Rumen Function - Causeway Produce Agency
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Transcript Rumen Function - Causeway Produce Agency
Kenneth Bruerton PhD
11 August 2011
Breaks down
◦ Protein
Digested to amino acids by rumen micro-organisms and
resynthesized into microbial protein.
This is digested in the small intestine to amino acids which are
absorbed and used for growth (enzymes, immune proteins, muscle
protein).
Some amino acids can be used to make glucose for energy
production in specialized tissues such as brain and formation of
rapid energy stores (liver and muscle glycogen).
◦ Fibre (cellulose, hemicellulose, lignin).
Only digested in the rumen by certain micro-organisms. What is
undigested is excreted in the faeces.
Producing volatile fatty acids (VFAs) such as propionate and
butyrate which are absorbed in the small intestine and used for
energy production and fat synthesis.
◦ Starch, sugars
Digested rapidly in the rumen to form lactate or acetate. Excess
fermentation of starch can cause acidosis, particularly in lotfed
cattle receiving grain.
Urea
Supplies Nitrogen (N).
Contrary to common belief Urea is not protein. Urea is a
simple N compound. Urea is ~45% N = 281% crude protein
equivalent.
Rumen microorganisms can convert N to ammonia which
is converted to amino acids and microbial protein.
Urea can supply up to 1/3 of the total protein requirement
of cattle. However at these levels sufficient fermentable
energy must be supplied to allow utilization of available N
Urea
CO2
Carbohydrates
Keto Acids
Microbial Urease
Microbial Enzymes
Keto Acids + NH3
Amino Acids
Amino Acids
Microbial Protein
Microbial Protein
Free Amino Acids
NH3 +
FA +
Microbial Enzymes
Microbial Enzymes
Small Intestine Enzyme
Free Amino Acids Absorbed
Toxic dose generally regarded as 0.5grams/kg LWT in a single
feeding episode.
Sulphate of Ammonia (NH4)2SO4
Supply N as with urea. Contains approx ½ the level
of N as urea
Important source of Sulphur (S)
Sulphur required as a precursor to the production
amino acids
N:S ratio should be in the range of 12-15:1
SO4 often used to control intake (more bitter than
urea )
More expensive source of N than urea
Elemental Sulphur
Source of S.
Less available source of S than SO4.
Protein Meal
Source of Rumen Escape Protein
Source of Energy to aid utilization of Urea.
Used to manipulate intake.
Commonly used meals include
Cotton Seed Meal 43%
Copra Meal 20%
Canola Meal 35%
Soybean meal 48%
PKE 15%
Very important to calculate the input cost of the protein.