The utilization of protein and non-protein N-connections by ruminants

1. The utilization of protein and non-protein N-connections by ruminants • Feed mass gets delayed in die rumen • Gets build into microbe cells • From the mouth to the abomasum the: • Protein ration gets changed • Part gets lost as ammonia • N-levels increase due to urea from liver through saliva and stomach wall

2. Two types of protein digestion: • Active protein digestion and reconstruction by micro organisms • Enzyme hydrolyses of protein in lower GIT + recirculation of urea • Prot from 2 sources: • Plants (+ Byproducts from animal, marine sources and N) + NPN • Endogen supply from liver

3. Total saliva excretion: • sheep 6-16 l • bees 98-190 l • Depending on type of ration, chew & ruminance • Parotus glands – NB’e contribution to saliva • Parotus saliva is watery liquid, isotonic (same osmotic pressure) to blood, BUT sodium carbonate en phosphate ↑ potassium en chlorides ↓ • Contains a lot of urea and small amount NPN

4. Recirculation of urea to ruminants advantage in 2 ways: • Additional N-source if N is low → cellulose digestion → unlocking of E • Increase in amount a/a – production, therefore 2nd chance for a/a production from NPN • Enough protein in ration, ammonia not used – get lost in urine • Urea which gets recirculated, available for a/a – synthesis again

5. N – savings mechanism for ruminants • ↓ Energy & ↓ N = –N-balance → Recirculation of urea cannot overcome shortage, animal can, however, survive longer • ↑ Energy & ↓ N = → Recirculation of urea can switch –N-balance to +N-balance

6. Micro-org can be divided in 3 fractions • Protozoa • Large bacteria • Small bacteria • Protein peptides a/a’s Carbon hydrogen skeleton NH3 + short chain fatty acids Construction of a/a’s Absorbed and lost through urine • Tempo of deamination & dispensing of ammonia varies en is ↑ when protein intake is ↑

7. If hydrolyses to NH3 is to fast → large quantities of ration N not utilized → absorbed as NH3 → lost in urine • Micro-organisms modifies a/a-composition • Essential a/a’e poor in ration, micro-org can improve it • Opposite, however, can also happen

8. Ration with ↑ protein → NH3 concentration in rumen liquid peak 1-4h after feed intake • Height of peak: • Hydrolyses of involved protein • Quantity and nature of carbohydrate component • ↑ Starch and sugar → microbe population is bigger and more active → released NH3 gets worked away more rapidly • High sharp peak → weaker utilizing of NH3 → more N lost in urine

9. Ruminant → Can satisfy N-requirements from NPN-sources → Notable savings • Urea NH3 • Urease - optimum pH7: ↓pH → NH3 released slower Urease (from bacteria) Rapid fermentation of starch & sugar → VFA’e E-source for micro-org → more active → NH3 removed more rapidly

10. Problem: • Urea used with fiber rich, low grade roughage as N-supplement to... • Unlock potential E in cellulose • Extra N have to enable micro-org to unlock E from fibers • With provision of easily hydrolyzed carbohydrates → ↓ digestion of cellulose

11. NH3 (van urea) a/a’e • Simultaneous presence of fast fermentable carbohydrates • Presence of / syntheses of carbon hydrogen skeleton of a/a’e { Urea better utilized with natural protein Deamination & fermentation of natural a/a’e → Volatile Fatty Acids → Carbon hydrogen skeleton Ruminant → Digestive processes in lower (from abomasum) GIT similar to monogastric animal