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Lesson Note

Subject: Agricultural Science
Topic: Animal Nutrition
Lesson Objectives: At the end of the lesson, learners should be able to:
i. State the classes of food nutrients,
ii. State the sources and functions of food nutrients,
iii. State the importance of water.


Animals require feed rations which are complex and balanced nutritionally. Each species or category of animal within a species has different nutritional requirements which must be calculated with care to ensure maximum productivity.
The nutritional requirements of animals can be broadly classified into organic and inorganic substances. The organic materials are represented by carbohydrates, proteins, fats and oils, and vitamins which are required for growth, repairs, respiration and other physiological activities. The inorganic materials are mainly mineral salts and water which are needed to maintain ionic, osmotic and pH balances within the body.
It therefore, means that animal nutrition is founded on the basic ideas of biochemistry and the physiology of the animals and feeds fed.

Sources, Functions and Deficiency Symptoms of Food Nutrients

(a) Carbohydrates:

These are organic compounds containing carbon, hydrogen and oxygen with hydrogen and oxygen occuring in the ratio of 2:1 as in the case of water. They are energy yielding food substances. They exist under different forms such as monosaccharides, disaccharides and polysaccharides. Examples of the monosaccharides are glucose and fructose. The disaccharides include the following sucrose, lactose and maltose sugar. A breakdown of these sugars gives rise to the following simple sugars (monosaccharides).
i. Sucrose glucose + fructose
ii. Lactose glucose + galactose (milk sugar)
iii. Maltose glucose + glucose

The polysaccharides are starch, cellulose and fibres.
When carbohydrates are broken down or oxidized in the body tissues during cellular respirations, they release energy which is used for various metabolic and physiological activities such as growth, Locomotion, heat production, reproduction and Excretion. Carbohydrates breakdown is represented with a single equation;
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
Carbohydrates oxygen carbondioxide water energy.

Sources of Carbohydrates: Yam, cassava, cocoyam, cereals such as maize, rice, millet and guinea corn.
i. It is an important source of body fat. The fat deposits act as both insulator and energy source.
ii. The glucose stored in the body provides energy for work. The energy is needed for the transport of materials and synthesizing of other essential body nutrients.
iii. They are constituent of milk (in diary animals), brain and cartilage as lactose sugar.
iv. It provides heat which helps to keep the body of the animal warm. That is in the regulation of body temperature.

(b) Proteins:

The basic units are amino-acids and they are linked together to form protein. Proteins are organic compounds containing elements such as carbon, hydrogen, oxygen, nitrogen as well as phosphorus and sulphur.
During digestion, proteins are broken down to form amino acids. Amino acids can be classified into essential and non-essential amino acids. They are essential in the diet if they cannot be synthesized in the body and non-essential if they are not needed to be included in the diet since they are synthesized by the body.
Sources: Fish meal, blood meal, meat, milk, eggs, melon cake, groundnut cake, beans, etc.

i. For production of animal products to build up flesh and some tissues or organs of the body.
ii. They provide very little energy and heat.
iii. They are used in forming digestive juices and other secretions.
iv. They are used in formation of egg and milk.
v. They are used in building protective coverings such as hairs, nails, hoof, horn, wool and feathers.
vi. Proteins help in the replacement of worn-out tissues in case of skin damage.

(c) Fats and Oils:

Fats are compounds of carbon, hydrogen and oxygen but the percentage of oxygen is lower than in Carbohydrates and proteins. They consist mostly of compounds of glycerol and fatty acids. Fat are found in both plants and animals but in plants fats are called oils.
Sources: Palm fruit, palm kernel, coconut, melon seeds, groundnut, soya bean, cotton seeds.
i. They are a source of energy to the animal and supply about 2.5 times as much energy as does carbohydrates per gram.
ii. They act as insulator to the body of the animal.
iii. They serve as carriers of non-fat nutrients notably fat soluble vitamins A, D, E and K.
iv. They promote the distribution of both vitamin A and Carotene.
v. Essential sources of fatty acids and glycerine.
vi. Fats protect vital organs like kidney and heart and are found under the skin.
i. Lack of fats in the diet of animals leads to retardation in animal growth.
ii. It also leads to scaly skin and kidney troubles.
(d) Vitamins: Vitamins are complex organic compounds effective in relatively small amount, but essential for normal growth and maintenance of life. They are therefore, necessary food factors needed in minute (small) quantities for maintenance of good health and proper growth of the stock.
Vitamins are classified into two groups namely the fat soluble vitamins such as Vitamins A,D,E and K and the water soluble vitamins such as Vitamins B and C. Deficiency of vitamins causes Avitaminosis..
Vitamins A (Sectional)
Vitamin A (fat soluble) is a derivative of a hydrocarbon and is synthesized by animals in the liver.
Sources: Carotene, milk, fish liver oil, carrot, grass.

