LIVESTOCK PRODUCTION

LECTURE 8

INTRODUTION Domestication of wild animals enabled

people to: Produce food i.e. meat, milk, cheese and

other dairy products, eggs etc. Produce leather for clothing, shoes, bags

and other by-products for the manufacture of glues, drugs, fertilizers etc.

Provide means of transport e.g. camels, donkeys and horses.

Provide farm power e.g. water buffaloes and bullocks for ploughing fields.

Classification of Farm AnimalsAnimals can be classified either

Scientifically or According to their nutrition (feeding habits)

Scientifically All common farm animals of the tropics

except poultry and rabbits belong to the class Mammalia and order Artiodactyla.

Cattle, sheep and goats belong to the family Bovidae whereas pigs belong to the family Suidae.

Classification of Farm Animals Cattle belong to the Bos genus, the sheep

belong the Ovis genus, the Goats to Capra genus and the pigs to Suis genus.

The domestic rabbit belongs to the family Leporidae and is derived from the species Oryctolagus cuniculus.

According to their nutrition farm animals can be grouped into Ruminants Non-Ruminants Herbivores

RuminantsThese are animals with a complex

stomach of four compartments.One compartment is the rumen where

the food that has just been eaten is temporarily stored.

The cellulose in the plant cell walls is digested in the rumen by the rumen bacteria.

From the rumen the food is passed into another compartment known as the reticulum.

RuminantsFrom the reticulum, food is regurgitated

back into the mouth where more chewing swallowing of the food occurs again.

This process is referred to as chewing the cud.

The other two compartments in which further digestion takes place are the omasum and abomasum

Non-ruminantsThese are animals with one stomach

compartment and omnivorous habitsThey include the pigs and poultry.Poultry describes all forms of

domesticated birds including chickens, turkey, ducks, guinea fowl, pea fowl, pigeons, gees and ostriches.

Pigs are particularly important in non-moslem countries where they are increasingly being reared under intensive conditions.

HerbivoresThese are non-ruminant plant eatersThey include

Rabbits, Guinea pigs, Larger farm animals such as

Camels Horses Donkeys

The larger animals are used mainly for transportation and as farm power.

Types and Classes of Domesticated cattle

Cattle are categorized as Beef Cattle Dairy Cattle Dual purpose cattle Draught Cattle

Beef Cattle These cattle are best suited for beef production

having a great width and depth of body. The udder is usually poorly developed and little

milk is produced. These animals are efficient in the conversion of

feed into high quality beef for human consumption.

Types and Classes of Domesticated cattle

Dairy Cattle Have a lean angular frame with a well-developed

mammary system, moderate girth and deep belly. One of the most important characteristic of dairy

cattle is good temperament.

Dual purpose cattle These are intermediate between beef and dairy

cattle in conformation and performance. Many indigenous breeds in the tropics are used as

beef, dairy and draught animals.

Types and Classes of Domesticated cattle

Draught Cattle These are characterized by great size and

length of body and strength given by their rugged form.

In many parts of the tropics, oxen are still used as a source of power for tilling the land.

Adaptation of Livestock to Tropical Environments

Early attempts to export temperate breeds of livestock met with dismal success.

After a relatively short time in the tropics, the productivity of many breeds of exotic stock decreased, their condition deteriorated and they became susceptible to tropical diseases.

In the recent years agricultural scientists have devoted attention to the subject of adaptation of livestock to hot climates.

Thus the environmental physiology of farm livestock, the effects of solar radiation and heat stress on their productivity in tropical and subtropical areas have been well documented.

Adaptation of Livestock to Tropical Environments

The basic principles of thermal adaptation are common to all vertebrates.

However different types of external covering (hair, wool, feathers and bristles) and the different types of underlying skin structure, give rise to variations in the mechanism of heat loss and the maintenance homeothermy (maintenance of an almost constant internal body temperature).

Effects of Heat on Tropical Livestock

A temperate animal taken to a hot climate is affected in two distinct ways. Directly by the influence of high

temperature and intense radiation and possibly humidity on the animal itself

Indirectly by the effect of heat on the animal’s environment including natural feed supply.

Direct Effects of Heat Every vertebrate animal has a particular

range of environmental temperature to which it is adapted and in which it is able to live most efficiently at minimal metabolic rate.

This is what is referred to as the comfort zone.

When animals are kept at temperatures below or above their comfort zones their metabolic rate is increased, either to keep the animal warm or to assist in heat dissipation.

Direct Effects of Heat Evaporative losses of water from the body

surfaces are the most fundamental processes concerned with heat regulation.

