Volatile Fatty Acids

Introduction

Microbes in the rumen ferment carbohydrates into volatile fatty acids which are absorbed through the rumen wall into the blood stream. Some of the volatile fatty acids are lost during eructation.

Volatile fatty acids are the main energy source for runimants, providing approximately 70% of the total enegy requirements. They are used primarily by the microorganisms for reproduction and growth, with the excess production being used by the ruminant itself.

The three main volatile fatty acids produced in ruminants are acetic acid, butyric acid and propanoic acid.

Acetic acid

VFA Graph- Copyright RVC 2008

• 50-60%

• Predominates on a high-roughage diet

• Precursor for mammalian milk fat

• Some used for muscle metabolism

• Some used for body fat

• CH3.COOH

Propanoic Acid

• 12-18%

• Predominates on a high concentrate diet

• Provides energy via the conversion of blood glucose in the liver

• Used in lactose (milk sugar) synthesis

• CH3.CH2.COOH

Butyric Acid

• 18-20%

• Provides energy to the rumen wall

• Used in milk fat synthesis

• Used for body fat when excess energy is present in the diet

• Doesn't vary in proportion to other volatile fatty acids, therefore has little influence in milk fat content

• CH3.CH2.CH2.COOH

Test yourself with the Ruminant Stomach flashcards

The Stomachs of the Ruminant Flashcards

Links

Acidosis