What are Ruminants ?

The word “ruminant” comes from the Latin ruminare, to think; the contemplative and placid expression on a cow’s face as she “chews her cud” does sort of give the impression that she’s dealing with serious world problems.

For the most part, the digestive system of ruminants is very similar to that of other mammals, but the stomach is considerably different from the so-called “monogastric” condition.

In monogastric animals, the stomach’s functions are limited to temporary storage and preliminary mastication of the food into a liquid mass; little or no absorption of nutrients takes place. Most absorption is in the intestines.

In ruminants, however, the stomach has an absorption function in addition to the usual functions of mastication and acidification. The evolutionary success of the ruminants as a group is based on the efficiency of their digestive system in extracting nutrition from low-quality food.

The key to the ruminant digestive system’s efficiency is the presence of symbiotic microorganisms in it, particularly in the forestomachs. These inhabitants and their capabilities turn a cow into a mobile fermentation plant for cellulose.

The symbiotic microorganisms produce cellulase enzymes, something no mammal can do on its own. The cellulase breaks down the cell walls of plant materials to release fatty acids into the gut. These fatty acids are absorbed by the cow, and constitute a significant portion of her overall energy budget input. Later, when the food passes into the intestine, absorption of amino acids, lipids, carbohydrates, etc., takes place as in other animals.

This “double digestion” system of ruminants allows them to exploit an energy source—cellulose—denied to other herbivores. Ruminants can usually survive on relatively poor ground unsuitable for other species.

An interesting theory of evolution of ruminants was aired on Discovery channel a few days back. It linked ruminant evolution with the evolution of C4 grass – a super-photosynthesis power plant. (or common grass )

It is now being hypothesized that C4 species in the African savannah created the conditions for the final evolution of rational intelligence. (us : ) )

 

~ by Raju Gurusamy on October 1, 2007.