Now is the time to plan for calving | TSLN.com

Now is the time to plan for calving

Dave Barz, DVM

For the Sept. 12, 2009 edition of Tri-State Livestock News.

Now that Labor Day has passed we are assured the summer is over. Most of the hay crop is gathered and the kids are back in school. It was a different summer as far as heat and precipitation went. I only hope the winter is not as wet and cold as the summer was. It may seem strange, because many of you still have bulls with your cows, but now is the time to plan your calving.

In recent years we have had many fertility problems in our area. We have tested for Trich and Lepto but have found no conclusive evidence. The only thing we see is extremely high BVD (Bovine Virus Diarrhea) titers. We pull a blood sample and send it to the SDSU diagnostic lab. They are unable to isolate BVD virus from the sample but when the antibodies to BVD I & II are measured, they are found to be very high. Researchers tell us that these levels are too high for the cows’ response to vaccination and could only develop after exposure to the virus. This means somehow the herds are exposed to wild viruses during the grazing season.

The scientific answer is somewhere there is an animal persistently infected with BVD in the herd. This is caused with a gestating cow exposed to BVD virus early in her pregnancy. The calf developing in the uterus becomes unable to develop any immune response to the virus. This calf is born dead, born weak, or born normal, but continually shedding BVD virus at high rates throughout its life. We tested all animals in the herds and have never found a PI in the thousands we’ve tested over the last five years.

Many of our clients vaccinate their cows with live virus products before breeding. In the past we have believed that this prebreeding vaccination gives us year long protection. Now we understand that these products only protect for months rather than the full year. Most protect long enough to prevent the PI from developing in the cow, but may not prevent the cow from having a later infection. The gestating calf may also be infected and result in a weak or dead calf. We also believe this is the reason we have fetal losses after pregnancy checking. In some of these herds 10-15 percent may not deliver a calf in the spring. The syndrome we see is poor initial breeding followed by failure of known pregnant cows to calf.

One solution for this syndrome is a second BVD vaccination at pregnancy check time. Not only will this help mid- and late-term calf infections, but it will also assure the cow produces colostrum high in BVD antibodies which will help protect the calf early after birth to BVD infections. Now we have several live BVD vaccines which can be used under certain circumstances in pregnant cows. We use a killed product in our normal preg test regime which gives us great titers for IBR and BVD. We are able to incorporate scour vaccines with this product and help prevent viral scours at calving. Our success has been excellent with these mid-gestation vaccinations.

Lepto hardjo bovis has also been a problem in our area. This organism is very hard to culture and we have not isolated it yet in our herds. The syndrome in these herds is very poor conception in first calf heifers and herd additions. We have used a combination of strategic vaccination and prophylactic antibiotics in these herds. Most herds have returned to above normal conception rates. We also must acclimate and vaccinate herd additions before they enter the herd.

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Reproduction is the driving force in an economically efficient herd. Live vigorous calves are a must for your herd’s future. Visit with your veterinarian to devise a vaccination and management program to carry your cows through gestation to calving. This will make things easier in the spring and reward you economically in the fall.

Now that Labor Day has passed we are assured the summer is over. Most of the hay crop is gathered and the kids are back in school. It was a different summer as far as heat and precipitation went. I only hope the winter is not as wet and cold as the summer was. It may seem strange, because many of you still have bulls with your cows, but now is the time to plan your calving.

In recent years we have had many fertility problems in our area. We have tested for Trich and Lepto but have found no conclusive evidence. The only thing we see is extremely high BVD (Bovine Virus Diarrhea) titers. We pull a blood sample and send it to the SDSU diagnostic lab. They are unable to isolate BVD virus from the sample but when the antibodies to BVD I & II are measured, they are found to be very high. Researchers tell us that these levels are too high for the cows’ response to vaccination and could only develop after exposure to the virus. This means somehow the herds are exposed to wild viruses during the grazing season.

The scientific answer is somewhere there is an animal persistently infected with BVD in the herd. This is caused with a gestating cow exposed to BVD virus early in her pregnancy. The calf developing in the uterus becomes unable to develop any immune response to the virus. This calf is born dead, born weak, or born normal, but continually shedding BVD virus at high rates throughout its life. We tested all animals in the herds and have never found a PI in the thousands we’ve tested over the last five years.

Many of our clients vaccinate their cows with live virus products before breeding. In the past we have believed that this prebreeding vaccination gives us year long protection. Now we understand that these products only protect for months rather than the full year. Most protect long enough to prevent the PI from developing in the cow, but may not prevent the cow from having a later infection. The gestating calf may also be infected and result in a weak or dead calf. We also believe this is the reason we have fetal losses after pregnancy checking. In some of these herds 10-15 percent may not deliver a calf in the spring. The syndrome we see is poor initial breeding followed by failure of known pregnant cows to calf.

One solution for this syndrome is a second BVD vaccination at pregnancy check time. Not only will this help mid- and late-term calf infections, but it will also assure the cow produces colostrum high in BVD antibodies which will help protect the calf early after birth to BVD infections. Now we have several live BVD vaccines which can be used under certain circumstances in pregnant cows. We use a killed product in our normal preg test regime which gives us great titers for IBR and BVD. We are able to incorporate scour vaccines with this product and help prevent viral scours at calving. Our success has been excellent with these mid-gestation vaccinations.

Lepto hardjo bovis has also been a problem in our area. This organism is very hard to culture and we have not isolated it yet in our herds. The syndrome in these herds is very poor conception in first calf heifers and herd additions. We have used a combination of strategic vaccination and prophylactic antibiotics in these herds. Most herds have returned to above normal conception rates. We also must acclimate and vaccinate herd additions before they enter the herd.

Reproduction is the driving force in an economically efficient herd. Live vigorous calves are a must for your herd’s future. Visit with your veterinarian to devise a vaccination and management program to carry your cows through gestation to calving. This will make things easier in the spring and reward you economically in the fall.