Subscribe
Share
Share
Embed
Hosted by members of the University of Minnesota Extension Beef and Dairy Teams, The Moos Room discusses relevant topics to help beef and dairy producers be more successful. The information is evidence-based and presented as an informal conversation between the hosts and guests.
00;00;11;03 - 00;00;42;04
Brad
And welcome to The Moos Room. Brad again here on the first day of spring. Today, as I record this, this wonderful heading. Towards 60s and 70s here in Minnesota, which makes it wonderful. Maybe spring is coming after a big snowstorm. The last weekend, but I was away and then I got home and got Covid, so that's always wonderful to be gone for a little bit and then be out of commission for a few days.
00;00;42;04 - 00;01;12;13
Brad
But I'm back doing some things and I really wanted to talk about some things that are happening in the spring. And one is flies. Are flies ready to come out? Well, as the temperature starts to warm up here, I think they are. And I wanted to talk a little bit about the research that we did last year on our horn fly vaccine study that we, we worked with and did all across the summer last year.
00;01;12;16 - 00;01;45;28
Brad
So let's give a first rundown about what horn flies are. So horn flies are flies that come from pastures. They don't aren't found in barns unless the cows come in with them. But they lay their eggs in manure, out on grass, out on pasture, and nowhere else. And so you see these a lot in beef cattle herds. You see it a lot in dairy cattle herds that are on pasture or heifers that are on pasture.
00;01;46;01 - 00;02;14;05
Brad
You will not find horn flies on cows in confinement or totally 100% confinement herds if the cows come in from pasture into the barn, yes, the horn flies will come with them, but they are found nowhere else besides on pasture. We all know that horn flies can negatively impact cattle, beef cattle, dairy cattle. They cause significant blood loss.
00;02;14;05 - 00;02;51;29
Brad
They're very annoying to the cattle. They create lots of behavioral issues and lots of behavioral things that we see going on. Reduced milk production, reduced weaning weight, reduced weight gain in animals. So it it has a big cost to cows, and they remain on the host almost constantly. So they're feeding probably 38 times a day, and they actually have a short life cycle, only about 9 to 12 days, which actually results in about 14 generations of horn flies per year.
00;02;52;02 - 00;03;23;15
Brad
So that's that's a lot. And this vaccine may be a long term sustainable solution that will help reduce the fly populations and become an important tool in the fight against horn flies. So we know that insecticides have been successful in the past. We know that, but the horn fly can be resistant. They can develop resistance to these insecticides, which can still cause issues on on the dairy farms.
00;03;23;18 - 00;03;49;03
Brad
So what did we do last summer? Well, we worked with a vaccine from med gene. So what is med gene? Will gene is a company based out of Brookings, South Dakota, and they develop vaccines that are only available with a prescription from a licensed veterinarian with a valid veterinary client relationship. And they develop vaccines for many different species.
00;03;49;03 - 00;04;23;22
Brad
They've developed them for swine, cattle, rabbits and deer. They've been developing some vaccines for cryptosporidium, horn flies. They have some tick vaccines. Brisby. They have a vaccine for New World. Screw worm BVD crypto. Lots of different vaccines for cattle. Cattle is probably their biggest, market. And we utilized their horn fly vaccine last year. So what is what is the vaccine supposed to do?
00;04;23;24 - 00;04;56;26
Brad
Well, it's supposed to target and use the cattle's immune system to produce antibodies that impact the ability of the horn fly to take a blood meal. Remember I said that the horn fly takes many different meals throughout the day, so horn flies use a protein called thrombus station as an anticoagulant. So when they feed on an animal, cattle, the host animal does not coagulate during feeding.
00;04;56;29 - 00;05;29;26
Brad
So typically horn fly vaccines induce the immune system to produce antibodies that would interfere with thrombus and protein. When the horn fly is feeding on an animal, it ingests the antibodies which block this activity. So the blood meal actually coagulates, which means that the fly takes a smaller blood meal and it negatively affects the reproductive cycle, which causes fewer eggs to be laid.
00;05;29;26 - 00;05;57;20
Brad
So that's how that's how the flies keep going is laying eggs. So if you have fewer eggs being laid, less horn flies, the idea would be to help reduce the horn fly population. So what did we actually do? Well, we vaccinated about half of the cows in both of our herds organic herd, conventional herd, organic herd is predominantly on pasture, so they're going to be exposed more to horn flies during the summertime.
00;05;57;22 - 00;06;23;20
Brad
The conventional herd is kind of in a a dry lot, outdoors, close to some pastures. So they're not going to be laying manure on the pasture the whole time. They're going to be in this dry lot. So they're more in confinement, I would say, but still outdoors. So they're still being exposed to horn flies. But we wanted to see what would happen there as well as, you know, would there be more horn flies there, or could we reduce horn flies because they still have horn flies on them?
