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April 9, 2018 Pregnancy Losses in Beef Cattle

Dates to Remember

April 12                      Soil Conservation District Meeting
April 23                      Youth for the Quality Care of Animals Training (4-H)
May 8, 15, 22              Caring for Kids, Mandan

Spring calving is underway for most producers in Morton County and around the state. It’s a great feeling to return to the calving barn to check on things and see a fresh calf nursing and see healthy calves hopping around on the straw. On the other hand, it’s tough to lose calves too.  While I haven’t gotten wind of it in our county, a number of producers in other Western counties are reporting higher calf death loss than normal with causes that include late-term abortions or stillbirths. In the piece below, Janna Kincheloe, Area Extension Livestock Specialist and Gerry Stokka, Extension Veterinarian share some ways to identify the cause of pregnancy loss in beef cattle and how to prevent loss in the future. Please be reminded that if you are experiencing death loss above normal rates, you may qualify for assistance through the Livestock Indemnity Program through the Farm Service Agency.

Pregnancy losses in beef cattle
There are three categories of pregnancy losses in beef cattle: early embryonic death, abortion, and stillbirth.  Early embryonic deaths are those that occur within the first 42 days of gestation.  After that point, losses are considered abortions.  Abortion involves the expulsion of a dead fetus prior to approximately d 270 of gestation, while stillborn calves include full-term calves that are either born dead or die within the first 24 to 48 hours after birth.  In a 2007 survey of beef cow-calf producers across the nation, USDA-APHIS reported that 2.9% of beef calves were stillborn.  Within a herd, a single stillborn calf may not be regarded as significant.  However, investigation may be warranted when several stillbirths occur within the herd.  The reasons for these losses are complex and not always easy to diagnose; however, some common causes of losses include dystocia, nutritional deficiencies, and infectious diseases.   

Dystocia or calving difficulty can result if calves are too big or do not exhibit normal presentation in the birth canal.  Stress and lack of oxygen during calving can result in stillborn calves; however, these losses are often attributed to other causes.  Dystocia and stillbirths are more likely to occur in first-calf heifers due to small pelvic area and/or in cows that are either overly conditioned or too thin. Protein and energy requirements increase by 15-20% during the last trimester of gestation. Inadequate nutrient intake in the cow may result in breakdown of fat and muscle stores and loss of body condition which can result in calving difficulty. Heifers should have obtained at least 85% of mature weight and have a body condition score of 6 at calving, while mature cows should calve in a condition score of 5.  Over-conditioned females may have accumulated fat in the pelvis which can limit space in the birth canal.

Proper vitamin and mineral intake is essential for placental and fetal development.  In particular, deficiencies of selenium, iodine, manganese, and vitamins A and E may result in abortion.  Although often ofterlooked, some abortions in late pregnancy may be due to injury or extreme stress.  The fetus is well protected from trauma to the cow by the fluid-filled uterus; however, pain or inflammation following maternal injury can cause stress and trigger release of hormones in the body that may initiate premature labor.  Other stressors include immune challenges, nutritional deficiencies as described above, and environmental factors such as wind, cold, rain/snow, etc. 

Infectious diseases caused by bacteria, protozoa, and viruses are often a cause of abortions and/or stillbirths in cattle.  Bacterial diseases include brucellosis, leptospirosis, and vibriosis, all of which have vaccines to reduce the risk of losses.  Diseases such as trichomoniasis, sarcocyctosis, and neosporosisare caused by protozoa and can be more difficult to manage since vaccines are either unavailable or may be ineffective. Common viral diseases include BVD (bovine viral diarrhea) and IBR (infectious bovine rhinotracheitis).  Vaccines to prevent losses due to IBR and BVD are available and effective; however, it is important to always follow label directions when using MLV vaccines in pregnant cows as off-label use may result in abortions.  To avoid this problem, producers should vaccinate cows when they are not pregnant or consider using intranasal or vaccines labeled to be used in pregnant cows. 

Laboratory diagnosis of disease issues that contribute to calf losses can be difficult because the infectious agents are often undetectable in tissue or blood samples.  The placenta is often key to obtaining a diagnosis; therefore, it is very important to submit the placenta in addition to the fetus itself whenever possible. Prompt identification of aborting cows and isolation from the herd is recommended to help prevent the spread of infectious diseases if applicable.  It is also helpful to have cows isolated in case blood samples from aborting cows are needed to try to identify abnormalities in blood mineral levels and/or titers for infectious diseases. When collecting aborted fetuses and tissues for analysis, be sure to use appropriate biosecurity measures such as latex gloves and a mask to avoid diseases that can be passed from livestock to humans.  The fetus and placenta should be placed inside a black garbage bag and kept cool until arriving at the laboratory.  Avoid freezing unless the fetus and/or placenta were already frozen when found. 

When trying to determine the cause of abortions, it may be helpful to estimate the age of the fetus based on size.  One standard measure used to do this is the crown-rump length, which is a diagonal measurement from the head to the tail.  A bovine fetal age calculator based on crown-rump length is available at: http://www.ansci.wisc.edu/jjp1/ansci_repro/lab/female_anatomy/crown_rump_calculators.htm. It is important to remember that each calf loss should be investigated individually as well as evaluating the situation on a herd level because there are so many potential causes for stillbirths and abortions. Additional factors that should be considered when trying to determine the cause of losses include the following: 

*Nutrition of the cowherd (feed analysis, mineral supplementation program, potential toxicities/deficiencies, etc.) 

*Age and parity of the cow

*Vaccination program (types of vaccines used, when administered, etc.)

*Body condition score of cows at calving

*Length of calving, calving difficulty, and whether or not assistance was used

*Presence of any visible abnormalities in the calf

*Cloudy eyes in the calf indicating it has been dead for several hours

Although diagnosis is not always possible even with necropsy or laboratory analysis, sample submission to the NDSU Diagnostic Laboratory is encouraged if abortion rates are in excess of 1-2%.  Producers should work closely with their local veterinarians for assistance and advice with diagnosis and future herd health and vaccination strategies to minimize losses.   

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