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Suggested Practical Activities in Livestock Nutrition
a) Learners to dissect a hen and display the digestive system to show the following organs the beak, esophagus ,crop proventriculus , gizzard ,duodenum , small intestine large intestines and clocca.
b) Observe the consistency of food materials along the digestive system and record your observation.
c) Carry out simple tests such as PH test in the stomach and small intestines and record your findings.
d) Draw and label the digestive system of poultry.
Identify and prepare a list of livestock feeds common in your school or in neighboring areas for the following animals.
Health plays a major role in determining the productivity of farm animals. In your previous studies, you learnt the role played by parasites and pathogens in livestock production. The health and productivity of farm animals is also dependent on the plane of nutrition exposed to them.In this topic you are expected to understand the diverse sources of livestock feeds, categorize them and explain their digestion in various farm animals.
See the video to appreciate preparation of livestock feeds
Livestock Nutrition Glossary
These are plants and animals derived dietary organic and inorganic substances contained in a feed material which can be digested, absorbed and utilized in the animals body tissue including carbohydrates, proteins lipids, vitamins, minerals and water.
This is defined as dietary substance containing one or more nutrients required by an animal.
Any dietary substance that provides the required nutrients to an animals body solely for satiety, maintenance, reproduction and production (products like milk eggs and services like draught power) and is prepared using various feedstuffs.
This refers to the portion of food refined in each animals body deducting losses through urine, faeces and gases. It is expressed as percentage digestibility or apparent digestibility.
Percentage digestibility=Feed retained/feed intake*100
Apparent digestibility =feed intake-waste products( faeces + urine )/dry matter in feed
Dry matter content
Actual % protein, carbohydrate and minerals in a feed.This can be investigated through drying and removal of bound water.The higher the dry matter content the higher the nutritive value depending on digestibility.
This expresses the energy value of a feed. It is investigated using a bomb calorimeter and expressed in calories.
This is the energy value of a feed that is equivalent to the net energy value of a certain amount of pure starch.
usually expressed as percentage ie a feed with starch equivalent 60% means that 100kg of the feed is equivalent to 60kg of pure starch.
Total digestible nutrients
This is the sum total of all the digestible nutrients (carbohydrates , fats and proteins) in a feed.
This is the sum total of all the nitrogenous compounds in a feed. Nitrogenous compounds include the proteins amides (peptides, mino acids and ammonium salts)
Digestible crude protein
This is the % amount of protein which can be digested in a feed by animals body.
This is the % amount of fat which can be digested and absorbed from an animals body
Digestive true protein
This is the % actual protein which can be digested and absorbed in animals body and expressed as follows
This is an expression of the average of the digestible true proteins. That is P.E=D.T.P+D.C.P /2
Sometimes expressed as PE=D.T.P +DCP-DTP / 2
Total digestible nutrient
This is the total or sum of all the nutrients that can be digested in a feed.
TDN=% of digestible carbohydrates and crude fiber +% of digestible proteins +% of digestible fats x2.25
Note the number of times that the fat produces energy in comparison to fats.
This includes cellulose and other fibber carbohydrates resistant and soluble in weak alkalis and acids.
The daily amount of food in the correct nutrient proportion given to an animal to cater for maintenance and production depending on body size, age and activity and level of production.
Expressed either as maintenance, production or balanced ration, it is the daily amount of food and the correct nutrients proportion given to an animal to cater for maintenance and production depending on body size, activity and level of production.
This is the propensity of a feed to be liked or disliked by an animal and qualitatively can be investigated basing on the relish upon which the feed is eaten by the animal
Feed conversion ration
FCR= Weight of feed consumed *100%
Live weight gain
By the end of this topic, you should be able to:
- identify and classify livestock feeds.
- define terms used to express feed values.
- compute a livestock ration.
- prepare balanced ration for various livestock.
- describe digestion in farm animals.
- describe digestive systems of cattle, pigs and poultry.
- demonstrate a caring attitude towards livestock during feeding.
Livestock Production II (Nutrition)
Introduction to nutrition in livestock
Apart from breeding, disease and parasite control, proper livestock feeding is another way of livestock improvement on the farm. Livestock nutrition constitutes the provision of adequate, proportionate and appropriate food substances to animals depending on their daily nutrient requirements.
See the video to appreciate livestock feeding
Components of livestock feeds
In this topic, you will be introduced to the components of livestock feedstuffs. Feedstuffs contain water, carbohydrates, proteins, lipids, vitamins and mineral salts in varying proportions.
