Dave Taylor's African Safari: Trophic Level II - The Herbivores - Hindgut Fermenters

Dave Taylor's African Safari: Trophic Level II - The Herbivores - Hindgut Fermenters - Page 39

Trophic Level II - The Herbivores
Hindgut Fermenters
Page 39

Hindgut Fermenters
(Donkey, Horse and Zebras)

As we have seen, the hindgut fermenters (see Ruminants) differ from the ruminants in several areas. Perhaps most important is that their food is only partially digested in their stomach and then passes to the large intestine, where microorganisms ferment ingested cellulose, completing the process. They do not chew cud.

The family is quite diverse. It includes horses and their relatives (Equids), the living rhinoceroses and the hippopotamuses. It also includes Asian and South American tapirs.

The advantage hindgut fermenters have over ruminants is that they can process food more rapidly and therefore get more nourishment from it. They are better suited for more arid conditions.

Summary of Hindgut Fermenters

Rate of passage: 48 hours
Cellulose Utilization: 45%
Waste: 55%

Equids

Today, the group known as Equids is the most successful of the hindgut fermenters. This is due in no small part to the popularity of the domestic horse as a beast of burden, a pet and as a riding animal. Horses and their relatives originated in the New World and emigrated to Asia across the Bering Strait Land Bridge during the ice ages. Horses became extinct in North America but prospered in Asia, Europe and Africa.

The Six Survivors

Today, there are only 6 species of equids left alive. They are:

domestic horse (which was re-introduced to the New World in the 1500s by the Spanish explorers)
Przewalski's horse, an endangered Asian species recently re-released into the wild
the African ass from northern Africa
Asiatic ass from Asia
Plain's or Common zebra from Africa south of the Sahara Desert
Grevy's zebra of northern Kenya and Somalia. It is listed as endangered.
Mountain zebra from South Africa are also endangered.

Equids eat grasses and sedges but will sometimes eat bark, leaves, buds, fruits, and roots. They consume more food than their ruminant competitors because their digestion process is faster (see Ruminants). This allows them to live in more marginal areas than ruminants. However, equids are water dependent and must drink regularly. They are unable to sustain themselves in true desert conditions where a few ruminants, the camel and the oryx are better equipped to survive.

In general, equids have two social patterns. Some, like the horse and the common zebra, are social and live in permanent herds with a resident stallion, mares and offspring.

Male Grevy’s zebras and African asses are territorial with territories up to 5 square kilometers (2 square miles). Within these, they attempt to gather a harem and mate with the females before they move on. These are only temporary associations and soon break up as the mares go in search of new pasture.

The males remain and mark territorial boundaries with middens (dung heaps) that they visit on a regular basis.

Like ruminants, hindgut fermenter females usually have one young at a time.

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