In Vitro Embryo Production: Technology that Came to Stay

In vitro fertilization (IVF), the process of fertilizing and growing cattle embryos in the lab, is not a new technology. 

Briefly, eggs (or oocytes) are harvested from cows: 1) through the use of a transvaginal ultrasound-guided needle (mostly used in cows with high genetic value – more expensive method); or 2) straight from the ovaries of cows sent to the slaughterhouse (a much cheaper method). Once harvested, these oocytes are brought to the lab and placed in solutions that mimic the uterine environment. This allows sperm to fertilize the eggs and the formed embryos to grow until transferred to recipient cows, roughly one week after oocytes were harvested from the ovaries. 

Although IVF technology is routinely used as an integral part of other countries" breeding programs, the commercial use of IVF in US dairy herds is still uncommon, but forecasted to increase in the future. In fact, in some areas of South America, more embryos are produced through IVF than through the more traditional method of super-ovulating cows and later flushing the uterus; I've personally been to dairy herds in which artificial insemination is no longer used and instead is totally replaced by IVF embryo transfer – obviously an extreme case. It is also true that one of the reasons why IVF became so popular in some countries is due to the fact that their cattle breeds (i.e. Nellore) can produce far more oocytes per collection than Holstein cows, making lab-production of embryos very efficient. However, in the case of breeds that produce less oocytes, efficiency of IVF can be significantly increased by pre-selecting donor cows with a greater population of ovarian follicles. These cows can be detected by either a single ultrasound exam or by measuring anti-Mullerian hormone (Souza et al., 2014). 

In practical terms, the more expensive ultrasound-guided IVF method could be used to spread genetics from heifers and cows of high genomic value to heifers with poor genomic tests. Alternatively, producers could also explore a cheaper method of producing high genomic value embryos by utilizing ovaries from a subset of their own cull cows on a weekly basis and, for example, fertilizing the oocytes from these cows with an outstanding sire – one straw of semen can fertilize as many as 500 oocytes or more.

*Souza, A., P. Carvalho, A. Rozner, L. Vieira, K. Hackbart, R. Bender, A. Dresch, J. Verstegen, R. Shaver, and M. Wiltbank. 2014. Relationship between circulating anti-Müllerian hormone (AMH) and superovulatory response of high-producing dairy cows. Journal of Dairy Science.