Compared with ruminants, hindgut fermenters may be less efficient at utilizing fibrous foods.

Compared with ruminants, hindgut fermenters may be less efficient at utilizing fibrous foods.

• A. They are more efficient
• B. They may not be as efficient
• C. They are equally efficient
• D. They cannot digest fibrous foods

Answer: (B)

The key idea is how the site of fermentation affects how much energy and protein an animal can get from fiber. In ruminants, microbial breakdown of cellulose happens in the rumen before digestion, so the animal efficiently converts fibrous plant material into volatile fatty acids for energy, and microbial protein from those microbes can be absorbed later in the small intestine. Hindgut fermenters, like horses or rabbits, ferment mainly in the cecum and colon after the small intestine. That means a portion of the energy and microbial protein from fiber isn’t as accessible to the host, and the process often happens with faster passage and less opportunity for thorough breakdown. So, they generally extract less energy from fibrous diets than ruminants, making the statement that they may not be as efficient the best fit.

The key idea is how the site of fermentation affects how much energy and protein an animal can get from fiber. In ruminants, microbial breakdown of cellulose happens in the rumen before digestion, so the animal efficiently converts fibrous plant material into volatile fatty acids for energy, and microbial protein from those microbes can be absorbed later in the small intestine. Hindgut fermenters, like horses or rabbits, ferment mainly in the cecum and colon after the small intestine. That means a portion of the energy and microbial protein from fiber isn’t as accessible to the host, and the process often happens with faster passage and less opportunity for thorough breakdown. So, they generally extract less energy from fibrous diets than ruminants, making the statement that they may not be as efficient the best fit.