Introduction to Animal Science

1. Animal Science 1
INTRODUCTION TO ANIMAL SCIENCE

2. 1 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
UNIT 3
REFERENCES
Coleen Brady (2008). An Illustrated Guide to Animal Science Technology with Interactive CD-Ron. Delmar Learning, 5
Maxwell Drive PO Box 8007. New York, USA.
Scanes, Collins. (2001). Fundamentals of Animal Science. Delmar Cengage Learning. Frandson, Rowen D. et.al. (2009).
Anatomy and Physiology of Farm Animals. 7th Ed. Blackwell Publication
W. Stephen Damron (2018). Introduction to Animal Science: Global, Biological, Social and Industry Perspectives 6th
Edition, Pearson Education, Inc
COURSE CREDIT/UNITS & CONTACT HOURS/WEEK:
3 units; 5 hours per week; 2 hours lecture;3 hours laboratory
Second Semester, A.Y. 2023-2024
COURSE DESCRIPTION:
Principles of breeding, physiology and nutrition in relation to production, processing and marketing of
animal products
OBJECTIVES:
At the end of the unit, the students must have:
1. appreciated the importance of animal nutrition and its application in the field of Animal Science.
2. described and given examples on the general functions and classification of nutrients.
3. determined the protein, vitamins. mineral and other nutritional requirements specific for each
animal classification.
UNIT 3: ANIMAL NUTRITION
a. Gross Chemical Composition of Plant and Animal Tissues
b. Classification of Nutrients, Functions and Deficiency Symptoms
c. Nutrient requirements of Farm Animals
d. Ruminant and Non-Ruminant Nutrition

3. 2 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
A. Definition of terms:
Nutrition- the series of processes by which an organism takes in and assimilates food for
promoting growth and replacing worn out or injured tissues.
Digestion- breakdown of feed particles into suitable products for absorption; may include:
mechanical forces, chemical action, enzyme activity.
Absorption- transfer of substance from gastro-intestinal tract (GIT) to the circulatory (blood
or lymph) system.
Metabolism-combination of anabolic and catabolic reactions occurring in the body with the
liberation of energy.
Enzymes-a complex protein produced in living cells that causes changes in other
substances within the body without being change itself (organic catalyst).
Nutrients- Any feed constituent, or a group of feed constituents of the same general
chemical composition that aids in the support of life.
May include synthetically produced vitamins, chemically produced inorganic salts or
biogenically synthesized amino acids.
The amount of these needed in the body depends on:
1. The species of the animal i.e. simple stomach vs. ruminants
Purpose of the animal:
a. Egg, meat, milk, or wool production
b. Lactation/reproduction
c. Growth
d. Maintenance
Many microorganisms have simple nutrient requirements. They are:
a. Inorganic elements
b. Water
c. Source of nitrogen
d. Source of energy
Note: All these can provide growth and production. Higher animals, including man, require
more complex nutrient needs. Simple stomach or monogastric animals (man, chickens, and
pigs) unlike ruminant animals (cows, sheep, and goats) require more complete proteins and
vitamins in their diet because they cannot produce protein that includes all of the essential
amino acids with Just a supply of nitrogen.

