What is the National Academy of Sciences? Imagine the perfect dairy cow. For eight years she has gotten pregnant on the first try, given birth easily, and produced gallon upon gallon of the best milk. Even when others in the herd got sick, she stayed healthy.
She is ideally suited to the climate in which she lives. The farmer has depended on this cow and her daughters in lean times to carry the farm through, but now she is at the end of her reproductive life. Biological copying is referred to as cloning. By cloning his prize cow, breeding the clones, and keeping their offspring, the farmer can introduce the natural positive characteristics into the herd quickly. It would take several more years to achieve these same improvements by conventional breeding.
Farmers can also clone animals to produce more uniform quality meat. Take, for example, a male swine boar that time after time sires offspring that mature quickly and provide lean meat. If a farmer has several of these boars he could quickly produce an entire herd with consistent, high quality meat.
Researchers have been cloning livestock since FDA then began an intensive evaluation that included examining the safety of food from these animals.
Cloning is a complex process that lets one exactly copy the genetic, or inherited, traits of an animal the donor. Livestock species that scientists have successfully cloned are cattle, swine, sheep, and goats. Scientists have also cloned mice, rats, rabbits, cats, mules, horses and one dog. Chickens and other poultry have not been cloned.
Most people think of livestock breeding taking place through traditional mating, in which males and females physically get together to reproduce. In fact, this is not often the case. Traditional mating is not that efficient, if the goal is to produce as many offspring as possible. For example, a male has enough sperm to produce many more offspring than would be possible by traditional mating.
Traditional mating also has certain risks: one or both of the animals may be injured in the process of mating. The female may be hurt by the male because he is often much larger, or an unwilling female may injure the male.
There is also a risk of infection or transmission of venereal disease during traditional mating. Because of these factors, many farmers use assisted reproductive technologies ARTs for breeding.
These include artificial insemination, embryo transfer, and in vitro fertilization a process by which egg and sperm are united outside the body. Artificial insemination was first documented in the breeding of horses in the 14th century. The first successful embryo transfer of a cow was in , and the first in vitro fertilization IVF -derived animal was a rabbit born in Livestock production in the United States now uses all these methods regularly.
The frozen semen can come from a bull many miles, or even many states, away. Cloning is a more advanced form of these assisted reproductive technologies. Much of the public perception of cloning likely comes from science fiction books and movies. After, the oocytes were aspirated by an Aloka ultrasound unit Aloka, Tokyo, Japan with 5 MHz convex transvaginal probe mounted with a needle guide Aloka, Tokyo, Japan was placed in position behind the camel.
Follicular fluid was transferred to mm diameter Petri dishes for oocyte collection under a stereomicroscope. Cumulus oocyte complexes COCs were recovered from antral follicles 2 to 6 mm in diameter by aspiration with an gauge hypodermic needle attached to a 10 ml disposable syringe. Cells were cultured and stored for subculture and use as donor cells for somatic cell nuclear transfer SCNT as previously described 16 , 17 , SCNT was performed according to Kim et al.
Somatic cells as nucleus donor were prepared immediately after enucleation, and a single donor cell was microinjected into the perivitelline space of each enucleated oocyte. The donor cell-oocyte couplets were fused in a fusion medium comprising 0. Embryo developmental competency to the cleavage and blastocyst stage was evaluated at 2 and 7 days of culture.
Recipients were synchronized and embryos transferred at day 6 following ovulation 3. Selection and preparation of donor and recipient camels. Embryos were transferred ipsilateral to the horn of the uterus with the ovary presenting the best corpus luteum Donors were prepared for aseptic flank laparotomy initially being walked into a specially designed padded crush and sat in sternal recumbency.
Sedation was achieved with an intravenous injection of both mg of Ketamine and mg of Xylazine. The surgery site was shaved and prepared for sterile surgery, an electrocautery patient return electrode was stuck to an appropriately shaved area on the dorsal left hind leg with a disposable surgical drape placed over the surgical site.
Using sterile gloves and instruments the skin and muscle were cut open using a combination of scalpel blade, surgical scissors and electro cautery Olympus, Tokyo, Japan to gain access to the peritoneal cavity and the left ovary.
After exteriorization of the left ovary and aspiration the follicles present, using a standard gauge needle with a 10 ml syringe, the fimbriae end of the oviduct was located.
