Download Animal Productio fet level 4 sb - Macmillan Education South Africa

Animal Production
Student’s Book
TVET FIRST
Level 4
W Burger I Nsahlai H Swatson
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TVET FIRST Animal Production NQF Level 4 Student’s Book
© W Burger, I Nsahlai, H Swatson 2008
© Illustrations and design Macmillan South Africa (Pty) Ltd 2008
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted in any form
or by any means, electronic, photocopying, recording,
or otherwise, without the prior written permission of the
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of the Copyright Act, 1978 (as amended).
Any person who does any unauthorised act in relation to this
publication may be liable for criminal prosecution and civil
claims for damages.
First published 2008
15 17 16
13 15 17 16 14
Published by
Macmillan South Africa (Pty) Ltd
Private Bag X19, Northlands, 2116, Gauteng, South Africa
Text design by Heather Brooksbank
Cover design by Deevine Design
Artwork by Alan Kennedy, Mike Parkin
Typesetting by Future Pre-Press
ISBN-13: 978-1-77030-392-8
e-ISBN: 978 14310 2074 4
WIP: 2094M000
It is illegal to photocopy any page of this book
without written permission from the publishers.
The publisher would like to thank the following for permission to
use photographs in this book:
Aaifotostock: Figure 5.6 on page 80; Figure 5.7 on page 81; Figure 5.11 on page 83;
Farmer’s Weekly Magazine: Figure 5.1, 5.2, 5.3, 5.4, 5.5 on pages 78-80;
Fotozone: Figure 5.19 on page 93; Figure 5.20 on page 98;
iAfrika: Figure 5.19 on page 93; Figure 5.21 on page 99;
Karin Duthie: Figure 5.8 on page 81;
Kim Thunder: Figure 5.9 on page 82;
Reinhardt Hartzenberg: Figure 5.10 on page 83;
The bigger picture: Figure 5.12 on page 84; Figure 7.10 on page 136.
A special thanks to Klein Karoo, Oudtshoorn for photographs and information supplied for Module 12.
Inside back cover photos used with permission from the University of Sydney: Figure 1 by D Kennedy;
Figure 2 from CSIRO Australian Animal Health; Figure 3 by W J Hartley
While every effort has been made to trace the copyright holders and obtain copyright permission from
them, in some cases this has proved impossible due to logistic and time constraints. Any copyright
holder who becomes aware of infringement on our side is invited to contact the publisher.
Note: Any reference to Further Education and Training (FET) in this book should be taken to mean
Technical and Vocational Education and Training (TVET).
To order any of these books, contact Macmillan Customer Services at:
Tel: (011) 731 3300
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Contents
Topic 1: Advanced animal nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Module 1: Components of an animal’s diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Unit 1.1: Carbohydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Unit 1.2: Lipids (fats) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Unit 1.3: Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Unit 1.4: Vitamins and minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Module 2: Digestion and absorption of feed in farm animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Unit 2.1: The non-ruminants (pigs and poultry) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Unit 2.2: The ruminants (sheep, goats and cattle) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Module 3: Animal nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Unit 3.1: Nutrient needs of animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Unit 3.2: Factors influencing nutrient needs of cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Unit 3.3: Factors influencing nutrient needs of livestock (excluding cattle) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Unit 3.4: Nutrient requirements of dairy and beef cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Unit 3.5: Feeding requirements of cattle and fodder supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Module 4: Nutritional problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Unit 4.1: Digestive disorders in the rumen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Unit 4.2: Deficiency symptoms and corrective measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Topic 2: Cattle farming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Module 5: Cattle types and breeds adapted to environmental conditions . . . . . . . . . . . . . . . . . 76
Unit 5.1: The main types and breeds of cattle adapted to Southern African conditions . . . . . . . . . . . . . . . . . . . . . . . . 77
Unit 5.2: Characteristics of cattle breeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Unit 5.3: The ecological regions of South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Unit 5.4: South Africa’s different veld types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Unit 5.5: Livestock breeds for different veld types of South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Module 6: Breeding cycles of cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Unit 6.1: The oestrus cycle of cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Unit 6.2: Identifying cows on heat in dairy herd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Unit 6.3: Planning calving and lactation times through restricted breeding seasons within beef cattle herds . . . . 116
