Fig. 2 shows the male reproductive system of a bull. (a) Name the parts labelled P, Q, R and S on the diagram. [4] (b) State the function of part P. [1] (c)...

Labelled answer diagram:

(a) The parts of the bull's reproductive system:

The testis is the primary male reproductive organ; the epididymis is a coiled tube attached to it where sperm mature and are stored; the vas deferens is the duct that carries sperm from the epididymis toward the urethra during ejaculation; and the penis is the copulatory organ used to deposit semen in the female reproductive tract.

(b) The function of the testis (part P) is to produce spermatozoa (sperm cells). [1] It also produces the male sex hormone testosterone, which controls the development of secondary sexual characteristics and sex drive in the bull. The testes are located outside the body cavity in the scrotum, where the temperature is slightly lower than core body temperature, because sperm production requires this cooler environment.

(c) Semen collection for artificial insemination follows this procedure:

1. A teaser cow (a cow in oestrus) or a dummy is used to stimulate the bull to mount. An artificial vagina (AV), which is a warm, lubricated tube that simulates the natural reproductive tract, is prepared and held in position. [1]
2. As the bull mounts, the artificial vagina collects the ejaculated semen into a graduated collection tube attached to one end. [1]
3. The collected semen sample is then taken to the laboratory where it is examined under a microscope to assess sperm concentration, motility, and morphology. Suitable samples are diluted with an extender solution and stored, typically frozen in liquid nitrogen at -196 degrees C. [1]

(d) Four advantages of artificial insemination over natural mating:

1. Genetic improvement: Semen from genetically superior bulls can be used to improve herd quality, even if the bull is located far away. [1]
2. Efficient use of semen: A single ejaculate can be divided into many doses (often 200-400), so one bull can serve far more cows than would be possible through natural mating. [1]
3. Disease prevention: AI reduces the risk of spreading sexually transmitted diseases (such as brucellosis or trichomoniasis) between animals, since there is no direct contact between bull and cow. [1]
4. Safety and cost: It eliminates the cost and danger of keeping a bull on the farm. Bulls can be aggressive and cause serious injury to handlers or other animals. [1]