Embryo transfer in cattle is a great tool to allow a producer to get multiple calves per year out of only one cow. Embryo transfer is a great idea if you have an exceptional individual cow, but to be cost-effective, it must be successful and end up with a live calf.

Dr. Paul Fricke, Professor of Dairy Science at the University of Wisconsin, said in the publication Bovine Veterinarian that progesterone, a hormone released in the ovary, is the key hormone in the establishment and maintenance of pregnancy.

Increasing the concentration of progesterone can increase pregnancy rates and decrease pregnancy losses after embryo transfer. One method of increasing progesterone is to administer the hormone human chorionic gonadotropin or HCG. HCG binds to another hormone and can induce ovulation if used seven days after ovulation.

HCG can induce a structure called corpus luteum, a hormone-secreting structure, to form on the ovary, and this structure produces progesterone.

Dr. Fricke recommends giving HCG during in-vitro fertilization-embryo transfer scenarios because in vitro fertilization embryos are not normal and have higher rates of embryo losses.

In vitro fertilization is a technique in which fertilization takes place in a lab and not inside the animal, and this process is sometimes referred to as a "test-tube baby". By administering HCG, the recipient animals will have a higher ovulatory response due to the formation of an extra corpus luteum, and this increases progesterone concentration.

A recent study tested the use of HCG on three hundred Holstein heifers, with one-half of the group receiving the drug and the other half remaining as controls. Results showed that treatment with HCG did not increase the number of pregnancies per embryo transfer, but it did help to reduce the number of pregnancies lost by 50% between days 32 and 67 of pregnancy.