AGRICULTURE O LEVEL(FORM FOUR) NOTES – LIVESTOCK PRODUCTION

THEME 2.0: LIVESTOCK PRODUCTION

IMPROVEMENT OF LIVESTOCK BREEDS

The primary goal of keeping animals is to produce sufficient and high-quality animal products. To achieve this, livestock keepers must ensure they have good quality animals, provide proper nutrition, and maintain their health effectively.

Livestock Improvement

The productivity of farm animals is determined by inheritance, which is the passing of genes from parents to offspring. However, the environment plays a crucial role in determining how much of this inherited potential is realized. Therefore, livestock improvement programs focus on enhancing both the genetic inheritance and the environmental conditions in which animals are kept.

Concept of Inheritance

Inheritance refers to the mechanism by which characteristics of parents are transmitted to their offspring. This mechanism resides in the sex cells (gametes) of both males and females, which contain chromosomes carrying units of inheritance called genes.

• Chromosomes occur in pairs within the nucleus. The number of chromosomes varies among species, for example: Cattle have 30 pairs, Sheep 27, Pigs 19, and Chickens 39.
• The members of each chromosome pair are called homologous chromosomes.
• Genes are located at specific positions on chromosomes called loci.
• Genes located at the same loci on homologous chromosomes are called alleles.
• If alleles have the same effect, they are termed homozygous.
• If alleles have different (antagonistic) effects, they are termed heterozygous.
• Sex cells undergo a special type of cell division, reducing the chromosome number by half to form gametes.
• When male and female gametes fuse during fertilization, the full chromosome number is restored, and offspring inherit genes from both parents.

The Concept of Heredity

Heredity is a numerical measure of the proportion of total variation among animals in a particular characteristic that is caused by the genes the animal possesses. It is expressed as a percentage (%).

For example, a heritability of 50% for a certain trait means that differences between animals in the herd for that trait are 50% genetic and 50% environmental.

Significance of Knowing Heritability of a Character

1. It helps breeders select the most appropriate breeding method.
2. It allows estimation of the expected progress towards improvement of animals.

Table to Show Heritability of Dairy Cattle

THE CONCEPT OF BREEDING

Breeding is the process of changing the genetic constitution of animals for future generations to improve desirable traits.

Objectives:

1. To increase the yield of meat, milk, eggs, and other products.
2. To improve disease resistance.
3. To enhance resistance to dry or hot climates.

Methods Used to Improve Genetic Makeup of an Animal

1. Selection
2. Mating systems (including outbreeding and inbreeding)

Selection

Selection is the process of allowing only certain animals with desirable traits to become parents of the next generation.

• Animals with undesirable characteristics are sold or removed, while those with desirable traits are retained for breeding.

Advantages of Selection

Selection increases the frequency of desirable genes in the herd and decreases the frequency of undesirable genes, leading to overall improvement.

Disadvantages of Selection

If desirable genes are absent in the herd, selection alone cannot introduce them, making it an ineffective tool for genetic improvement in such cases.

Note: Effective selection requires skill, proper record-keeping of animal performance, and monitoring of offspring performance.

Mating System

The mating system involves the breeder deciding which sire (male) mates with which dam (female), usually after selecting the breeding herd.

Types of Mating

• Outbreeding
• Inbreeding

OUTBREEDING

Outbreeding is the system of mating unrelated sires and dams.

Objectives of Outbreeding

• To introduce new genes into the herd. For example, Zebu cattle lack genes for high milk yield, but Friesian cattle possess these genes. By mating a Friesian bull to a Zebu cow, the offspring inherit the high milk yield trait from the Friesian sire.
• To obtain hybrid vigor (heterosis), where offspring grow faster and perform better than their parents when unrelated sires and dams are mated.

INBREEDING

Inbreeding is the system of mating related sires and dams.

Objectives of Inbreeding

• To ensure that sires and dams from the same herd selectively transmit desirable characteristics.

Advantages of Inbreeding

• Increases the number of homozygous gene pairs for specific traits.
• Increases uniformity within the herd, producing a pure line of animals.

Mating System Methods

1. Natural mating system
2. Artificial insemination

Natural System

Mating occurs naturally by allowing copulation when the female shows signs of heat.

Artificial Insemination

• Performed by trained inseminators who introduce selected semen into the reproductive tract of the dam using specialized instruments.
• Semen is collected from the sire using an artificial vagina and a teaser animal, then stored in deep-frozen tubes.
• The semen can be diluted and used to inseminate 50 to 200 dams from a single male sire.

Advantages of Artificial Insemination

• Reduces the risk of spreading viral diseases that might be transmitted by the male.
• Semen from high-quality sires can be made widely available at a low cost.
• Transportation and distribution of semen are easier since it is stored in small containers, unlike natural systems that require moving the sire.

Disadvantages of Artificial Insemination

• Requires skilled personnel to perform the procedure correctly.
• If not done properly, semen from heavy breeds may be introduced to light breeds, causing birthing difficulties.

