Preface
Today, the artificial insemination has become a normal method
of breeding quality cattle. A large number of cows and buffaloes
are inseminated artificially. The technique of artificial
insemination is particularly more useful in a country like
India where the paucity of quality sires has been the main
hurdle in the way of cattle improvement. This booklet describes
the process of artificial insemination in detail including
methods or semen collection, semen dilution, management
of sire for artificial insemination use and sterilization
or apparatus to be used.
I. Introduction
Artificial
insemination is the technique in which semen
with living sperms is collected from the male and introduced
into female reproductive tract at proper time with the help
of instruments. This has been found to result in a normal
offspring. In this process, the semen is inseminated into
the female by placing a portion of it either in a collected
or diluted form into the cervix or uterus by mechanical
methods at the proper time and under most hygienic conditions.
The first scientific research in artificial insemination
of domestic animals was performed on dogs in 1780 by the
Italian scientist, Lazanno Spalbanzani. His experiments
proved that the fertilizing power reside in the spermatozoa
and not in the liquid portion of semen. Few further studies
under research station conditions helped this technique
to be used commercially allover the world including India.
Artificial insemination is not merely a novel method of
bringing about impregnation in females. Instead, it is a
powerful tool mostly employed for livestock improvement.
In artificial insemination the germplasms of the bulls of
superior quality can be effectively utilized with the least
regard for their location in far away places. By adoption
of artificial insemination, there would be considerable
reduction in both genital and non-genital diseases in the
farm stock.
II. Advantages of Artificial Insemination
Artificial insemination has following advantages over natural
breeding.
1. The main advantage of artificial insemination (A.I.)
is that it increases the usefulness of superior sire to
an extra ordinary degree. It makes available sires of inheritance
for milk and butter fat production to all dairymen within
a limited area. Previously only a few could get the advantage
of good bulls.
2. The services of superior sires are greatly extended.
By natural services, a bull can be bred to 50 to 60 cows
per year. On the other hand, by artifical insemination technique
thousands of cows can be sired in one year by one bull.
3. The breeder does not need to maintain a herd sire and
thus can avoid the botherations accompanied with the management
of a bull. It helps to regulate the breeding programme and
the space between successive calvings without unnecessarily
prolonging the dry period.
4. The dairyman does not have the problem of searching and
purchasing a new herd sire every two years to avoid inbreeding.
5. The technique of artificial insemination can be made
useful in cross breeding for hybrid vigour by quickly transporting
the semen by air to different continents. 6. The intensity
of the spread of genital diseases is minimized if artificial
insemination is conducted under complete sanitary conditions
by the specially trained persons.
7. It overcomes the difficulty of size and weight.
8. It increases the rate of conception in females.
9. Outstanding animals located apart can be mated.
10. It helps in better record keeping.
11. Old, heavy and injured sires can also be used with
Disadvantages
However, despite a number of advantages over natural breeding processes, aritifical insemination has certain limitations. These are as follows.
1. It requires well trained operators and special equipments.
2. It requires more time than natural services.
3. It necessitates the knowledge of structure and function of reproduction on the part of the operator.
4. Improper cleaning of the instruments and insanitary conditions may lead to lower fertility.
5.Market for the bulls is reduced while that for the superior germplasm is increased.
6. Selection of the sire should be very rigid in all respect.
7. Preservation and transportation of
semen is difficult
under severe climatic conditions like those prevailing in
most parts of India.
III.
Properties of Semen
Semen or germplasm is the complete-discharge of the male genital tract occurring at the time of
ejaculation
by the male. It is a white, opaque, creamy fluid, occasionally yellowish green due to the pigment carotene. Semen consists of cellular part spermatozoa or sperms and the fluid parts, known as seminal plasma.
Spermatozoa is a male germ cell apportioned into three regions: head, middle piece and tail. The shape of the head of the sperm in the bull, ram, boar and rabbit is a blunt ovoid. In fowl, the sperm head appears as elongated cylinder. In the bull, the spermatozoa measuring 80 microns in length resembles an agile tadpole. The head is a blunt ovoid structure known as acrosane.
The liquid portion of semen i.e. seminal plasma is nothing but the secretions of accessory sex glands such as the prostrate, seminal vesicles and cowper's glands. Seminal plasma present an ideal medium for the viability and mobility of the male germ cells.
The volume of single ejaculate in the bull ranges from 2-10
mI. Variations in quantity may be due to breed differences
and also age, frequency of service, season and nutritional
status of the individual.
IV. Methods of Semen Collection
Various methods of collection of semen have been devised from time to time. The older unsatisfactory methods have been gradually replaced by the newer modern techniques.
The three most common methods are: (i) use of an
artificial
vagina, (ii) by
electro-stimulation
technique, and (iii) by massaging the ampulae of the ductus difference through rectal wall. Suitability of a particular method depends on the type and condition of a species, e.g. artificial vagina method is applicable to almost all of our domestic animals but certainly not on poultry, where the massage method is the only practical solution to get ejaculation.
The
ideal method of
semen collection will be one that is safe for the sire and the semen collector, the semen obtained is really a representative of a normal ejaculate, free of contamination and lastly it is protected from thermal shock.
Next :
Methods
of Semen Collection - Artificial vagina method
