Digestion and utilization of RDP and RUP and NPN substances in rumminants

1. Digestion & Utilization of
RDP,RUP and NPN substances in
ruminants
Submitted by: Sarmad Jamshaid
Reg.# F23BNUTR3M01002
M.Phil. Animal Nutrition 2nd semester
Course: RUM NUTR 32204
Submitted to: Prof. Dr. Nasir Ali Tauqeer

2. Introduction
 Protein is important for ruminants.
 Growth and development
 Reproduction
 Milk production
 Rumen microbial health
 Enzyme functions
 Ruminant protein digestion differs from mono-gastric animals, with the
rumen being a specialized foregut where microbial fermentation is pivotal
for protein breakdown and utilization.

3. Digestion of protein

4. Fractions of dietary protein
• Rumen degradable Protein (RDP)
• Rumen undegradable protein (UDN)
• Rumen Degradable Protein (RDP) is the fraction of Crude Protein (CP)
consumed which is broken down by rumen microbes.
• And remaining protein which reaches the small intestine without
degradation called as Rumen undegradable protein (UDN).

6. Digestion of Rumen degradable Protein (RDP)
• Rumen degradable Protein (RDP) hydrolysed to peptides and amino
acids by rumen microorganisms,
• But some amino acids are degraded further, to organic acids,
ammonia and carbon dioxide.
• The main proteolytic organisms are Prevotella ruminicola,
Peptostreptococci species and the protozoa.
• Two major steps are involves in protein degradation in the rumen:
1- Hydrolysis of peptide bonds to produce peptides and amino acids.
2- Deamination and degradation of amino acids.

7. • The ammonia produced due those processes , together with some
small peptides and free amino acids, is utilised by the rumen
organisms to synthesise microbial proteins.
• Some of the microbial protein is broken down in the rumen and its
nitrogen is recycled (i.e. taken up by microorganisms).
• The new NRC (2001) suggests that maximum milk and milk
protein yields occur when RDP is 12.2% of diet dry matter.

8. • An important feature of the formation of microbial protein is that bacteria are
capable of synthesising indispensable as well as dispensable amino acids.
• The ammonia in rumen liquor is the key intermediate in microbial
degradation and synthesis of protein.
• Estimates of the optimum concentration of ammonia in rumen liquor vary widely,
from 85 mg/L to over 300 mg/L ( Gumilar et al. 2018)

9. • If the food is poorly supplied with protein and the concentration of ammonia in
rumen liquor is low.
• The quantity of nitrogen returned to the rumen as urea from the blood may
exceed that absorbed from the rumen as ammonia.
• This net gain in ‘recycled’ nitrogen is converted to microbial protein, which
means that the quantity of protein reaching the intestine may be greater than that
in the food.
• With most feeds each kilogram of organic matter digested in the rumen
yields approximately 200 g of microbial protein.

10. Limitations of RDP
• Ammonia : Excessive intake of RDP can lead to ammonia toxicity and
nitrogen loss through urinary excretion.
• Supplementation frequency: According to Bohnert et al. (2002) DM
digestibility decrease with increase in RDP from daily to every 6 days.
• Crude Fiber: There is negative correlation between CF and RDP. High CF
content in diet will decrease RDP and increase RUP.

11. Factors Affecting Ruminal Protein Degradation
Chemical Nature of the proteins
•Solubility – More soluble proteins degraded faster some soluble proteins not
extensively degraded
Egg ovalbumin, serum proteins
• 3-dimensional structure – Affects solubility & availability
• Chemical bonding
Disulfide bonds – Reduces degradation

12. • Physical barriers
• Cell walls of plants
• Cross linking of peptide chains – Reduces degradation
E.g. Aldehydes, Tannins
• Feed intake
• Rate of passage – Time proteins remain in the rumen
• Feed processing
• Rate of passage
• Heat damage – Complexes with carbohydrates

13. Rumen undegradable protein (RUP) digestion
• Rumen undegradable protein (UDN) is also called bypass protein or
escaped protein or rumen undegradable protein (RUP).
• It is the portion of intake protein that escapes rumen degradation and is
digested directly in the small intestine.
• About 80 to 85 % of the microbial bacterial protein or true protein that
flows out of the rumen is digested in the small intestine and it is expressed
as a percentage of crude protein (CP).

15. Protein digestion in the small intestine
• The nitrogen entering the duodenum is a combination of microbial protein,
undegraded protein and endogenous protein.
• Nitrogen entering the small intestine from the stomach can range from 30-
100% microbial protein and 0-70% undegraded protein.
• Digestion of protein in the abomasum and the small intestine in ruminants is
similar to that in monogastric animals.
• The digestion of protein in the abomasum is carried out mainly by pepsin in a
very acidic environment (pH 2).

16. Absorption of amino acids and peptides
• The most active site of amino acid and peptide absorption is the mid
to lower ileum.
• There is a preferential absorption of essential over non-essential
amino acids from digesta flowing through the small intestine.
• For example, absorption of lysine and histidine is higher than the
absorption of glutamine and glycine.

17. Sources of Bypass Protein
 Naturally Protected Proteins
 Heat Treatment (Maillard reactions)
 Chemical Treatment (Formaldehyde, lignosulfate)
 Esophageal Groove (For young one, liquid protein)
 Post Rumen Infusion (Fistula)
 Encapsulation of Proteins
 Amino Acids Analogs (Methionine hydroxyl)
 Lowering Ruminal Protease Activity
 Decreasing Retention Time in Rumen

18. Naturally Protected Proteins
Feed UDP %
Maize (grain) 53-60
Barley 21( 11-27)
Sorghum 52
Bajra 68
Oat grain 14–20
Wheat grain 20–36
Cotton seed meal 41–50
Linseed meal 11–45
Ground nut meal 30
Rapeseed meal 23
Soybean meal 34-42
Sunflower meal 24
Subabul 51 – 70
Feed UDP %
Blood meal 76 – 82
Fish meal 71 – 80
Meat meal 53 – 76
Brewers dried 53
Corn gluten 53
Wheat bread 29
Corn silage 27
Rice straw 63
Wheat straw 45
Para grass 52
Cow pea 32 – 45
Berseem 37 – 52
Alfa-Alfa 28
(NRC, 2001); INRAE

19. Importance of Bypass Protein
• Required for medium and high lactating and growing animals mainly
in early lactation.
• Increase in Milk production by 10-15 %.
• Good increase in live weight gain of meat purpose animals. Exposes
essential and limiting amino acids directly to Intestine. Reduces Milk
Production cost.

20. Why Limit High RUP Proteins in Lactating Cows
• Animal byproducts tend to reduce feed intake Palatability
decreased feed intake reduces microbial protein synthesis
• Plant byproducts may have poor amino acid balance
Corn proteins deficient in lysine and
• Quality of RUP proteins can be variable
• Protein requirements may have been met
• First limiting amino acid might not be increased
• Overestimation of degradation of other supplemental proteins.

21. Comparison of Degradable and Un-degradable Protein
Feature Degradable Protein Undegradable Protein
Degradation site Rumen Small intestine
Degradation
products
Ammonia and amino acids Amino acids
Utilization Microbial protein synthesis Direct amino acid supply
Benefits High-quality protein source Essential amino acids
Limitations Ammonia toxicity, nitrogen
loss
Reduced microbial protein synthesis

22. Non-Protein Nitrogenous Substances (NPN)
• NPN are nitrogen-containing compounds that are not protein.
• NPN sources
• Urea
• Ammonia (NH3)
• Nitrates (NO3)
• young grass
• silage
• immature root crop

23. THANK YOU