Agricultural Science 2021 Jamb Examination

Agriculture plays a fundamental role in sustaining life by providing food for humans and animals. This primary function supports nutrition, health, and economic stability. While agriculture also contributes to industrial raw materials and export earnings, its most essential role remains the direct provision of food that sustains populations globally.

Subsistence agriculture involves farming mainly for the farmer’s household consumption rather than for sale. Consequently, production is limited to meet family needs, resulting in small surpluses for trade or storage. This system typically uses simple tools and small plots, leading to low yields compared to commercial farming.

Gestation period refers to the time interval between conception—when fertilisation occurs—and parturition, which is the process of giving birth. During this period, the embryo or foetus develops inside the mother's womb until it reaches maturity for birth. The duration of gestation varies among animal species.

Oxytocin is the hormone that stimulates milk let-down in lactating animals. It is secreted by the posterior pituitary gland and acts on the muscles around the alveoli in the mammary glands, causing them to contract and release milk. Testosterone and androgen are male hormones, while FSH regulates follicle development in females.

An adult male cattle is known as a bull. Bulls are intact males used for breeding and are generally larger and more muscular than females. A ram refers to a male sheep, a boar to a male pig, and a duck is a type of bird, making ‘bull’ the correct term in this context.

Limestone is an important source of calcium carbonate, which is essential for strong eggshell formation in laying birds. Layers therefore require more calcium than growers to maintain consistent egg production and shell quality. Calcium deficiency can result in weak or thin shells, hence the inclusion of more limestone in their feed.

Continuous grazing leads to overgrazing, soil compaction, and poor grass regeneration, which degrades rangeland quality. Proper rangeland management involves rotational grazing, periodic reseeding, and weed control. Continuous grazing is therefore counterproductive and not a method of improving rangeland.

The liver fluke, *Fasciola hepatica*, passes through several larval stages: egg, miracidium, sporocyst, redia, cercaria, and metacercaria. The miracidium is a ciliated larva that hatches from the egg and infects a snail, the intermediate host. Roundworms, tapeworms, and ticks do not have a miracidium stage.

Foot and mouth disease is a highly contagious viral infection affecting cloven-hoofed animals. Its symptoms include fever, drooling, blisters on the mouth and feet, and lameness. Blood-stained diarrhoea, however, is not a common symptom and typically indicates another condition, such as enteritis or parasitic infection.

Liver flukes lodge in the bile ducts, where they cause inflammation and blockage. This obstruction prevents the flow of bile into the intestine, reducing fat emulsification and absorption. Since bile is crucial for breaking down fats, the blockage directly leads to poor fat digestion and subsequent malnutrition in affected animals.