Wednesday, September 14, 2011

  1. AI Part:

                       Introduction, history, development, advantages and disadvantages of A.I.

AI involves:
1.      Selection of bulls
2.      Semen collection
3.      Semen evaluation
4.      Semen extension/dilution
5.      Semen storage/preservation
6.      Utilization of semen
7.      Fertility
History of AI in Abroad:

Ø  It started as early as in 1322 AD.
Ø  Arab Chief (14th century): Horses --- semen collected by cotton plug--- inserted in other mare’s vagina----- conception achieved.
Ø  Anton Van Leewenhoek and Hamm (1677): Spermatozoa --- “Animal cells”/ “Animal Cules”.
Ø  Lazzaro Spallenzani- (Italian), 1780 :Ist AI in dogs at room temp.
Ø  Prof. Amantea- (Rome)1937: Designed Ist AV for dogs.
Ø  Milovanov (1938): Designed Ist AV for bull and Ram.
Ø  Perry and Handerson (1938): Ist cattle breeding organization of AI in USA.
Ø  Semen dilutors/extenders:
  • Lardy and Phillips (1940): EYP
  • Salisbury et al. (1941): EYC
  • Thacker and Almquist (1953): Cow milk.

Ø  Frozen semen
  •    Polge et al. (1949): Dry ice (-79°C
  • 954): Liquid nitrogen (LN2) (-196°C).
  •  Larsen (1938): Rectovaginal method of AI.
  • Advantages of AI:

    Ø  Quick genetic improvement.
    Ø  Control of venereal diseases.
    Ø  Maximum possible use of best sires.
    Ø  Quick progeny testing.
    Ø  Early detection of undesirable genetic traits in the progeny.
    Ø  Minimizing the no. of bulls in the farm.
    Ø  Good programme for small holding dairy farmers.
    Ø  Economical (Large no. of cows can be inseminated at lower cost in short time).
    Ø  Mating between disparate size of cows and bulls is possible.
    Ø  Lame cows can be bred and lame bulls can be used.
    Ø  Long storage of semen, progeny even after the death of the sire.
    Ø  Hybridization is possible.
    Ø  Easy to transport the semen at distant places.
    Ø  Pregnancy and other diseases of genitalia can be diagnosed.

    Disadvantages of AI:

    Ø  Requires high standards of technical efficiency.
    Ø  Proper and timely detection of estrus.
    Ø  Proper knowledge of reproduction is required to avoid AI in unwanted conditions.
    Ø  Genetic defects may be transmitted quickly if selection of a bull is not perfect.
    Ø  High risk of inbreeding.
    Ø  Costly equipments are required.
Methods of semen collection in various species:

  1. Pan collection method
  2. Vaginal spoon method
  3. Sponge method
  4. Breeder’s bag method
  5. Sperm collector method
  6. Artificial vagina (AV) method (most commonly used)
  7. Massage method (Used for semen collection from lame bulls and in dogs)
  8. Electro ejaculation (From lame bulls)
  9. Fistula method
  10. Dummy females
 a)      Buffaloes/cows:
                                                  i.            Short A.V. 20-30 cm length
                                                ii.            Massage method
                                              iii.            Electro ejaculation

b)      Stallion:
                                                  i.            A.V. method

  1.       Russian model
American model / Missouri model / Mississipi model (Complecated than Russian model).

c)      Ram:
                                                  i.            Anestrus ewe
                                                ii.            A.V. 15×5 cm, length
                                              iii.            Electrical stimulation.

d)     Goat/Buck:

                                                  i.            Goat in heat

e)      Boar:

                                                  i.            A.V.
                                                ii.            Hand stimulation

f)       Dog:

                                                  i.            A.V.
                                                ii.            Massage method

g)      Poultry:

                                                  i.            Massaging dorsolateral lumbo-sacral region and also the abdomen which cause erection of copulatory organ.
  • Semen Evaluation
    Introduction: Semen evaluation is must before cryopreservation and artificial insemination (AI). On the basis of evaluation criteria, only good semen samples should be processed for cryopreservation and AI purpose. Although semen evaluation alone can not be interpreted as the sole indicator of the fertility of bull, but it provides significant information on the sexual functions. So it should never be neglected. Quality of semen can only be confirmed after a series of tests. As soon as semen is received in the laboratory, it is kept in the water bath at 30-35oc till the examination is over. While evaluating the semen, care should be taken to avoid damage to the cells during collection and processing. All the glassware required for semen evaluation is kept at 37oc. Following errors should be taken into care-
    • Delay in commencement of evaluation, particularly motility and pH.
    • Exposure of semen to sudden change in temperature, because it results in high number of dead cells, abnormalities and high temperature and humidity lead to agglutination of spermatozoa.
    • Mechanical damage to sperms during making smears.
    • Avoid undue shaking and exposure to sunlight, because both can kill the sperms.
Standard Tests of Semen Evaluation:

  • Gross Examination/ Macroscopic Evaluation:

1. Colour: Colour of semen may be creamy to white, rarely varying shades of yellow which may be due to the content of riboflavin. The normal colour of-
  • Buffalo bull semen- Milky white
  • Cattle bull semen- Creamy white
          Any deviation from the normal colour indicates pathological conditions in the
             genital tract. Therefore:

  • Brownish colour indicates orchitis or catarrhal conditions of the genital tract.
  • Greenish colour due to the presence of pseudomonas aeruginosa.
  • Reddish colour due to blood contamination as a result of injury to the penis or prepuce.
2. Volume: Volume of an ejaculate is measured immediately following semen collection using graduated centrifuge tubes. The volume of semen is related to the age, breed and size of sires to some extent. Certain external and internal factors also affect semen production. Volume of semen increases with increasing age up to 6-8 years and after that the level is more or less maintained. There are evidences of a decline in fertility with increasing volume and age of the animal. The average volume of semen in
  • Cattle bull: 3-6 ml
  • Buffalo bull: 2-4 ml
  • 3. Consistency and Density: Semen may be milky, creamy or watery in consistency, depending on the concentration of sperms. According to different scientists semen can be classified as creamy, milky and watery or thick creamy, medium creamy, creamy and watery.
  • On the basis of density arbitrary estimation of the concentration of sperms is judged macroscopically. Certain physiological conditions of tests and accessory sex glands affect the consistency of semen. In the initial stages of epididymitis the semen become thinner and less milky. Thick viscous semen is indicative of catarrhal conditions of accessory sex glands. Large purulent flocculi in semen may be seen in cases of brucellosis, due to inflammation of the seminal vesicles.
Microscopic Evaluation of Semen

An important part of any breeding soundness programme is an evaluation of sperm morphology. Besides macroscopic examination of semen i.e., colour, volume and density, the following parameters are routinely used in the evaluation of semen for andrological purposes i.e.
  • Relative proportion of motile/ immotile spermatozoa
  • Degree of motility
  • Percentage and type of abnormal spermatozoa
  • Degree of contamination by microorganisms
  • Admixture of leucocytes and other cellular material
  • Sperm penetrability of cervical mucus
  • Departure from normal chemical composition
1. Mass Activity: It is the collective movement of sperms or their wave motion, which can be judged by examining a drop of neat semen on the clean dry glass slide immediately after the collection without a cover slip under lower power magnification on a warm stage (Biotherm). Mass activity can be classified into five grade scale depending upon the wave motion and rate of activity:

AI Part:                        Introduction, history, development, advantages and disadvantages of A.I. AI involves: 1.     ...