FELASA Module 6: Nutrition
Most animals can be fed a complete diet in the form of pellets
These pellets can have its components divided into fractions of macronutrients
Carbohydrates come in a digestible form and non-digestible forms known as fiber
Some fibers may be digestible under some circumstances (e.g. if an animal has
different gut bacteria)
If we burn the pill all the macronutrients will burn but the minerals will remain as ashes
These minerals are essential for the animal
Essential nutrients
In the fat fraction there should be the essential fatty acids linoleic, linolenic and
arachidonic acid
These should compromise around 1-1.5% of the metabolizable energy
The protein fraction must contain arginine, histidine, isoleucine, leucine, lycine,
methionine, phenylalanine, threonine, tryptophan and valine
Macrominerals should be supplied with more than 100mg per day
Thid includes calcium, phosphorus, magnesium, sodium, potassium, chloride and
sulfur
Microminerals can be supplied with less than 100mg per day
These include iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc
and molybdenum
Vitamins are organic molecules which essential but are not covered by the terms
essential fatty or amino acids or minerals
Vitamins A, D, E and K are fat soluble and there is a minimum daily need
B vitamins are water soluble and some daily needs can be defined
Vitamin C is essential and only considered a vitamin in guinea pugs and primates,
whereas other animals can synthesise it themselves
Energy
When burning a food pellet a certain amount of gross energy is released
When an animal eats the food pellet only some of it is digestible energy
The rest will pass through the gut and leave the animal as feces
Some of the digestible energy that enters the systemic parts of the animal is secreted
as urine
Out of the food pellet eaten only a fraction is metabolizable energy
Catabolism- breakdown of complex molecules into smaller ones
Releases energy
Anabolism- building larger molecules out of smaller molecules or atoms
Uses energy
Just because an animal has a certain intake of metabolizable energy it might not be
able to use it all for catabolism, and therefore create energy
If fed freely the animal will eat to fulfill its need for energy
This won’t always be valid
Precise energy needs are difficult to define
Growing animals need more energy and more protein than adult animals
Pregnant or lactating need energy for producing foetuses and milk
Therefore animals in these conditions have different food intakes and their diets
should be adapted
The gastrointestinal tract consists of the stomach, the small intestine and the large
intestine
Broken into smaller bits it also includes the esophagus, stomach, duodenum, jejunum,
ileum, cecum, ascending colon, descending colon and rectum
Animal species differ in relation to how much of their gastrointestinal tract is large or
small intestine
Cats and dogs have more small intestine than humans
Pigs, rats, mice and rabbits have more large intestine than humans
The high fraction of small intestine in cats makes them carnivores
, Humans are omnivores with them needing proteins and slow digestible
carbohydrates
Rabbits are herbivores and need lots of slow digestible carbohydrates and fibers
Dogs, pigs, rats and mice are omnivores due to them living close to humans for
many generations
Their gut anatomy has adapted to reflect this
There is a wide range within species of what diet components are needed
If mice and rats are given high protein diets they will grow quickly but develop
tumours
Guinea pigs have a need for vitamin C but other species don’t
At least 15% of the diet needs to be fiber for rabbits
Because animals are usually fed from pellets from big suppliers you don’t have to worry
too much about what to feed them
If manipulating diet in a study you need to know what you can and can’t do
Some nutrients can be overrepresented in the diet without complications
Others should be closely dosed
Nutrient Requirement of Laboratory Animals from the US National Research Council tells
you the requirements
Diets for laboratory animals are produced by commercial laboratory animal diet producers
You can purchase a complete diet fulfilling all nutrient requirements
Some companies offer standard diets based on natural ingredients and special7purified
diets based on synthetic ingredients
Some companies work with a closed formula which tells you the level of nutrients but
not the components
Others work with an open formula which tells you which ingredients are used
In most cases of animal nutrition diets in the catalogues of commercial diet producers
are used
This is the case for studies where the diet is not an experimental factor
Also used within large research areas like diabetes, obesity, osteoporosis an vitamin
research
Purpose made diets can be ordered for some research diets
Normally at least 10kg of pills will need to be ordered as it is difficult to make a
uniform diet in small amounts
Purpose made diets are usually based off of the standard diets
Natural Ingredient diets
Also known as chow
Made of:
Whole grains (corn, barley and wheat)
Mill by-products (bran)
High protein meals (like soybean fish and casein)
and mineral sources (like bone meal)
Advantages:
Cheap
Animals like it
Nutritious
Disadvantages:
Variation between batches from the same producer
Even higher variation between producers
Can’t remove a single substance without removing major fractions of the diet
Contains uncontrolled biologically active compounds
Contamination risk for pathogens like Salmonella
Can be differences in natural ingredients across the world
In Europe wheat and barley are used in North America wheat and corn are used
Wheat and barley contain gluten which corn does not
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