A balanced ration should provide the following nutrients in adequate and proportionate levels;-
- mineral salts
Sources and functions of water in livestock
Livestock obtain water from three major sources namely free, bound and metabolic. Water constitutes up to 83 % of livestock products and 50% of actual body weight. A water requirement in livestock depends on ambient temperature, size, type of feed taken and the level of production.
Role of water in animals
- Help maintain body shape
- Act as a body cellular component
- Regulates body temperature and is an excretory medium among other factions
Sources and functions of carbohydrates
Carbohydrates are obtained from pastures, grains, root crops and byproducts of the sugar industry. They occur as sugars, starch and cellulose.
Role of carbohydrates
- Provide energy
- Synthesis of livestock products
Sources and functions of proteins
Proteins provide nitrogen, sulphur and phosphorous over and above carbon, hydrogen and oxygen. Usually, proteins are obtained from animal byproducts, leguminous pasture, seedcake and young green grass.
Roles of proteins
- Production of eggs ,wool etc
- Growth, repair and replacement of body tissues
- Production of enzymes, hormones and antibodies
- Increased fertility
Sources and functions of lipids
Lipids provide two to three times of the energy provided by carbohydrates to livestock .When stored as subcutaneous fat, lipids provide insulation against cold. Fats line the walls of internal organs to absorb physical shock.
Sources of lipids
- Animal products and byproducts
- Pasture and other foliage
- By-products of oil seeds
Sources and functions of vitamins.
Vitamins are classified as water and fat soluble. Water soluble vitamins include the B - complex while the fat soluble include A,D,E and K.
Functions of Vitamins
- Promote resistance to diseases
- Help in bone formation
- Enhance blood clotting
- Promote muscular activity
- Catalyze metabolisms
Sources and roles of mineral salts
Mineral salts are required in small quantities but are an essential component of livestock feed.
Mineral licks that provide mineral salts.
Sources of Livestock feeds
Livestock feeds are largely obtained from plants and to a lesser extent from animal products (blood meal, fishmeal, bone meal). Feedstuffs of plant origin are usually high in fiber content but low in proteins except the concentrates.
Classification of livestock feeds
Animal feeds are broadly classified basing on their Bulkiness and Nutrients content. They are either classified as roughages or concentrates
Livestock feeds are classified as Roughages or Concentrates
Roughages originate from plants and are either classified as dry or succulent roughages.
Concentrates are of a higher nutritive value than the roughages. They are either classified as energy or protein concentrates depending on the major nutrient component.
Characteristics of roughages
Roughages are classified primarily depending on moisture content as
Succulent roughages or Dry roughages
Succulent roughages have
- high moisture content,
- low protein content,
- high fiber content,
- high vitamin content,
- high carbohydrate content for example fresh silage, freshly cut and fed napier grass.
- Low moisture content
- High dry matter content
- Low protein content
- Low vitamin content
- Low in feed value e.g. straw, hay , maize stalk, dried plants and crop residues
Characteristics of concentrates
Concentrates are classified basing on nutrient content into Energy (carbohydrate) and protein concentrates
Supply energy to the animal
Obtained as byproducts of flour mills for example bran, Maize germ
Supply protein to the animal
Originate from either plant for example oil seed cakes, Cotton sunflower, simsim or from animal origin for example bone meal, Blood meal.
Minerals and vitamin supplement
Whereas these two nutrients occurs in roughages and concentrates, commercial feeds manufacturers do add the same to guard against deficiencies.
Calcium and phosphorous deficiency leads to milk fever in lactating cows, Oesteomalacia, rickets and pica.
Feed additives include antibiotics, hormones and medicants. Whereas these are non -nutritive, they improve feed conversion efficiency, stimulate growth as well as prevent and cure diseases.
Coccidiostat is a feed additive
Farm animals require nutrition on a daily basis for maintenance and production.
The quality and quantity depends on body size, age, activity and level of production. The feeds must be palatable to enhance physical satiety.
Preparation of livestock rations
On farm preparation of livestock feeds will reduce the production costs. Extra care should be taken not to compromise on quality in favour of satiety.
There are many methods of preparing livestock rations. Among the most commonly used are trial and error method and Pearsons square method.
Computation of Livestock rations by trial and error method
Various combinations of feedstuffs are used and resultant animal responses recorded. The combination that gives the highest production guides the farmer in determining the right proportion of various animal feeds when computing the rations.
Procedure of Computing Livestock rations using Pearson square method
- Place the percent feed value of the desired ration at the centre of the square.
- Place names of feeds and their percent feed values at each of the left corners.
- Subtract diagonally across the square and record resultant figures at the right corners, ignoring the signs.