Module 7: Rearing calves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Unit 7.1: Rearing calves – feeding, housing and weaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Unit 7.2: Care for calves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Module 8: Principles and methods of selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Unit 8.1: Principles of selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Unit 8.2: Methods of selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Module 9: Diseases and parasites affecting cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Unit 9.1: Disease that affect cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Unit 9.2: External parasites that affect cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Unit 9.3: Internal parasites that affect cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Module 10: Handling of cattle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Unit 10.1: Handling of calves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Unit 10.2: Handling of cows and bulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Unit 10.3: Handling of the cattle herd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
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Topic 3: Dairy farming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Module 11: The operation of a milking parlour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Unit 11.1: Udder structure and physiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 11.2: The milking machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 11.3: Parlour hygiene, milk cooling and milk cooling devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 11.4: Types of records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 11.5: Milk products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 11.6: Dairy enterprise analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
195
200
205
214
221
227
Topic 4: Ostrich farming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Module 12: Ostrich farming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Unit 12.1: General overview and feasibility of ostrich farming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 12.2: Ostrich breeds, housing systems and management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 12.3: Ostrich feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit 12.4: Diseases and pests in ostriches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
235
241
254
259
Portfolio of Evidence Guideline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
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Topic 1
Advanced animal
nutrition
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Module 1
Components of an
animal’s diet
Overview
In this module you will:
• explain the main components of an animal’s diet
• complete simple food tests.
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Unit 1.1: Carbohydrates
1.1.1 Introduction
As you learned in Level 2, plants can produce their own food through
a chemical process called photosynthesis. During this process,
carbon dioxide (CO2) from the atmosphere and water from the soil
are used to manufacture (or synthesise) carbohydrates such as sugar
and starch. Photosynthesis requires two things: the presence of
chlorophyll, which is the green pigment in the leaves of plants, and
solar energy, which is energy from the Sun in the form of sun rays.
The Sun radiates light energy to the plants. Plants receive this
energy and use it to start chemical reactions in the plant cells
(photosynthesis). These chemical reactions lead to the manufacturing
of food for the plant. This food is the main source of all food used by
humans and animals on planet Earth.
1.1.2 The origin of carbohydrates
During photosynthesis the carbon atoms (C) of carbon dioxide (CO2) are
bonded together to form a chain of carbon atoms. Any molecule made
up of carbon atom chains is called an organic molecule. All organic
molecules, or compounds of these molecules, are made up mainly of
carbon chains linked to other carbon, hydrogen and oxygen atoms.
Did you
know?
Other ato
ms are als
o fo
in organic
compound und
s,
example n
itrogen (N for
) sulphur
(S) fluorin
e (F
bromine (B ), chlorine (Cl),
r) and iod
ine (I).
1.1.3 Classes of carbohydrates
All carbohydrates consist of carbon, hydrogen and oxygen.
Carbohydrates are subdivided into three main classes:
• monosaccharides (mono = one sugar)
• disaccharides (di = two sugars)
• polysaccharides (poly = many sugars).
The monosaccharides
This class includes all the simple (or single) sugars like glucose,
galactose and fructose. Due to some of the chemical properties of
these compounds, the carbon atoms form a ring. These rings are
formed when two carbon atoms are linked by an oxygen atom.
Refer to Fig. 1.1 to see an example of this. (This is not for examination
purposes.)
Fig. 1.1: Glucose molecule
Unit 1.1: Carbohydrates
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The disaccharides
These sugars form when two monosaccharide molecules join to form
one disaccharide molecule and a molecule of water is produced.
It is called a condensation reaction. This process happens during
photosynthesis in the plant tissue. The reaction is shown below:
monosaccharide + monosaccharide à disaccharide + water
Example: glucose + glucose à maltose + water
glucose + fructose à sucrose + water
The polysaccharides
Did you
know?
The revers
e of this re
action
takes plac
e when th
e
disacchari
de
into two m molecule is split
onosacch
arid
molecules
in the alim e
entary
canal of h
um
animals. T an beings and
his reactio
n is know
as food dig
n
estion.
A polysaccharide is formed when a large number of monosaccharides
are joined together. This also occurs through a condensation reaction.
The general formula for a polysaccharide is (C6 H10 O5)n, where
n indicates the number of monosaccharides in the molecule of
polysaccharides.
