Animal Nutrition (Food Substances) – Classes of food, vitamins, and minerals
Food is a complex, energy-rich organic matter that living organisms feed on to obtain nutrients and substances necessary for life. Food substances are classified to six groups
(i) Carbohydrate (ii) Protein (iii) Fat and oils (iv) Mineral salts (v) Vitamins (vi) Water and roughages.
Carbohydrates are made up of carbon, hydrogen and oxygen. They have a general formula (CxH2O)y. carbohydrate consists of simple sugars, starches, cellulose, and glycogen. They are grouped into simple sugar or monosaccharides, double sugar/disaccharides, and polysaccharides. The common sources include yam, cassava, potatoes, bread, cereals e.g., rice, maize, e.t.c.
Simple sugar or Monosaccharide
These are the simplest sugar that consists of one molecule of simple sugars. They have a general formula C6H10O6. Examples are glucose, fructose and ribose (C5H10O5) or galactose
Disaccharide/Reducing sugar
These are sugars which consist of two molecules of simple sugar which formed by condensation with the general formula C12H22O11. Examples are sucrose, maltose, and lactose
Sucrose: It is a non-reducing sugar which is formed from a molecule of glucose and a molecule of glucose is the main source
Maltose: This is obtained from the condensation of two molecules of simple sugar. It is reducing sugar
Lactose (milk sugar): It is a reducing sugar. It is obtained from the condensation of a molecule of glucose and a molecule of galactose
Polysaccharide
These are complex carbohydrates. Examples are starch, cellulose, chitin and
- Starch: It has the formula C6H10O5)n, where n represents a large number. It is formed from the condensation of numerous molecules of simple sugar. Examples of the sources of starch are yam, cereals, cassava, and bread
- Cellulose: This is composed of several condensed unit of monosaccharides. It makes the cell wall of plant source of cellulose include whole meal bread, cereals, fresh fruit and vegetables.
iii. Glycogen (Animal starch): This is the form in which animals store their carbohydrate, usually in the muscle or liver
Importance of Carbohydrate
- It provides the energy required by animals for their daily activities
- It provides heat through it oxidation used in maintain the body temperature
- It forms a certain body part of arthropods (exoskeleton)
- The mucus, which is an important lubricant in the body, is formed carbohydrates
PROTEIN
Proteins are complex molecules and are made of smaller units called amino acids. Proteins have to be digested to amino acids before they are absorbed in the body of an animal. The breakdown of proteins during digestion takes place in the following
Protein —-> Peptone —-> Polypeptide —-> Amino acid
Protein is composed of carbon, hydrogen, oxygen, phosphorus, and sulphur
Sources of protein include both animal source and plant source
The animal source includes milk, egg, fish, cheese, meat and chicken while the Plant sources are beans, groundnut, soya beans and melon.
Importance of Protein
- Protein is needed for the growth of young ones
- It is used for the repair of worn-out tissues or cells
- It aids reproduction
- It is used for the production of enzymes
- It is needed for the production of hormones
- It is needed for body building block
FATS AND OIL
Fat and oils are also called lipids. They consist of only carbon, hydrogen and oxygen. However, the amount of oxygen in each lipid is very little e.g. tristearin, is C57H10O6. Fats are solid lipid at room temperature. Plant sources of oil include groundnut, palm oil, soya beans oil; coconut oil and melon oil white animal sources of fat include butter, fish or cod oil.
Fat and oil are hydrolysed during digestion to fatty acid and glycerol
Importance of Fat and Oil
- Fat and oil provide more energy to animals than carbohydratess
- Fat supplies essential fatty acids to animals
- Fat and oil act as solvents for fat-soluble vitamins
- They help in the maintenance of body temperature
- They act as an insulator to animal, which help them to conserve heat
MINERAL SALT
Mineral salts are food substances that are required in trace for vital body processes. They are taken in their ionic forms. Animal takes in their elements mainly by feeding on plants or their products, except a few of them, such as sodium chloride (table salt). Lack of mineral salts will result in nutritional deficiency. These mineral elements or salts include phosphorus, calcium, iodine, manganese, fluorine, copper and cobalt.
