Ammonia Toxicity:
Symptoms:
1. muscle
tremors
2. slurred
speech
3. blurred
vision
4. ataxia,
incoordination
5. tetany,
violent spasms
6. comotose
state
7. death -
accute = 30 min.; or could take days
Urea Cycle
1. Ammonia detoxification
2. N for
urea synthesis enters as NH3 (from deamination)
3. Requires
4 high energy phosphate bonds per urea molecule
4. Fate of
urea in blood (BUN) - blood urea nitrogen
a. urine
b. rumen - via saliva
c. cecum
b. & c. are
recycling
Birds - use
uric acid as excretory product - requires glycine
Ruminants = recycle
urea to rumen (horse to cecum??)
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.