Ruminant
Protein Digestion
Bacteria: secrete
protease eventually broken to NH3 & carbon skeleton
Microbial protein = protein synthesized by
microbe (themselves??)
NPN: (urea)
use NH3
+ carbon skeleton (from starch and fiber also) to make AA. Can meet tissue AA
requirements by feeding NPN (essential amino acids???)
Escape Protein: (by-pass protein) does not undergo ruminal degradation.
Heating protein source will ¯ solubility Þ
escape value.
Grass < SBM < Fishmeal
NH3 & carbon skeleton: NH3 rapidly produced, need source of carbon
skeleton available at the same time. Feeding NPN only beneficial when proper
CHO's are fed also.
Example: Urea and Hay
Urea
= protein Hay = carbon skeleton Þ not a good match!!
Urea will be absorbed ®
kidney - urinated on the ground because fiber (cellulose) not digested quickly.
Microbial Proteins = come from both NPN & soluble protein in diet
AA available to
animal tissue are from escape and microbial protein
Ruminant & low protein: can survive because of urea and recycling
Ruminant and man: don't compete for food because NPN, an met AA
requirements.
Microbial and Escape protein: digested and absorbed in S.I.
Adult = 100% requirements can be met with microbial protein
Young (growing) or
lactating = only 75% requirements met with
microbial protein Þ to meet requiremetn (25%) feed insoluble (escape) proetin.
Decrease Protein Solubility escape value
1. heat it
2. coat
with fat - bacteria cannot get to it
3. chemically
treat, formaldehyde
Biological Value
|
Protein Source |
BV |
|
Egg Protein |
95 |
|
Milk Protein |
90 |
|
Meat Protein |
90 |
|
SBM Protein |
75 |
|
Meat & Bone Meal |
70 |
|
Cereal Grain |
60 |
|
|
|
Microbial protein ~75-80 BV
Look at BV and solubility.
Milk BV = 90 and is
soluble Þ ¯ value from 90 ® 75-80