00;06;23;23 - 00;06;46;29
Brad
They're not in a free stall barn. And then we looked at our heifers. So we looked at heifers that were on pasture. Because if you look at historically, the heifers in our herd on pasture have probably had the worst amount of horn flies on them. Sometimes you can go down there and I swear you could count to to 500 flies on some of these heifers.
00;06;46;29 - 00;07;14;15
Brad
It's, it's bad. And we all know from a grazing standpoint, especially in the organic herd, you need to be spraying these animals daily to keep the flies off of them. So it's it's really difficult to manage flies in an organic situation. And vaccines can be useful in doing that and working with our cows. So basically we vaccinated our animals.
00;07;14;15 - 00;07;42;23
Brad
So last May we started vaccinating them. We wanted to vaccinate before the horn flies came out. So before they started to emerge and maybe June, ideally the peak horn fly season is around the 4th of July, at least up here in the upper Midwest. So we wanted to have cows vaccinated long before that. This vaccine is is comes in two doses.
00;07;42;26 - 00;08;17;21
Brad
And so you vaccinate them once and then about a month later you vaccinate them again. So this vaccine is a prescription. So we had to work with our veterinarian to get to get the prescription here for the the horn fly vaccine. It's two mils. So basically we're administering a two mil dose subcutaneously into an animal. And then 21 days later, so three weeks later we're vaccinate them.
00;08;17;21 - 00;08;43;26
Brad
So this is a subcu vaccine. And 21 days later you give them a booster as well. So we did that not on all of them because we wanted to see what would happen. So we had our heifers and our cows. So we vaccinated about half of the cows in each of the herds, vaccinated about each of the half of the heifers, because we wanted to have the control, you know, were there more flies on control animals versus vaccinated animals?
00;08;43;26 - 00;09;08;17
Brad
And then we wanted to look at how horn fly populations behave across the the whole season. So we also had some students doing lots of work. So they were counting flies on these animals. So we had 500 dairy animals on site last summer. So they counted flies on every single animal. And there is a method to counting the flies.
00;09;08;19 - 00;09;32;23
Brad
And they did this twice a week for the whole summer season and into the fall. So it was actually a lot of work, a lot of work to do all, of, all of this fly counting and to see what was actually going to happen. So what did we actually find? So let's talk about a couple of the other flies that we we measured as well by recording fly numbers on face flies and stable flies.
00;09;32;23 - 00;09;54;25
Brad
We wanted to see what was going on. By no means was this vaccine meant to control face flies or stable flies, but we wanted to count those flies to see actually what would happen. Now, if you look at face flies across, the 20 weeks of of the study that we did, we didn't find, you know, no difference between vaccinated or unvaccinated.
00;09;54;28 - 00;10;18;05
Brad
You see, face fly numbers really low, you know, one and two flies per animal. And then and then about mid-July, we see this explosion of face flies around 8 to 10 flies per animal. So we know exactly what it does. Face flies a pasture fly as well. And then we see those numbers drop off towards the end of the study.
00;10;18;07 - 00;10;43;05
Brad
Exactly what we would expect them to do. If you look at it in the heifers you see similar results. And in the heifers, the same, maybe less face flies on the heifers than what we see in the cows. But again, around mid-July, explosion of numbers and then kind of tapering off. So around, you know, 4 to 5 flies per animal if you look at stable flies.
00;10;43;05 - 00;11;08;10
Brad
So these are the flies on the legs of an animal. You actually see stable flies in confinement. So they're biting flies on the legs of animals. So they will be found in confinement again. We started collecting fly scores around the end of May to see what would happen. And by about July, again, we see large number of stable flies per leg of animal.
00;11;08;10 - 00;11;29;08
Brad
You know, we're 15 flies per animal. We did not see any difference in vaccinated animals or heifers on stable flies. And that's what we expect. You know, the vaccine was not meant for those type animals. So what about corn flies? What did we find in horned flies in all of our groups? So we'll kind of go through our groups.
00;11;29;10 - 00;11;51;21
Brad
If we look at the conventional cows, remember they're kind of confinement. But outdoors on a dry lot, we didn't see as many flies. We didn't find a difference in vaccinated versus unvaccinated in the conventional animals, which is really what I expected. You know, I didn't necessarily expect to find a difference just because they're not necessarily out on pasture.
00;11;51;23 - 00;12;18;00
Brad
Like the the other cattle are exposed to grass, and many things are kind of in the the same area. They did have some horn flies on them from the end of May until early July. You know, 1 or 2 flies per animal kind of peaks. A little bit goes up. We see, you know, five or 6 or 10 horn flies per cow in some of those places, but not a lot and no different.
00;12;18;00 - 00;12;40;12
Brad
So kind of finding what I expected, you know, you have to have these animals on pasture quite a bit to kind of see, what what is going on. So what about our organic cows and what what did we find there? Well, if you look at it from about may, we have lots of flies on on cows. They kind of have a a peak surge in the beginning.