Polysaccharides are synthesised during photosynthesis by the
condensation of a large number of glucose molecules. The most
important polysaccharides are starch, cellulose and glycogen.
Some better known examples of polysaccharides are:
• Starch is found in plants such as rice, wheat, mealies and potatoes.
• Glycogen is found in the liver and muscles of animals.
• Cellulose is found in the cell walls of plants where it provides
support.
• Lignin is found in the woody parts of older plants.
Did you
know?
Alimenta
ry: refers
to
nourishm
ent or sus
tenance.
The alime
ntary can
al is the
entire pas
sage in th
e body
through w
hich food
passes. It
starts at th
e
at the anu mouth and ends
s.
1.1.4 Function of carbohydrates
• The monosaccharides that are the end-product of digestion, are the
most important source of heat and energy for humans and animals.
• Carbohydrates serve as a source of glycogen, which is a
polysaccharide, in the body of an animal.
• Once the liver’s glycogen reserves have been built up, excess
carbohydrate intake is converted and stored as fat in the body.
• Polysaccharides in the form of cellulose and lignin (crude fibre of
plants) provide bulk to the ration. We will learn more about rations
in Module 3.
In the workplace
It is necessary to have bulk in the food ration to ensure proper functioning of the alimentary canal
of the ruminant (and also of the non-ruminant, like humans). This function is known as peristaltic
movement. Remember that a ruminant is an animal that chews the cud and has four stomachs, like
cattle, sheep and goats.
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Assessment activity 1
Think about it
Testing for carbohydrates
Participate in the following food tests in your college’s laboratory
to determine the presence of carbohydrates:
What happens with
disaccharides during
digestion also happens
with polysaccharides in the
alimentary canal of humans
and animals. The condensation
of monosaccharides into
polysaccharides during
photosynthesis is reversed
and polysaccharides are
broken down into their
building blocks, i.e. the
monosaccharide glucose.
Fehling’s test for glucose
• Mix equal quantities of Fehling’s solution A and B in a test
tube (about 2 ml of each).
• Shake the mixture to obtain a deep blue colour.
• Prepare a glucose solution of about 5 g of glucose in 50 ml of
water.
• Add 10 ml of this solution to the Fehling’s A and B solution.
• Shake thoroughly.
• Heat the test tube over a flame until the solution boils.
Result: The test for glucose is that a reddish-orange, yellow or
brown precipitate of copper oxide (CuO) is formed. (A precipitate
is a dissolved substance that separates from the liquid and hangs
in suspension.) This colour change occurs when glucose reacts
with the Fehling’s solution.
Think about it
Test for starch
• Mix 2 g of starch with a small amount of water to form a
paste.
• Place the paste in hot water to form a colloidal solution.
• Add one or two drops of iodine solution to the (colloidal)
starch solution in the test tube.
If you are fattening your
livestock for sale you feed
them carbohydrates – usually
in the form of starch. The fat
in an animal is built up from
excessive carbohydrates in the
ration.
Result: The solution turns dark blue (almost black) if starch is
present.
??
?
Assessment activity 2
Carbohydrates: a writing assignment
Write a paragraph with the following title: “Carbohydrates as the
primary source of energy for humans and animals”
You may consider using the following key terms when writing
your paragraph:
Sun’s energy, photosynthesis, glucose, disaccharides,
polysaccharides.
Did you know?
You can prepare an iodine
solution by dissolving 2 g of
potassium iodine in 300 ml of
water. Then add 1 g of iodine
crystals. Shake until the
crystals have dissolved.
Unit 1.1: Carbohydrates
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Assess yourself
Assess your performance in the following activities:
1
2
3
4
5
Testing for carbohydrates
Carbohydrates: a writing assignment
1 = not achieved, 2 = not yet competent, 3 = competent, 4 = highly competent, 5 = outstanding
Summary
The unit deals with the origin of the primary source of energy on Earth – the monosaccharides.
It then goes on to explain how these monosaccharides bond together to form disaccharides and
polysaccharides. The general functions of carbohydrates are spelled out. The unit concludes with
laboratory tests on carbohydrates.
Unit 1.2: Lipids (fats)
??
?
1.2.1 Introduction
Within the organic compounds known as lipids or fats, you can
distinguish two phases in which lipids occur. There are the fats which
are in a solid phase and the oils which are in a liquid phase. In other
words, oils are melted fat – or fat is solid oil.