- Add the two figures obtained on the right. Use the figure to calculate the proportionate amount of each feedstuff in the desired ration.
Digestibility of livestock feeds
The amount of feeds retained in an animals body after digestion varies with different feeds. Dry roughages have high indigestible fiber content and hence low in digestibility while protein concentrates have high digestibility.
Digestibility of feeds is affected by:
- Form in which feed is presented to the animal
- Chemical composition of the feeds.
- Species and type of the animal.
- Amount food already present in the alimentary canal of animals.
- Stage at which the feed was harvested
Appropriate livestock handling techniques while feeding
Animals should be handled appropriately when receiving their nutrition. This is to avoid injury, stress and infection of the animals from contamination.
Artificial feeding enhances better management of production in dairy farm animals and reduces scours in calves.
Regurgitation of food
Animals chewing cud referred to as food moving from mouth into rumen and back into mouth before it enters the reticulum
Reticulum sieves and separates fine from coarse food materials. It retains indigestible ingested foreign materials such as nylon paper. Finely chewed food then moves to the omasum
Omasum grind and sieve food but its main function is water absorption from food.
Abomasums is the fourth stomach compartment and it is the true stomach.
Enzymatic digestion of proteins takes place here. Mechanical digestion also occurs where food is churned by stomach walls forming chyme.
Stomach wall produces gastric juice which contains:
(i)Pepsin- breaks down proteins into proteoses and peptones
(ii)Renin- coagulates milk, to increase surface area for the action of enzyme pepsin
(iii) Hydrochloric acid-creates suitable acidic medium for the action of stomach enzymes and kills harmful microorganisms in food.
The duodenum receives pancreatic juice from pancreas and the bile salts from the liver. The pancreatic juice contains Sodium hydrogen carbonate (NaHCO3) which neutralizes the acidic condition of chyme from the stomach as well as provide an alkaline pH ideal for enzymatic activities of pancreatic and intestinal enzymes.
Digestion and digestive systems in farm animals.
The structure of digestive systems of monogastric and polygastric farm animals has different adaptations that enable them digest respective food components.
Digestion in ruminants
Ruminant animals have four stomach compartments. They regurgitate and chew cud. Digestion starts in the mouth where mechanical breakdown of food material into smaller particles takes place. Food is mixed with saliva, softened, formed into bolus and swallowed into the rumen which is the largest stomach compartment.
Role of rumen includes:
- Temporary storage of food.
- Microbial digestion of cellulose in food.
- Breakdown of protein to peptides, amino acids and ammonia.
- Absorption of fatty acids and ammonia gas.
Food is regurgitated back into the mouth and chewed further then re-swallowed into the reticulum through oesophagal groove.
Digestion in the jejunum
The wall of jejunum produces intestinal juice which contains enzymes Maltase, Sucrase, Aminopeptidase (erepsin) and Lactase:
- Maltase-converts maltose to glucose
- Sucrase (invertase)-converts sucrose to glucose and fructose
- Lactase - converts lactose to glucose and galactose
- Aminopeptidase (erepsin)-converts peptones and peptides to amino acids
Digestion in the ileum
This is the last portion of the small intestine and has many fingerlike projections called villi. These increase the surface area for absorption of digested food including glucose, amino acids and fatty acids.
Digestion in the large intestines
Materials such as cellulose which may not have been digested are broken down through extensive microbial activity in the caecum to release volatile fatty acids which are absorbed in this region. Water absorption takes place in the large intestines.
Indigestible food substances are temporarily stored in the rectum and are voided through the anus.
Digestion non ruminants (eg. pigs)
Pigs are omnivorous and their digestion compares to that of human beings. Food obtained in the mouth undergoes mechanical digestion through chewing.
- There is enzymatic digestion of starch in the mouth into maltose.
- No microbial digestion of cellulose except in those animals that have a well developed caecum.
- Most digestion and absorption takes place in small intestines.
Digestion in poultry
The digestive system of poultry is slightly different from other non ruminants. Poultry have no teeth and food is swallowed whole upto the crop, an enlargement of the oesophagus.
The gizzard breaks down food mechanically to form paste which enters the duodenum. It is adapted to mechanical digestion due to:
- Presences of thick and tough muscles that slide against food particles
- Presence of grit picked during feeding.
Moistened food leaves the crop and proceeds to the proventriculus (true stomach). Although Pepsin enzyme is produced here, very little enzymatic digestion takes place, as food passes quickly into the gizzard.
Digestion in the duodenum, jejunum ileum and the caecum compares that of digestion in ruminants.
Poultry usually absorb most of the water in the large intestines. Egestion takes place through the cloaca.
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