Transcript Food and Feeding

Food & Nutrition
 Food
supplies the animal with energy
for all animal activities.
 To provide the materials for growth and
repair of cells
 To provide materials for production of
hormones and enzymes.
 To provide raw materials for milk, egg
and wool production etc.
The six most common elements found in food are
Carbon (C), Hydrogen (H), Nitrogen (N) Oxygen
(O), Phosphorous (P) and Sulphur (S).
 The elements found in dissolved salts include
Sodium (Na), Magnesium (Mg), Chlorine (Cl),
Potassium (K) and Calcium (Ca).
 Trace elements are required in our body in very
small amounts and include Iron (Fe), Copper (Cu)
and Zinc (Zn).
 These elements, when combined in different ratios
form larger units called biomolecules.
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 There
are five main food groups:
• Carbohydrates
• Lipids (Fats and Oils)
• Protein
• Vitamins
• Minerals
 Water
is often considered the sixth food
group, due to the huge importance it plays in
our bodies.
 Green
plants can make their own food in
a process known as PHOTOSYNTHESIS.
 Therefore plants are known as
autotrophs or autotrophic.
 Animals have to ingest their food and
cannot make all their food needs.
 Animals are known as heterotrophs or
heterotrophic.
 The
food pyramid is a diagram
illustrating which proportions of food
types are required in our everyday diet.
 Complex Carbohydrates (Starch and
Fibre) are the most important.
 While fats and sugars are to be taken in
the least amount.
 The diagram is shown on the next slide.
 The
main sources of carbohydrates in our diet
are starches and sugars.
 Carbohydrates are made up of Carbon,
Hydrogen and Oxygen molecules with the
common formula Cx (H2O)x
 Carbohydrates are classified by their number
of sugar units, called saccharides.
 Monosaccharides (1 sugar unit),
Disaccharides (2) or Polysaccharides (many).
 Are
glucose, fructose
and galactose.
 All have the formula
C6H12O6 but
arranged differently.
 Sources of
monosaccharides are
energy drinks, but
indirectly through all
other sugars.
 Contain
two sugar
units:
 Maltose =
Glucose +
Glucose
 Lactose = Glucose
+ Galactose
 Sucrose = Glucose
+ Fructose
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Starches, Cellulose, Chitin and glycogen etc.
Humans cannot digest cellulose.
However cattle and horses (and other ruminants)
can, by a symbiotic relationship with bacteria in their
stomachs.
While monosaccharides and di-saccharides provide
energy for our bodies, polysaccharides are mainly
structural.
Benedicts or Fehlings
solution is added to
the food sample
(dissolved if
necessary) and
placed in a water
bath.
A brick red colour is a
positive result.
Iodine solution is
used to test for
starch
A blue / black
colour is a positive
result.
 The
main sources are lean meat, egg
white, fish, milk, pulse and nuts.
 Contain the elements Carbon,
Hydrogen, Oxygen and Nitrogen
(sometimes Sulphur)
 Proteins are made up of units called
amino acids.
 There are over 80 known amino acids,
but only 26 occur in proteins.
 These
amino acids form long chains which
come together as a protein molecule.
 A typical Protein molecule has 500+ amino
acids
 Some amino acids can be made by our body
and these are called non – essential amino
acids.
 Other amino acids can only be brought into
our bodies by ingestion.
 These are known as essential amino acids.
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There are no essential
amino acids for
ruminants.
Proteins are used in the
body for growth and
repair of cells.
The Biuret Reagent is
used to test for the
presence of protein in a
food sample.
A lilac colour indicates a
positive result.
Sources of fats are obvious –
butter, oils, nuts, milk and
general fatty foods.
 Contain the elements Carbon,
Hydrogen and Oxygen but
not in any given ratio unlike
Carbohydrates.
 A unit of fat (called a
triglyceride) is made up of
one molecule of Glycerol with
three fatty acids chemically
attached.
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 Fats
provide energy to the body (twice as
much as carbohydrates), insulation and
contain vitamins (known as Fat Soluble).
 Phospholipids
are oil like substances but
contain a phosphate group instead of one
fatty acid.
 Phospholipids
are important as they form
cell membranes.
Fats can be known as saturated or
unsaturated.
 Saturated means that as many Hydrogen atoms
as possible are attached to the Carbon atoms.
 Saturated fats are usually solid at room
temperature and are related to heart disease.
 Unsaturated fats contain fewer Hydrogen atoms,
and contain what are known as double or triple
bonds.
 They are usually oil at room temperature.
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Vitamins have many functions in the body.
Vitamins mainly act as co-enzymes, which means
they trigger enzymes to work.
Vitamins can be water soluble or fat soluble.
Vitamin C (A water soluble vitamin)
• Found in Citrus Fruits
• Involved in the absorption of Iron & Respiration
• Lack of Vit. C causes Scurvy!!
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Vitamin A (A fat soluble vitamin)
• Found in the carotene pigment (found in carrots).
• Involved in formation of the visual pigments.
• Lack of Vit. A causes night blindness.
• Minerals have no energy value but are used in
the body for many different reasons
• Osmo-regulation (control of water levels)
• Acid – Base balance (pH balance)
• Formation of enzymes, pigments and
hormones.
• Triggers or activators in different
reactions.
• Iron for Haemoglobin in Blood (Anaemia)
 Water
has no energy value but again is
essential for all bodily functions
 Our
bodies are made up of 75% water.
 Waters
main function is as a medium where
other food items are stored and moved.
 Of
course our blood is made of nearly all water
so it is vital that the human body gets 3 – 4
pints of water a day.
 Carbohydrates:
• Cellulose as a component of Cell Walls
 Protein:
• Fibrous proteins like Keratin are found in
hair and nails.
• Myosin is found in muscles.
 Lipids:
• Phospholipids are a major component of
cell membranes.
Enzymes are biological catalysts.
 They are natural substances, which speed up the
breakdown of food substances and other materials.
 They work by combining with the substrate
forming the enzymes – substrate complex.
 The enzymes – substrate complex breaks down
and forms the product and releases the enzyme.
 The enzyme can then be used again.
 Enzymes are very specific and will only work on one
substrate.
 Enzymes are very important in the breakdown of
food in our digestive system.
 Enzymes work at specific pH’s. Most at pH 7 but
pepsin works only at pH 2 & 3.
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