NUTR 3000 - Protein and Amino acids

Soybean meal is abundant in what amino acid?

lysine

Canola meal is abundant is what amino acid?

methionine

There is no dietary requirement for _________________, only for _______________

protein, amino acids

An amino acid is an

organic group with an amino group

Proteins are

polymers of amino acids

two amino acids that are joined are called

a dipeptide

Many amino acids that are joined are called a

polypeptide

Is a protein a dipeptide or a polypeptide?

A polypeptide

The dietary requirements for amino acids change due to certain factors or certain periods such as:

-periods of growth or maintenance, including pregnancy

-genetics

-sex (male or female, higher for males)

What two amino acids can replace each other

cysteine and methionine

What nonessential amino acid is essential for birds?

glycine

What amino acid is essential for felines?

Taurine is

How to determine essential AAs when added in diet

a non essential amino acid would have a flat line graph no matter the diet, since the body can already synthesize it. An essential amino acid would increase then begin to plateau if it was included in the diet.

We estimate protein content from

nitrogen content

Protein is what percent nitrogen

16%

The protein factor is

6.25 (100/16)

How to determine crude protein from nitrogen content

CP=N content*6.25

The estimation of CP from nitrogen content includes

true protein and non-protein nitrogen

NPN is

non protein nitrogen

Some people use the word protein to mean any N containing compounding, but we should use the word protein to mean only

polymers of amino acids, in order to be accurate about the nutritional content of the food

examples of NPN are

urea, biuret, ammonium bicarbonate

Non-ruminant omnivores with more advanced digestive tracts are able to use non-protein N for

microbial synthesis of amino acids in the hindgut (cecum, LI)

Adult ruminants are able to synthesize amino acids using

non-protein N and carbohydrates (via rumen microbes) to meet their amino acid requirements

Example of microbial synthesis of amino acids in the presence of carbohydrates in ruminants

A cow can consume carbon and NPN and under the presence of rumen microbes, make AA's. The carbon in the form of straw with ammonia will do this. It will not work in a cat or a horse since it travels to the stomach first (no microbes). The ammonia will be absorbed and kill them. In the rumen, it will be converted first

In the presence of NPN and carbohydrates, microbes

synthesize amino acids and protein

Examples of NPN

Urea (48% N)

Biuret

Ammonium bicarbonate

Ammonia

A problem that can occur to ruminant fed NPN too quickly or too high in quantity is

ammonia toxicity

Ammonia absorption increases at

higher pH

It is possible to feed urea if the diet is readily

fermentable

Symptoms of ammonia toxicity in ruminants

• Uneasiness

• Labored breathing

• Excessive salivation

• Muscle and skin tremors

• Incoordination

• Tetany

• Death within 1-2 hours (from symptom onset)

What compound poisoned pet food in 2007? What is it derived from and normally used for?

Wheat gluten containing melamine (found in resins, but toxic in feed) was fed to cats and dogs in Canada and US. They were poisoned. Any food with wheat gluten was recalled.

What happened with baby food in 2007-2008

Why did this happen/how is it prevented now?

Melamine found in some baby foods, 6 kids died.

people were imprisoned and resigned

These events happened because Protein nitrogen was not distinguished from NPN, and it increases the appearance of protein and masks dilution with water.

in 2008 cyanuric acid

an illegal additive with 33% nitrogen found in pet foods

Protein is a bad source of energy and is only used if we are deficient for energy We should consider energy content relatic to protein content. This protein to energy ratio

are deficient of energy, like in ketosis

Animals eat to meet

energy requirements

In a high energy, low protein diet, animals can become

protein deficient

In a high protein, low energy diet, animals may

use protein as an energy source (should find a better balance, poor source)

Excess protein in diet increases

excretion of N

N is secreted as

-urea in mammals

-uric acid in birds

-ammonia in fish

why is N concentrated in lizard excretions

to conserve water

when protein is fed in excess, it means the diet is not

feeding enough energy

When protein is fed in excess (symptoms)

-there is a linear drop in growth with increasing intake

• Reduced feed intake

• Dull, coarse hair

• Altered liver protein and water content

• Enlarged liver and kidney

Protein needs to supplied at the rate necessary for:

-synthesis of body tissue

-synthesis of products such as milk or eggs

What is AA antagonism

when excess of one AA is countered by more of another

excess lysine in chicks is counteracted by additional arginine

AN example of amino acid antagonism in chicks

excess lysine in chicks is counteracted by additional arginine

Excess lysine and adequate arginine can induce an

arginine deficieny

Why might inducing an arginine deficiency through AA antagonism be intentional?

some viruses require arginine (lysine can actually treat some viruses)

Signs of protein deficiency

• Anorexia

• Reduced growth rate

• Reduced blood serum protein concentration

• Anemia

• Fat accumulation in the liver

• Edema (severe cases)

• Reduced birth weight of young

• Reduced milk production

• Reduced synthesis of enzymes and hormones

Amino acid toxicity is when

excess of an AA cannot be counteracted by adding more of another (ex. methionine)

We are limited by the

first limiting AA, the most deficient AA, ie barrel picture where water is growth potential

cysteine can make up for a deficiency of

methionine

the filaments in feathers hold together by disulphide bonds, which you need _____________ to make

cysteine (has S-S bonds)

Excess AA are not

stored