UCD Nutrition (Ruminant Protein Nutrition)

what are proteins in the ruminant digestive system?

complex organic compounds of high molecular weight

contain carbon hydrogen and oxygen, nitrogen and sulfur

found in all living cells

what are amino acids?

building blocks of proteins

when are amino acids produced?

when proteins are hydrolyzed by enzymes, acids and alkalis

what are amino acids characterized by?

having a basic nitrogenous group generally an AA group and an acidic carboxyl group

what is the primary structure of amino acids?

peptide chains

what are the essential amino acids in ruminants?

arginine

histidine

isoleucine

leucine

lysine

methionine

phenylalanine

theronine

tryptophan

valine

what is responsible for protein digestion in the rumen?

microorganisms

bacteria and protozoa

what are some sources of rumen nitrogen?

feed

- protein nitrogen (protein feeds such as soy bean meal, grass, legumes)

-non protein nitrogen (urea)

endogenous nitrogen

- saliva, rumen wall

metabolize protein (MP)

the true protein that is digested post ruminally and the component amino acids that are absorbed by the small intestine

used for protein milk synthesis

Rumen Degradable Protein (RDP)

protein that is degraded and modified by microbes in the rumen and converted to microbial protein

Rumen Undergradable Protein (RUP)

protein that "escapes" rumen degradation

soluble protein

comprised of non-protein nitrogen (urea) peptides, and other protein compounds

nonstructural carbohydrates (NSC)

Comprised of starch and sugars

structural carbohydrates

cellulose, lignin and hemicellulose

the most common measure is neutral detergent fiber (NDF)

Acid Detergent Fiber (ADF)

measures only cellulose and lignin

how are food proteins hydrolyzed?

to peptides/amino acids by rumen microorganisms

what is included in microbial protein production?

-

what is important about microbial proteins?

when the organisms are carried thru to the abomasum and small intestine, their cell proteins are digested and absorbed

bacteria and capable of synthesizing indispensable and dispensable amino acids

what is the process of digestion and metabolism of nitrogenous compounds into the rumen?

-protein initially broken down into peptides

-further digestion yields amino acids and eventually ammonia

-protein used by the cow may be directly from feed pr produced from the microbes (ammonia is toxic in the rumen environment so it gets converted quickly)

what is a major source of protein in the cow's diet?

rumen microbes

what does RDP get broken down to?

amino acids and ammonia

what is the importance of ammonia?

the ammonia in the rumen liquor is the key intermediate in microbial degradation and synthesis of protein

microbial protein entering the small intestine is determined by available energy

when concentration of ammonia is low and the growth of rumen microorganisms is slow, the breakdown of carbs for energy will also be slow

what is ammonia the end product of?

digestion

how is ammonia transported thru the body?

ammonia is absorbed into the blood, carried to the liver, and converted to urea

how can the ruminant produce more proteins than it takes in?

low protein in feed = low ammonia in rumen liquor

the net gain of recycled nitrogen is converted to microbial protein = the quantity of protein reaching the intestine may be greater than that in food

Non-Protein Nitrogen (NPN)

compounds that are not true protein in nature, but contain N and can be converted to protein by bacterial action in the ruminant animal

what is urea?

A waste product formed in the liver. The blood transports it to the kidneys where it is removed.

where are microbes continually flushed from?

flushed from the rumen through the omasum and abomasum

where do amino acids that were produced from digested microbial proteins go?

they are absorbed in the small intestine

what happens to the microbes in the abomasum?

they die and are broken down which is good for the rumen

the nitrogen in food protein is either ...

rumen degradable (RDP) or rumen undegredable (UDP)

what is the RDP fraction typically used for?

microbial protein synthesis or absorbed across the rumen wall as ammonia

what is special about UDP?

resistant to microbial attack and escapes degradation

why is dietary protein important

for health, breaks down into AAs during digestion which is used to build other proteins in the body

the protein that is directly available to the cow or that has escaped microbial digestion us undegradable dietary protein (UDP)

where is dietary protein digested?

the abomasum and small intestine

what provides a greater diversity of amino acids than from microbial protein?

UDP and RDP

how do we maximize productivity of microbial proteins?

they must be supplemented with a supply of amino acids from foods or synthetic sources in a form that is not degraded by the microorganisms

what are two likely limitations of microbial protein synthesis?

energy available

NH3 available

these must be synchronized

what proteins leave the rumen?

microbial proteins

escape protein

these enter the abomasum and small intestine

what has a significant effect on amino acids reaching the small intestine?

microbial populations

why do we not need to supply protein content to ruminants at all times?

because they can be productive without a source of dietary true protein

enables them to use NPN efficiently

what does not affect the amino acid composition of bacteria and protozoa leaving the rumen?

the type of feed

how can urea have >100% CP?

-

ruminants have ___% efficiency of nitrogen use

25%

what are some consequences of nitrogen excretion?

lower production performance, less economic efficiency and increased emission of gasses into the environment

what happens to nitrogen when it is consumed?

75% is excreted in feces (25%), and urine (50%)

on farm nitrogen use varies between _____

15-40%

where must essential amino acids and nitrogen be absorbed by?

the small intestine

this supports the synthesis of milk and the maintenance of body tissue

what is a major part of the protein available to support milk protein synthesis?

microbial protein that flows into the lower gut

what is the most important factor contributing to the inefficient use of nitrogen in ruminants?

rumen metabolism

what is the key to improving nitrogen efficiency of the cow?

balance the various protein fractions along with providing adequate CHO

when do nutritional imbalances arise?

when nitrogen is fed in excess of requirements. excessive rumen degradable protein (RDP) or soluble protein are fed relative to fermentable CHO, or inadequate amounts of amino acids

how is ammonia recycled?

NH3 as a source of energy by microorganisms

ammonia is toxic so it is immediately converted to urea