2. Nutrition

Question 1

Lipids/Fats/Oils

Answer 1

organic compounds insoluble in water but soluble in organic solvents (glycerol + fatty acids = triglyceride)
in general fats refer to solid lipids, and oils to liquid lipids, but terminology used interchangeably
major role is energy storage
in some species fat has role in temperature regulation(brown fat in young animals, release energy as heat)
energy dense(more energy in body fat than glycogen)

Question 2

Lipid functions

Answer 2

provide energy(x2 as much as carbs)
source of essential fatty acids(cannot be synthesized in animals)
important for heart disease
immunity
inflammation
joint disease
skin health
reproduction
carrier for fat soluble vitamins, ADEK
constituent of cell membranes

Question 3

Lipids

Answer 3

composition of fatty acids important
saturates fatty acids, no double bonds in CHO chains
saturated shorter chain solid at room temp
unsaturated long chain fatty acids usually liquid at room temp
type of fatty acid important for animal and human health

Question 4

Essential fatty acids

Answer 4

linoleic acid (C18:2n-6) and linolenic acid (C18:3n-3) cannot be synthesized, must be fed
arachodonic acid needed if linoleic fatty acids not available only synthesized at slow rate de-novo
essential requirement related to:
produce eicosanoids e.g. prostaglandin
hormone like substances
regulate e.g. blood clotting, blood pressure, smooth muscle contraction, reproduction and immune response
EPA and DHA important for cardiovascular function, brain function and rheumatoid arthritis

Question 5

Signs of deficiency of essential fatty acids in non-ruminants

Answer 5

reduced growth rate
dry scaly skin
lack of sheen on hair
infertility
poor wound healing
irritating skin conditions
e.g. pigs under 30kg need 3% energy as linoleic acid and 2% of energy as arachadonic acid

Question 6

Benefits of adding dietary fats

Answer 6

concentrated energy source
flavour/palatability
satiety effect
fat soluble vitamin carrier
source of essential fatty acids
decreased feed dust
pelleting lubricant

Question 7

Clinical abnormalities associated with lipid metabolism

Answer 7

obesity main contributor high fat diet
artheroclerosis heart disease, artherosclerotic plaque from cholesterol
low density lipoprotein - cholesterol and coronary heart disease
high circulating triglycerides and coronary heart disease
fatty liver - increased liver lipogenesis, high fat or high cholesterol diet

Question 8

Protein

Answer 8

complex organic compounds
CHO, Nitrogen and Sulfur
nitrogen 16-18%
protein made up of sequence of amino acids up to 200 naturally occurring amino acids (20 commonly found)
amino acid CH chain with COOH group and NH2 group
chains of amino acids are called peptides: di, tri and poly
some proteins one polypeptide chain, some many more than one

Question 9

Proteins

Answer 9

found in all living cells
connected with all phases of activity that constitute the life of the cell
collagen part of CT 30% of total mammalian body protein, lots of hydroxyproline
keratins in wool, hair feathers contain high levels of sulphur containing amino acids, methionine and cysteine
elastin protein found in elastic tissues such as tendons, rich in arginine and glycine

Question 10

Essential amino acids

Answer 10

animals can synthesise most but not all amino acids
ruminant and monogastric requirements quite different
rumen micro-organisms can synthesise essential and non essential
monogastrics complex requirements

Question 11

Essential amino acids

Answer 11

must be supplied pre-formed in diet
pigs, dogs and rats require 10
cats somewhat different taurine normally synthesised from methionine and cystine cannot be synthesised at sufficient rates in the cat and must be supplied in diet
deficiency: central retinal degeneration, impaired vision, reproductive failure, cardiac abnormalities
chickens -10 plus glycine

Question 12

Non essential amino acids

Answer 12

adequate tissue synthesis:
glycine
alanine
serine
aspartic acid
citrulline
cystine
tyrosine
glutamic acid
proline
hydroxyproline

Question 13

First limiting amino acid

Answer 13

establish which one or two essential amino acids are limiting growth or production
provide these in correct amount, then with normal diets, other essential amino acids are likely to be OK
poultry: methionine
pigs: lysine or tryptophan
equine lysine
dairy lysine and methionine often limiting
commercial inclusion of specific amino acids

Question 14

Ruminant protein requirements

Answer 14

at rumen level as substrate for microbes
simple N compounds converted to microbial protein (both essential and non-essential amino acids produced)
at host tissue level for amino acids
from rumen microbes(microbial protein) and diet (rumen undegradable protein)

Question 15

General effects of low protein

Answer 15

usually a combined deficit of protein and energy
decreased intake and feed utilisation
decreased growth rates
decreased wound healing
poor colostrum quality
catabolism of body protein
immune response: are amino acids used to provide energy or to produce antibodies when animals are in a negative energy balance? yes

Question 16

Protein as energy source

Answer 16

amino acids often used as an energy source when energy is limiting
this happens by removing the amino group in a process called deamination
this happens mainly in the liver
urea is produced and must be excreted in urine
production and excretion of urea has an energy cost and therefore protein is a very inefficient way to provide energy
excess protein costs energy
this is why atkins diet works
places liver and kidney under extra metabolic stress