1.2.2 Plant and animal fats
Did you know?
Fatty acids contain the
carboxyl group (-COOH). When
an alcohol, like ethanol or
buthanol, combines with a
fatty acid, an ester (or glycerol)
is formed. These esters are
known as glycerides or fats
(lipids).
Plant fats differ from animal fats in their melting points. Plant fats
have a much lower melting point than animal fats.
Most plant fats are still soft below 20 °C due to the fact that most
plant fats contain a large percentage of unsaturated fatty acids. The
presence of the unsaturated fatty acids in the acid component tends
to lower the melting point of the plant fats and they are therefore still
liquid at lower temperatures.
The most common animal fats are lard and butter. Lard is made from
pig fat. Butter is a dairy product, i.e. made from cow or goat milk.
These fats contain saturated fatty acids with a high melting point,
which means they become softer at a higher temperature.
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Think about it
Margarine has a plant fat basis
and is much softer at the same
temperature than pure butter
which has an animal fat basis.
Hydrogenation of unsaturated (plant) fats
??
?
Hydrogenation is the conversion of an oil into a fat by a chemical
method. Through this method plant oils are changed into a more
usable form by making them more solid. They can then be used in
place of animal fat (butter).
Fatty acids which have a
double bond between two
carbon atoms are known as
unsaturated fatty acids. Fatty
acids where the carbon atoms
are bound by single bonds
are known as saturated fatty
acids.
1.2.3 Functions of lipids
• Lipids are part of the structure of cell membranes.
• Fats are the most concentrated source of energy and are stored in
the animal’s body in the form of reserve fat.
• A fatty layer under the skin of animals serves as an effective layer
of insulation against heat loss during cold weather spells.
• The fat layer around internal organs such as the kidneys helps to
protect these organs.
Assessment activity 1
Testing for fats
Did you know?
??
Participate in the following food test in your college’s laboratory
to determine the presence of fat (lipids). You can perform this test
on seeds, fruit, tubers, bulbs and on fat-rich animal tissue.
?
Did you know?
A solvent can be ether or
carbon-tetrachloride.
• Grind the test material into a fine form.
• Dissolve some of this material in a small quantity of solvent in
a test tube.
• Filter the solvent and let a drop of the filtrate fall onto a clean
piece of filter paper.
• Let the paper dry.
Result: The presence of fat will leave a translucent (see-through)
fat stain on the filter paper.
Assessment activity 2
Lipids: a writing assignment
Write a paragraph with the following title: “Lipids as the ‘highenergy source for humans and animals’
You may consider using the following key terms when writing
your paragraph: plant fat, animal fats, energy reserve, insulation,
protection.
Unit 1.2: Lipids (fats)
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Assess yourself
Assess your performance in the following activities:
1
2
3
4
5
Testing for fats
Lipids: a writing assignment
1 = not achieved, 2 = not yet competent, 3 = competent, 4 = highly competent, 5 = outstanding
Summary
The unit distinguishes between plant and animal fat and highlights the properties of their melting
points related to human use. After a summary of the functions of lipids the student is guided
through a test for fat and a writing assignment.
Unit 1.3: Proteins
1.3.1 Introduction
Protein molecules are very large molecules. They vary from those
molecules which are soluble in water to those which are not soluble in
water.
Proteins are influenced by heating and change their natural
appearance as they are heated. For example when you heat the white
of an egg (which is pure protein called albumen), the transparent,
jelly-like substance turns into a solid white substance.
1.3.2 The structure of the protein
molecule
Protein consists mainly of the elements carbon (C), hydrogen (H),
oxygen (O) and nitrogen (N). Many protein molecules also contain the
elements of sulphur (S) and phosphorus (P).
Proteins are built from amino acids. Amino acids are organic
molecules that have an amino-group (NH2) and a carboxyl group
(-COOH).
This structure can be illustrated as follows:
??
?
Did you know?
The symbol “R” in this formula
represents a carbon chain.
Fig. 1.2 The structure of an amino acid
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Topic 1: Module 1
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When two (or more) amino acids are joined together a peptide bond
is formed. The product is known as a dipeptide. Protein molecules are
composed of many different amino acids joined together by peptide
bonds. A single protein molecule may consist of thousands of these
amino acids known as polypeptide chains.
