Additional Vitamin A is Likely Needed When Cattle are Eating Brown Forage

0:00Welcome to the Beef Watch Podcast. I'm Aaron Berger, an Nebraska Extension educator. For today's Beef Watch Podcast, we're going to discuss the topic of vitamin A. It's important and role in cow-calf production and why this year with drought conditions that maybe something we need to pay more attention to. To have a conversation about this, I'm joined today by Dr. Mary Janowski, who's a beef systems extension specialist at the University of Nebraska Lincoln. Thanks for joining me today. Oh, I'm happy to be here, Aaron. Dr. Janowski, let's first talk about what vitamin A does as we think about beef cattle and its role in just health, reproduction, all of the different facets that it's important to in terms of the animal. Well, I think you just hit the nail on the head when we're talking about vitamin A and its importance that the first one I usually think about is honestly immunity.

1:03And with cows, we really don't think about them having a large immune problem. Cows are pretty robust, but vitamin A is very important for epithelial integrity and what that really means is like thinking about things like your skin, your reproductive track, your respiratory tract, your digestive tract, all of those are epithelium. And they're all quickly turning over, which means that you need to make sure that they are forming correctly and creating barriers and basically productive organs, even skin is an organ, which is kind of interesting. So when we think about cows, when we say, okay, with vitamin A, if a cow is low in vitamin A, where might that show up? I would say the common clinical symptom when they get very, very deficient is actually night blindness. And that's something that's really hard to pick up on. But when we step back just a few more notches and say, okay, they are subclinically deficient,

2:04meaning that they are deficient enough to where it's starting to impact their biology. That's probably where we're risking in the case of drought situations. And what I'd likely see in those situations would be actually some reduction in reproduction would probably be the number one. I know everybody thinks about abortion in vitamin A, but honestly, you have to be extremely deficient in vitamin A to see a lot of abortions. Usually what happens is there's something else like a disease or some other reason that they are compromised where the vitamin A being low is associated with that, but it's because it's not creating that barrier, if that makes sense. So the bottom line is for the cow, we typically would say in situations where we have nice green grass, they go out there, they graze for five or six months, we usually don't see deficiencies. But in the case of confinement or in situations where they're grazing even brown forages

3:10like this year with this drought, then we can start getting low and we might see some effects on the cow. But even more importantly, and I would say the most susceptible animal in our cow calf system is that baby calf. And regardless of drought, we do see that is a challenge to get that baby calf to have enough vitamin A to be able to amount an immune response. And we all know how challenging it can be for us to keep those baby calves healthy. And vitamin A, as I said, is extremely important for that epithelial integrity. And we talk about the GI tract, so the digestive tract. One of the common things we see with the efficiency of vitamin A in baby calves is diarrhea. And diarrhea at a fairly young age, really three days to about three weeks at the other one would be, of course, respiratory disease because again, it's important for the integrity of that respiratory tract.

4:12So that baby calf is probably the one that I usually focus on in most years and worry about trying to meet its need, which means we got to meet the cows need and we got to have enough in the diet when that cow is forming the colostrum because that's how that baby calf gets it. Let's talk about vitamin A right now, just thinking about for many parts in Nebraska, we have had some precip in some places the last six weeks. And so there's some green coming now, but prior to that, at least in the western half of the state, a lot of cows grazing dormant forage in the summer. As we think about going into this fall, both for the cow and the calf, what should we be paying attention to as we think about potential vitamin A deficiencies because of the conditions that we've been experiencing? Yeah. So beta carotene is correlated with the greenness of forage. And beta carotene is basically a precursor to vitamin A. So it's what is naturally in our forages that supply vitamin A to the cow.

