Vet’s Voice: Health concerns with new arrivals | TSLN.com

Vet’s Voice: Health concerns with new arrivals

Dave Barz, DVM

For the November 5, 2011 edition of Tri-State Livestock News.

Fall has definitely arrived! The cool north winds remind us that winter isn’t too far away. This summer’s extreme drought in the southwestern U.S. has resulted in the sell-off of hundreds of cows and calves, many of which have found new homes in feedlots and pastures near us.

Over the past five to ten years, we’ve seen an increase in small feedyards near us. These lots are permitted for 999-2,500 head. Most feedlot operators have fed cattle in the past, primarily sourcing calves from the northern plains. When we have health problems at these lots, we are usually familiar with the issue and are able to respond with few problems. This summer there have been some real wrecks with southern calves – a new experience for many of feedlot operators.

Most calves in the northern plains are adequately vaccinated for bovine viral diarrhea (BVD). Timely and appropriate use of BVD vaccines assures immunity to field strains of BVD which pass through herds like the flu or a cold. They also help prevent and minimize persistently-infected (PI) calves. PIs occur when the cow is exposed to wild BVD virus during specific stages of pregnancy. If the cow develops the disease while pregnant, the calf becomes infected in the uterus. This result, is the calf believing BVD virus is a normal part of its body makeup. When calf is born, usually alive, it continues to shed huge quantities of BVD virus throughout its life. This continuous source of virus infects all other animals on farms and feedlots.

In our area we have checked breeding bulls, breeding heifers and entire cow-calf herds for PIs before turnout. In the past 10 years we have only identified one PI-calf from the thousands we have examined yearly. I believe this is because we have used live BVD vaccines in our area for the past 30 years. Colleagues of mine in other areas of the state have had similar results, attributing the findings to vaccination.

This summer we cultured BVD virus from the lungs of several southern calves we posted. We don’t know if these were PIs, or merely calves infected with wild virus. Treatment in these groups of calves was not very rewarding. Most of the calves were not vaccinated before shipping, nor when they arrived at their destination. This highlights the need to know the source of cattle entering a new environment, with appropriate measures implemented for “high risk” calves.

Another common problem in these calves was mycoplasma. We were able to culture this pathogen from animal deaths. Mycoplasma is tough to treat with normal antibiotic regimes because it has no cell wall.

Recommended Stories For You

We recommend producers get new arrivals eating and drinking as soon as possible after arrival because they are nutritionally-stressed from drought and may have traveled long distances. We prefer high vitamin levels in receiving rations to help these deficient calves better respond to vaccinations.

Your veterinarian should be a valuable resource in feedlot and herd health protocols. They are able to post any deads, providing an accurate report on the cause of death. Together you can assess treatment and revaccination procedures to best eliminate health problems.

If BVD is an issue, you may need to individually test complete pens of cattle for PIs to eliminate viral shedding. If you have a cow-calf herd, or purchased southern cows and calves or feedlot calves, you may have inadvertently put your herd in a compromised position. Exposures to BVD and mycoplasma from purchases can infect the herd even if spring vaccinations were administered. Visit with your nutritionist, extension specialist and veterinarian to minimize further problems and keep your operation functioning at full potential.

Fall has definitely arrived! The cool north winds remind us that winter isn’t too far away. This summer’s extreme drought in the southwestern U.S. has resulted in the sell-off of hundreds of cows and calves, many of which have found new homes in feedlots and pastures near us.

Over the past five to ten years, we’ve seen an increase in small feedyards near us. These lots are permitted for 999-2,500 head. Most feedlot operators have fed cattle in the past, primarily sourcing calves from the northern plains. When we have health problems at these lots, we are usually familiar with the issue and are able to respond with few problems. This summer there have been some real wrecks with southern calves – a new experience for many of feedlot operators.

Most calves in the northern plains are adequately vaccinated for bovine viral diarrhea (BVD). Timely and appropriate use of BVD vaccines assures immunity to field strains of BVD which pass through herds like the flu or a cold. They also help prevent and minimize persistently-infected (PI) calves. PIs occur when the cow is exposed to wild BVD virus during specific stages of pregnancy. If the cow develops the disease while pregnant, the calf becomes infected in the uterus. This result, is the calf believing BVD virus is a normal part of its body makeup. When calf is born, usually alive, it continues to shed huge quantities of BVD virus throughout its life. This continuous source of virus infects all other animals on farms and feedlots.

In our area we have checked breeding bulls, breeding heifers and entire cow-calf herds for PIs before turnout. In the past 10 years we have only identified one PI-calf from the thousands we have examined yearly. I believe this is because we have used live BVD vaccines in our area for the past 30 years. Colleagues of mine in other areas of the state have had similar results, attributing the findings to vaccination.

This summer we cultured BVD virus from the lungs of several southern calves we posted. We don’t know if these were PIs, or merely calves infected with wild virus. Treatment in these groups of calves was not very rewarding. Most of the calves were not vaccinated before shipping, nor when they arrived at their destination. This highlights the need to know the source of cattle entering a new environment, with appropriate measures implemented for “high risk” calves.

Another common problem in these calves was mycoplasma. We were able to culture this pathogen from animal deaths. Mycoplasma is tough to treat with normal antibiotic regimes because it has no cell wall.

We recommend producers get new arrivals eating and drinking as soon as possible after arrival because they are nutritionally-stressed from drought and may have traveled long distances. We prefer high vitamin levels in receiving rations to help these deficient calves better respond to vaccinations.

Your veterinarian should be a valuable resource in feedlot and herd health protocols. They are able to post any deads, providing an accurate report on the cause of death. Together you can assess treatment and revaccination procedures to best eliminate health problems.

If BVD is an issue, you may need to individually test complete pens of cattle for PIs to eliminate viral shedding. If you have a cow-calf herd, or purchased southern cows and calves or feedlot calves, you may have inadvertently put your herd in a compromised position. Exposures to BVD and mycoplasma from purchases can infect the herd even if spring vaccinations were administered. Visit with your nutritionist, extension specialist and veterinarian to minimize further problems and keep your operation functioning at full potential.

Go back to article