Ruminant Nutrition: Digestion and Utilization

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Questions and Answers

What is the primary function of the rumen in the digestive process of a ruminant?

To mechanically break down food into smaller particles

To store food until it is needed by the rest of the digestive system

To absorb nutrients directly into the bloodstream

To ferment and break down carbohydrates and fibre into useful products (correct)

What is the approximate holding capacity of the rumen in an adult cow?

100-200 litres (correct)

200-500 litres

50-100 litres

20-50 litres

What is the term for the process of regurgitating and re-chewing food in the rumen?

Fermentation

Digestion

Rumination (correct)

Mastication

What is the primary source of energy for a ruminant?

The products of fibre digestion Signup and view all the answers

What is the term for the compounds produced during fibre digestion in the rumen?

Volatile fatty acids Signup and view all the answers

What is the percentage of the total stomach volume that the rumen occupies in a neonate ruminant?

25% Signup and view all the answers

What is the pH range of rumen in normal conditions?

pH 6.0 - 6.5 Signup and view all the answers

What is the primary function of the fibre mat in the rumen?

To facilitate rumen movements and saliva flow Signup and view all the answers

What is the approximate size of particles required to leave the rumen?

3-4 mm Signup and view all the answers

What is the primary function of the reticulum?

Mechanical breakdown and microbial fermentation Signup and view all the answers

What is the result of high roughage diets on digestion?

It decreases digestion and increases transit time Signup and view all the answers

What is the role of the cranial nerve X in the rumen?

Control of rumen contractions Signup and view all the answers

What is the primary reason why Volatile Fatty Acids (VFAs) are the major end products of fermentation?

The inability to completely oxidize C-skeletons in the absence of oxygen Signup and view all the answers

What is the primary purpose of rapidly absorbing Volatile Fatty Acids (VFAs) into the bloodstream?

To minimize acidosis Signup and view all the answers

What percentage of a cow's energy is provided by Volatile Fatty Acids (VFAs)?

70% Signup and view all the answers

What is the primary role of Volatile Fatty Acids (VFAs) in the liver?

Energy source for gluconeogenesis and lipogenesis Signup and view all the answers

What is the relationship between Volatile Fatty Acids (VFAs) and milk synthesis?

VFAs are used as an energy source for milk synthesis Signup and view all the answers

What is the primary function of butyric acid in the rumen?

Provides energy to the rumen wall Signup and view all the answers

What is the net gain of ATP per mole of acetate entering the Krebs cycle?

10 Signup and view all the answers

What percentage of VFAs is propionic acid?

18-21% Signup and view all the answers

What is the fate of undegraded dietary proteins in the rumen?

They pass to the abomasum Signup and view all the answers

What is the primary function of propionic acid in the body?

Converts into glucose in the liver Signup and view all the answers

What is the composition of microbial crude protein?

80% true protein, 80% digestible Signup and view all the answers

What is the primary role of the liver in the digestion of excessive RDP?

To convert NH4 into urea Signup and view all the answers

What is the purpose of adding urea to the diet?

To act as a nitrogen source for microbial protein synthesis Signup and view all the answers

What is the result of insufficient protein in the diet?

More ammonia is produced in the rumen Signup and view all the answers

What is the primary site of lipid digestion?

Small intestine Signup and view all the answers

What is the effect of high levels of ammonia in the bloodstream?

Toxic levels of NH4 in the blood Signup and view all the answers

Study Notes

Ruminant Digestive System

The rumen is a storage facility allowing time for foodstuffs to be digested sufficiently, with soluble components (e.g., sugars) fermented quickly and insoluble components (e.g., fibre) broken down gradually by microbes.
The fibre mat is important for rumen movements and saliva flow, with particles needing to be around 3-4mm to leave the rumen.
High roughage diets increase transit time due to salivation, but this decreases digestion, so it's ideal to have quickly digestible small-sized concentrates that provide maximum energy quickly without rumen acidosis.

Reticulum

The reticulum has no absorptive capacity and is controlled by the vagus nerve (Cranial nerve X).
It is responsible for mechanical breakdown, and rumen contractions start here.
Microbial fermentation occurs in the reticulum, and it is proportionally larger in small ruminants.

Volatile Fatty Acids (VFAs)

VFAs are the end products of anaerobic microbial fermentation of carbohydrates in ruminants.
They are readily absorbed into the bloodstream and transported to the liver, where they are converted to other sources of energy.
VFAs determine milk fat and protein content, provide 70% of a cow's energy, and help promote growth of rumen papillae.

Protein

The protein that reaches the abomasum and small intestine is either Microbial Crude Protein (MCP) or Undegraded Dietary Protein (UDP).
Non-Protein Nitrogen (NPN) can be excessive or insufficient, affecting the amount of protein reaching the small intestine.
Rumen acts as a leveller to ensure a constant stream of protein passing to the small intestine.

Lipids

Minimal digestion of lipids occurs in the rumen, with long-chain fatty acids (LCFAs) not being absorbed by the rumen.
Fats are hydrolysed by lipases, and most fats consumed are triacylglycerides (TAGs) which are saturated in the rumen.
Fats pass to the small intestine for digestion, and treated dietary fats can remain unsaturated when they reach the small intestine, affecting milk fat content.

Glossary

ADF: Acid Detergent Fibre
CP: Crude Protein
DCP: Digestible Crude Protein
DE: Digestible Energy
DMI: Dry Matter Intake
DUP: Digestible Undegraded Protein
ERDP: Effective Rumen Degradable Protein
FME: Fermentable Metabolisable Energy
GE: Gross Energy
LCFA: Long Chain Fatty Acids
MCP: Microbial Crude Protein
ME: Metabolisable Energy
MP: Metabolisable Protein
NDF: Neutral Detergent Fibre
NE: Net Energy
NP: Net Protein
RDP: Rumen Degradable Protein
TMP: Total Mixed Ration
UDP: Undegraded Dietary Protein
VFA: Volatile Fatty Acids

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Description

Test your knowledge on ruminant nutrition, including the breakdown of carbohydrates and fibre, energy derivation, and the utilization of protein and lipids in the ruminant diet. Learn how nutrition affects various aspects of ruminant health, such as milk yield, fat content, and immunity.