Importance of Vitamin A
i. It is required as a protective compound since it prevents the animals from being affected by diseases.
ii. It is needed for growth, production of milk, reproduction and maintenance of ill-health.
i. It retards growth in animals
ii. A ration deficient in vitamin A renders the respiratory tract liable to infection.
iii. Lack of vitamin A results in Keratinisation of tissues.
iv. It causes night blindness in animals
v. It may lead to abortion or birth of weak calves in cattle.

Vitamin D (Fat soluble)
It is a vitamin promoting the assimilation and utilization of the mineral calcium and phosphorus which are mainly responsible for teeth and bone formation in animals. The vitamin can be synthesized by animals which are exposed to the ultra violet rays and are responsible for this synthesis.
i. It causes serious bone disorder such as incomplete calcification of bones (rickets) in young growing animals.
ii. It causes dental decay
iii. It leads to thin shell in poultry, poor hatchability in poultry and weak muscles.
Sources: Sunlight, Cod liver oil, Butter, Egg yolk, Cream, Margarine.

Vitamin E: It is a fat soluble vitamins essential for reproductive purposes since it is associated with the placental functions of female animals, hatchability of eggs and sperm production. It compliments the effect of Vitamin A during reproduction.
i. It may cause sterility in animals or abortion
ii. It may cause paralysis in calves and lambs
iii. It may cause liver and cardiac muscle abnormality.
Sources: Grains, Cereals, Oils of soyabean, groundnut, cotton seed, green vegetables, milk, meat, eggs.
Vitamin K: It is a fat soluble vitamin that regulates the functioning of the blood since it is associated with blood cloting or coagulation.
i. It leads to non-clotting of blood and hence excessive bleeding.
ii. It leads to haemorrhage and anaemia
Sources: Cereals, fish products, green leafy plants, liver, egg yolk.
Vitamin B: Vitamin B is a water soluble vitamin and has many components and is generally referred to as vitamin B complex. Vitamin B1, B2, B3, B4, B5, B6 and B12 form this complex. Although they differ in composition they are responsible for growth and carbohydrates metabolism.
Vitamin B1 (thiamine): It assists in the functioning of the heart, nerves and muscles. It is essential for carbohydrates metabolism.
i. It leads to nervous defects such as Beri-beri
ii. It leads to loss of appetite and decrease of digestive juice.
Sources: Brewers yeast, liver, kidney, egg yolk, beans, sillage, etc.
Vitamin B2 (Riboflavin): It works in conjunction with vitamin B1 in promoting tissue metabolism and in regulating the functions of the eye.
Deficiencies: It results in the cracking of lips, pellagra. In poultry, there is failure of growth, poor egg hatchability and skin eruption in pigs.
Sources: Milk, egg, liver, kidney, leafy vegetables, Brewers yeast.

Vitamin B3 (Niacin): it is essential part of enzyme system. It may be involved in protein synthesis when tryptophan is deficient. It is needed for healthy skin and tongue development. Deficiency in pig is characterised by a dry scaly skin and anaemia. At times, it is followed by nervous fit and scouring. Poultry shows dermatitis and inflammation of the tongue.
Sources: Liver, muscles, yeast, milk, lean meat.

Vitamin B6 (Pyredoxine): It is a coexyme and essential in metabolism of amino acids and fats. It is also essential for healthy skin development, vision and nervous system. It’s deficiency leads to severe anaemia in young farm animals such as pigs.

Vitamin B12 (Pantothenic acid): It is a co-enzyme. It is essential in the metabolic processes of the body. In pigs, there is diarrhoea usually with mucous and sometimes with blood. There is coughing and the loss of hair and in co-ordination of gait. In poultry there is emaciation, dermatitis and crusts at the angle of the beak, on the eye lids and on the feet. In calves there is weakness and diarrhoea.
Sources: Yeast, hay, green fodder, liver, egg yolk

Biotin: It is essential for the work of many micro-organisms including yeast. This vitamin is essential for egg hatchability. Deficiency in pigs causes dermatitis and cracks in the feet. In chickens there is dermatitis round the eyes.
Sources: Yeast, fodders, Brewers yeast.

Folic acid: It is very essential for the formation of red blood cells.
Deficiency: It’s deficiency in the diet leads to poor feathering, pigmentation and slow growth.
Sources: Yeast, leafy vegetables, liver, kidney.

