Bob Judd, DVM, DABVP (Equine Medicine), DABVP (Canine and Feline Practice)
Fetal loss is a major concern in the beef and dairy cattle business. Checking the viability of the fetus is something your veterinarian can do.
Dr. Andrea Lear, DVM, Ph.D., DACVIM-LAIM, of the College of Veterinary Medicine, University of Tennessee, says in the publication Bovine Veterinarian that fetal viability is a combination of two things. First, how is the baby doing during the pregnancy, and second, what is the likelihood the baby will survive outside the uterus?
A study done two years ago found that the rate of embryonic death and fetal mortality in beef cattle in the United States was 5.8%, which is less than the 10-20% reported in dairy cattle.
Any pregnant animal that has gone through stress, such as transport, or is suffering from a disease, could be susceptible to losing the fetus. Any animal that is pregnant due to in vitro fertilization or other alternative methods of fertility is more likely to suffer challenges. These embryos are also more valuable due to the difficulty in establishing the pregnancy, so these are the animals you certainly would like to watch closely for signs of problems.
Although checking progesterone levels of the cow is available, it is not very effective in determining the health of the fetus. A rectal exam is used to evaluate the fetus, but ultrasound is much more accurate as you can examine the placenta, the calf’s heart rate, and the volume of fetal fluids.
Fetal heart rate in beef cattle normally decreases from almost 200 beats per minute at 2 months of gestation to just a little over 100 beats per minute before calving. There is a test for pregnancy-associated glycoproteins (which are molecules that consist of a carbohydrate plus a protein) and the higher the level, the healthier the pregnancy. The lower the number, the more the likelihood of the death of the fetus.
Cloned calves typically have higher values of pregnancy-associated glycoproteins as they usually have larger placental areas compared to traditionally conceived calves.