Faster horses
Well-known member
I read this information in Cattle Business Weekly and thought it was too important not to share. I've always been steadfast that we use killed vaccine (Virashield) but there has been a big push to use MLV. This article is on page 8 of the May 29th issue.
I'll try to shorten it up and just post the highlights of the article.
In 2004 some MLV vaccines got the green light for use in pregnant animals, but recent research by university researchers and veterinarians demonstrated that MLVs can put pregnancies and conception rates at
risk, unlike their INV (inactivated vaccine) counterparts.
Researchers reported that MLVs can have a detrimental effect on reproduction, resulting in abnormal estrous cycles, reduced conception rates and potentially, abortions.
Two articles published in peer-reviewed scientific journals to support these findings; raising questions about using MLVs in breeding females and naïve heifers.
U of WYOMING HERD EXPERIENCES 25% CALF CROP LOSSES
Animals in the UofW had been appropriately vaccinated prebreeding with a MLV and they were vaccinated again at about 7 months of pregnancy. Starting around 30 days of postvaccination, a series of abortions began which continued out to about 50 days. The total reproductive loss was a disturbing 25%.
They found even though they followed the label directions, the heifers had classical lesions caused by IBR and there was no evidence of any other
causes of abortion in the animals.
SDSU Study: Abnormal heats, Lower conception rates.
Producers believe that IBR is just a respiratory disease, but the virus has an important role as a pathogen in the reproductive tract. They discovered a modified live IBR vaccine affected conception rates in cattle. They found that MLV is more likely to get into the bloodstream than a field strain, affecting follicle development and estrogen level in heifers. In the trial heifers given MLVs experienced more abnormal estrous cycles and lower pregnancy scores.
DAIRIES DRAMATICALLY IMPROVE HERD REPRODUCTION WITH INACTIVATED VACCINES
Dr. Doug Scholz DVM, director of vet services for Novartis Animal Health,
points to two large dairy operations in Co. that were frustrated by low conception rates and high pregnancy losses. Heifers in both herds got three or four doses of a five-way IBR MLV.
Their abortion rates regularly exceeded 20% and would jump to 25-35% at any given time. Diagnostic tests indicated high IBR titers in blood samples. In another test, a university diagnostic lab confirmed IBR virus in aborted fetus. Once both dairies replaced the IBR MLV with ViraShield (trademark),
an inactivated vaccine, there were dramatic Improvements in the conception and pregnancy rates.
Dr. Clinton Jones, a virologist at the Uof Nebraska, explains that vaccination with an IBR MLV may create problems for reproduction. Like field strains of IBR the vaccine strain has the potential to reactivate from latency following a stressful event or immune suppression.
MLVs, if reactivated, are likely to enter the blood system and cross the placenta. The IBR virus prefers actively growing tissue, which is characteristic of a developing embryo. Jones worries that the cow vaccinated with a MLV has the ability to infect others in the herd by shedding IBR virus. He says the most important thing about managing IBR and MLVs in herds is that one should NEVER vaccinate a pregnant cow with MLV.
Dr. O'Toole sums it up saying "if you are going to vaccinate animals for IBR
use an inactivated vaccine. Inactivated vaccines are very safe and have a good track record in terms of efficacy. There is no reason to risk using a MLVB in pregnant cattle."
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Like I said, I just hit the high spots. I left out some Drs. names but they all can be found in the article. They also talked about using MLV's in naïve heifers. A friend of ours has started vaccinating his replacement heifers with MLV IBR in the spring the last three years and since then has had a noticeable difference in more heifers not being bred. I showed him this article, forgetting that he has had problems with those heifers getting bred of late and he brought it up. Hopefully that is the missing link and he can
change his procedure which will make a difference. Time will tell.
Hope this helps!
I'll try to shorten it up and just post the highlights of the article.
In 2004 some MLV vaccines got the green light for use in pregnant animals, but recent research by university researchers and veterinarians demonstrated that MLVs can put pregnancies and conception rates at
risk, unlike their INV (inactivated vaccine) counterparts.
Researchers reported that MLVs can have a detrimental effect on reproduction, resulting in abnormal estrous cycles, reduced conception rates and potentially, abortions.
Two articles published in peer-reviewed scientific journals to support these findings; raising questions about using MLVs in breeding females and naïve heifers.
U of WYOMING HERD EXPERIENCES 25% CALF CROP LOSSES
Animals in the UofW had been appropriately vaccinated prebreeding with a MLV and they were vaccinated again at about 7 months of pregnancy. Starting around 30 days of postvaccination, a series of abortions began which continued out to about 50 days. The total reproductive loss was a disturbing 25%.
They found even though they followed the label directions, the heifers had classical lesions caused by IBR and there was no evidence of any other
causes of abortion in the animals.
SDSU Study: Abnormal heats, Lower conception rates.
Producers believe that IBR is just a respiratory disease, but the virus has an important role as a pathogen in the reproductive tract. They discovered a modified live IBR vaccine affected conception rates in cattle. They found that MLV is more likely to get into the bloodstream than a field strain, affecting follicle development and estrogen level in heifers. In the trial heifers given MLVs experienced more abnormal estrous cycles and lower pregnancy scores.
DAIRIES DRAMATICALLY IMPROVE HERD REPRODUCTION WITH INACTIVATED VACCINES
Dr. Doug Scholz DVM, director of vet services for Novartis Animal Health,
points to two large dairy operations in Co. that were frustrated by low conception rates and high pregnancy losses. Heifers in both herds got three or four doses of a five-way IBR MLV.
Their abortion rates regularly exceeded 20% and would jump to 25-35% at any given time. Diagnostic tests indicated high IBR titers in blood samples. In another test, a university diagnostic lab confirmed IBR virus in aborted fetus. Once both dairies replaced the IBR MLV with ViraShield (trademark),
an inactivated vaccine, there were dramatic Improvements in the conception and pregnancy rates.
Dr. Clinton Jones, a virologist at the Uof Nebraska, explains that vaccination with an IBR MLV may create problems for reproduction. Like field strains of IBR the vaccine strain has the potential to reactivate from latency following a stressful event or immune suppression.
MLVs, if reactivated, are likely to enter the blood system and cross the placenta. The IBR virus prefers actively growing tissue, which is characteristic of a developing embryo. Jones worries that the cow vaccinated with a MLV has the ability to infect others in the herd by shedding IBR virus. He says the most important thing about managing IBR and MLVs in herds is that one should NEVER vaccinate a pregnant cow with MLV.
Dr. O'Toole sums it up saying "if you are going to vaccinate animals for IBR
use an inactivated vaccine. Inactivated vaccines are very safe and have a good track record in terms of efficacy. There is no reason to risk using a MLVB in pregnant cattle."
------------------------------------------------------------
Like I said, I just hit the high spots. I left out some Drs. names but they all can be found in the article. They also talked about using MLV's in naïve heifers. A friend of ours has started vaccinating his replacement heifers with MLV IBR in the spring the last three years and since then has had a noticeable difference in more heifers not being bred. I showed him this article, forgetting that he has had problems with those heifers getting bred of late and he brought it up. Hopefully that is the missing link and he can
change his procedure which will make a difference. Time will tell.
Hope this helps!