Choline: Choline is essential for the building and maintenance of body structure. It plays vital role in fat metabolism and transportation. Its deficiency symptoms include poor growth in all species especially poultry and very young pigs and calves. Poultry suffer from slipped tendons.
Sources: Yeast, liver, kidney, cereals
Cyano Cobalamin (Vitamin B1): It assists red blood formation. It’s deficiency results in anaemia, abnormal bone formation, poor growth and poor hatchability in poultry.
Sources: fish, lean meat.
Vitamin C (Ascorbic acid): This is a water soluble vitamin needed for healthy body cell development. It is important in oxidation reduction system in the body. It behaves as a tissue catalyst. It is concerned with the formation of teeth and bone and the inter cellular substance in cartilage. It is essential for the resistance of body diseases and for the maintenance of the walls of the blood vessels and for the gum.
The deficiency symptoms include scurvy-swollen, bleeding and ulcered gum, weak bones and fragile capillaries, resulting in internal haemorrhages.
Sources: Citrus fruits, tomatoes, green leaf vegetables, potatoes.

(e) Minerals:

Minerals are elements needed for their importance in the vital activities of the body. They are needed fairly in small quantities and they exist in the body of the animals as ions or as component of organic compounds of the body.
The minerals are left behind as ash when food is burnt. About eight elements namely calcium, phosphorus, potassium, sulphur, sodium, chlorine, magnesium and iron are called major mineral elements (Macro-nutrients) commonly present in food. Others occur extremely in small amounts and are called minor elements (Micro-nutrients). The elements include iodine, cobalt, copper, zinc, selenium and maganese. They are also called trace elements.

f) Phosphorus and Calcium:

It is neessary for the formation of bones (skeleton). It I essential for the formation of egg shells in poultry as well as production of milk in diary animals. It is also essential for fertility in farm animals. Phosphorus is also essential for respiration.

Deficiency Symptoms of Calcium and Phosphorous
i. It leads to poor bone and teeth formation
ii. It leads to low production of milk in diary animals
iii. It leads to impaired fertility and reduced egg yield.
iv. It results in subnormal growth and appetite and lowered feed conversion effeciency
Sources: Grains, oily seeds, fruits, leaves, bones, flesh, blood, milk, eggs.

7. Iron

Iron is required in the body for the utilization of oxygen by the tissues. Iron is essential for the formation of red blood cells. Lack of iron in thehe diet of the animal leads to anaemia.
Sources: Blood meals, leafy vegetables, iron injection, salt licks.

8. Iodine

This element is present in most livestock feeds in small quantities. It is needed by the body for the formation of thyroxine, an iodine-containing hormone which is secreted by the Thur gland. It controls the rate of metabolism in the body.

Deficiency symptoms: The deficiency of iodine in the diet of animal results in the enlargement of the thyroid gland, producing a condition known as goitre. It may lead to death of newly born calves and lambs. Young pigs without hair are the result of iodine deficiency in the diet of mother pig. The disease is controlled by adding iodized salt to the diet of most pregnant animals.
Sources: Green plants such as legumes and vegetables

9. Zinc

It is required for the formation of hairs and is particularly important in the diet of pigs. A deficiency of zinc leads to a retarded growth rate, scaliness and cracking of the skin.
Potassium: It controls both the growth and functioning of the muscles.

10. Sulphur

It assists in protein synthesis.

11. Molybdenum: It regulates enzyme activity. Sources of this element are salt licks, grasses, legumes fish meal.

12. Water

Water (which is composed of hydrogen and oxygen in the ratio of 2:1) is the largest single constituent of all living plants and animal tissues. It is an essential component of the protoplasm of body tissues. The body tissues of animals and those of most living organisms consist of more than 70% water.

Sources of water

i. It is a source of most animal feeds such as fresh grass, legumes and vegetables and fruits.
ii. Through metabolic processes of the body
iii. Through drinking water. Water is taken by animals independently of other items in the diet or ration.

Importance of Water
i. It is necessary for food mastication, ingestion, digestion, absorption and distribution throughout the body.
ii. It is necessary for the removal of waste products from the body
iii. It helps in regulating body temperature by dispersing heat in sweat
iv. It is necessary for maintaining proper consistency of the blood.
v. It acts as a lubricant in the joints of farm animals.