4. 3 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
UNIT 3: ANIMAL NUTRITION
Lesson 1: Gross Chemical Composition of Plant and Animal Tissues
COMPOSITION OF ANIMAL BODY AND PLANTS AND ITS INTERACTION
Basis of expressing the chemical composition:
The chemical composition of the feed stuffs can be expressed in two ways
1. On fresh basis (as such basis): On as such basis means expressing the chemical
composition of the feed as is fed to the animals. The advantage of this expression is that it
helps in computation of ration.
2. On dry matter basis: Chemical composition of feed stuffs is expressed on dry matter basis.
The advantage of dry matter basis is that various feed stuffs can be compared among
themselves by bringing at same standard unit of measurements.
The average chemical composition in round figures of the common feed Comparison of
plants and animal body composition:
Though the plants and animal bodies are made up of same constituents, but their proportion
is variable. There are a lot of differences in animal and plant composition.
In animals the major structural material is protein and minerals in the ratio of 4:1 on moisture
and fat free basis which remain almost constant.
Whereas plants are made up of carbohydrates like cellulose, hemicellulose, pectin and
lignin. Other differences are tabulated as:
NO PARAMETER ANIMALS PLANTS
Major constituent water Water
Major organic constituent protein Carbohydrates
Structural component Protein and mineral Carbohydrates
cellulose,
hemicellulose
Reserve material Fat (glycogen) Carbohydrates
(starch)
Carbohydrates amount Generally
consistent
Wide variation
Mineral amount Wide variation
Variation in composition less Wide
The following factors affect the plant composition:
1. Plant factor: There is a marked difference in the chemical composition between the
different varieties of the same species of forage because of different genetic material.
2. Agro-climatic condition: When a forage plant is exposed to variable agro-climatic
conditions it shows variable growth performance, which directly reflects the chemical
composition. The factors like atmospheric temperature and humidity affect the chemical
composition of plants.
3. Cultivation practices: The cultivated forages, under the same agro-climatic conditions
perform in different ways depending on the cultivation practices. The seed rate, seed
treatment, time of sowing, method of sowing, manure and fertilizer, irrigation, weeds and
disease control measures not only influence the growth and yield of the forages but also
chemical composition.
4. Stage of growth: There is a relationship between the stage of growth of the plants and its
chemical composition. The content of crude protein, soluble ash, phosphorus and potash is
higher just before flowering and goes down at bloom and seed formation stage whereas,

5. 4 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
crude fibre and dry matter content increase as the plant matures. Ether extract goes down
with the progressive maturity of the plant.
5. Processing and preservation practices: The changes in chemical composition of plants are
very much influenced by method of processing and preservation. Different processing
methods may change particle size, particle shape, nutrient contents and also composition of
plant materials.
Biochemical basis of soil, plant and animal:
A close inter-relationship the plant synthesized their feed from CO2 and H20 in the
presence of sunlight and chlorophyll in the form of carbohydrates, which is structural as well
as storage component of plants.
They absorb minerals (Inorganic component) as well as water from soil and precede various
biochemical reactions in plant body. Many factors like application of manures and fertilizers,
irrigation, stage of growth, frequency of cutting, type of variety and strain and soil composition
affect the chemical composition of the plant.
As the composition of soil changes, it also affects composition of plants. Similarly, animals
utilize the plants and plant by products as their food. So, composition of plants and soil also
reflected into animal body composition.
When plants and animals died, they are mixed into soil as a decaying organic material or as
inorganic material when these are burnt.
Animals also nourished the soil by their faeces, urine and other excretion and waste products.
Similarly, plants dropped their dried leaf and fruits on the soil.
So plant and animals affect the chemical composition of soil and the soil also have the same
function. So there is a close inter-relationship between plants, animals and soil. And they are
closely interrelated with each other.
This indicates the biochemical basis of soil, plant and animals.

