Question

The proportion of which volatile fatty acid will be higher in the rumen of animals fed on a high roughage diet?

• A. Butyric acid
• B. Propionic acid
• C. Acetic acid
• D. Valeric acid

Hint:

Fiber/Roughage \(\rightarrow\) Cellulolytic microbes \(\rightarrow\) High Acetate (Acetic acid) (crucial for milk fat synthesis).
Concentrate/Starch \(\rightarrow\) Amylolytic microbes \(\rightarrow\) High Propionate (Propionic acid) (gluconeogenic precursor).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Ruminants digest complex carbohydrates in their diet through microbial fermentation in the rumen. This process produces volatile fatty acids (VFAs), primarily acetate (acetic acid), propionate (propionic acid), and butyrate (butyric acid).

Step 3: Detailed Explanation:
The ratio of volatile fatty acids produced depends significantly on the type of feed consumed:
1. High Roughage (Fiber) Diet: Diets rich in cellulose and hemicellulose favor cellulolytic bacteria. These microorganisms ferment structural carbohydrates to produce high proportions of acetic acid (acetate), often resulting in an acetate-to-propionate ratio of greater than \(3:1\).
2. High Concentrate (Starch) Diet: Diets high in grains and starch favor amylolytic bacteria, which ferment carbohydrates primarily to propionic acid (propionate).
3. Thus, a high roughage diet results in a significantly higher proportion of acetic acid in the rumen.

Step 4: Final Answer
The correct option is (C).