Why is caecum large sized in certain herbivores?

Explanation

### Step-by-Step Solution:

1. **Understanding the Cecum**: The cecum is a pouch-like structure located at the beginning of the large intestine. Its primary function is to aid in the digestion of food, particularly in herbivores.

2. **Role of Herbivores**: Herbivores primarily consume plant material, which is rich in cellulose. Cellulose is a complex carbohydrate that is difficult to digest.

3. **Symbiotic Association**: Many herbivores have a symbiotic relationship with certain microorganisms, such as bacteria and methanogens, that reside in their digestive systems. These microorganisms help break down cellulose into simpler sugars.

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