NUTRITION IN ANIMALS

ANIMAL NUTRITION

Animals generally cannot manufacture their food. Rather, they depend directly or indirectly on plants for their food. Hence they are called heterotrophs. Based on their food types, animals are grouped into three:

Carnivores which feed on flesh or other animals e.g. lion.
Herbivores which feed on plants e.g goat.
Omnivores, which feed on both plants and animals e.g man.

CLASSES OF FOOD SUBTANNCES

Foods eaten by animals are generally classified into seven i. e.

Carbohydrate
Proteins
Fat and oil
Mineral Salt
Vitamins
Water
Roughages

CARBOHYDRATE

This is got from food like bread, yam rice etc. It basically consists of carbon, hydrogen and oxygen. Carbohydrates are of three types:

Monosaccharides (Simple sugars) which include glucose, fructose and galactose
Disaccharides (Reducing sugars) which include maltose, sucrose and lactose.
Polysaccharides (Complex sugars) e.g starch, cellulose, chitin under the action of enzymes like ptyalin, maltase, lactase etc, and starch yields glucose as product of its digestion. Excess carbohydrate is stored in the body in form of glycogen in muscles and liver. This can be reconverted to glucose during starvation.

Importance of Carbohydrates

It gives animals energy.
It provides heat needed to maintain body temperature
It can be used for lubrication e.g mucus.
It provides the body with a strong framework e.g. exoskeleton in insects.

PROTEINS

These are complex molecules made up of smaller units called amino acids. Protein is made up of carbon, hydrogen, oxygen, nitrogen and sometimes phosphorus and sulphur. Food like egg, meat, fish, beans etc gives you protein. Proteins are broken down into amino acids under the action of enzymes like pepsin, rennin, trypsin and erepsin.

Importance of Proteins

Growth in young ones.
Repair of worn-out tissues.
Production of enzymes.
Production of hormones.
It supports reproduction.
It is for tissue and all formation i.e body building.

FATS & OIL (LIPIDS)

Fats are solid lipids at room temperature while oil is the liquid. Fat and oil consist of carbon, hydrogen and little oxygen. When digested, it gives rise to fatty acids and glycerol. Foods like palm oil, groundnut, Soya beans give fat and oil. Lipids are broken down to fatty acids and glycerol when acted upon by lipase enzymes.

Importance of Fat and Oil

It gives you energy even more than carbohydrates
It supplies essential fatty acids to the body.
It helps in the maintenance of body temperature
It provides the body with fat-soluble vitamins

MINERAL SALT

These are usually taken in very small quantity in the food we eat except sodium chloride (table salt) and iron tablet, which can be taken directly by man. The lack of these salts results in nutritional deficiency. The minerals include calcium, magnesium, potassium, Phosphorus, sulphur, chlorine, iron, Iodine, fluorine, manganese, copper, cobalt and sodium.

Importance of Mineral Salts

Regulate body metabolisms
Components of bones and teeth
Aids blood formation
Control chemical reactions in the body
Aids the formation of enzymes and pigment

VITAMINS

These are organic food substances needed by man and other animals in small quantity for normal growth and development. Lack of or inadequate supply of any of these vitamins results in nutritional deficiency.

Vitamins can be grouped into two:

Water-soluble vitamins
Fat – soluble vitamins

The water-soluble vitamins include: vitamins B complex and vitamin C. Vitamin B complex include vitamin, B₂, B₃ , B₅, B₆ and B₁₂

Fat-soluble vitamins include vitamins A, D, E and K.

VITAMINS, SOURCE FUNCTIONS AND DEFICIENCY SYMPTOMS

SOURCE

FUNCTION

DEFICIENCY SYMPTOMS

Vitamin A

Liver, eggs, fish

milk, palm oil, fish Vegetables

(i) Normal growth of

body cells and skin

(ii) Proper vision of the eye

(i) Night blindness

(ii) Reduced resistance to disease

Vitamin B₁

Yeast, milk, beans,

Ground nut

(i) Normal growth

(ii) Proper functioning of heart

and nervous system

Beri-beri (wasting of

Muscles), paralysis

Vitamin B₂

Yeast, soya beans,

egg, milk, green

Vegetables

(i) Growth, proper functioning

of the eye

(ii) Formation of co-enzymes

(i) Slow growth

(ii) Dermatitis

Vitamin B₃

Yeast, beans, milk,

Vegetables

Formation of co-enzymes for cellular respiration

Pellagra

Vitamin B₁₂

Kidney, liver, fish

Milk

Formation of red blood

Cells

Pernicious

Anaemia

Vitamin C

Fresh fruits and

Green vegetables

(i) Aids wound healing

(ii) Helps to resist infection

Scurvy

Vitamin D

Fish, milk, egg,

Liver, sun’s

Ultraviolet rays

(i) Increases absorption

Of calcium and phosphorus.

(ii) Calcification and hardening Of bones

Ricket;

Osteomalacia

Vitamin E

Green vegetables,

Egg, butter, liver

Promotion of fertility

In animals

Sterility

Premature abortion

Vitamin K

Fresh green vegetables, liver

Aids blood clotting

Hemorrhage

WATER

This is of utmost importance to all organisms and it is made up of two elements, hydrogen and oxygen. Water can be got from food, river, stream, pond etc. water makes up 75% of the human body.

IMPORTANCE OF WATER

Metabolic activities of the body of animals.
Digestion of food.
Maintenance of body temperature.
It is a medium of transportation for all nutrients.
It helps to maintain the osmotic balance in body tissues.
It helps in excretion of metabolic waste from the body e.g urine.

ROUGHAGES

These are indigestible fibrous materials got from vegetables, fruit, carbohydrates and proteins. Roughages aid digestion, lack of which can lead to constipation.

EVALUATION

State three importance of; A. Carbohydrate Protein C. Lipids.
Mention five disease that may result from the deficiency of vitamins.

BALANCED DIET

Balanced diet is a diet containing a correct proportion of all the food substances. On a general note, a balanced diet contains 15% protein, 15% fat and oil, 10% vitamin, minerals and water and 60% carbohydrate. Once a food is taken at these proportions, there is a normal growth and development in the body

FUNCTIONS OF BALANCED DIET

It makes us healthy.
It gives ability to be resistant to diseases
It makes available energy needed to carry out all biological activities.
It prevents malnutrition and deficiency symptoms. For examples, a diet that lacks protein results into a nutritional disease called kwashiokor in children.

The protein deficient child has the following features

Retarded growth.
Loss of weight.
Swollen legs effect (oedema).
Cracked / split stomach and thin legs e.t.c.