Livestock Production II (Nutrition) - Agriculture Form 2 Notes

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Introduction

  • Animals are fed for the purpose of production and body maintenance.
  • The edible material given to animals is called food.
  • It is digested, absorbed and· utilized in the body.
  • Nutrients are organic and inorganic substances contained in the food materials.


Components of Food Material

  • Water,
  • Protein,
  • Carbohydrates,
  • Fats and oils,
  • Vitamins
  • Mineral salts.

Water

Sources

  • Free water (through drinking)
  • Bound water (contained in feeds).
  • Metabolic water (obtained from oxidation of food).

Functions

  • Regulates body temperature.
  • Transport agent in the body.
  • Universal solvent in the body.
  • Gives shape to the cells (turgidity).
  • Acts as a lubricant.
  • Acts as constituent of body fluids.

 

Factors Determining the Requirements of Water by Livestock

  • Production level.
  • Amount of dry matter eaten.
  • Temperature of the surrounding area.
  • Type of animal.
  • Type of food eaten.

Protein

Sources:

  • Groundnut cakes,
  • cotton seed cakes,
  • fish meal,
  • meat meal.

Functions:

  • Growth of new tissues.
  • Repair of worn out tissues (body building).
  • Synthesis of antibodies.
  • Synthesis of hormones and enzymes.
  • Production of energy during starvation.

Digestion of Proteins

  • In non-ruminants, protein digestion takes placed in the stomach.
    • Food is subjected to mechanical breakdown through chewing into small particles.
    • Protein is acted on by enzymes to turn into amino acid which is assimilated into the bloodstream.
  • In ruminants, protein digestion initially takes place in the rumen.
    • Food is acted on by micro-organisms into microbial protein.
    • Later, enzymatic action takes place in the "true stomach" or abomasum where proteins are broken down into amino acids which are then assimilated into the bloodstream.

Carbohydrates

Sources:

  • Cereals,
  • tubers
  • commercially mixed feeds.

Functions:

  • Supply energy and heat to the body.
  • Excess is stored in form of fat for insulation of the body.

Digestion of Carbohydrates

  • In non-ruminants;
    • carbohydrate feeds are broken down by chewing into small particles.
    • Then enzymatic action further breaks down carbohydrates into glucose, fructose and galactose which are then assimilated into the bloodstrea
  • In ruminants;
    • mechanical breakdown of carbohydrate feeds is followed by microbial activities which break down cellulose into volatile fatty acids.
    • These are absorbed through the rumen walls.
    • Some carbohydrates are broken down by enzymatic action in the "true stomach" or abomasum.

Fats and Oils

Sources:

  • Cotton seeds,
  • soya beans
  • groundnuts.

Functions:

  • Supply energy and heat to the body.
  • Excess is stored as fat adipose tissues.
  • Source of metabolic water in the body.
  • Required for the development of neural system.
  • Insulator in the body.

Digestion of Lipids in Ruminants

  • Fats are hydrolysed in the rumen into fatty acids and glycerol.
  • Others are fermented into propionic acid,
  • The shorter chains are passed to the true stomach where enzymatic action takes place.

Vitamins

Sources:

  • Green materials,
  • dried grass
  • fish liver oil.

Functions:

  • Protects the body against diseases.
  • Regulate the functions of all parts of the body.
  • It acts as a co-enzyme in the body.

Examples:

  • Vitamin A,
  • vitamin B2
  • vitamin C,
  • vitamin E
  • vitamin K.

Minerals

Sources:

  • Salt licks,
  • bone meal,
  • legumes
  • cerea

Functions:

  • Form part of the tissues such as bones and teeth.
  • Work together with the enzymes.
  • Act as acid -base balances.
  • Act as electrolyte in the body.
  • Regulate osmotic balance in the body.

Examples:

  • Calcium,
  • phosphorus,
  • magnesium,
  • iron,
  • iodine,
  • sodium
  • chlorine.

Calcium and phosphorus -

  • Needed for teeth and bone formation.
  • Lack of these minerals leads to rickets, osteomalacia.

- Lack of iron leads to anaemia.



Classification of Animal Feeds

- This is based on nutrient composition:

  • Roughages.
  • Concentrates.
  • Feed additives.

Roughages

  • Are feeds of low available nutrients per unit weight and high fibre content.

Examples:

  • Dry roughages,
  • succulent roughages,
  • residues from agricultural by products and conserved materials.

Characteristics

  • Low level of available nutrients.
  • Have high level of calcium especially legumes.
  • Good source of vitamin A.
  • Have high fibre content.

 

Concentrates

  • Are feeds of high available nutrients per unit weight.

Examples:

  • Maize germ and bran,
  • malt extract,
  • milk products,
  • soyabeans,
  • oil seed cakes,
  • meat meal,
  • bonemeal
  • bloodmeal.

Characteristics

  • Low fibre content.
  • Feed content is consistently high.
  • High digestibility of the feed.
  • High in nutrient content.

Feed Additives

- These are substances added to the feed to increase;

  • palatability,
  • medication
  • or hormones to make animals produce more.

- There are two types:

  • Nutritive additives, such as mineral licks (maclick).
  • Non-nutritives additives, such as;
    • medicants (coccidiostats),
    • Stilboestrol (used in beef animals)
    • oxytocin (to increase milk let down).

