Numbers And

There are about 3400 million ruminants in the world, of which 3100 million (90%) are domestic. Cattle are about 1300 million, sheep 1200 million, goats 460 million, and buffalo 130 million. Yaks, camels, camelids, and reindeer together total less than 25 million. The majority of ruminants are in the developing world. Domestic cattle in Canada and the United States are only 6% (~90 million) of the total world cattle. Statistics for wild ruminants are less reliable. The largest populations are in Africa, where there may be 100 500 million. The rest of the world has lower estimates around 30 million.[1]

Domestic ruminants have been associated with human societies before the dawn of history. While they are mainly used for meat and milk in North America and Europe, they provide more diverse benefits to some other parts of the world. A particular example is the sacred cows in India, where may number several hundred million. The cows provide milk that Hindus consume. They subsist on straw, other cellulosic wastes, garbage, etc., and do not compete for human food resources because 99% of arable land is in cereal crops. Manure is dried into bricks for domestic cooking fuel, which is a billion-dollar industry. They provide tillage and haulage in a country that is oil-

poor. Tillage and haulage are important in other parts of Asia and Africa.[1]

Ruminants harvest plant material in rangelands and other untillable lands. This converts otherwise unusable plants into food and useful products. In most of the developing world these systems are extensive and have low efficiency. This is in contrast to the management of beef and dairy animals in North America and Europe,

Table 2 Classification of the family Bovidaea

Subfamily and tribe

Example

Feeding habita

Cephalophinae

Cephalophini

Duikers

Selector

(2)b

Antelopinae

Neotragini (8)

Klipspringer,

Selector

Suni, Dik dik,

Selector

Royal antelope.

Selector

Oribi

Grazer (selective)

Steenbok

Intermediate grazer

Antelopini (7)

Gerenuk

Selector

Gazelles

Intermediate grazer

Hippotraginae

Hippotragini (3)

Sable and

B + Rc

Roan antelope

B + R

Oryx

B + R

Reduncini (5)

Waterbuck

B + R

Kob

B + R

Reedbuck

B+R

Alcephalini (5)

Topi

B+R

Wildebeest

B+R

Hartebeest

B+R

Impala

Intermediate grazer

Bovinae

Tragelaphini (4)

Kudu

Selector

Eland bushbuck

Selector

Boselaphini (2)

Nilgai

Selector intermediate

4 horned

Selector intermediate

antelope

Bovini (6)

Cattle, yak

B+R

Buffalo, bison

B+R

Capriniae

Saigini (2)

Chiru, saiga

Intermediate browser,

or grazer

Rupicaprini (4)

Goral, chamois,

Intermediate browser

Mountain goatsd

Ovibovini (1)

Musk ox

Intermediate browser

Caprini (5)

Goats

Intermediate browser

Sheep, ibex

Grazer (selective)

Antilocaprinae

Pronghorn

Intermediate grazer

Classification according to Hofmann.[4] bNumber of genera given in parenthesis. cB+R bulk and roughage eaters. dMountain goat may belong in the Caprini. (Taxonomy according to Refs. 2 and 3.)

Classification according to Hofmann.[4] bNumber of genera given in parenthesis. cB+R bulk and roughage eaters. dMountain goat may belong in the Caprini. (Taxonomy according to Refs. 2 and 3.)

Fig. 1 Appearance and development of angiosperms and ungulates. questioned. (From Ref. 3.)

(From Ref. 1.) Postulated ancestral groups A and B have been

Fig. 1 Appearance and development of angiosperms and ungulates. questioned. (From Ref. 3.)

(From Ref. 1.) Postulated ancestral groups A and B have been where intensive feeding management and animal breeding have produced high levels of production.

DIGESTIVE SYSTEM

The ruminant stomach is four chambered, consisting of rumen, reticulum, omasum, and abomasum.[4] The rumen and reticulum or the reticulorumen, as they are called are the primary sites of fermentation. The reticulum is involved in sorting food for rumination and, with the omasum, for regulating selective passage to the aboma-sum, the site where gastric digestion begins. The tylopods and tragulids lack an omasum.[5] The omasum is less developed in the smaller selectors and most developed in the bulk and roughage eaters.[4]

Young ruminants are essentially monogastric when they are born, and thus dependent on amino acids and B vitamins, which as adults they receive from the ruminal fermentation. The rumen develops and grows and probably receives its organisms from the mother or other ruminants in the months after weaning from salivary slobber and fecal material.

The ruminant system is more efficient in extracting dietary energy because of selective retention, and all of the microbial products must pass through gastric digestion, whereas in a nonruminant hindgut, fermentation loses much of the microbial protein to the feces because it is postgastric. Compared to nonruminant herbivores, ruminants can exist on smaller intakes of food through higher digestive extraction. This has played a role in herbivore evolution. Ruminants have become the dominant herbivores, replacing many nonruminant herbivores in the oligocene and pleistocene. The rumen probably evolved, in part, as a detoxification system for secondary compounds; this is important in selector and browser species. The effect is to allow the animal access to a wider range of plant foods.[1]

CONCLUSIONS

Most of the world's ruminants are domesticated and represent an important economic resource for food and other benefits for humans. The relationship between humans and domesticated ruminants goes back to prehistory, and the animals have become dependent upon humans. Their contribution derives in part from the ability to convert low-quality fibrous feeds into edible products. Wild ruminants are only about 10% of the world's total and include some endangered species.

ARTICLE OF FURTHER INTEREST

Rumen Microbiology, p. 773

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