In Vitro Fertilization
In Vitro Fertilization – What is it and Why use it?
The impact cattle genetics has on enhancing the value of a cow or cow herd has become an important focus for many producers. Genetics set the potential for the upper and lower levels of production limits an animal can achieve. Depending on the specific needs of an operation, genetic improvement allows for the producer to improve the herd’s overall contribution to enterprise profit, in addition to herd management practices and reducing operational costs.
The needs of a breeding program differ from one herd to the other and depend on the goals identified by the operation. As a result, it’s important for producers to be aware of the reproductive technologies available to them and understand how each can be used to support their desired goals. While many producers are familiar with embryo transfer (ET), in vitro fertilization (IVF) is gaining in popularity as a unique tool that can drive herd genetics to the next level, multiply the success of a breeding program in a short time frame, and ultimately lead to increased profitability.
An increasing number of breeders are implementing IVF into their reproductive programs, so what is it? IVF is the process of harvesting unfertilized oocytes, or unfertilized eggs, directly from the ovaries of a donor cow or heifer. Recovered oocytes are fertilized 24-hours after aspiration (or collection) and transferred into recipients seven days later. Over this eight-day period, the oocytes are cultured and grown in an incubator and controlled environment to match the conditions of a cow’s uterus. They are transferred into the recipients seven days after estrus (or standing heat). There are a number of advantages to using IVF within a breeding program.
Donor IVF collections can be performed every two weeks, whereas ET collections take place every 60-days. IVF technology retrieves approximately 20 oocytes per collection. On average, 30 percent will develop into viable embryos, resulting in four-to- five grade-one and grade-two embryos. Semen from several different bulls can be used to fertilize each of the retrieved oocytes or can be used to fertilize oocytes from several different donors. This offers greater opportunity to achieve genetic diversity from collection on a single cow. IVF helps maximize the value of rare, sexed, or expensive semen, as it requires only one unit of semen compared to ET that usually requires the use of two to three units of semen per donor.
IVF is a reproductive technology that allows breeders to produce offspring from open cows, pregnant cows, virgin heifers, and females that have historically had difficulty responding to conventional breeding attempts, such as ET. In rare cases, it is even possible to retrieve oocytes from donors shortly after death for one final collection. Breeders often start their donors on IVF programs at 10 months of age and can collect on pregnant donors throughout their first trimester (until day 100-120), after that period the ovaries cannot be reached. Within the average cow’s natural lifetime, she will produce only a few females, if any. Breeders that utilize IVF technology have the prospect to obtain more offspring from valuable females in their herd.
For those considering implementing IVF technology within their breeding program, it is important to be aware of not only the advantages, but also limitations. The technology has a slightly lower average in embryos produced per collection. For this reason, IVF may offer a more cost-effective solution when it comes to low embryo-producing donors that operations are looking to keep in the production cycle. IVF has slightly lower pregnancy rates when compared to ET: averaging 6-7% disadvantage on embryos transferred fresh and 10% disadvantage on embryos that were frozen and then transferred. IVF collections require a well-developed skill set, which makes working with an experienced professional very important. IVF protocols are still being developed in some countries, which creates the potential to run into red tape on exports in countries where IVF protocols are not in place. In addition, it is commonly known that IVF technology can get expensive, however, the costs need to be analyzed on a long-term basis with the overall projected improvement of the herd. While the cost of the technology is higher than that of ET, it offers breeders another option.
IVF technology is a powerful tool that is becoming more widely used in breeding 8programs, especially in operations looking to maximize the impact of their most valuable cows, or to quickly increase their herd size. While the technology may not be for every breeder, or for every cow even, it has the potential to do great things. It is important for breeders to be aware of the reproductive technologies available to them and understand how each can be used to support their desired outcomes and meet the needs of their operation.