking about post-metaphylactic interval, part of it is just trying to let the cattle calm down.
We know they're high-risk. We know they're probably stressed out because that's what makes them high-risk. To work that group or continue to pull animals from that group, we're adding stress to the situation, and that might actually be more harmful than beneficial. The other cool thing about a post-metaphylactic interval is it refocuses everyone's attention. When we know that we can't pull animals for BRD in a group, we still need to ride and look for other problems and decide if there's other things going on, but it allows people to refocus their energy on the things that matter most, and that's where we're back to management.
We've talked about management a ton on this podcast, but it matters and it matters a lot, and especially for incoming high-risk cattle, if I don't have to concentrate on pulling BRD cases because I can't, I can focus on bedding, making sure waters are straight and that the feed gets delivered appropriately at the right time, and it's mixed well. So many things that matter just as much if not more, and I can concentrate on those because I'm not worried about pulling BRD cases. Now we know what post-treatment intervals and post-metaphylactic intervals are. We know some of the benefits of adopting this kind of practice.
The real reason that I'm talking to you today is I read a new paper. It's fairly new, and it specifically compares different post-metaphylactic intervals for a specific antibiotic given to a large group of calves. This is really cool work, and it's done very well. It's one of the few papers we have available that compares different post-metaphylactic intervals. Now, again, this is all specific to a specific antibiotic. We can't make comparisons unless we're using this metaphylactic treatment in these type of animals and for these specific post-metaphylactic intervals that they chose to compare in the study.
For example, they used a 13-day post-metaphylactic interval as one of the groups in this study. I can't take the results of this data and comment on anything past 13 days. I can't say, "Well, maybe 20 is better based on this data." That's not how it works for this paper. Enough disclaimers. Let's get into actually looking at this paper. The paper itself is titled Health and performance outcomes from a randomized clinical trial of post-metaphylactic intervals fFollowing tildipirosin metaphylaxis for control of naturally-occurring Bovine Respiratory Disease in commingled lightweight yearling steers in a commercial feedlot.
That's a mouthful. Right off the bat, what drug are we talking about? Tildipirosin, that is Zuprevo made by Merck Animal Health. We need to know that because, like I said already, what we're going to talk about today is specific to the use of Zuprevo. Now, I love this study and I love how it's set up. I think the concept applies to a lot of different things, and that's why we're talking about it today.
There are similar studies out there that look specifically at post-metaphylactic interval. One involves Excede and the other involves Micotil. Now, the results were a little different than this study with the Excede study because they had a much higher risk group of calves, so hard to compare this study and that study. On the Micotil side, they only carried it for 60 days rather than the entire feeding period so also a little tough to compare there.
We can talk about those studies at a different time if we want. Today, we're going to focus on this one. Let's go over the basics. This study was set up with lightweight crossbred yearling animals from a bunch of different sources, a bunch of different states, mostly from the south and southeast, and they were all placed in a feedlot in a Texas panhandle for the entire feeding period, which ended up being 217 days. When I say lightweight yearling, we're talking about an average overall in weight of 650 pounds approximately at the beginning of this study.
The different post-metaphylactic intervals were 4, 7, 10, and 13 days post-metaphylaxis. Everyone got Suprevo on arrival, and then they were given or assigned a different post-metaphylactic interval at a pen level. I'm not going to really beat around the bush on this. We're going to get right to the punchline. There's a lot of data here to go through, and frankly, that's going to be boring for me to go through it with you just listening. I will provide the link to the paper. You're welcome to read it, ask me questions about it. We can go over it together if you'd like. The big conclusion here is that there was no difference in performance, whether that was in the feedlot or with the carcass at the end between the different groups. Despite the post-metaphylactic interval getting longer, we saw no difference between the groups. What we did see is that we had more polls and more incidents of BRD in the groups that had a shorter post-metaphylactic interval. Now that makes sense. They were eligible to be polled for more days. The point of setting the post-metaphylactic interval is to say these animals don't need an additional treatment for this specific disease process before this time.
It makes sense that more polls were made the shorter the post-metaphylactic interval because those cattle were eligible to be polled for more days. The cool thing about this paper is they also tracked enough data to tell us that despite there being less polls in the longer groups, we saw no difference in performance on a pen level and we saw that on those pens they were continuing to gain weight over that post-metaphylactic interval timeframe despite not being eligible to be treated for BRD. Often the concern with a post-metaphylactic interval is that we're leaving animals ineligible to be treated when they might need treatment.
According to this study, that's not the case. For this specific drug in this specific type of cattle, the paper can very reasonably conclude that in the shorter post-metaphylactic interval groups because we saw no difference in performance in any way between all the groups, there was probably some cattle that were treated that didn't need to be in the shorter post-metaphylactic interval groups and that's the point. That would mean that potentially we spent money that we didn't need to and we used antibiotics more often than necessary. Very cool study. I really like it.
I will leave the link in the show notes, so be sure to check it out if you want information. Send me questions if you have any. Again, be very careful using this data and applying it to other groups and other drugs. That's not the point and probably not responsible to do. What's the point? What's the conclusion? What's my takeaway for this paper? Well, what it tells me is that if I have long yearlings and they're moderate risk and I use Zuprevo for metaphylaxis, there is no reason to set a post-metaphylactic interval shorter than 13 days. That would be my choice with this specific type of cattle, with this drug.
I believe this concept can be applied to other drugs and that's something you need to talk to your veterinarian about to figure out what post-metaphylactic interval you're going to set based on the data that is available. I'm not going to make comments on other drugs today because I don't have the data to do so, and I don't know your specific operation, the sources you're getting your cattle from how high-risk they are. I can't make a blanket general statement about what to do with post-metaphylactic intervals. What I can say based on this paper is light yearling cattle that are moderate to high risk given Zuprevo for metaphylaxis, I would say we have enough data to say that you should set your post-metaphylactic interval at 13 days.
Hopefully, you're not too frustrated by me being very specific with that statement. You know the drill. If you have comments, questions, scathing rebuttals to this episode, please send them to the moosroom@umn.edu. That's T-H-E-M-O-O-S-R-O-O-M@umn.edu. Catch us on Twitter @UMNmoosroom and @UMNFarmSafety. Catch Bradley on Instagram @umnwcrocdairy. Check out the website extension.umn.edu. Thank you for listening everybody. We will catch you next week. Bye.
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