How can embryo transfer systems be maximized in industrial dairy herds

23 يوليو 2020
How can embryo transfer systems be maximized in industrial dairy herds

When doing something to scale, it's important to look for key points where you can optimize efficiencies to get the most value for your dollar

One of the advantages of operating a donor group within a large herd, is a larger pool of donor candidates from which to pick

Donor selection

Genomic testing is the first instrument to assess which females will have the greatest effect on the genetic potential of a herd. This figure usually ranges between 5 per cent and 10 per cent of the population anywhere

One screening factor to remember is the count of antral follicles, to really concentrate on being cost-effective. Antral follicle count is essentially the amount of follicles that are visible on the ovary using ultrasonography at any stage in its process (except for an estrus day). Although the count of antral follicles varies within a cow population, it can be replicated within an person and is positively correlated to the number of oocytes a donor will produce

Having your veterinarian scanning ovaries, and thus selecting the top half of potential oocyte producers, will significantly improve efficacy. The rate-limiting step in the equation of how many embryos can be produced is the number of oocytes with which the laboratory begins, thus this parameter helps eliminate the poor performers. Alternatively, count of antral follicles is somewhat heritable.Hence, on average, their daughters are more likely to produce more oocytes when choosing high-oocyte-producing dams

Treat your donors like donors

When the population has been chosen, per age donors will be housed in small groups at one venue. It would promote monitoring of their health and diet, as well as providing appropriate shots of the follicle-stimulating hormone (FSH). This will also make it easier to transfer them on ovum pickup (OPU) day into the collection area. If donor housing and labor distribution to handle donors on your dairy is not feasible, find a donor housing facility where dedicated workers will provide best care for the elite animals

Give them FSH

The positive effect of FSH has been published numerous times on oocyte numbers and the consistency. It has also been shown that stimulation and synchronization are important to gather a group of oocytes at the same developmental level. It gives them the best chance of becoming an egg, and potentially a child

Every year the American Embryo Transfer Association (AETA) gathers data on embryo development. Latest evidence indicates that dairy donors collected without FSH make up an average of 2.3 viable embryos per collection (47,018 donors collected) versus 5.2 when used with FSH (36,724 collected donors). And if you don't use FSH compared to a single set of FSH, you will have to find a donor and pay for the consumables and aspirator 2.3 times, and take more time to make genetic progress. It is obviously more effective to gather donors using FSH

Be flexible on sire selection

Many bulls, like donors, result in higher development of the embryos than others. IVF laboratories keep track of the development of embryos by bull, and this is typically repeatable. Ask your service provider for that information when selecting sires, and use it in your decision making process

Regardless of their genetic merit, avoid using below-average output bulls, as these choices would have a huge impact on how cost-effectively you can produce embryos. Some labs may also be able to check bulls on slaughterhouse oocytes before using them on donor oocytes to maximize efficiency, if a bull has not been used before

Recipient selection and setup

Once the donors are collected and the selection of sires is made, they are sent to the laboratory to produce embryos which will be transferred eight days after collection of donors. Much as with donors, very good animal treatment is important for ensuring optimum levels of pregnancy

Receiver synchronization doesn't have to be difficult, it can be as simple as a prostaglandin double shot. Instead, you might just continue utilizing the usual synchronization process that your dairy uses for A.I., but only keep those heats over as recipients rather than breeding

Embryo transfer

There are two choices once embryos are created: have them sent to your dairy for fresh transfer, or hold them in the laboratory for freezing for later transfer. For situations where there are more recipients than embryos available, having a frozen embryo bank to transfer is ideal. Nevertheless, fresh transfer embryos are usually less expensive to handle than freezing, and a higher number of embryos are approved for transfer versus freezing, making fresh transfer the more commonly used method on large dairies

Every transfer day an incubator arrives in tiny tubes of fresh embryos. The veterinarian will assign the embryos a grade and stage, and load them for fresh transfer into straws. Veterinarians who transfer these embryos operate alongside non-veterinary workers trained in embryo transfer procedures at certain major dairies

The American Veterinary Medical Association 's position on embryo transfer procedures states that they are a feature of veterinary practice due to the need for treatment, requiring pharmaceuticals and possible surgical use. It also notices that non-veterinarians will work under veterinarian supervision. Individual state activity, however, varies according to who may conduct collections and pass a and if a veterinarian’s supervision is required

Regardless of who carries out the transfers, a veterinarian, ideally one approved by the AETA, will supervise every embryo transfer programme