Several methods of obtaining bull semen for artificial insemination in farm animals have been developed, the most common of which are electro-ejaculation and the use of the artificial vagina. The early method of recovering semen from from the vagina after natural mating is rarely used, since such semen become contaminated with the cow’s secretion. Collection by massage of bull’s ampule and accessory glands, via the rectum, has passed out of usage, since semen collect this way is frequently contaminated with urine and large number of bacteria.
The artificial-vagina method is most widely use today. The bull is allowed to mount a teaser cow and ejaculates when the penis is directed into the artificial vagina. The artificial vagina consists of a firm cylindrical tube with a thin-walled holding a collection receptacle which is attached to one end of the artificial vagina is lubricated and applied carefully, it yield a high degree of success.
In recent years the collection of bull semen by electrical stimulation has come into use. A bipolar rectal probe is use to electrically stimulate the nerves in the region near the accessory glands and the base of the penis; this produces erection and ejaculation. This method is especially useful with bulls that are unable to mount and thus cannot use an artificial vagina.
Precaution To Take while carrying Out Artificial Insemination In Farm Animal are;
- What ever method of collection is used, cleanliness is essential to prevent contamination of the semen.
- Proper and careful treatment of bull is necessary for adequate pre-collection stimulation, which will increase the quantity and quality of semen obtained.
- If sex drive is to remain unimpaired, the teasers and the environment may need to be changed frequently.
- Adequate facilities for controlling the bull and the teaser must be maintained so that the danger of injury to the collection as well as the animal is minimized.
Types of Artificial Insemination in Farm Animals;
There are three major types of artificial insemination which are commonly use are;
- Aritificial vagina
- A bipolar rectal probe
SEMEN COLLECTION: Method of Semen Collection
The method of collecting bull semen have undergone several changes over the years, and many of these changes have been important steps in the advancement of artificial insemination.
1. The Massage Method: As early as 1925 Case (Roa and Hart 1948) reported the collection of semen from the bull”by pressing on the seminalvasicles through the rectum”. This leadwas followed by Miller and Evans who used the massage method to collect bull semen (Foote 1964)
The massage method is useful in that it provides a means of obtaining semen from bulls that cannot mount or frombulls that, for some reason, will not mate either naturally or with the artificial vagina.
However, semen collected by this method is apt to be contaminated with urine, have too high a proportion [oof seminal vesical secretion, or be otherwise less well balance in its componates than ejaculation semen this method is also used in semen collectionfrom cocks.
2. The Aritificial Vagina Method: The artificial vagina eliminatws several of the disadvantages of collection from the vagina and of collection by massage.The artificial vagina is simple to construct and use. Semen cllected with it is fairly clean, and the ejaculate is more normal.
Types of Atificial Vagina:
Apparently, the first aritficial vagina for bulls was design in russia. It consisted of a rigid cylider of rulinder was a thin-walled rubber tube, the ends of which were turned back over the outer cylinder, forming a water-tight jacket. Into one end of the atificial vagina was fitted a graduated, glass semen receptacle of slightly smaller diameter then the cylineder. The jacket was filled through a screw-plug hole with water hot enough to bring the inside of the atificial vagina to a few deggrees above body temperture.
4. The Electo-Ejaculation Method: Apparently, the first attempts at including ejaculation by electricalk stimulus were made by Battelli in 1922, who introduced an electrical shock (30 volts, 47 cycles alternation current) at the base of a brain of a mature male guinea pig. After that a number of investigation of electro-ejaculation was carried out with laboratory animals. Gunn, of Australia, Pioneered the investigations of eletro-ejaculation of farm anmial with his work on rams, which he reported in 1936. Gun’s method consised of stimulating the spinal cord between the forth lumber and the first sacral vertebrae by placing one eletrode in the rectum and the other in back muscle.By passing few 5 to 10 second rhythmic stimuli (30 volts, 50 cycles alternating current) through the electrodes, ejaculation was produced and semen was collected in a glass tube.
4. Gloved had Technique: This method is effective in semen collection from boars. In this, the boar is brought to a teaser or dommy sow while the technican wearing the hand glove stand-by. As soon as the boar mounts applied a mild pressure. The boar then ejaculates and the semen collected with a collection vial