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Complete summary of the reader and the lectures of principles of animal nutrition (ANU-20306)
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Principles of animal nutritionGeneral introduction
Feeding strategies take into account: animal species, nature of production (meat, wool), required
intensity of production, environmental factors and social factors.
Diet: material which, after ingestion by animals, is capable of being digested, absorbed and utilised.
Components capable of being utilised are called nutrients.
The energy trapped by plants from sunlight. This energy is then used by animals to maintain life and
synthesis of own body tissue
Food:
1. Water
2. Dry matter organic (carbohydrates, lipids, proteins etc.) and inorganic (minerals)
Nutrient: any chemical compound or element that supports normal reproduction, growth, lactation
or maintenance of life processes.
Nutrient requirements:
1. Maintenance requirements;
- Body weight and composition
- Physiological balances
- Normal activities of organs and tissues for these purposes
- Body temperature
- Moving, eating, chewing, etc.
2. Requirements for production:
- Growth
- Reproduction
- Milk/egg production
Chapter 1: Nutrient requirements
Essential nutrients: required in the diet, because the body cannot metabolised this type of nutrients
1.1 Nutrients in animals
Vertebrates have an internal skeleton for structure and protection of vital organs. Furthermore, the
skeleton has attachment points for muscles, which are important for movement.
The building blocks for composing and functioning of the body are: lipids, carbohydrates, nucleic
acids and proteins. Also, animals are made up from water and minerals.
Body composition changes during life, for example when an animal becomes older or it changes with
the seasons.
Macro minerals/elements: in % or g/kg (Ca, P, K, S, Na, Cl, Mg)
Micro minerals/trace minerals: mg/kg or µg/kg (Zn, Fe, Mn, Cu, I, Co)
Average weight of an egg: 57 gr
All milk is more of less the same in composition
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,1.2 Functions of nutrients
Muscle tissue is composed of protein and water
Proteins: are an part of all cells as components of cell walls, main constituents of connective tissue
Fats: making up lipoproteins that are found in cell walls
Carbohydrates: part of glycoproteins (constituents of connective tissue)
Animal cells are thermodynamically unstable and need constant energy. A lot of energy is thus
needed for tissue maintenance.
Muscle proteins are build from amino acids. Chemical energy is needed to make the amino
acids react
Energy: lipids and carbohydrates. Proteins are more difficult to metabolise for energy, but often it is
too expensive
Nutrients can also act as regulators, such as sodium potassium or vitamins. Vitamins and minerals
function as cofactors or activators of enzymes
1.3 Essential nutrients
The number of essential nutrients reflects the natural dietary habits of the animal species. If an
animal gets enough of the nutrient via his diet, the ability to synthesise the nutrient will disappear
after some time.
Cows and horses do not have a dietary requirement for vitamin B
Amino acids
Non-essential amino acids can be synthesised by the animal itself when amine group (-NH 2), carbon
skeletons and enzymes for transamination are present (about 22 amino acids).
- Amine group: from the metabolism of other amino acids or non-protein nitrogen
- Carbon skeleton: from degradation of other amino acids or from intermediates from
carbohydrate metabolism.
Semi-essential: amino acids which can be synthesised from essential amino acids (cystine or tyrosine)
Functions:
1. The monomeric unit from which proteins are synthesised
2. Source of energy
3. Some are precursors of other important compounds, such as adrenaline
In all tissues there is a continues protein synthesis and protein breakdown. The net protein synthesis
had the biggest effect on amino acid requirements. As consequence, the requirement for digestible
amino acids by producing animals is almost completely determined by the amino acid composition of
the synthesised product and by the level of production.
Basic structure of an amino acid: R-COOH(NH 2)
Amino acids for protein synthesis are available as the end product of digestion or as result of
synthetic processes in the body.
Primary structure: sequence of amino acids along the polypeptide chain
Secondary structure: conformation of the chain, due to formation of hydrogen bonds between the
imino and carboxyl groups.
Tertiary structure: interaction of chains with each other
Quaternary structure: if the protein contains more than 1 polypeptide chain.
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, Protein formation: all amino acids will be used that are necessary. Excess of amino acids will be
deaminated carbon skeleton: energy, NH4+: urea (mammels), uric acid (birds), ammonia via gills
(fish).
Classification of proteins:
A. Globular proteins, soluble in water or in dilute acids or in alcohol (albumins, globulins)
B. Fibrous proteins, insoluble in water, resistant to digestive enzymes (collagens, elastins)
C. Conjugated proteins, contain a wide array of compounds of a non-protein nature (protein-
lipid, protein-carbohydrate complexes)
Protein turn-over: simultaneously protein catabolism (degradation) and anabolism (synthesis). So
proteins are not only for growth, but also for maintenance.
Fatty acids
Mammels are not able to synthesise fatty acids with double bonds closer than carbon atom 9 from
the terminal methyl group so these are essential
Function of essential fatty acids:
1. They are an integral part of the lipid-protein structure of cell membranes
2. Play an important part in the structure of several compounds called eicosanoids
Function lipids:
1. Supplying energy
2. Serving as carrier of the fat-soluble vitamins A, D, E and K
No dietary requirements exist for lipids, except for essential fatty acids and because of their role as a
solvent for vitamins.
General structure: RCOOH, where R is the carbon chain
Fatty acids can contain a double bond as a cis or a trans
Isomer important for biological activity
most fatty acids have an even number of carbon atoms in animals. Ruminants can contain uneven
carbon atom fatty acids, due to fermentation.
Liver, adipose tissue and mammary gland are major sites of biosynthesis of fatty acids and
triglycerides.
Liver: synthesis of fatty acids from carbohydrates, lipogenic amino acids etc.
Biosynthesis of fatty acids: begins with acetyl-CoA from carbohydrates, lipogenic amino acids or
degraded fats.
A high amount of cholesterol depresses the synthesis in the liver
Mono-, di- and triglycerides are esters of glycerol and fatty acids. An ester is formed by a reaction
between an alcohol and an organic acid. A triglyceride can be mixed or homogeneous.
The degree of softness depends on the number of double bonds and on chain length. Fewer than 10
carbon atoms: liquid, more than 10: solid at room T. If the chain length increases, the melting point
increases. If the number of double bonds increases, the melting point will decrease.
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