Two to three embryos were loaded into a catheter Sherwood Medical, St. A male camel was introduced to the group of surrogate recipients to test for behavioral indicators of pregnancy, such as the tail reflex around 10 days post ET and blood samples for progesterone were taken from all animals around 16 days post transfer.
Progesterone analysis was done on serum using Chemiluminescence Immunoassay Roche, Basel, Switzerland. Cloned calf parentage was confirmed alongside donor cells and surrogates using the standard procedure of short tandem repeat STR profiling was carried out using 17 camelid specific microsatellites Supplemental Table S1. Unrelated female Dromedary camel was used as a control.
The PCR conditions were as follows: The 17 microsatellites used in the matching test were grouped into four multiplexes of 11and 6 loci. Follicular aspiration yielded varied amounts of fluid per ovary which ranged from clear to blood tinged with some follicles appearing almost as whole blood. OPU resulted in range of follicular fluid per follicle, with a minimum amount of follicular fluid collected of 2 ml from a left ovary with 7 follicles with diameters of mm to a maximum of 16 ml left ovary with 8 follicles ranging from 10 to 14 mm in diameter.
Fluid varied from clear through to blood tinged and some collection appeared as blood and contained clots. Blastocyst formation rate of fused OPU derived oocytes, was compared to pregnancy rates for all 11 individuals Fig.
The cell lines for the nuclear donors showed no statistical difference in overall blastocyst formation rate Table 1. Blastocyst development did not vary significantly between camel breeds in either oocyte derived from abattoir ovaries, nor did rates differ significantly in blastocyst formation from OPU derived oocytes Table 1. An analysis of oocyte origin on blastocyst development was investigated and shown to differ significantly Table 1.
During the experimental period ovaries were obtained, which yielded oocytes were subjected to IVM of which reached maturity metaphase II and Omitting all data from batches where early stage embryo transfer was performed, blastocysts developed at an average rate of 8. The total number of oocytes recovered by OPU was from which were used to obtain blastocysts at an average rate of Over a period of 4 months a total of individual embryo transfers were completed resulting in 47 pregnancies The pregnancy rate did not differ significantly between the groups which varied between These pregnancy rates obtained from OPU oocytes alone, to minimize confounding cytoplast variation.
Of the resultant 47 pregnancies there were 28 births and 19 calves survived and are presently healthy and thriving Table 2. Pregnancies were obtained from 85 early stage embryo surgical transfers which resulted in a 12 The remaining transfers were transvaginal blastocyst transfers which resulted in 35 Comparing embryos derived from OPU oocytes alone, early stage pregnancies obtained from surgical embryo transfer were more than twice as likely to be resorbed than pregnancies obtained from transvaginal blastocyst transfer Table 2.
Previous reports on camel cloning have been done using a single or limited number of donor individuals and resulted in few offspring. Here we show 19 healthy clones from 10 distinct donor cell lines.
As such this is the first known report addressing the large scale camel cloning. Other camelids have been hybridized with dromedaries but there are no known reports of cloning in the other species, or between camel types other than the Bactrian camel 8. Several barriers to hybridization have outlined a number of issues related to interspecies reproductive methods, including cloning. Overcoming these interspecies barriers may provide insightful information regarding general ART methods and efficiencies Here we show a minimum of three individuals from each Dromedary breed, which illustrates that the potential barriers observed in other species, are not likely present between camel breeds.
The economic significance commented on during the initial cloning report by Wani et al. The developments of camel dairies and the advancements in camel stocks used for racing, dairy and for show continue in many countries, further illustrating this significance.
Obtaining quality donor oocytes was the most challenging technical aspect of this project. In our hands IVM oocytes from abattoir samples required 40—42 h to mature, this in contrast to work shown by Wani et al. The camelid family comprises the Old World camelids or Dromedary and Bactrian camels and the New World camelids llamas, alpacas, guanacos and vicunas.
The capacity for interspecies camelid cloning may assist in conservation of endangered camelids and information gained in one species may be relevant in others as with the Bactrain camel Camelus bactrianus 8. The first creation of identical twins in camels, from the bisection of embryos, was done to provide for potential research prospects, for racing, in the areas of exercise physiology and nutrition The creation of multiple clones from a single champion individual could provide a more consistent baseline to investigate the scope of this potential.