Livestock Breeding Stations in Tanzania

• Kitulo – Iringa
• Uyole – Mbeya
• Mpwapwa – Dodoma
• Tengeru – Arusha
• Maruku – Bukoba (Kagera)
• Mabuki – Mwanza

Principles of Good Livestock Breeding

1. Selection of desirable sires and mates.
2. Proper care of sires and dams before service.
3. Breeding at the appropriate age.
4. Servicing (coition) at the right time during the female’s heat cycle.
5. Use of an appropriate breeding system.
6. Care of pregnant animals up to parturition.
7. Care of young animals to ensure healthy growth.
8. Castration of unwanted male animals to control breeding.
9. Culling of unproductive or undesirable animals.

FISHERIES

Fisheries refer to the process of producing and rearing fish, commonly known as fish farming or aquaculture.

• This is done by keeping fish in aquariums or tanks or by breeding fish and then releasing them into dams, ponds, and rivers.
• Fish species reared must be adaptable to the climatic conditions of the area.
• It is advisable to construct fish ponds on level ground near a reliable water source such as a river or stream.

• A fish pond should be able to hold water throughout the year to sustain fish life.
• Avoid constructing ponds on sloped areas or porous soils; sandy soil is unsuitable, while clay soil is ideal.
• The pond should neither be too shallow nor too small; a depth of at least 1.5 meters and a width of 20-25 centimeters is recommended.
• The walls of the pond should be raised and covered with grass to stabilize the soil and prevent erosion.
• There should be sufficient nutrients in the pond water to support the growth of aquatic plants, which serve as food for fish.
• The pond must be protected from pollutants to maintain water quality and fish health.

A fish pond should have:

1. An inlet where water enters the pond.
2. A spillway to allow overflowing water to flow back into the river or stream.
3. An outlet pipe at the bottom of the pond for draining water when necessary.
4. A fence to keep away thieves, animals, and other creatures that might pollute the pond.

Significance of Fish Farming in Tanzania

• Provides a source of high-quality protein for human consumption.
• Creates employment opportunities and recreational activities.
• Generates income for fish farmers and related businesses.
• Contributes to foreign exchange earnings through fish exports.

Main Types of Fisheries

1. Marine fisheries, which involve fishing in the ocean.
2. Freshwater fisheries, such as those in the Pangani and Rufiji estuaries, which are also sites for prawn farming.

Common Species/Fish Types in East African Ponds

• Tilapia, black bass, catfish, and trout are common species found in East African ponds.
• Catfish is well adapted to freshwater environments.
• Tilapia is the most preferred species, including varieties such as T. sparrmani, T. galilae, T. heudeloti, T. esculenta, T. leucostica, and T. andersonii.

Advantages of Tilapia

• Local consumers are accustomed to their taste, making them popular in the market.
• The climate is suitable for tilapia, typically between 20-30°C, although T. sparrmani can survive at temperatures as low as 8°C.
• Young fish for stocking ponds are readily available.
• Tilapia are either omnivorous or herbivorous, making them easy to feed.
• They breed and grow quickly, allowing for efficient production.
• They are affected by relatively few parasites compared to other fish species.

Characteristics of Herbivorous Tilapia

• They primarily consume plants.
• They have high production potential, examples include Tilapia tholon and Tilapia zillii.

Characteristics of Omnivorous Tilapia

• They eat both plants and small animals such as snails, mosquito larvae, and worms.
• They practice mouth brooding, where they keep their eggs in their mouth until they hatch. Examples include T. macroch, T. mossambia, T. rulotica, and T. nigra.

FEEDING

• Tilapia should be fed daily, preferably with commercial feeds such as pellets, rice bran, groundnut cake, or maize bran.
• Overfeeding should be avoided as it can reduce oxygen levels in the pond; feeding should be adjusted according to pond size and fish population.

HARVESTING

• Fish are harvested when mature; for example, Tilapia are ready for harvest at about 8 months old, reaching lengths of 20-30 cm.

Methods of Harvesting

1. Hook and line fishing.
2. Using catching nets.
3. Draining the entire pond water to collect fish.
4. Using cast nets with appropriate mesh sizes.

Diseases and Parasites of Fish

• Many fish die due to pollutants that cause diseases; decomposing fish can infect the pond and spread diseases further.
• Certain birds nesting near ponds may also spread diseases to fish.

Care and Maintenance of the Ponds

• Ponds should be fertilized twice a week to promote the growth of natural fish food.
• Water levels should be checked regularly to ensure adequate depth for fish survival.
• Grasses and weeds around the fish pond should be regularly slashed to prevent overgrowth and maintain pond integrity.
• Any leaks or damages to pond walls should be repaired promptly to prevent water loss.

MARKETING

• Fish are sold in local and town markets.
• Some fish are exported to other regions or countries.

STORAGE

• Fish can be stored in a frozen state to preserve freshness.
• They can also be dried under the sun after removal of offal and scales.
• Salting and drying is another common preservation method.
• Smoking is used to preserve fish and add flavor.