Functions

  • Stimulate growth and production.
  • Improve feed efficiency.
  • Prevent disease causing organisms.


Compounded Feeds

  • These are the feeds prepared and mixed by use of machines.
  • These feeds can be round, pelleted, pencils, cubes or mash.

Classification of Poultry Feeds

  • Chick mash having 20% D.C. given to chicks.
  • Growers mash having 16% D.C. given to growers.
  • Layers mash having 12-15% D.C.P. given to layers.

Terms used to Express Feed Values

  • Nutritive ratio (NR):
    • Is the proportion of protein to carbohydrates and fats.
    • In young animals 1:3:6
    • In old animals 1:8.
  • Crude protein (C.P): Is the total amount of protein contained in a feed.
  • Digestible Crude Protein (D.C.P): Is the portion of crude protein which an animal is capable of digesting.
  • Crude Fibre (C.F.):
    • Is the total amount of fibre contained in a feed.
    • It is mainly lignin and cellulose.
  • Digestible Fibre (D.F.): Is the portion of the total fibre contained in a feed which an animal is capable of digesting.
  • Dry Matter (D.M.): Is the material left in a feed after water has been removed.
  • Starch equivalent (S.E.): Is the amount of pure starch which has the same energy as 100kg of that feed.
  • Total Digestible Nutrients (T.D.N.): Is the sum of all the digestible organic nutrients such as fats, proteins, carbohydrates and fibre.

Computation of Livestock Rations

  • Ration:
    • Is the amount of food that will provide essential nutrients to an animal in a 24 hour period to enable that animal to meet its maintenance and production requirements.
  • Balanced ration:
    • Is the ration that contains all the essential nutrients in required amounts and in the right proportion.
  • Maintenance ration:
    • is the portion of a feed required by an animal to continue with the vital body processes with no loss or gain in weight.
  • Production ration:
    • Is the feed required by animals over and above maintenance ration to enable the animal to produce;
    • for example; milk, eggs, wool, grow in size, perform work, reproduce and fatten.

Steps in Ration Formulation

  • Finding out the animal's feed requirement based on body weight.
  • List all the available feeds, with their nutrient composition and their prices.
  • Calculate the amount of ingredients required in the ration to meet the animals needs.

Methods used in Ration Formulation

  • Trial and error method
  • Pearson’s square method
  • Graphical method
  • Linear programming(use of computers)

Examples;

Mix a Pigs ration 22% protein using soya bean meal 40% DCP and maize meal containing 8%DCP.

pearson's square method.PNG

Soya bean meal (14 × 100) = 43.75kg
                         32
Maize meal   (18  × 100) = 56.25kg
                    32



Digestion and Digestive Systems

  • Digestion is the process through which food is broken down into small particles in the alimentary canal ready for absorption into the blood stream.
  • Digestion of food in livestock takes place in three stages;
    • Mechanical breakdown and chewing
    • Microbial breakdown by bacteria and protozoa in the rumen of ruminants
    • Chemical breakdown by enzymes.

Digestive System of a Ruminant

digestive system of a ruminant.PNG

Rumen

  • Breakdown of food by micro-organisms and also stores food.
  • Synthesis of vitamin B-complex.
  • Synthesis of amino acids from ammonia gas.
  • Proteins are broken to peptides and amino acids.
  • Carbohydrates are broken to volatile fatty acids.

Reticulum:

  • Separates large food particles from the small particles.
  • Retains foreign materials such as stones, hard wood and sand.

Omasum:

  • Breaks up food by grindin
  • Reduction of water content from the feed stuff.

Abomasum:

  • Enzymatic digestion takes place here ..
  • Contains some microbes which digest cellulose.
  • Breaks up food by grinding.
  • It is also found in non­-ruminants.

Digestive System of a Non-Ruminant

digestive system of a non-ruminant.PNG

Comparison Between Digestion in Ruminant and Non-ruminants

Differences

 Ruminants Non-ruminants 
  •  Chew the cud
  • Have four stomach chamber - thus polgastric
  • Regurgitate
  • Can digest cellulose. Have micro-organisms in the rumen that digest cellulose
  • Have no ptyalin in saliva hence no enzymatic digestion in the mouth
  • Most digestion and absorption takes place in the rumen
  • Have alkaline due to presence of ammonia
  •  Do not chew cud
  • Have one stomach chamber - thus monogastric
  • Cannot regurgitate food once swallowed
  • Have no micro-organisms in the stomach hence cannot digest cellulose except those animals with microorganisms in the caecum
  • Have ptyalin in the saliva hence enzymatic digestion starts in the mouth
  • Most digestion and absorption takes place in the small intestines
  • The saliva is neutral pH

Similarities Between Digestion In Ruminants and Non-Ruminants

  • Digestion in young ruminants is similar to that in non-ruminants as they do not have a developed rumen-reticulum complex.
  • Final protein digestion takes place in the small intestines in both cases.
  • Water absorption takes place in the colon in both ruminants and non­ ruminants

Digestion System of Poultry

 digestion system of poultry

Functions of the Parts of Poultry

Crop:    

  • Storage of food.
  • Softening of food by secretions from small glands in the walls.

Proventriculus: Enzymes start the breakdown of food.

Gizzard:-Crushes and grinds the coarse food (has small grit and gravel).


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