6. 5 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
UNIT 3: ANIMAL NUTRITION
classes of nutrients and their composition
Lesson 2: Classification of Nutrients, Functions and Deficiency Symptoms
Lesson 3: Nutrient requirements of Farm Animals
1. WATER
a) General
a. Cheapest and most abundant nutrient.
b. Makes up to 65-85% of animal body weight at the birth and 45-60%
body weight and maturity.
c. Percentage of the body water decreases with animal age and has an
inverse relationship with body fat.
d. Accounts for 90-95% of blood and many tissues contain 70-90%
water.
e. Found in the animal body as:
1. Intracellular water- mainly muscles and skin
2. Extracellular water- mainly interstitial fluids, blood plasma,
lymph, synovial and cerebrospinal fluids.
3. Water present in urinary and gastro- intestinal tract.
b) Function and deficiencies
a) Functions
1. Transport of nutrients and excretion
2. Chemical reactions and solvent properties
3. Body temperature regulation
4. Maintain shape of body cells
5. Lubricates and cushion joints and organs the body cavity
b) Deficiencies or restrictions
1. Reduced feed intake and reduced palatability
2. Weight loss due to dehydration
3. Increased secretions of nitrogen and electrolytes such as Na and K
c) Sources of water in the Animal
1. Drinking water- consumption affected by many factors
2. Water contained in or on feed- about 8 to 30% water
3. Metabolic- many accounts for 5-10% total water intake.
d) Water losses from the animal body
1. Urine
2. Feces
3. Vaporization from lungs
4. Sweat from the sweat glands
e) Approximate water consumption
1. Swine - 1.5 to 3 gal/hd/d
2.Sheep - 1 to 3 gal/hd/d
3.Poultry - 2 parts water for each part of dry feed
4.Horses - 10 to 14 gal/hd/d
5.Cattle - 10 to 14 gal/hd/d
2. CARBOHYDRATES
a) General
a. Made up of C (40%, H (7%) and O (53%) by the molecular weight.
b. Include sugar, starch, cellulose and gums
c. Very little occurs as such in animal body
d. CHO make up approximately ¾ of plant dry weight and thus the
largest part of animal’s food supply
e. Formed by photosynthesis in plants
b) Structure
a. Structure consists of C atoms arranged in chains to which H and O
are attached
b. May contain an aldehyde or a ketone group in their structure
c) Classification (based on number of sugar molecules)
a. Monosaccharides
1. Hexoses- glucose, fructose, galactose, mannose
2. Pentoses- arabinose, xylose, ribose
b. Disaccharides (two sugar molecules)
1. Sucrose, maltose, lactose, cellobiose

7. 6 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
c. Polysaccharides (many sugar molecules)
1. Starch-amylose, amylopectin’s, glycogen
2. Cellulose-glucose molecules in B-linkage
3. Mixed polysaccharides-hemicellulose, pectin’s
4. Lignin
d) Functions and deficiencies
a. Functions in the animal body
1. Source of energy
2. Source of heat
3. Building stores for other nutrients
4. Stored in animal body by converting to fats
b. Deficiencies of abnormal metabolism
1. Ketosis
2. Diabetes mellitus
3. FATS (lipids or either extract)
a) General
a. Made up of (molecular weight of C (77%) H (12%) and O (11%)
b. Insoluble in water but soluble in organic solvents
c. Fat will yield 2.25 times or more energy than carbohydrates or
proteins
b) Classification
a. Simple lipids
b. Compound lipids
1. Phospholipids- contain phosphoric acid
2. Glycolipids
3. lipoproteins
c) Derived lipids
1. Fatty acids
2. sterols
d) Structure of fat
a. Glycerol and fatty acids
b. Saturated fatty acids
c. Unsaturated fatty acids
e. Functions and deficiencies
a. Functions
1. Dietary supply
2. Source of heat, insultation and protection for animal body
3. Source of essential fatty acids- linoleic, linolenic and arachidonic
acid
4. Serve as a carrier for absorption of fat-soluble vitamins
b. Deficiencies and abnormal metabolism
1. Skin lesions, hair loss and reduced growth rate
2. Ketosis-catabolism of body fat
3. Fatty liver- abnormal metabolism of liver
f. Location of natural sources of fat
a. Animal body
1. Subcutaneous
2. Surrounding internal organs
3. Marbling and milk
b. Natural sources-most feeds have less than 10% fat except oil seeds 20%
4. PROTEINS
a) General
a. Made up (by molecular weight) of C (53%), (7%), O (23%) , N (16%)