At low environmental temperatures, non-evaporative cooling (i.e. loss of heat due to conduction, convection and radiation) is responsible for more heat loss than evaporative cooling.

As the environmental temperature rises, the proportion of evaporative cooling rises and the proportion of non-evaporative cooling falls.

Direct Effects of Heat The principal effect of sweating is to limit the

rise in skin temperature. Since skin temperature largely governs

respiration rate a high sweating rate will be associated with a relatively low respiration rate.

The major ways in which animals adapt to tropical heat include: Heat tolerance Coat characteristics Skin pigmentation.

Heat toleranceA heat tolerant animal is one that has a

high efficiency of energy utilization and allows productive processes to continue at high level without the production of excessive amounts of heat.

Heat tolerance index is used to describe the heat tolerance range of different animal species.

Coat characteristics The role played by the hair coat in thermal

balance in a hot environment is twofold: It affords a certain degree of protection against

radiant heat from the sun. It interferes with the dissipation of heat from the

animals body surface. The most important characteristics include: Coat color Coat Texture Skin pigmentation

Coat characteristics Coat colour is important in reflecting or

absorbing solar radiation. Hair fibres which are light in colour reflect more

solar radiation than hairs which are dark. The amount of sunlight reflected can be as much

as 50% in the case of a white-haired animal, but considerably less with a dark-coloured animal.

The coat colour is of much importance during periods of high light intensity (summer) than during periods of low light intensity (winter).

Coat characteristics Coat Texture affects the mean absorption

coefficient of animals. The rectal temperatures and respiration rates of

Woolly-coated animals are invariably higher than those of animals with fine, glossy coats.

The nature of the hair has a bearing on the insulative properties of the coat.

Skin pigmentation A pigmented skin is most desirable in the tropics

since it is less susceptible to sunburn and photosensitivity disorders.

Indirect Effects The most important indirect effect of climate on

tropical livestock is that associated with water requirement and feed intake.

The quantity and quality of feed on offer to tropical livestock is primarily dependent upon the climatic factors influencing, and possibly limiting, plant growth.

The second most important indirect effect of climate on farm animals is its influence on the distribution of the major pests and diseases and the arthropod vectors which are responsible for their spread. For example, the distribution of Tsetse fly is directly related

to the presence or absence of suitable breeding sites, and these are themselves influenced by the climate of that region.

Animal Feeding/Nutrition Animals require feed rations that are

complete and balanced nutritionally. Each species and category of animal within a

species has different nutritional requirements that must be calculated with care to ensure maximum productivity.

The two main types of feedstuffs are Roughage, with high crude fibre content, and Concentrates with low crude fibre content.

Roughage Roughage is fed fresh or in the form of hay or

silage to supply some protein, energy, vitamins and minerals.

The commonly used grasses are Guinea grass, Elephant grass and giant star grass.

Maize, millet and sorghum are usually cut for making silage.

The common legumes include clover. Concentrate feeds provide energy and

protein needs.

Forage Conservation The surplus grasses and cultivated crops

produced during the growing season can be conserved a hay or silage to be utilized during the dry season when available grass becomes fibrous and unpalatable.

Hay Forages are cut and dried naturally, by air and sun

drying, or artificially. The forage is cut at sufficiently early stage of

maturity to ensure nutritional excellence. Drying usually lowers the water content below

25% so that the hay can be stored without becoming mouldy or fermented.

Forage ConservationHay

Properly cured hay is close to the original forage in nutritional value.

Silage Grasses and cultivated crops such as

maize, sorghum and millet are conserved as silage by chopping them into pieces, placing them in a silo and compressing them sufficiently to exclude most of the air.

Fermentation of soluble carbohydrates takes place producing organic acids, mainly lactic acid, with some ethanoic acid.

Forage ConservationSilage

The low pH of the mass prevents growth of undesirable bacteria that cause putrefaction (making it to go bad).

Fermentation ceases after sufficient acid has been produced.

The silage will keep for a long time with little change if stored in airtight bins and protected from rainwater.

Animal Health Animal diseases and disorders cause

considerable losses, which include: Death of the animals Increased cost of production Lowered quality of meat, hides and skins Greatly reduced efficiency of animal production

Some diseases and parasites are transmitted from animals to humans by contact, contamination of water or when a person eats food products from a diseased animal.

Signs of ill health in farm animals

Disease is any condition of the animal, which differs from normal health.

All the vital processes of feeding, digestion, respiration, blood circulation movement and all related activities function satisfactorily in healthy animals.

Departures from some or all of these processes indicate ill health.

