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Animal Production Student’s Book TVET FIRST Level 4 W Burger I Nsahlai H Swatson Animal Productio fet level 4 sb 1 19/9/08, 9:20 am 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 copyright holder or in accordance with the provisions 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 Fax: (011) 731 3535 E-mail: [email protected] Animal Productio fet level 4 sb 2 19/9/08, 9:20 am 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 Animal Productio fet level 4 sb 3 19/9/08, 9:20 am 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 Animal Productio fet level 4 sb 4 19/9/08, 9:20 am Topic 1 Advanced animal nutrition 1 Animal Productio fet level 4 sb 1 19/9/08, 9:20 am 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. 2 Topic 1: Module 1 Animal Productio fet level 4 sb 2 19/9/08, 9:21 am 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 Animal Productio fet level 4 sb 3 19/9/08, 9:21 am 3 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. 4 Topic 1: Module 1 Animal Productio fet level 4 sb 4 19/9/08, 9:21 am 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 Animal Productio fet level 4 sb 5 19/9/08, 9:21 am 5 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. 6 Topic 1: Module 1 Animal Productio fet level 4 sb 6 19/9/08, 9:21 am 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) Animal Productio fet level 4 sb 7 19/9/08, 9:21 am 7 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 8 Topic 1: Module 1 Animal Productio fet level 4 sb 8 19/9/08, 9:21 am 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 Animal Productio fet level 4 sb 9 19/9/08, 9:21 am 9 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. 10 Topic 1: Module 1 Animal Productio fet level 4 sb 10 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 11 19/9/08, 9:21 am 11 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 Animal Productio fet level 4 sb 12 19/9/08, 9:21 am 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 13 19/9/08, 9:21 am 13