25. Cattle improvement (ET, OPU and IVF)
In order to improve the livestock, the daughters of the best cows are kept for further breeding. But cows deliver only one calf each year and half of these are bull calves. On average, dairy cows are only kept on the farm up to approx. their fifth year and can produce four calves during that time. And so on average, a cow produces only two daughters. Improving the stock in this way is a slow process: it will take years and years to make any significant progress in terms of the hereditary qualities of the livestock regarding, for example, how many litres of milk the animal can produce and the protein and fat content of the milk.
Embryo transplant (ET)
Once a cow has been covered by a bull or after the bull’s sperm has been inserted into the cow (the cow has been artificially inseminated), her Fallopian tubes contain millions of sperm cells. If an egg-cell is then released from the ovary into the Fallopian tube, one of the sperm cells penetrates the egg-cell. This fertilization marks the start of the development of the embryo, that gradually reaches the uterus through the Fallopian tube. In cows, this 'journey' takes three days. Upon arriving in the uterus, it lodges in the uterus wall. Before the embryo attaches itself there, it can be rinsed from the uterus and transferred (transplanted) to some other cow, a so-called surrogate mother or recipient. This is called an embryo transplant (ET). Afterwards, the donor-cow can once again become oestrous and be inseminated again. The best cows can produce more than one calf per year in this way. Surrogate mothers are the less productive animals and they do not have offspring of their own in this way. ET therefore accelerates the selection of the better production animals. It has been applied on Dutch dairy farms since the beginning of the eighties.
The number of calves from a donor cow can be considerably increased even more by treating her with hormones before the ET procedure. The hormonal cycle of cows normally lasts three weeks. This means they are oestrous once every three weeks and one egg-cell is usually released from the ovary during the ovulation. But if the cow is treated with hormones during her cycle, it is possible to have ten to twenty egg-cells released during the ovulation. This is called a super ovulation. The donor-cow is inseminated two or three times and all of the embryos are rinsed from her uterus a week later. They are then retrieved from the rinse water under a microscope and some are immediately placed in the uterus of the surrogate mothers; the rest of the embryos are frozen in liquid nitrogen and will be implanted in surrogate mothers later on.
Ella 17 is a large studbook-cow with a lovely udder and good production results. The Ella-stock is the pride of the farm. But this Ella has only one daughter: Ella 18. All of her other calves were bull calves. Improving the stock on the farm is not going anywhere. The farmer therefore requests embryo transplants at the AI-association. It provides the sperm for the Artificial Insemination (AI) and the scenario for the ET. It specifies the days upon which Ella 17 is to be injected with hormones for the purpose of inducing the super ovulation. Four days later, she is fiercely in heat and is inseminated three times with the sperm of a top-notch bull. Her uterus is rinsed out a week later. The rinse water contains eleven embryos. Of these, four are immediately implanted in surrogate mothers and the remaining seven are frozen for later use. But of these four surrogates, two become oestrous again a few weeks later. This means that their gestation has ended because the implanted embryos have died. The gestation of the other two progresses as hoped. One by one, the seven frozen embryos are thawed and implanted in surrogate mothers. The gestation of these mothers also passes off smoothly. Two calves are born nine months after the first successful embryo transplants. That number gradually increases to a total of nine: five heifer calves and four bull calves. The AI-association purchases two of the young bulls: their ancestry is excellent and if they mature well and meet all of the requirements, they will become new sperm suppliers for the association. One of them actually goes so far as to become an AI-bull. He became so popular among breeders after one daughter became Dutch national champion at the studbook inspection that the demand could no longer be met, not even with forty-thousand doses of his sperm.
five daughters born via ET: Ella 19 through 23
Ovum pick up (OPU)
The transplant of embryos is still practiced on Dutch dairy farms in 2015. But now there is an even quicker way to improve the stock. A farm that is specialised in breeding techniques purchases a few hundred yearlings around the country from the very best breeding lines of the studbook. As many egg-cells as possible are collected from these young female animals by means of ovum pick up (OPU): each follicle in the ovary is pricked through the vaginal wall and the egg-cell (ovum) is sucked out (picked up). This procedure is carried out using a local anaesthetic and is guided by an echogram. Each procedure yields an average of eight to ten egg-cells from each animal. The yearlings are pricked twice a week untill a total of fourty or more usable egg-cells are obtained. All in all, bringing the grand total of all yearlings to a few thousand egg-cells containing high-quality hereditary qualities.
In vitro fertilisation (IVF)
Each egg-cell is placed in a separate test-tube to allow for further maturing (for a day), after which a drop of bull sperm is added for fertilisation purposes. Test-tube fertilisation is referred to as in vitro fertilisation (IVF). Which bull’s sperm is used for which egg-cell depends upon what the breeders want. The test-tubes containing the fertilised eggs are then placed in the incubator for a week, after which the development of the embryo's is such that they are ready to be implanted in surrogate mothers on the farms of the buyers. Or they can be frozen in liquid nitrogen. So OPU and IVF are no longer a gynaecological tour de force in the livestock industry of the 21st century, but rather a commercial production technique for the purpose of obtaining high-quality breeding material. As a result, it is possible to achieve an even faster cattle improvement than by ET alone.
In terms of production, a dairy farmer is only interested in female cattle. By sorting the sperm of a bull into the half of his sperm cells with the X-chromosome (and the other half of sperm cells with the Y-chromosome), artificial insemination can be used to produce only heifer calves. In fact this so-called sexed sperm is used in insemination practice on farms in the Netherlands. Sexed sperm can also be used in test-tube fertilisation. So the sex of the embryo is clear and the farmer knows what he is buying when he invests in such an embryo: a heifer calf with hereditary qualities that ensure a large production. Thanks to the application of all of these techniques, the stock improvement has reached full gallop.
nitrogen container with sperm for AI
The procedures embryo transplant (ET), ovum pick up (OPU) and in vitro fertilisation (IVF) are also used in humans to solve certain fertility problems. But they can also serve other purposes. Like in the cattle industry, these techniques can be used to quickly improve and steer the hereditary qualities of humans in a certain direction. I am brushing the ethical considerations aside for now: I am merely referring to the technical possibilities. For example, OPU could be used to obtain a lot of egg-cells from a number of highly gifted female students. These egg-cells can then be fertilised in a test-tube (IVF). To that end, highly intelligent male scientists should be selected to provide the sperm. After a week, the embryos can be implanted in surrogate mothers (ET) or stored in liquid nitrogen for an indefinite period. In the same way, from champions in athletics could be born some forty or more sons and daughters each, fathered by different male top athletes, without any pregnancy of the female donor athletes. It sounds futuristic, but is it really?
These techniques have been used on a large scale in humans in Iran for a number of years now: In 2006, twenty-thousand women were treated in this way in the Royan Institute in Teheran (Jan Leyers: De weg naar Mekka. Halewyck, 2007). And that is only one of the forty-three institutes in Iran where this techniques are used in humans. Are so many Iranian women infertile? Or are these institutes cultivating potential scientists, for example, in order to outpace the western world in that respect? It sounds all paranoid. But if you think about it, it’s creepy.
© Leo Rogier Verberne