Furthermore, the potential to compare selected variables in determining non-genetic effectors for racing and dairy camels may additionally become relevant with the ability to routinely produce genetically identical individuals at a relevant scale. Comparing the results to reports in other animals, including cattle, the recovery rate and total oocytes retrieved were slightly lower in camel transvaginal OPU than in other species Our recovery rate, which averaged 8.
Optimization of protocols and techniques are likely to result in higher recovery rates and increased efficiencies. Although at present it cannot be ruled out that difference may exist between camel breeds or breeds, individual cell lines can be clearly seen to account for a greater amount of variation than we would expect to find.
With this preliminary finding it appears conclusive that if there exist any differences between camel breeds and cloning efficiency it is greatly overshadowed by individual variation Table 1. Our efficiency data appears to vary from other reports 5 , 28 although seasonal variations may play a partial role, they should be considered when making comparisons The oocyte conditions, both daily and throughout the season may additionally be a factor in our total results.
Due to this potential we specifically compare data from OPU derived oocytes to minimize variation in oocyte quality. The comparison of blastocyst rates to pregnancy appears to illustrate cellular contribution to the individual variation observed, potential causal elements are however not yet known.
Larger sample sizes would assist in the determination of the factors influencing the variations observed between cells, groups, oocyte source potential and embryo development. The failure to obtain offspring from of one of the 11 cell lines was likely due to the limited pregnancy number compared to reabsorption and loss rates Table 2.
After years of detailed study and analysis, FDA has concluded that meat and milk from clones of cattle, swine, and goats, and the offspring of clones from any species traditionally consumed as food, are as safe to eat as food from conventionally bred animals.
In addition, cloning may also be a way to duplicate a disease-resistant animal, and over generations create a disease-resistant herd. Well, okay, but how about cloning endangered species?
Scientists have cloned sheep from very small populations, members of rare cattle breeds, and the gaur and banteng, two species closely related to domesticated cattle species. Back to the top Myth: Offspring of clones are clones, and each generation gets weaker and weaker and has more and more problems.
Back to the top Myth: Clones are always identical in looks. Not necessarily. In fact, many clones have slight variations in coat color and markings. Back to the top Myth: Clones have exactly the same temperament and personality as the animals from which they were cloned. Back to the top Myth: Cloning results in severely damaged animals that suffer, and continue to have health problems all their lives. Back to the top Myth: Cow clones make human pharmaceuticals in their milk.
Back to the top Myth: When a chicken clone lays eggs, the chicks that hatch are clones. Back to the top Myth: Meat from clones is already in the food supply. Back to the top Myth: Cloning can cure diseases in livestock. Back to the top Myth: Scientists can bring back extinct species by cloning them. Back to the top. SCNT involves transferring the genetic information from one animal into an empty oocyte, or egg.
This process results in an embryo, which is implanted into a surrogate mother who carries the pregnancy to term. How does cloning affect the DNA of animals? Cloning does not change DNA, and clones are not genetically engineered animals.
It is simply assisted reproduction, similar to embryo transfer, artificial insemination, or in vitro fertilization. Is animal cloning a new technology? Animal cloning has been rigorously studied for decades, since the earliest research on embryo splitting in the late seventies and early eighties.
The U. Food and Drug Administration has analyzed numerous scientific studies on the subject, conducted over 30 years and encompassing several generations and large families of livestock. Does cloning cause animal suffering? Cloning enhances animal wellbeing, and is no more invasive than other accepted forms of assisted reproduction such as in vitro fertilization. Breeding the best possible stock improves the over-all health and disease resistance of animal populations. Additionally, because these breeding techniques can improve the over-all health and disease resistance of an animal, cloning will greatly reduce animal suffering.
Are animal clones healthy? Decades of research has shown that cloned animals are as healthy as conventional animals. Somatic cell cloned cattle reportedly were physiologically, immunologically, and behaviorally normal. How does the neonatal mortality rate of animal clones compare to other animals? Any animal conceived through any assisted reproductive technique — AI, embryo transfer, etc.
In the hands of skilled scientists, the neonatal death rate of cloned animals approaches that of animals produced by in vitro fertilization.
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