Types of Ration/Diet and their uses

Farm animals such as cattle, sheep, goats, pigs and poultry need a regular supply of food to ensure a healthy and productive life. They require food to supply their energy for movement and for maintenance of body temperature as well as for the growth of their skeletons, muscles, hair, etc. Healthy animals will produce milk, meat, eggs and fat of an excellent quality for human needs.
The nutritional requirement of animals can be broadly classified into organic and inorganic substances. The organic substances are represented by carbohydrates, proteins, fats, oils and vitamins and the in organic compounds are mainly mineral salts and water needed to maintain ionic, osmotic and pH balances within the body.
The food given to these animals for their body maintenance and production purposes is referred to as ration. The food given to animals is called feed.

Balanced Ration/Diet and its Components

A balanced ration or diet is the one that contains all the essential nutrients for normal growth and production of farm animals in adequate quantity and proportion. The ration refers to the meal compounded to meet the daily nutritional needs for water, proteins, carbohydrates, minerals and vitamins.
A ration made from combination of feeds providing different nutrients in such proportions, amount and form in such a way that a given animals or groups of animals kept for a particular purpose can be nourished properly without a waste is also referred to as a balanced ration. Certain considerations are also made while compounding the different types of ration. These include the following – kind of productive activity by the animal, stage of life, species of animals.
The components of a balanced diet or ration are carbohydratesproteins proteins, fats and oils, minerals, vitamins and water.

Production Ration

Production ration is the amount of feed added to the quantity of maintenance ration to produce a different ration for a producing animal
This ration is generally richer in food constituents than maintenance ration. It is compounded to provide for the animal’s growth and for production. For example, it is given to cows which produce milk and layers which produce eggs, work animals and pregnant animals.
Production ration is used for flushing in female animals. Flushing is a way of increasing the fertility rate by keeping the female animal at high nutritional level when she is about to be put to the male.
It is also used for “steaming up”. This is a special diet given to pregnant animals for some weeks before parturition or birth.

Maintenance Ration

Maintenance ration or diet is a minimum amount of food required to keep an animal alive without gaining or losinv weight. The amount of feed supplied under this condition ensures that all physiological processes of the body are carried on normally. It must have each class of food and the age and size of the animal to be fed must be borne in mind when deciding the quantity to be supplied to the animal.
This ration is needed to maintain the body temperature, blood circulation and other physiological functions of the body. This type of diet is commonly fed to 3-montha old broiler and beef cattle.

Malnutrition – Causes, Symptoms and Correction in Farm Animals
This is a condition caused by lack of sufficient food or food delicacy in certain essential nutrients. It may cause some nutritional diseases which may occur as a result of lack of some part of the ration. Malnutrition results in varying degrees of ill-health or death in serious cases. Some farm animals suffer from anaemia (shortage of blood).

Causes of Malnutrition in Farm Animals
There are some factors that contribute to the malnourishment of farm animals. Some of these factors include shortage of food for feeding the animals, low income of the farmer to provide feeds, poor quality of the feed given to the animals.

i. Low resistance to diseases and infection
ii. Low production (in yield) in terms of egg and milk production.
iii. Slow and retarded growth
iv. Emaciation of the animal
v. Dull rough hair coat and high mortality rate.
Correction of Malnutrition in Farm Animals
i. Balanced ration must be supplied to the animals at all times
ii. Under feeding of the animals should be avoided
iii. Provision of supplementary feeds in form of concentrates
iv. A good legume grass mixture should be provided to the grazing animals
v. Feed supplement should be added to the feed because they contact certain essential nutrients which may not be sufficiently contained in prepared feeds e.g green feeds.

Nutrient Disorders or Metabolic Diseases e.g Ketosis (Acetonemia)
There are various factors responsible for ketosis in farm animals. These include excess protein, insufficient carbohydrate in the diet or excess formation in the rumen. It is a serious disorder in sheep and cattle. It is called pregnancy toxaemia. It leads to milk reduction.
Milk Fever
It is caused by excess withdrawal of calcium from the arterial blood supply to the udder. The disease is very common in cattle. Symptoms are loss of appetite, constipation and general depression of the animal.
Rickets: A disease of the young animals, characterised by softness of bones with swollen ends caused by vitamin D deficiency in the diet of the animal.
Beri-beri: This is a disease symptom due to lack of vitamin B in the diet of farm animals. It may lead to nervous paralysis.
Sillage and Hay: They are forms of plants cut and preserved for dry season feeding of the animals. Sillage is made by cutting forage crops when they are not fully matured and packing them after chopping under pressure in containers called Silos. It is used for maintenance and production.
Hay is made by cutting forage crops when crops are fully mature. The cut crops are sun dried, baled and preserved for future use. It is used mainly for maintenance since the food value is very low.

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  1. State the classes of food nutrients.
  2. State the sources and functions of food nutrients.
  3. What are the importance of water?

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