Using Reproductive Technologies for Genetic Improvements

 By Jaclyn Krymowski for American Cattlemen Magazine

 Do you have a plan in place to optimize the elite genetics of your herd? Or do you know what direction you’d like to take your breeding in, but have yet to build a roadmap of the fastest way there? The most basic principles of genetic selective have remained the same for as long as we’ve bred cattle. You breed the best of what you have, and always try to create something better than what you had before.

Today’s reproductive technologies follow this, but the big difference between now and then is the ability to amplify genetic excellence faster than ever before.  Many producers, especially in the seedstock segment, are taking advantage of these resources. As a result, the pursuit of elite genetics is an accelerating race,

ET
Embryo transfer (ET) is a procedure where a developing embryo is flushed from a donor and placed in a recipient. The ideology is very simple, pick your best animals and increase the number of offspring they provide you with per year. This way, each superior cow will produce a greater number of calves than she otherwise would throughout the span of her lifetime. This is a great way to allow the small top percent of your herd makes the fastest genetic progress. Additionally, embryos have the option to be frozen for years later.
The superovulation process makes a female ovulate more than a single oocyte. There are a variety of hormonal therapies to accomplish this. You will want to work with your ET technician to decide on a plan and schedule that works best with your plan. If you have a sizeable group you’ll be flushing at the same time, you will also need to make use of a timed-A.I. protocol.
As the time to flush approaches, you will want to keep your donors in optimal condition. Besides her genetic superiority, an ideal donor should be a prolific ovulator with regular estrous cycles and excellent conception and pregnancy records behind her.  
Additionally, your recipient animals will also have to be synchronized. However you have the flexibility of doing the transfer fresh, immediately after flushing or later with frozen embryos. These recipient females are nearly as valuable as your donors, they should also be in excellent health and prolific themselves with good calving and pregnancy records behind them.
With timed-A.I. techniques, hormonal therapies and an increasing availability of technicians, this process work can be integrated to most operations with minimal additional labor. But success does require competent and knowledgeable members on your reproduction team and some thought ahead of time.

IVF
In-vitro fertilization is another way to utilize your superior females. It can also pick up some of the animals that won’t work for ET. For example, virgin heifers can still be aspired and collected for IVF. Animals that are unable to maintain or accept a pregnancy can also benefit from this method. Additionally, this procedure can be done much more frequently than ET, as much as weekly or biweekly on a single animal. In fact, with IVF, a producer can make as much as four times the genetic impact compared to using ET.
This procedure involves taking the oocytes from an animal and fertilizing them in a lab. Because the oocytes are more sensitive, they are less fertile than ET and require an air-controlled facility to be collected.

Comparison
In either ET or IVF, you will want to use sexed semen. While this raises your up-front cost, it also increases the value of the pregnancy. If you have genetically elite animals, you can use this as a marketing tool when you ship, sell and trade your embryos. Freezing allows, virtually, entire herds worth of embryos to be shipped from coast to coast at a reasonable cost for buyers and sellers. If you are on the other side and looking to expand your genepool, investing in embryos can be a great inexpensive way to increase diversity in your herd if you have a supply of capable recipient animals.
Other disadvantages include the significantly lower success rate than traditional A.I.
In the case of ET, the embryos are fairly hearty and don’t require a specialized environment to be flushed and transferred. Because there is less “tampering” the procedure is more likely to result in a live calf. With the oocytes, IVF aspiration must be done in a sterile temperature-controlled environment and handled with extreme care.
Regardless of what reproductive aids are most convenient for you, knowing what to make the best of can help you make long strides with the animals you have.  Remember, no amount of monetary investments or the highest quality technicians helping you can replace knowing your animals and knowing your goals. Before expanding your breeding program, be sure to have identified your best animals, the goals for your future replacements and the market for your offspring.