00;12;40;12 - 00;13;21;26
Brad
So that's as they emerge from dormancy over the winter time. You have a large number of flies. And then they kind of go down a little bit just because we see that and then it spikes again, you know, mid-July, July 4th, we see this huge increase in in horn fly activity through then we didn't necessarily see any difference in in horned fly numbers on our cows, which we wouldn't necessarily expect because the horn flies are coming out, they're laying eggs and they're producing lots of horn flies and with the vaccine, we really think about long term and the generational impact and how we can reduce the horn fly numbers throughout the season.
00;13;21;28 - 00;13;47;02
Brad
But once we start getting towards July and August and into September, now we see a reduction in horn fly numbers on those animals that were vaccinated, and it's about 30%. So about a 30% reduction over time on forward and fly numbers on these cows. So that's quite significant. You know you think about reducing fly numbers 30% is is quite a bit.
00;13;47;04 - 00;14;15;17
Brad
And I didn't have any expectation I really didn't know what was going to happen. When when we did this. But a 30% reduction is is quite nice. Across time obviously I'd like to see those numbers not even sort of increase, but we did see reduction towards the end of the season in, in lactating cows, lactating cows, you know, are about 30 to 50 horn flies per, per animal.
00;14;15;17 - 00;14;38;04
Brad
So, you know, if we can reduce 30%, that's 10 to 15 per cow. That's, quite a bit. If you look at the heifers, that maybe tells a little bit different story and somewhat sometimes the cows are a little deceiving because they come into the milking parlor. So, you know, they're not manure. And constantly on pasture because they're coming up to milk twice a day.
00;14;38;04 - 00;15;02;15
Brad
So some of their manure gets lost in the holding area in the parlor. And so those horn flies are not coming up with them. Yes, yes, they do come up with them, but they're not necessarily laying eggs in the manure on the holding area or in the parlor or anything like that. So you're maybe not seeing the, the full effect that, that you might find in the heifers.
00;15;02;18 - 00;15;28;18
Brad
Heifers. Different story constantly on pasture 100% always manure out. They're always in there. They're not going anywhere else. Well what did we find again at the end of May. Low horn fly numbers. And then we see this spike about the end of June where we see a gradual increase in in horn fly numbers. Obviously horn fly numbers are peaking into mid July.
00;15;28;20 - 00;15;57;01
Brad
We see a difference between the vaccinated and unvaccinated. So the vaccinated animals have consistently lower horn fly numbers than the unvaccinated animals. And that starts right away at six weeks after we started collecting. So right away in late June, we see lower numbers. And those lower numbers are consistent throughout. Do the vaccinated animals have horn flies on them?
00;15;57;01 - 00;16;34;03
Brad
Yes. I don't think that the vaccine is promoting that you would have zero flies on them, but we certainly have lower number of flies. We have less flies on those animals. And again, we see about 30 to 40% reduction in horn fly numbers in the vaccinated animals compared to the unvaccinated animals. So that really has helped kind of show that we do see a big difference in in these horn flies, in animals that are consistently on pasture and throughout the season.
00;16;34;03 - 00;16;53;10
Brad
We see this a big difference in reducing horn fly numbers. And it's kind of exciting that that this tool is able to do that with just a simple vaccination where we can reduce horn fly numbers in these animals. So I'm quite excited about it last year. If you think about the weather here in the Midwest, it was quite rainy.
00;16;53;17 - 00;17;15;08
Brad
So we maybe didn't have as many horn flies as what we normally would throughout the season because of weather, cooler weather, rainier weather. So you probably have less horn flies throughout the season, but it was still quite exciting to see this reduction in in horn fly numbers for these animals. So where do we go from here? Well it's interesting.
00;17;15;08 - 00;17;45;20
Brad
I think we'd like to continue to work with this, vaccine to to see what it can do and maybe look at it from a, you know, a different perspective and, and see, can we continue to lower horn fly numbers, across dairy cattle or beef cattle, on pasture? So with that, I hope you actually learned something today and learned a little bit about, you know, vaccination and and learned about this new horn fly vaccine that's out there for producers and, and veterinarians to to help reduce horn flies.
00;17;45;22 - 00;18;05;01
Brad
Only horn flies. Remember not not for the other species, but only for horn flies. And I think it provides a a great tool in the toolbox for reducing fly populations in cattle. So with that, I think we'll leave it there today. And if you have any comments, questions or scathing rebuttals, feel free to contact me at the newsroom.
00;18;05;01 - 00;18;23;23
Brad
That's tag m o s r o m at Umkc edu or find us on the web at University of Minnesota Livestock Extension or Uom and WC Rock dairy. And with that, I hope you have a great week and hopefully you're able to control the horn flies by.