ARTIFICIAL INSEMINATION IN CANINES - FROZEN SEMEN - ITS IMPORTANCE

In our country, artificial insemination with fresh semen is becoming more and more popular. There are certain breeds that, due to their morphological characteristics or the preference of breeders, are using artificial insemination as a routine method.

This method consists of the manual collection of semen and its subsequent deposit in the vagina of a bitch in heat.

The main reason why this method must be used is the impossibility of performing a natural mating between a female and a male.

The causes in the female include: racial characteristics, congenital (non-hereditary) or acquired abnormalities, lack of acceptance of the male, vaginal narrowing, pain, hindquarters weakness, psychological disorders, etc. On the part of the male, the natural service can be hindered by conformation defects that prevent penetration or buttoning. Arthritis, spine pain, hindquarters weakness, premature erection that makes proper penetration impossible, psychological problems such as shyness, inexperience, lack of libido. etc Artificial insemination prevents the spread of infectious diseases, preventing specimens of high reproductive value from being exposed to these risks.

In the bovine species, semen freezing has been used for many years in order to widely disseminate the genetics of higher animals. Because dog semen lacks sufficient concentration to divide an ejaculate into many doses, until recently, freezing has not been given importance.

The use of preserved semen allows the greatest dispersion of desirable genetic traits, disease prevention, cost reduction by not having the need to transport animals, reducing the dangers of shipping a dog and avoiding transport stress. The additional advantage of semen freezing is the possibility of preserving the genetics of a certain specimen for a long time (years), even long after it has died, making it possible to reuse its genes several generations after its disappearance, when its genetic characteristics They begin to fade and disappear. In the presence of non-hereditary terminal diseases, when it is known for certain that a valuable specimen is going to die in the short term, storing its semen allows the breeder to continue using his dog even after death without altering his breeding plan. It also allows prominent parents to be used more extensively.

Artificial insemination can be used in three different ways:

1. Fresh Semen:

It is the procedure most used by breeders and veterinarians that consists of the manual extraction of the semen and its immediate deposit in the vagina of the bitch.

2. Refrigerated semen:

It consists of diluting the semen and refrigerating it at 5ºC, allowing it to be preserved for a period of at least 4 days. Extender helps protect sperm membranes from damage caused by changes in temperature and jolts during transport. This gives us all the advantages of semen transport and remote insemination, and allows us to avoid the damage that occurs to the spermatozoa when freezing them, with pregnancy results generally being somewhat better than those obtained with frozen semen.

3. Frozen Semen:

It consists of making a dilution of the semen and its subsequent freezing. It is a long-term preservation, which allows obtaining all the aforementioned genetic advantages. Frozen canine semen can be stored almost indefinitely by keeping the temperature at -197°C in a liquid nitrogen tank. Countless studies have been carried out on frozen semen, varying the composition of the extenders, the speed of cooling and the final presentation of the semen. Semen is usually frozen in straws or pills. Straws are currently preferred for their ease of identification and storage. The number of inseminating doses that can be obtained from a single extraction varies with the quality of the semen, being able to achieve between 0 and 5 doses per ejaculate. During the freezing and thawing process, semen suffers damage that drastically decreases the survival time of sperm within the female genital tract. In turn, the passage through the cervix is hindered. This makes the deposit of semen directly inside the uterus of great importance, since the conception rates are much higher in intrauterine insemination than in deep intravaginal insemination. It is also evident that it is necessary to determine with extreme precision the fertile moment of the bitch, since frozen semen only lives 12 to 24 hours. in contrast to fresh semen (of optimum quality) which can live for several days in the female tract. The determination of the time of ovulation should be established by Pap smear, serum progesterone concentration, and vaginoscopy.

However, despite the obvious advantages of the method, the use of frozen semen from top males of each breed would represent a considerable cost represented by costs for freezing and storing the semen, and the conception rates and size of the litters would be somewhat lower than those obtained with fresh semen.

In 1981, the American Kennel Club approved the registration of litters resulting from artificial insemination with frozen semen, and the method is being widely used in the USA and Europe. The genetic advance that could be achieved with the use of frozen semen from top males of each breed would represent a great advance in the short term for Argentine cinophilia. In December 2008, the Argentine Cynological Federation regulated and approved the use of frozen and refrigerated semen.

FROZEN SEMEN / ITS IMPORTANCE

In recent years, international interest in the use of frozen canine semen has increased notably. The possibility of preserving the genetic potential of an outstanding specimen for many years allows the breeder to have new technology for their breeding plans.

The reuse of the genetic material of a specimen after several generations, allows restoring desirable characteristics that began to fade or disappear.

Outstanding breeders of different breeds can be more easily used by breeders around the world, thus expanding their genetic diffusion.

Many countries, outstanding references for the breeding of certain breeds, have legislated the use of frozen semen for years.

France, Germany, Belgium, Switzerland, Sweden, Norway, Spain, England, Australia, Italy, Denmark, Hungary, Finland, Brazil, Canada, the United States and more recently Argentina are just some of the countries that have canine semen banks.

There are so many indisputable benefits that the use of frozen semen brings to breeding, that the current breeding director of the SV of Germany (main Club of the German Sheep Breed), Dr. Helmuth Raiser, in his election speech of December 2002 that led him to occupy the position, stressed the need and importance that the possibility of having a semen bank would mean for the breed.