Signs of ill health in farm animals

Signs of ill health in farm animals include: Dullness. Restlessness or nervousness. Loss of appetite or complete avoidance of feeding Indiscriminate feeding Severe loss of body mass in severe cases Uncoordinated movement Death

Signs of Good HealthThe state of health of an animal can be

assessed from observations on: Pulse Rate Body temperature Body Conformation Condition of skin or coat Visible mucous membranes Feeding habits

Signs of Good HealthPulse Rate

This is the rate and force of blood passing through the blood vessels per minute.

This reflects the heart beat. The normal pulse rates per minute for

cattle is 50-70, for the horse is 28-42 and for the sheep is 68-90.

When the pulse rate is outside the normal range, unless it can be explained physiologically (e.g. exercises increase rate) ill health may be suspected.

Signs of Good Health Body temperature Normal body temperatures in °C are:

Cattle 37.6-39 Horse 37.5-38.3 Sheep 38.3-39.3 Pig 38.3-39.3

Any change in temperature above or below the normal range may indicate ill health.

Signs of Good HealthBody ConformationExcessive fatness may result from

overfeeding or disease while leanness or emaciation may be a result of under-feeding, starvation or disease.

A normal animal usually shows the proportions or body organs and tissues characteristics of the breed or strain of the animal.

Signs of Good Health Condition of skin or coat

The skin of a healthy a normal is usually smooth and slips back easily when pulled.

The hair is bright, clean and unruffled. Extremely dry hair or staring coat where the hair

sticks up, are symptoms of ill heath. Excessive sweating causes the hair to form a mat

on the skin and indicates ill health it is not a result of exercise.

Similarly, loss of hair, abnormal out-growths or swellings of the skin, eruptions and boils, presence of parasites on or under the skin of animals are all signs of ill-health.

Signs of Good Health Visible mucous membranes

The inside linings of the eyelids, nose, mouth and the external urinogenital tract of normal animals are usually moist and pinkish.

When an animal is ill, these linings may appear bright red or pale and anaemic or yellowish or bluish depending on the type of disease from which the animal is suffering.

Signs of Good Health Feeding habits Healthy animals consume enough food when

available according to nutritional needs. A sick animal may develop abnormal appetite

for non-feed materials and eats anything indiscriminately.

Healthy ruminants chew the cud in between feeding but sick animals do not and in some cases the animal may vomit the ingested feed.

The consistency, texture, colour, smell and frequency of defecation or urination may also indicate ill health.

Causes Diseases and Disorders

Animal diseases and disorders can be caused by living organisms such as bacteria, fungi, viruses, nematodes and trematodes (helminthes), ticks, lice and flies and by non-living substances such as chemical poisons.

Other causes include insufficient or poor-quality feed as well as deficiencies of nutrients such as carbohydrates, proteins, mineral elements and vitamins.

Some diseases or disorders are due to one or more of these causes.

Causes Diseases and Disorders Poorly fed animals are more prone to succumb to

attacks by living organism. Under the traditional system of animal husbandry in

the tropics, animals are poorly fed. A cause that excites a disease is always directly

associated with it whereas a predisposing cause reduces an animal’s resistance to the exciting cause.

The causes can be categorized as: Physical causes Mechanical causes Chemical causes Biological causes

Causes Diseases and Disorders

Physical causes Abnormal ambient temperatures are

important although in the tropics it does not fluctuate so much.

Animals imported from temperate regions are most affected.

Causes Diseases and DisordersMechanical causes

Pressure on body tissues from tumours or parasites, polyps (small growths) in the nose and urinogenital system are often disabling especially where they affect a vital organ such as the brain or liver.

Obstruction of the air and food passages by feed or other materials or strictures of the orifices caused by contraction of the muscle or coats are other common mechanical problems.

Causes Diseases and Disorders

Chemical causes Retained waste products of body

metabolism such as urea, other nitrogenous compounds or excessive carbodioxide can cause illness as well as poisonous substances such as acids and caustic alkalis.

Heavy metals and animal toxins may be inhaled, ingested or taken in through the skin.

Causes Diseases and Disorders Biological causes

A large number of parasitic bacteria, fungi, viruses, protozoa, helminthes (worms) insects and ticks actively invade animal tissues and organs.

These invasions result in localized or generalized disease conditions that may be fatal in very severe cases.

Feeding animals on unbalanced feed or dirty water can cause nutritional deficiencies or introduce disease-causing organisms respectively.

Diagnosis of Disease This is normally done by veterinarians

through a combination of physical examination, observation of clinical symptoms and chemical and microbiological tests in the laboratory.

The results give a basis for the application of preventive and curative measures to combat or control the disease.

