In the beef and dairy industries, technologies such as drawing blood for pregnancy detection are gaining in popularity. With this increase in use, many adopters of this technology are looking to maximize their efficiencies by performing as many tests as they can using the same blood sample.
Using these samples for more than one test has the potential to provide their management team with more information, allowing them to make management decisions with an increased amount of background information.
Blood drawn for a pregnancy test can be used to determine many things outside of pregnancy status, such as disease status in dairy cattle.
This article will describe some of the additional disease diagnostics available and can be performed using the same blood sample drawn for blood-based pregnancy testing.
A producer also needs to keep in mind that there are numerous components of a disease control surveillance program and veterinary consultation is essential before any program is initiated. Additionally, any test results should be discussed with a veterinarian before a decision is made to sell or retain animals.
Disease diagnostics
Neospora
The parasite Neospora caninum is becoming increasingly recognized as a cause of reproductive failures in dairy and beef cattle. This parasite can be found throughout the U.S. in populations of wild or domestic canines.
Canines are one of the original hosts for the Neospora parasite, and once infected, they shed large numbers of oocytes in their feces. These feces then can contaminate many things such as feed commodities, water sources and pastures, etc.
One common site of contamination on an operation is feedstuffs or commodities. When a contaminated feed is ingested by an intermediate host, such as cattle, they become infected with the parasite.
Neospora causes the female to abort mid-gestation (ranging from 3.5 to eight months). Prior to the abortion, a female typically does not display any clinical signs of an infection.
Diagnosing Neospora- infected cattle can be done by simply testing serum for virus-specific antibodies. Visit the USDA's website for more information about Neospora.
Bovine viral diarrhea
Bovine viral diarrhea (BVD) virus is a disease that affects both dairy and beef cattle. There are many ways that this disease can economically impact a dairy operation. Some of the effects include a loss of milk production, increased number of open animals, increased respiratory disease and other reproductive failures.
The BVD virus can be transmitted by an animal breathing in or ingesting the virus, making it a disease that is very hard to control exposure to. One of the largest economic losses comes when a cow is infected with the BVD virus between 42 and 125 days of gestation.
In utero, the unborn calf is infected with the virus and will never be able to overcome the disease. This calf is then born persistently infected (PI) with the disease and is continuously shedding the virus.
This also ensures the survival of the disease because the PI animal is constantly infecting other animals with the disease transiently (for a period of time), some of which are pregnant females in the afore-mentioned stage of pregnancy.
Many producers assume that these animals are recognizable, but many PI animals are very normal and can become pregnant and continue to produce other PI animals.
Diagnosing BVD can be done by testing a serum sample for virus-specific antibodies.
Johne’s
Johne’s disease, or paratuberculosis, is a contagious, chronic and usually fatal infection that can affect all ruminants. Most animals infected with Johne’s contracted the disease in the first few months of their life.
One of the most common methods of infection is swallowing small amounts of infected manure or from the udder of the dam. In most cases, signs of the disease do not appear until two or more years after infection has occurred.
More research is needed to understand what causes an animal that has been infected by Johne’s for an extended period of time to suddenly become sick from the infection.
In cattle, there are two signs to watch for when monitoring for Johne’s disease. They are rapid weight loss and diarrhea despite normal feed and water intake. To test for Johne’s, a serum sample is tested for virus-specific antibodies.
Visit this website for more information on Johne’s disease. This website is maintained by the University of Wisconsin School of Veterinary Medicine and is a great resource.
Bovine leukosis
Bovine leukosis (BLV) is a virus that infects beef and dairy cattle. This virus targets parts of the immune system. Infection with this virus most often does not cause any clinical signs.
Economic losses from this disease may include increased replacement costs due to reduced reproductive efficiencies, loss of income from condemned carcasses of cull cows infected with the disease and reduced milk production.
Signs of the disease can become visible when tumors begin to invade different tissues. Such signs may include weight loss, decreased milk production, enlarged lymph nodes, loss of appetite, rear-limb weakness and other signs.
Diagnosing BLV-infected cattle can be done by simply testing serum for virus-specific antibodies. Visit the USDA’s website to learn more about BLV.
If you use blood testing to check cows for pregnancy status, don’t overlook the additional information that can be gained from further disease testing. A sudden drop-off in pregnancy rates could be an indicator of potential disease problems.
Blood can be drawn from heifers and cows and tested for pregnancy at 28 days or later, after breeding, and cows must be at least 73 days post-calving. PD
Jeremy Howard is a reproduction specialist with BioTracking.
References omitted due to space but are available upon request. Click here to email an editor.
PHOTO
If you use blood testing to check cows for pregnancy status, don’t overlook the additional information that can be gained from further disease testing. A sudden drop-off in pregnancy rates could be an indicator of potential disease problems. Photo courtesy of BioTracking.
Jeremy Howard
Reproduction Specialist
BioTracking LLC