| MINERAL | SOURCE | FUNCTIONS | DEFICIENCY SYMPTOMS |
| CALCIUM | Milk, Cheese, Egg and Fish | (i) Bone and teeth formation and development (ii) Needed for blood clotting (iii) Normal Functioning of the heart, nervous system and muscle |
(i) Rickets (ii) Osteomalacia (iii) Tooth decay |
| PHOSPHORUS | Milk, cheese, egg, fish and wheat | (i) For strong development of teeth and bone (ii) It forms part of DNA and RNA (iii) Needed for respiration |
i) Rickets (ii) Osteomalacia (iii) Tooth decay |
| MAGNESSIUM | Green, vegetables, milk, meat | (i) For muscle contraction (ii) Needed for utilization of iron (iii) Needed for teeth and bone |
Nervous disorder |
| POTASSIUM | Fruits and other Natural food | (i) Needed for functioning of the muscles (ii) For transmission of impulses in nerves |
It leads to muscle paralysis |
| SULPHUR | Beans, fish, meat & egg | Constituent of proteins, amino acids and vitamin B | Poor growth |
| SODIUM & CHLORINE | Table salt, fish fruit | (i) Transmission of impulses (ii) Maintenance of osmotic balance of the cell
|
(i) Dehydration (ii) Muscle cramp |
| IRON | Eggs, liver, kidneys, beans, vegetables | (i) Formation of haemoglobin in red blood cell | Anaemia
|
| IODINE | Sea foods | (i) Required by the thyroid gland to make thyroxine
|
Goitre |
| MARGANESE | Egg, Milk, Meat | (i) Required for normal growth (ii) Acts as co-factors in some enzymatic reactions |
|
| COPPER | Green vegetables, eggs, milk, meat | (i) It catalyses the use of iron (ii) For proper respiration in some aerobic organisms |
Anaemia |
VITAMINS
Vitamins are organic food substances that are needed in small quantities or traces for normal body growth and healthy development in man and other animals. Absence or insufficiency of vitamin supply in diet may lead to deficiency diseases
Groups of Vitamins
(i) Fat-Soluble Vitamins: These are vitamins that are soluble only in fat e.g. vitamins A,D, E and K
(ii) Water Soluble Vitamins: These are vitamins that are soluble in water e.g. vitamins B-complex and vitamin C. some members of vitamin B2(Riboflavin), B3 (Niacin), b5 (Pantothenic) B6 (Pyridoxine), B12, (cyanocobalamine), Folic acid e.t.c.
| VITAMIN | SOURCE | FUNCTION | DEFICIENCY/SYMPTOMS |
| VITAMIN A (Retino) |
Liver, eggs, fish, milk, palm oil, fresh vegetables | (i) Required for the normal growth of cells and skin (ii) For proper vision of the eye |
(i) Night blindness (ii) Reduced resistance to diseases |
| VITAMIN B1 | Yeast, unpolished rice, milk, beans, palm wine | (i) Required for normal growth (ii) Formation of co-enzymes involved in cellular respiration |
(i) Slow growth (ii) Dermatitis |
| VITAMIN B2 | Yeast, soya beans, egg, milk, green vegetables | (i) Required for growth healthy skin and proper functioning of the eyes (ii) Formation or co-enzymes involved in cellular respiration |
(i) Slow growth (ii) Dermatitis |
| VITAMIN B3 | Yeast, beans, milk, palm wine, yam, and vegetables | Needed for cellular respiration | Pellagra ( a skin disease and digestive problem |
| VITAMIN B12 | Kidney, liver, fish, and milk | Formation of red blood cells | Pernicious anaemia |
| VITAMIN C (Ascorbic acid) |
Fresh fruits e.g., Orange and green vegetables | (i) Aids wound healing (ii) Helps to resist infection |
Scurvy (characterized by bleeding gums, poor healing of wood and low resistance of infection) |
| VITAMIN D Calciferol |
Fish, milk, egg, liver, form in the skin by light | Needed for strong bone and teeth formation and development | Ricket, osteomalacia |
| VITAMIN E (Ergo sterol) |
Green vegetables, butter, and liver | Promotion of fertility in animals | Reproductive failure e.g. sterility and pre mature abortion |
| VITAMIN K Phylloquinone |
Fresh green vegetable/cabbage spinach | Aids blood clothing | Haemorrhage |
WATER
Water is composed of two elements: hydrogen and oxygen. Sources of water available to animals include metabolic water from food, drinking water from rivers, rain, ponds e.t.c.
Importance of Water
(i) It is required for metabolic activities in the body
(ii) Water is necessary for the digestion of food
(iii) It can be used for the maintenance of body temperature
(iv) It serves as a medium of transportation of nutrients
(v) It helps in the excretion of metabolic waste products from the body, e.g., urine
(vi) It is the basis of body secretion from the endocrine gland
(vii) It helps in the maintenance of the osmotic content of the body