Today, there are many tools a dairy producer can use to influence the rate of genetic change and have lasting effects on the performance of their herd. Over the last decade, the use of assisted reproductive technologies (ART) has steadily increased.
Traditionally, ART technologies such as multiple ovulation ET and in vitro fertilization (IVF) have been used to increase the number of offspring from genetically superior animals. In the past, costs associated with the use of these technologies have been too high to implement on a large scale in commercial operations.
Recent advancements, however, have made these tools more economically feasible for implementation on a commercial dairy.
The use of ART programs has increased selection intensities and reduced generation intervals in the dairy industry. Also during this time, the accuracy and use of genomics has increased, allowing for more knowledge when making donor, recipient and breeding selections.
The combination of these technologies now allows the producer to identify genetically superior animals very early in the herd, and they are able to generate elite replacement females faster than previously possible.
The success of ART programs is highly dependent on the management of donor and recipient animals. There are many factors that need to be taken into account when managing these animals, and that requires a balanced approach developed by all members of the dairy’s management team, including the nutritionist, veterinarian, reproductive manager and others.
The ultimate goal of ART programs is to obtain as many high-quality oocytes and embryos from genetically superior females as possible that will result in the birth of a healthy calf. The success of these programs is highly dependent upon oocyte and embryo quality.
The nutrition plane an animal is on prior to and during oocyte or embryo collection has a major impact on their quality and ultimately the likelihood of pregnancy following transfer of the embryos.
As reproduction is not necessary for the survival of a cow, its efficiency is reduced when an animal is on a plane of inadequate nutrition. It is critical to the success of these programs that the nutritional needs of the donor are met but not exceeded.
Two of the most critical times for nutritional management are during transition and at puberty in heifers. During early lactation, cows that stay in a state of negative energy balance for an extended period can delay resumption of ovulation, leading to a reduction in the number of follicles on the ovary and reduced oocyte quality.
In the case of prepubertal heifers, a delay in the initiation of cyclicity can be observed, ultimately delaying the use of ART. Both of these situations ultimately delay the use of these programs to maximize the genetic advancement of the herd.
At any stage, it is important to monitor body condition. Over-conditioned females, particularly those that are non-lactating, may experience lower success rates with these programs.
2. Donor selection
When selecting a donor for your program, it is important to have your end goal in mind and develop a selection criteria that helps you achieve that goal. Some farms have developed their own indexes they use to select their donor animals.
After selecting your potential donors, it is important to understand there are additional factors beyond the genetic merit of the donor that will have an impact on the success of the program. One factor that needs to be taken into account is the age of the donor.
Age has an effect on the number of viable embryos collected from superovulated cattle or oocytes recovered when doing OPU. For example, virgin heifers tend to produce fewer embryos than mature cows.
3. Recipient selection and management
The way in which recipient females are chosen and managed significantly impacts ART success. Proper selection of recipient animals can increase the likelihood of having good conception rates following embryo transfer. As a general rule, much like in A.I., conception rates of embryo transfer are higher in heifers than in mature lactating cows.
In lactating cows, initial selection criteria includes parity, age and body condition. Further cuts will need to be made based upon other factors such as cyclicity status, presence of cystic ovaries, retained placenta, reproductive history and lactation number.
In general, you want to select a pool of recipients that have the highest likelihood of staying in the herd for the length of gestation and establishing a viable pregnancy.
It is vitally important for the success of the program that these animals be on a proper plane of nutrition prior to transfer of the embryos and after to maximize the likelihood of a pregnancy going to term.
4. Protocol compliance
Your service provider for multiple ovulation ET and IVF will have a protocol developed for managing the estrus cycle of both your donor animals and recipients. It is vitally important this protocol be followed to the letter. Failure to do so will have a negative effect on your program.
It can result in reduced response and lower oocyte or embryo production in response to the protocol. This will result in an increase in costs per embryo and per live calf.
Technologies such as multiple ovulation ET and IVF can be used to increase efficiencies of production in dairy operations, but their success requires paying additional attention to detail with donor and recipient animals. As with any change on an operation, a cost benefit analysis should be performed before making the change.
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