The carcass of a dead animal is examined for any signs of lesions of the killing disease in a post-mortem examination.

Transmission of Disease Diseases are transmitted from one animal to another

when pathogens escape from an infected animal and spread to healthy animals.

Many disease-causing organisms are destroyed by the defensive mechanisms of the host,

others are eliminated in its secretions and discharges and may invade other animals or re-infect the same animal.

Thus an animal that dies from an infective disease should be properly disposed of by burning or burying the carcass deep in the soil.

This ensures that the pathogens are destroyed and do not spread the infection.

Transmission of Disease In some cases the pathogen and its host can co-exist

so that the pathogen does not produce disease symptoms and the animal’s body does not destroy the pathogen.

Predisposing factors such as poor nutrition or inter-current diseases can upset the balance and allow the pathogen to become infective.

The animal then develops the disease symptoms. High levels of nutrition, management and sanitation

help animals to resist invading pathogens.

Sources of Infection The ways by which pathogens reach their hosts

include: Direct or immediate contact with other diseased

animals resulting in the transfer of the disease. Skin diseases and some venereal diseases are transferred in this way.

Indirect contact with objects such as dirty utensils, vehicles used to transport sick animals or railings in animal houses which may carry over pathogenic organisms from sick to healthy animals.

Contact with symptomless carriers. Soil-inhabiting spores of some bacteria invade animals

through wounds e.g. tetanus, anthrax and clostridial infections are often picked up by grazing or trekking animals.

Sources of Infection Ingestion of contaminated feed. Airborne infection in overcrowded housing e.g. most

respiratory diseases caused by bacteria, fungi or viruses.

Blood-sucking and biting flies, fleas, lice and ticks transmit disease organisms through their bites. E.g. Trypanosomiasis, tick fever and some filarial infections.

Condition loss due to stress. Some bacteria live in mucous membranes of animals

without causing disease but in cases of stress, the organism becomes pathogenic.

Routes of infection Main route of entry of parasites and pathogens into

an animal’s body is through the organs and tissues of the animal including the alimentary canal, urinogenital organs, eyes, nose, and skin.

The skin, which serves as a protective coat over the body organs and tissues, may become a route of entry for pathogens wherever it is mechanically damaged or weakened. Many fleas, ticks and lice attach themselves directly to the

skin or merely live on the surface of the skin protected by the hair or the feathers. In sucking blood or biting the animal, they inject pathogens.

Pre-natal and post-natal infections of young animals may occur through the placenta or poorly managed umbilical cords.

Routes of infectionSome pathogens of poultry can be

transmitted through the egg from an infected hen.

The respiratory tract, conjuctiva and mammary glands are also routes of infection.

Disease Course After infection and before disease symptoms occur

there is usually an incubation period. This is the time lag between the entry of the infective

organism into the animal and the outward expression of signs of the disease.

During this period the animal appears normal but it can infect other animals.

Once the symptoms of a disease appear, the disease may progress rapidly into an acute condition, which may progress to death or recovery.

In chronic cases, the disease persists for a long time and may or may not cause death of the animal.

If the animal contracts another disease during this time, it may die after prolonged suffering and extensive loss of condition.

Defense against Disease Normal animals protect themselves against disease

by: Primary defensive mechanism which hinder or prevent the

entry of pathogens Secondary defensive mechanism which attack the

pathogens which enter the body. The secondary defensive mechanism either prevents

multiplication and spread of the pathogen in the animal’s body or inactive toxins produced by pathogen.

The white blood cells can produce antitoxins against specific pathogenic secretions.

This is what is referred to as immunity

Defense against Disease Any foreign protein (antigen) entering an

animal’s blood makes the white blood cells produce antibodies.

These chemicals attack the antigen and immobilize or destroy it.

The types of immunity include: Natural immunity Artificial immunity

Natural immunity The animal’s white blood cells have the ability to

produce antibodies to some antigens before they are exposed to infection by those antigens.

Defense against DiseaseNatural immunity may be

Inherited Passively acquired through the colostrum

and milk of the mother Actively acquired after infection – whether

or not the animal exhibits symptoms of the disease.

Defense against Disease Artificial immunity

Active artificial immunity is achieved by the injection of a non-pathogenic attenuated (reduced in strength) form or a small amount of the living pathogenic organism.

Secretion of antibodies in response confers a state of immunity, which may be temporary or permanent.

Usually the process is repeated periodically to ensure that the immunity does not fade away.

Defense against DiseasePassive artificial immunity is conferred

by injecting serum obtained from an animal that has recovered from a disease into another animal that is susceptible to the same disease.

The antibodies in the serum confer immunity to the recipient animal only for a short time.