5:15In the case of brown forage or even just light green forage, it will be low in beta carotene and thus low in vitamin A. So what was happening right now in the situation of those cows who have been, let's say they came out of the winter, they were on brown forage, maybe some stored hay, maybe corn stocks, right? They didn't have a lot of vitamin A and they were using stores to meet their needs. Then we get into the spring, maybe we got a little bit of green, they got a little bit of vitamin A and now we went back and were on brown forage again. They probably did not build up a lot of stores during that period where they did have some green and not enough to get them through now what's going to become almost a full year without a lot of high beta carotene or vitamin A. And so what we have to be thinking about is that yes, the cow coming off of that green grass can have stores that can last even six months. And so that's one of the things we normally depend on in our traditional systems is that

6:19during that winter period, yeah, we're using some of that up. But now we have a situation where we're not building it back up. So it's just like thinking about I have this storage tank and I have now depleted the stores and I have nothing left and that's where we start running into problems. So likely now is the time where people might be starting to get into some situations where that cow is deficient. So what do we need to do? Well, the first thing we have to think about is how are we supplying vitamin A to the cow? Traditionally, we have said that the requirement is essentially 30,000 international units per day of vitamin A. And if you look at a lot of free choice minerals, they are slated to supply basically about 150,000 international units per pound, you need a quarter of a pound. It's about what we say the supplemental requirement is. That is not nearly enough in situations where cows are actually on the brown forage for

7:20long periods of time. We actually have some data. We get a project out at Scots Bluff with cows and confinement where we were feeding them the recommendation of about that 30,000 international units per day. And that did not keep their stores anywhere near adequate. In fact, they were about half of where they needed to be. So we did look at feeding some various levels and found that we honestly probably need to be about two and a half to three times that amount in the total diet to be meeting needs. So I usually tell people I'm shooting for 75,000 international units per day if I do not have green forage. 75,000 international units per day if supplemental would be basically 350 to 400,000 international units per pound in a four ounce mineral. If I'm looking at my mineral tag and I see that that is not where I'm at, how can I increase

8:21that or do I ask my mineral supplier? What is my approach to try to address that deficiency? Yeah, that's a great question. I mean, there's probably three options that we can think about. I mean, the simplest one is probably looking and seeing what other options you have for mineral or if you're going to be providing cake or something like that, can you add two supplemental sources together if that makes sense? So maybe I provide my free choice mineral and I have a cake that has some fortification and together they do what I'm looking for. The idea of well, I can just go and see if I can find another one this may be a little bit better fortified or if you are working with a co-op, you might ask them if they can make a mineral that is more fortified. And in fact, that's probably fairly simple if they are making mineral themselves. There are some co-ops that will do that for you. One of the challenges I would say with that is usually how much you need to order for that to be a viable option. Some will go as little as ton, but most are required to, maybe even four tons.

9:26And that becomes a little bit problematic unless you have some friends that maybe will go in with you and they'll take some of that mineral and you can get something that works. And the last one which again's a little more effort on your part is that you can ask the local mill to get you some vitamin A premix and we can add a small amount of that premix into your mineral to make sure that you are fortifying it at the level you are looking for. One other option is to think about trying to find some nice green hay that you're going to use as supplement. I will say that's a bit of a challenge though because even green hay, it's really hard to get levels exactly where we're wanting, but at least it would help buffer some of that in addition to supplying it through the mineral. So there's a lot of different ways to think about it. I can help you come up with how much you need to supplement if you got a premix because

10:27premix has different concentrations. But one of the things to really focus in on is kind of looking at and being intentional about where are my cows getting vitamin A. And making sure that there is a source of vitamin A that is going to meet their needs. And this is where I'm going to switch gears a little bit because when we're talking about meeting the cows needs, I really want to make sure that everybody focuses on we're getting to the time of year, we're going to get to weaning, some of them are probably already weaned and that's fine. That doesn't mean we're out of the woods yet. We now have this cow who maybe doesn't have high stores, but she has enough to meet her needs. But as soon as we get into that late gestation period, we're going to run into some big trouble with those young calves because we are counting on that cow to have some stores. About 40% of what goes into the colostrum is from that cow's liver. About 60% is from the diet. I really need the cow to have some to give as well as then I need to make sure that I'm fortifying the diet during that period of time.

