Proteins and Amino Acids, Quality Flashcards
refers to the availability of amino acids that the protein supplies, and digestibility considers how the protein is best utilized.
protein quality
Animals do not have a protein requirement, rather they have an?
amino acid requirement
The basic function of dietary protein is to supply adequate amounts of required?
amino acids
are the essential amino acids that interrupt protein synthesis due to its limited amount and the great demand for them.
Limiting amino acids
The two most common limiting amino acids in animals fed corn- and soy-based commercial diets in the US are?
lysine and methionine.
The digestibility of protein can be defined as the fraction of the protein ingested that is ? by the animals —that is, not excreted in feces
absorbed
The digestibility of protein can be defined as the fraction of the protein ingested that is absorbed by the animal—that is, not?
excreted in feces
can therefore be calculated by measuring dietary protein input and fecal output
Digestibility
are a favored technique for measuring the availability of amino acids.
Digestibility assays
Most common and published values on the digestibility of protein and amino acids in monogastric animals are based on?
fecal or excreta analysis
are not always accurate because the microbes in the hindgut affect the results.
Fecal-based digestibility measurements
Digestibility can be divided into?
fecal and ileal
are done through fecal collection and analysis
Fecal digestibility assays
are done through digesta collection at the ileal junction
ileal digestibility assays
is simply the rate at which amino acids are absorbed and become available for protein synthesis.
Bioavailability of amino acids
This type of protein are more balanced with essential amino acids and nonessential amino acids.
Animal proteins
can have antinutritional factors (e.g., trypsin inhibitor) that can affect protein digestibility and availability of amino acids.
Plant proteins
can disrupt antinutritional factors like trypsin inhibitor in soybean meal.
Feed processing methods
makes amino acids unavailable due to a complex reaction with sugars.
overheating
This could interfer with the metabolism of another amino acid, making them unavailable (e.g., lysine and arginine) can precipitate amino acid imbalance.
excesses of one amino acid
Protein quality can be assessed by ? using live animals or chemical assay.
bioassays
This is a measure of the proportion of absorbed protein from a feed that becomes incorporated into the proteins of the animal’s body.
Biological Value (BV)
It determines how readily the digested protein can be used in protein synthesis in the animal
Biological Value (BV)
assumes protein is the only source of nitrogen and measures the proportion of nitrogen absorbed by the body that is then excreted (fecal and urine).
Biological Value (BV)
must have been incorporated into the proteins of the animal’s body.
remainder
A ratio of nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein/
“usability” or BV
measures the percent of absorbed protein retained in the body.
Biological value (BV)
determines the ratio of amino acid converted to proteins in the body to the ratio of amino acids supplied in the diet.
Net Protein Utilization (NPU)
indicating 100% utilization of dietary nitrogen as protein
value of 1 (or 100)
indicated that none of the nitrogen supplied was converted to protein.
value of 0
This food protein has a high value of 1 (or 100)
Egg
was the first method adopted for routine assessment of the protein quality of food.
Protein Efficiency Ratio (PER)
R is based on the weight gain of a test animal divided by its intake of a particular food protein during the test period
Protein Efficiency Ratio (PER)
amino acid score is done through laboratory analysis of amino acid profiles using?
high-pressure liquid chromatography
high-pressure liquid chromatography results are compared to a?
standard protein
high-pressure liquid chromatography results are compared to a standard (or reference) protein such as egg protein (albumen) and given a?
score
they do not give any information on palatability, digestibility, or availability.
amino acid score