Think about it
The process of hydrolysis takes
place in the alimentary canal
of animals – a process also
known as protein digestion.
Enzymes act as catalysts in
this process. Catalysts speed
up a chemical reaction without
undergoing any change
themselves.
The process of condensation and hydrolysis
When protein molecules are formed in the liver of animals, peptide
bonds are formed when two amino acids join. A water (H2O) molecule
is split off. This process is called condensation.
Hydrolysis is the opposite process as in this instance water is added.
The protein molecule is broken down to shorter peptide chains. These
peptide chains are eventually broken down to amino acids.
1.3.3 Functions of proteins in the animal’s
body
• Proteins in the animal’s body are used to repair worn tissues.
Proteins are also essential for the building up of new tissue during
the growth process of the young animal.
• Proteins make up part of hormones and some enzymes by the
animal’s body.
• When there is an excess of protein in the animal’s body these
protein molecules may be broken down and serve as a source of
energy.
• Protein molecules serve as building blocks in the synthesis of bone
tissue (collagen).
• A lot of protein molecules are needed during animal production of
wool, eggs and milk.
• Proteins play an important role in the process of reproduction and
metabolism of the body in general.
Words &
Terms
Enzyme:
a biologic
al catalys
t
Catalyst:
a chemica
l
that cause
a chemica
s
l reaction
without
undergoin
g changes
itself
Metabolis
m: all the
chemical
processes
that take
place in th
body so th
e
at growth
takes plac
and energ
e
y is produ
ced and
waste is e
liminated
Think about it
1.3.4 Essential amino acids
Plants and micro-organisms can synthesise proteins from nitrogen
compounds such as nitrates (NO3). Animals, however, cannot
synthesise all the amino groups. Those amino acids that can be
synthesised by the animal’s body are known as non-essential aminoacids. Those amino acids that cannot be produced by the animal’s
body are known as the essential amino acids.
In the case of ruminants
the essential amino acids
are synthesised by rumen
microbes.
The essential amino-acids are called essential because they must be
present in the feeds of all non-ruminant animals. If there is a shortage
of these amino acids in the feeds of non-ruminants, the animals
– which can not synthesise their own proteins – will suffer from
malnutrition.
Unit 1.3: Proteins
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Assessment activity 1
Testing for protein
Participate in the following food tests in your college’s laboratory to determine the presence of
proteins.
Yellow colour test
• Add a few drops of concentrated nitric acid to a protein solution (heat slightly if necessary). A
yellow colour is obtained.
• Add a few drops of an ammonium solution. The yellow colour turns to dark yellow or orange.
Biuret test
• Add a few drops of a water solution of copper sulphate to about 5 ml of a protein solution.
• Add small amounts of concentrated caustic soda solution (NaOH) until the colour will changes
to violet.
• Do a control test using the same amount of caustic soda and the same amount of water instead
of a protein solution.
Assessment activity 2
Proteins: a writing assignment
Write a paragraph with the following title: ‘Proteins as the building blocks of the human and animal
body’.
You may consider using the following key terms when writing your paragraph: amino acids,
protein molecules, building new tissue, hormones, enzymes, bones, agricultural products.
Assess yourself
Assess your performance in the following activities:
1
2
3
4
5
Testing for proteins
Proteins: a writing assignment
1 = not achieved, 2 = not yet competent, 3 = competent, 4 = highly competent, 5 = outstanding
Summary
The unit explains the individual organic compounds (amino acids) that form a protein molecule. It
highlights the importance of proteins and concludes with several protein tests.
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Topic 1: Module 1
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19/9/08, 9:21 am
Unit 1.4: Vitamins and minerals
??
?
1.4.1 Vitamins
The animal (human) body requires vitamins in very small quantities.
Vitamins play the role of a catalyst in the body. In other words, they
are essential for normal metabolism.
Fat-soluble vitamins can be
built up in the body to form
a reserve. Water-soluble
vitamins cannot be stored in
the body and must be taken up
daily in sufficient quantities.
Vitamins are indicated by letters, e.g. A, B, C, D, etc. Some of these
vitamins are water-soluble while others are fat-soluble.
Vitamins are grouped together according to their functions. There are
more than 18 different vitamins. They are found in natural foodstuffs,
because plants manufacture their own vitamins from raw materials
that they obtain from the soil, water and the air.