More and more breeders are interested in using this technology, since they can have breeders from anywhere in the world, without having to move their females, thus avoiding unnecessary costs and risks. Outstanding parents can be used more extensively allowing greater and better marketing of their services.

Canine semen freezing consists of manual collection of the same, its evaluation, dilution and subsequent freezing. Once processed, the semen is preserved in liquid nitrogen at a temperature of -196ºC.

Countless studies have been carried out to optimize the canine semen freezing technique, varying the composition of the extenders, the cooling speed and the final presentation. The semen can be frozen in straws or pills. Straws are currently preferred for their ease of identification and storage. During freezing and thawing, a significant number of spermatozoa die, which is why not all ejaculates are feasible to freeze. The number of inseminating doses that can be obtained from a single extraction varies with the quality of the semen, being able to achieve between 0 and 5 doses per ejaculate.

In numerous species, a very important genetic improvement has been achieved through the dissemination of outstanding reproducers, especially using their semen once the positive characteristics transmitted by said specimens were known, and what could be expected genetically from them.

The genetic improvement, the strict control of the fertility and health of the donors, the reduction of costs and risks in the transfer and storage of semen for an indefinite period, produced a significant advance for the benefit of breeders and owners.

FROZEN SEMEN

1) Where and under what conditions is the frozen semen stored?

Once the spermogram has been completed and processed, the semen is loaded into small plastic tubes called straws, which contain 0.25 to 0.5 ml of semen with extender. Each straw must be correctly identified with the breed, the name of the specimen, genealogical record number, date and country where it was frozen. These straws are kept submerged in thermoses with liquid nitrogen at a temperature of -196 °C.

2) How long can canine semen remain frozen?

As long as the temperature of -196 °C does not change, frozen semen can be kept indefinitely.

3) What happens if the cold chain is broken?

Since the frozen semen is highly sensitive to changes in temperature, any change in the cold chain causes the death of sperm. Semen thawing is as delicate and important as freezing, and the slightest alteration in this process also causes sperm mortality.

4) The frozen semen stored in a bank, to whom does it belong, to the breeder, to the veterinarian, to both?

Veterinarians specializing in reproduction, who work in semen freezing centers, charge professional fees for processing and subsequent annual storage. The straws are the property of the male's owner, who freely disposes of their use or commercialization. Veterinarians cannot dispose of the semen without the authorization of the owner.

5) How to make sure that a frozen semen corresponds to a certain stallion?

The acting professionals provide with their trajectories and knowledge the seriousness and responsibility that the prosecution demands. On the other hand, there is an obligation to identify the player with a microchip and the determination of his DNA. Finally, each straw is identified, being controlled at the time of thawing prior to insemination.

6) How is insemination with frozen semen performed?

After thawing the inseminating dose (2 to 4 straws), the semen must be deposited inside the uterus. The artificial insemination technique is extremely important to obtain good pregnancy rates. Significantly better results are obtained when the semen is deposited inside the uterus compared to that made deep in the vagina. Two techniques are mainly used. The surgical one, which consists of performing a small laparotomy and the subsequent inoculation of the semen into the uterus, and the transcervical one where the semen is deposited in the uterus through the vagina and cervix using a special catheter designed for this purpose.

7) At what time to inseminate? Is more precision necessary with the higher peak fertility of the female?

Considering that the lifetime of the spermatozoa after thawing is a few hours, the moment of insemination is extremely important. The responsibility of choosing the right moment of the bitch's estrous cycle to perform artificial insemination falls on the inseminator veterinarian; follow-up by means of exfoliative vaginal cytology, vaginoscopy and hormonal determinations is essential. It is, therefore, necessary to specify exactly the moment of greatest fertility.

8) Percentage of effectiveness in inseminations with frozen semen?

Performing a correct determination of the moment of ovulation, the percentage of pregnancy achieved with frozen semen, using intrauterine insemination, is 70%.

9) FCI and AKC positions on frozen semen.

In 1981 the AKC approved the registration of litters resulting from artificial insemination with frozen semen. As of October 1, 1998, the DNA certificate was required for those stallions who want to freeze semen.

The FCI International Breeding Regulations mention frozen semen in the paragraph referring to Artificial Insemination. Many FCI member countries have their own regulations regarding the use of frozen semen. Since December 2008, the Argentine Cynological Federation has regulated and approved the use of canine frozen semen.

10) In which countries is the technique more developed?

Many countries, outstanding references for the breeding of certain breeds, have legislated the use of frozen semen for years.

The USA, France and Sweden are just some of the main countries that have important banks of canine semen and that make frozen semen a common use. It is worth mentioning that Brazil has legislated the importation of semen since June 1999.

11) What are the advantages of frozen semen?

The use of frozen semen allows the greatest dispersion of desirable genetic traits, disease prevention, cost reduction by not having the need to transport animals, reducing the dangers of shipping a dog and avoiding transport stress. The additional advantage is the possibility of conserving the genetics of a certain specimen for a long time (years), even long after it has died, making it possible to reuse its genes several generations after its disappearance, when its genetic characteristics begin to be diluted and disappear.

12) Does it present any cons?

Despite the obvious advantages of this technique, the use of frozen semen represents an expense in semen freezing and storage, and the conception rates and litter size are somewhat lower than those obtained with fresh semen.

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