Applied digestive physio of Ru 2: degradation and synth of N-containing substances in the Rumen

Question 1

Nitrogen metab: CP

Answer 1

This consists of true protein and NPN

Formula: Total Nx 6.25

Question 2

Protein degradation

Answer 2

Protein converted to peptides by bact protease

Peptides converted to aa’s by peptidase

AA’s converted to NH3, VFAs and CO2 by desaminase (IC)

Urea converted to NH3 by urease

Question 3

High RDP, and what are the 3 examples

Answer 3

80% of protein is degraded in the rumen

• Wheat
• Barley
• Sunflower meal

Question 4

Medium RDP

Answer 4

60% of the protein is degraded in the rumen

• Corn
• Extracted soybean and grass

Question 5

Low RDP

Answer 5

40% of protein is degraded in the rumen

animal products e.g sorghum (these are now banned in the EU)- means that UDP of around 70% will enter the abomasum and intestine

Question 6

How to incr UDP content of the feedstuff (4)

Answer 6

1. Heat the protein- this decr the RDP
2. Formaldehyde treatment: aldehyde group binds to the free amino group of the protein- later decomposed in the intestine
3. Maillard reaction: degrades connection btw the protein and carb e.g calked soy pass for soybean
4. Capping- lipid layer around methionine (this is the limiting aa)- prevents ruminal breakdown by the microbiome

Question 7

Connection btw ammonia liberation and E production in the rumen

Answer 7

Mismatch btw E and ammonia- means there is waste (of xs ammonia)

Can give molasses because of its rapid E mobilisation- so both curves of the graph meet eachother

Question 8

Urea fermentable potential

Answer 8

How much urea you can get from 1kg of DM

1.044 TDN-dg divided by 2.8

Question 9

UFP: meanning of the values

Answer 9

+ TDN > NH3 liberation

0 TDN= NH3 liberation

(-) TDN< NH3 liberation

Question 10

dg and the influencing factors

Answer 10

Protein degradation

Solubility

Amnt and source of carbs

Question 11

What is the E source for protein degradation?

Answer 11

The ATP from the carb degradation i.e the production of VFA’s

Question 12

What is MP (metabolizable protein) and what does it consist of?

Answer 12

It is the aa’s that are available and can be absorbed by the SI

• UDP/bypass
• RDP: microbial protein synth from the feed protein degraded in the rumen

Question 13

What are the 2 MP values

Answer 13

Nitroegen dependent: MPN

E dependent: MPE