When there is a shortage of a particular vitamin in the animal’s ration,
the animal’s body will show specific symptoms as caused by this
shortage – we call it a deficiency disease. The functions and main
deficiency disease symptoms of vitamins in the animal’s body will be
dealt with in Module 4.
Did you know?
??
?
Did you know?
Animals and humans obtain
their vitamins from the
vegetable substances in their
diet. An exception is Vitamin D,
which is produced in the skin
as a result of the action of the
ultra-violet rays of the Sun.
Assessment activity 1
Experiment to determine the influence of temperature on the
actions of an enzyme
Investigate the influence of temperature on the actions of an
enzyme, salivary amylase, which contains vitamins.
• Collect 5 ml of saliva in a test tube.
• Dilute the saliva with a few millilitres of water.
• Prepare a colloidal solution of starch (a suspension of strach in
water i.e. the starch is not properly dissolved.
• Take two test tubes and pour about 2 ml of saliva solution into
each.
• Add 2 ml of starch solution to each test tube.
• Shake both of them thoroughly.
• Place the one tube (tube A) in a water bath at 65 °C for about
15 minutes.
• Place the second tube (tube B) in a water bath at 40 °C for
about 15 minutes. See sketches in Fig. 1.3.
• Using a pipette, take a few drops from the contents of each
tube and add these drops to separate iodine solutions.
Think about it
Enzymes – containing proteins
and vitamins – are sensitive
to heat and function at an
optimum temperature. This
temperature ranges between
30 °C and 40 °C. At higher
temperatures vitamins become
denatured.
Result: The contents of tube A turn blue with the iodine solution
– i.e. starch is present.
The content of tube B does not turn blue – i.e. starch is no longer
present.
Unit 1.4: Vitamins and minerals
Animal Productio fet level 4 sb
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Assessment activity 1
Conclusion: Salivary amylase functions well at about 40 °C and
starch was hydrolysed to disaccharides and monosaccharides. At
65 °C the amylase has been denatured and could not act on the
starch.
Words &
Terms
Optimum
: tha
the best re t which produces
sult
Denature
d: the pro
perties are
changed
Think about it
Fig 1.3 Apparatus to investigate enzyme action
The animal’s skeleton contains
most of the minerals (80%).
1.4.2 Minerals
Mineral salts make up 3% to 5% of an animal’s body. In spite of these
small quantities, mineral salts are absolutely essential for most body
functions.
Minerals occur in the bone and teeth of animals as well as in the soft
body tissues like the blood, and organic compounds such as protein.
From a feeding perspective we can distinguish between essential and
non-essential mineral elements. The term ‘essential mineral’ is used for
those elements that play a role in the body’s metabolism.
We make as further distinction according to the amount of a mineral
required in the animal’s body. Mineral elements are divided into two
main groups:
• the macro-elements which occur in large quantities in the body
• the micro-elements which occur in concentrations of no greater
that 1 part in 20 000 in the animal’s body.
Table 1.1: Division of mineral elements in the body
Essential elements
Non-essential elements
Macro mineral
elements
Micro mineral
elements
Calcium
Phosphorus
Potassium
Sodium
Chlorine
Sulphur
Magnesium
Iron
Zinc
Copper
Manganese
Iodine
Cobalt
Molybdenum
Selenium
12
Ca
P
K
Na
Cl
S
Mg
Fe
Zn
Cu
Mn
I
Co
Mo
Se
Fluorine
Bromine
Barium
Strontium
F
Br
Ba
Sr
Topic 1: Module 1
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As in the case with vitamins, characteristic symptoms of mineral
shortage will occur, resulting in deficiency diseases. The functions and
main deficiency symptoms of minerals in the animal’s body will be
dealt with in Module 4.
Assess yourself
Assess your performance in the following activities:
1
2
3
4
5
Experiment to determine the influence of temperature on the actions
of an enzyme
1 = not achieved, 2 = not yet competent, 3 = competent, 4 = highly competent, 5 = outstanding
Summary
The unit describes the nature of vitamins and minerals and briefly deals with their role in the
animal body. The symptoms of deficiency will be dealt with in more detail in Module 4.
Unit 1.4: Vitamins and minerals
Animal Productio fet level 4 sb
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19/9/08, 9:21 am
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