What is the importance of amino acids?
Amino acids are essential for protein synthesis, amino acid metabolism and nitrogen losses from the body
What is an essential amino acid?
One that is not made within the diet and must be consumed
What is a non-essential amino acid?
One that is synthesised by transamination and is not required in the diet
Rank the following in terms of greatest need to the lowest need for protein in the diet: carnivorous fish, members of the feline family, camelids, Llamas and Alpacas:
Carnivorous fish = very high
Feline family = high
Camelids, Llamas and alpacas = low
What are the potential fates of dietary protein within monogastrics?
- Used as energy
- Used for protein synthesis- retained in tissues (muscle, organs) and eggs + milk
- Excreted as urinary nitrogen
- Excreted as faecal nitrogen
What is the dietary fate of rumen microbes?
- Rumen microbes ferment dietary nitrogen and there is a high efficiency of recycling through saliva and conversion to absorbable amino acids
What are the two key sources of amino acids (metabolisable) in the small intestine of the ruminant?
- Microbial protein
- Undegraded dietary fibre (UDF)
What are the three main factors that will influence the level of rumen degradability?
- Variation between feedstuffs
- With level of intake and rumen transit time (More feedstuffs in rumen = more escape from the rumen)
- Processing
What rate is microbial protein capacity capped at?
About 14% of crude protein
How can protein be supplied to an animals diet to meet requirements of ruminants in different physiological states?
- select food with a high undergradable protein content
- process the food to increase the undergradable protein content (grinding, chemical treatment, heating)
- increase the level of feeding (reduces the ruminal resistance time and increases the ruminal outflow (escape))
What are the three basic factors that determine the protein value of a ration?
- Amount of protein (QUANTITY)
- Mix of essential amino acids relative to target protein (QUALITY)
- Digestibility of the protein (QUALITY)
What are the weaknesses of crude protein as a measure of protein accuracy?
- Crude protein will not accurately predict true protein and does not give an indication of protein quality
What is meant by the term rate limiting amino acid and what is the most common one?
- essential amino acid that determines the efficiency of other amino acids
- refers to the amino acid that is in greatest deficit compared to target protein
- lysine - rate limiting amino acids in most systems
What is the “ideal protein” method of expressing amino acids?
- expressing everything relative to lysine
