FUTURE FOR IVF(IN-VITRO FERTILIZATION) IN COMMERCIAL DAIRY CATTLE
Compiled & shared by- DR RAJESH KUMAR SINGH, JAMSHEDPUR
DR RAJEEV KUMAR, SCIENTIST, ICAR
Technological advancements are credited with helping the dairy industry propel itself into a modern era of efficient production, striving to attain the ability to provide food for an ever-growing world population.
From on-board tractor GPS navigation units being utilized for planting crops to robots that are now feeding calves and milking cows, evidence of modern technologies are visible in many aspects of commercial dairies.
Incorporating advanced reproductive technology programs into the herd health management on dairies can greatly enhance the genetic basis of the herd, which ultimately leads to an increase in profitability.
Cattle genetics are no longer just a focus for the registered breeder
Registered cattle breeders are known for their deep devotion to dairy cattle genetics and passion for analyzing pedigrees.
Their goals are to constantly enhance each generation while striving to make increasingly better cows that will produce more milk, hold their type and live longer. Should the goals of the commercial dairy producer be any different? Not really.
A cow that makes more milk, breeds back sooner and holds her dairy type is a profitable cow on any dairy. Her genetics should be propagated to make more daughters similar to her – and the fastest way to achieve this is through advanced reproductive programs involving embryo transfer and in-vitro fertilization (IVF).
The average cow will only produce a few, if any, female offspring in her natural lifetime. Embryo transfer and IVF programs can potentially allow for one genetically superior cow to produce 10 to 25 (and sometimes even more) female calves within one year.
An objective currently utilized by some commercial dairies is to flush and IVF the top 10 percent of their cows. Embryos from these cows are then placed into the dairy’s heifers.
Due to the fact that heifers have not yet proven themselves for their dairy potential, it can be advantageous for them to carry calves from proven valuable milking cows.
Ultimately, genetic gain in the herd should intensify at a faster rate because an increasing proportion of calves would be coming from the farm’s best cows.
What is IVF?
IVF is an advanced reproductive technology that is slightly more complex than the traditional embryo transfer flushing program. During IVF, a veterinarian will use an ultrasound-guided needle to aspirate follicles off of a cow’s ovary through the vaginal wall.
A vacuum system is used to recover the contents of each follicle, including the important oocyte. Once all the follicles are aspirated from the cow’s ovaries, the fluid is taken to a lab and a microscope is used to identify the oocytes.
The recovered oocytes are washed and placed into a special media that will allow them to mature for 24 hours. Once they have matured, the oocytes will be fertilized with semen and the resulting embryos placed in an incubator for an additional seven days.
Following this time, the embryos can be transferred into recipient animals that are approximately seven days post-heat, similar to traditional embryo transfer programs.
IVF was once thought of as a salvage procedure, performed as a final effort to create calves from an infertile donor. This is no longer the case.
Many producers have realized the benefits of IVF programs and choose to primarily enroll reproductively healthy cows and heifers in their advanced reproductive rosters.
The differences between a conventional MOET programme and IVF
MOET
• Starts with the donor cow receiving hormonal treatments, to encourage the production of multiple eggs.
• The cow is inseminated after showing a standing heat and her embryos are flushed from the uterus a week later, before being transferred fresh into recipient females, or frozen in liquid nitrogen for future transfer.
IVF
• Promotes high egg production, but it uses unfertilised eggs which are collected from the donor and transferred to a laboratory.
• The donor cow is given an epidural anaesthetic, with an ultrasound vaginal probe carrying a guided needle used for egg removal. This process is known as ‘ovum pick-up’ (OPU).
• The eggs are matured and fertilised 24 hours later, spending a further seven days in an incubator. The machine is designed to mimic the embryo’s natural environment, in terms of growing media, temperature and humidity.
What are the advantages of IVF?
IVF offers many advantages to dairy producers over conventional embryo transfer programs. A large variety of calves can be attained in a very short time frame.
Oocyte aspirations can occur on a donor cow every two weeks, and a different bull can be used to fertilize her oocytes for each collection.
These types of aggressive IVF programs can result in 50 or more calves produced from one cow within a year. This is double the calf production achieved in conventional flush programs.
Producers are able to start their donors on IVF programs as early as prepubescent heifers around 7 months old. Additionally, since IVF does not involve the uterus, pregnant donors can still be collected throughout the first trimester of pregnancy.
This allows producers to breed genetically valuable donors on time while still capitalizing on creating additional offspring.
Conventional flushing often requires the use of two to three units of semen for each flush session.
Since oocytes in an IVF session are fertilized in a microscopically controlled environment, significantly less semen is needed.
In fact, one unit of semen can be used on the recovered oocytes from up to 12 or more donors.
Additionally, if a donor cow produces a large number of oocytes during a collection, they can be split into different groups and fertilized by different bulls.
This allows for the opportunity for greater genetic diversity resulting from one cow.
The average consumer is growing increasingly aware of shots and hormones administered to dairy cattle. It may be likely that hormone administration will become more heavily scrutinized and regulated by the laws in the future. IVF has an advantage in that it can be done with fewer amounts of hormone shots and can even be performed unstimulated.
The era of genomics and how IVF can be used on a commercial dairy
The word “genomics” has become a hot buzzword within the industry. It is a genetic tool gaining favor with many, while causing much skepticism and doubts in others.
For those who are firmly on board with genomics, the potential for even quicker genetic advancement on the dairy is thought to be possible.
The concept of genomics allows for genetically superior animals to be identified as young calves through DNA testing. Once these animals reach puberty, they can be started on an intensive IVF program.
The resulting embryos from these genetically superior heifers can be implanted into the genetically inferior heifers, resulting in a majority of the calves in the subsequent generation having a greater genetic value.
For those who still believe in making a cow prove herself, regardless of what the DNA test says, IVF can be utilized in other manners. Producers can analyze their current milking cows for what traits are important to them.
They can pick the cows that they feel are genetically valuable and choose to enroll those cows in an IVF program. The resulting embryos can be placed into other cows and heifers.
Additionally, it has been shown that conception rates for embryos in cows during times of heat stress are better than traditional breeding.
Transferring frozen embryos from conventional flushing during times of heat stress may help improve conception rates during the times that it is hardest to get cows to settle.
Is IVF economical, and does it pay?
It’s no secret that IVF technology can get expensive, especially with costs that typically double that of traditional embryo transfer flushing. However, the costs of IVF programs need to be analyzed on a long-term basis.
Similar to building a new freestall shed or updating a parlor, these projects are typically not paid for instantaneously – rather they are offset by the overall long-term improvement of the cows on the dairy.
IVF programs allow for the greatest genetic progress in the shortest amount of time. Decreasing generation intervals serve to improve the genetic base of the herd, which will result in more milk with greater components and a cow that ultimately lasts longer in the herd.
No matter what your formula is for defining a “genetically valuable cow,” the genetic basis of your herd improves with your selection intensity, defining what is important on your dairy.