8. 7 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
and P (1%)
b. Principal constituents of organ and soft structures of the animal body
c. Dietary requirement (%) is highest in the young growing animals and
decline gradually to maturity
d. Large molecules
b) Structures of proteins
a. all proteins have one common properly, their basic structure is made
up of single unit amino acids
b. twenty-two amino acids are commonly found proteins, they are
linked together by peptide bonds.
c. The arrangement of amino acids in the chain helps determine the
composition of protein
d. The classification of amino acids depends on the number of acidic
and basic group that are present
c) Classification of proteins
a. Simple (globular proteins)- those yielding only amino acids or their
derivatives upon hydrolysis, i.e. albumins, histones, protamine,
globulins, glutelin, prolamins.
b. Fibrous protein- constitute about 30% of total protein in animal
body, connective tissues, i.e. collagens, elastin, keratins.
c. Conjugated proteins- those in which simple proteins are combined
with non-protein radical, i.e., nucleoproteins, glycoproteins,
phosphoproteins, hemoproteins, lactoproteins, lipoproteins,
metalloproteins.
d) Protein terminology
a. True protein-composed of amino acids
b. Non-protein (NPN) compounds that are not true protein in nature
but contain N and can be converted to protein by bacterial action,
e.e urea.
c. Crude protein-composed of true protein and any nitrogenous
products; crude protein = % N X 6.25
d. Essential amino acids- those amino acids which are essential to the
animal and must be supplied in the diet because the animal cannot
synthesize them fast enough to meet its requirement:
1. Phenylalanine
2. Valine
3. Threonine
4. Tryptophan
5. Isoleucine
6. Methionine
7. Histidine
8. Arginine
9. Leucine
10. Lycine
e. Non-essential amino acids- which are essential to the animal but are
normally synthesized or sufficient in the diet and need not be
supplement
1. Alanine
2. Asparagine
3. Aspartic acid
4. Cysteine
5. Cystine
6. Glutamic acid
7. Glutamine
8. Glycine
9. Hydroxyproline
10. Proline
11. Serine
12. Tyrosine

9. 8 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
f. Protein quality- refers to the amount and ratio of essential amino
acids presents in protein
e) Functions and Deficiencies
a. Functions
1. Basic structural unit of the animal body, i.e collagen, elastin,
contractile protein, keratin proteins, blood proteins
2. Body metabolism-enzymes, hormones, immune antibodies,
hereditary transmission
b. Deficiencies and Abnormalities
1. Symptoms or protein deficiencies: reduced growth rate and feed
efficiency, anorexia, infertility
2. Amino acid deficiency- a lack of an important amino acids which
results to deamination
5. MINERALS
a) General
a. Inorganic solid, crystalline chemical elements
b. The total mineral content of plants or animals is often called ash.
c. Make up to 5% of animal body on dry weight basis
b) Classification
a. major minerals-normally present at greater level in animal body or
needed in relatively large amounts in the diet. Includes Ca, P, Na, Cl, K,
Mg, S.
b. trace minerals- normally present at low levels in animal body or needed
in very small amount in the diet. Include Cu, Zn, Co, F, I, Fe, Mn, Se, and
are toxic at large quantities.
c). General functions
a. Skeletal formation and maintenance-Ca, P, Mg, Cu, Mn
b. Function in protein synthesis – P, S, Zn
c. Oxygen transport -Fe, Cu
d. Fluid balance (osmotic pressure)- Na, Cl, K
e. Regulating acid-base balance of the entire system Na, Cl, K.
f. Activators and or components of enzymes systems- Ca, P, K, Mg, Fe, Cum
Mn
g. Mineral- vitamin relationship-Ca, P, Co, Se
6. VITAMINS
a) General
a. Organic components of natural food but distinct from carbohydrates, fat
protein and water.
b. Present in foods in minute amounts and effective in the animal body in
small amounts
c. Essential for development of normal tissue necessary for metabolic
activity but do not enter into structural portion of the body.
d. When absent from the diet or not properly deficiency disease or
syndrome
e. Cannot be synthesized by the animal
f. Related substances
1. Provitamins or precursors, i.e carotene

10. 9 | P a g e
An Sci 1
INTRODUCTION TO ANIMAL SCIENCE
2. Antivitamins, vitamin antagonists or pseudovitamins
b) Classification and Structure
a. Fat soluble – ADEK
b. Water soluble vitamins – thiamine, riboflavin, niacin, pyridoxine,
pantothenic acid, biotin, choline, folic acid
c) Functions and Deficiencies
a. Play role as regulators of metabolism; necessary for growth and
maintenance
b. Vitamin requirement may also increase in old age due to difficulties in
absorption and utilization