WAEC SSCE - Animal Husbandry - 2014

Maelezo ya Majibu

(a) Definitions

Hay: Hay is grass or other forage (usually including legumes) that is cut while still green and dried to a low moisture content of about 15 to 20 percent so that it can be safely stored and fed to farm animals during the dry season or any period of feed scarcity.

Silage: Silage is green, succulent forage that is cut and preserved by fermentation under airtight (anaerobic) conditions in a silo, so that its nutritive and feeding value is retained for later use.

(b)(i) Two types of pasture

1. Natural (native) pasture.
2. Artificial (established or cultivated) pasture.

(b)(ii) Four advantages of establishing a grass-legume pasture

1. The legume fixes atmospheric nitrogen, which fertilises the soil and improves the growth of the grass.
2. It provides a balanced diet, the grass supplying energy (carbohydrate) and the legume supplying protein.
3. It gives a higher yield of more nutritious and more palatable herbage that is readily acceptable to livestock.
4. The dense cover protects the soil, reduces erosion and leaching, and prolongs the grazing season.

(b)(iii) Three advantages of rotational grazing

1. It allows grazed paddocks to rest, regenerate and regrow before they are grazed again.
2. It helps to control internal parasites, pests and diseases by breaking their life cycle.
3. It ensures even and efficient utilisation of the pasture and prevents overgrazing and soil compaction.

(c) The digestive tract of a hen

The digestive tract of a hen (fowl) is drawn and labelled below. Food passes from the beak through the oesophagus into the crop, where it is stored and softened. It then moves to the proventriculus (true stomach), where gastric juices act on it, and into the muscular gizzard, where it is ground with the aid of swallowed grit. The paste passes into the small intestine (duodenum, jejunum and ileum), where digestion is completed and nutrients are absorbed. The two caeca ferment fibre, and undigested matter passes through the large intestine (rectum) into the cloaca (vent), from which faeces and urine are voided together.

Maelezo ya Majibu

(a) Definition of animal improvement

Animal improvement is the application of the principles of genetics and good management to bring about a change in the hereditary make-up of farm animals so as to raise their productivity and general performance, for example higher yields of meat, milk or eggs, faster growth and greater disease resistance.

(b) Explanation of terms

• Cross breeding: This is the mating of animals of two different breeds or varieties of the same species, for example crossing a White Fulani cow with a Friesian bull, in order to combine the desirable qualities of both parents and to obtain hybrid vigour in the offspring.
• Out-breeding: This is the mating of animals of the same breed that are not closely related (they have no common ancestor for at least four to six generations), and it is used to introduce new desirable genes and to reduce the harmful effects of inbreeding.

(d) Completed table

Maelezo ya Majibu

(a) Anthrax disease

Causative organism:

Anthrax is caused by the bacterium Bacillus anthracis, a large, rod-shaped, spore-forming bacterium. Its spores are extremely resistant and can survive in the soil for many years.

Two modes of transmission:

1. Ingestion of contaminated feed and water - animals swallow anthrax spores while grazing on pasture, or feeding and drinking from feeders, drinkers or water sources contaminated with the spores.
2. Through open wounds or body contact - spores enter the body through cuts, wounds or abrasions on the skin; the disease can also be spread mechanically by biting flies and other vectors, or by inhalation of spores.

(b) The reproductive tract of a hen

The domestic hen has a single functional reproductive system on the left side of the body (the right ovary and oviduct remain undeveloped). The tract consists of an ovary bearing a cluster of developing ova (yolks) and a long, coiled oviduct made up of the infundibulum, magnum, isthmus, uterus (shell gland) and vagina, which opens into the cloaca (vent).

As the yolk (ovum) is released from the ovary it is caught by the infundibulum, then passes through the magnum (where thick albumen/egg white is added), the isthmus (where the shell membranes are formed), the uterus or shell gland (where the hard calcareous shell and shell pigment are deposited), and finally through the vagina and out through the cloaca (vent) as a fully formed egg.

Maelezo ya Majibu

(a)(i) Meaning of culling

Culling is the deliberate removal or elimination of unproductive, old, sick, deformed or otherwise undesirable animals from a herd or flock, so that only healthy and productive animals are kept.

(ii) Two reasons why culling is practised in cattle production

• To remove poor producers, old and barren animals so that only economic, high-yielding cattle are kept.
• To control the spread of disease and to improve the overall quality and productivity of the herd.

(b) One major function each of the enzymes during digestion in rabbits

• Ptyalin (salivary amylase): digests (breaks down) starch into maltose in the mouth.
• Rennin: coagulates (curdles) the soluble milk protein caseinogen into casein in the stomach.
• Pepsin: digests protein into peptones and polypeptides in the stomach.

Maelezo ya Majibu

(a) Meaning of malnutrition in farm animals

Malnutrition is a disorder that results when farm animals are fed with feed that is deficient in one or more essential nutrients, or in which the nutrients are supplied in the wrong proportion (either in excess or in short supply). It leads to poor health, retarded growth, low productivity, deficiency diseases and, in severe cases, death.

(b) Distinction between maintenance ration and production ration

Maelezo ya Majibu

(a) Four advantages of artificial insemination (A.I.)

• One superior sire can serve a very large number of females, spreading good genes widely.
• It prevents the spread of venereal and other breeding diseases transmitted during natural mating.
• It removes the cost, danger and difficulty of keeping a large, aggressive bull on the farm.
• Semen can be stored and transported over long distances, allowing use of sires that are far away or already dead.

(It also allows mating between animals of very different sizes and overcomes physical disability of a sire.)

(b) Five functions of the rumen

• Provides a site for microbial fermentation and digestion of cellulose (roughage).
• Stores large quantities of ingested food.
• Allows synthesis of microbial (bacterial) protein used by the animal.
• Enables synthesis of B-complex vitamins and vitamin K by micro-organisms.
• Produces volatile fatty acids that serve as a major source of energy, and releases gases by belching.