11:30You mentioned many folks are weaning right now. If I've been through the summer, it's dry, cattle have been on brown forage, I've got a cow now and I got a calf that I'm weaning and I'm realizing, ooh, I may be deficient in vitamin A here. What would be a strategy right now to address that issue with the weaned calf and as the cow maybe heads to corn stalks? Yeah, so one option that's kind of like a little band aid they might consider is giving an injection of vitamin A. I will caution though that there's a combination of a vaccine which I cannot think of at the moment, an injectable vitamin A which sometimes causes some problems in cattle and so I usually don't like to give injectable vitamin A when you're vaccinating that just eliminates the potential issue. So if I'm looking at giving vaccinations and I think if I remember correctly, it's a scours vaccine that is the one that causes the problem. But I would be a little bit cautious about doing the injection then however the injection

12:31can be a good way of like bumping them up, getting them started a little bit but then I would not sit back on my laurels and think, okay, I fixed my problem because you have not fixed your problem. You have giving them something that they can use immediately and thinking about like a young weaned calf for instance, you know, you've got a lot of stress going on. You have a lot of potential pull for vitamin A and so giving them a little bump is never a bad idea but I would be careful about giving it at the exact same time that I'm giving something like a scours vaccination. As we think about going through the rest of the winter, getting ready to next spring, you've highlighted a number of times the importance of the status of that cow in terms of vitamin A, her liver stores what she's getting from her diet in that last trimester prior to calving when she's making that colostrum. Anything else folks should know about in relation to that as they think about the calf as we think about the cow as we go through the next six months. Yeah, so the one of the things that I'm still trying to figure out to be honest is how

13:36late I can go with bumping up my supplementation in terms of, you know, can I go maybe one or two months before calving before I really get intensive about adding that extra supplementation. I said 60% comes from the diet and what we've seen is that the levels that we need to feed to get enough into the calf is not the levels that we need to maintain stores in the cow. And so the cow, the way I think about as the cow's requirement is lower and then we have this period of time where I really need to supply the diet just to make the colostrum have what we're looking for in it. And so my question is like how late can I go right now? My suggestion is that last trimester so that last three months, I'm actually doing a study this winter to try to look at can I go a little bit later with bumping up my supplementation. But I think the kind of the current I guess way to think about it is I'm going to make

14:39sure that in those last three months I am hitting at least 75,000 international units per day of supplemental vitamin A. One thing to point out is that we often use free choice minerals to do that and free choice mineral intake is variable among cows and that is a challenge to get enough into them. If you have a situation where you're feeding a supplement like a cake, if you can get your cake fortified that would be ideal. Let's say you're feeding a pound, say a pound of cake, then you would want 75,000 international units per pound to be meeting those needs. Those are levels that you can find in cake and so I would do some looking to see if you can find a cake that will fit your needs because that is the best situation because it's going to be much more uniform in terms of intake and more of your cows are going to be hitting the target in terms of the supplement that you're looking for.

15:41Dr. Jean-Auske, where would you point folks to if they wanted to learn more about our conversation today, some of the research you've done and resources related to that? Yeah, so we've done a few research projects that of course are on the beef.unl.edu website. In fact, coming out in September we have an article that's going to outline some of the things that we've talked about today to help you think about making sure you're meeting the cow and the calf need. And so if you don't remember all the numbers that I throw around, that would be a good place to go and look. Well, for more information on the topic we talked about in today's beef watch podcast, you can find that at beef.unl.edu. If you have questions around vitamin A, is there a link to supplementation and levels and how you might meet that? And Dr. Jean-Auske's contact information is available also at the beef.unl.edu website. Yeah, thanks Aaron. I'm always happy to try to help people work through their situation and how to accomplish

16:42their goals.