|Auburn University Digital Library|
|Microlivestock - Little-Known Small Animals with a Promising Economic Future|
source ref: b17mie.htm
|Part IV : Rodents|
Vizcachas (Lagostomus maximus) are soft-furred South American rodents that look like long-tailed guinea pigs. They can weigh as much as 8 kg and are resilient animals, inhabiting dry pampas and shrub lands in northern Argentina and neighboring countries. They seem to have promise for producing meat and hides in marginal zones whithin their native habitat.
Like chinchillas (page 277), these rodents provide a prized furry pelt. They also provide meat that reportedly tastes "as good as hare," which in Europe is considered the epitome of dining. They are easily trapped alive in cheap, homemade, multiple-catch, funnel traps. And they are thought to be suitable for farming on a large scale.
On the other hand, vizcachas are currently considered pests because they take grazing from cattle and sheep and because they build large burrows that undermine the land. Government campaigns have eradicated them in the richer agricultural areas of Argentina, but the animals are still common in marginal zones. There is evidence that they become more abundant when domestic livestock overgraze the land. In improverished marginal sites, where other livestock enterprises are unsuitable, the potential exists for game-ranching vizcachas.
AREA OF POTENTIAL USE
Because of the potential hazard to new areas, vizcachas can be used only in the pampas regions of southern South America where they are already widespread.
APPEARANCE AND SIZE
Vizcachas have short front legs, long, muscular hind legs, and round eyes and ears. Their heads seem oversized in proportion to their bodies. Males weigh 5-8 kg, females 2-4.5 kg.
Members of the same rodent subfamily as the chinchilla, they have a thick, soft, valuable fur that is grey or brown above, whitish or greyish below. They are, however, much larger than chinchillas.
Although basically running animals, vizcachas often jump bipedally (like kangaroos), and they sit erect while eating or grooming. The forefeet have four long flexible digits used to grasp food. Their soles and palms are naked and have fleshy pads (pallipes).
Vizcachas once swarmed widely over the savannas of southern Paraguay, Bolivia, and Argentina, but they are being systematically exterminated. Today they inhabit isolated areas of north, central, and western Argentina and southern Paraguay.
Since 1907, these animals have been mercilessly hunted. The governments of the Argentine provinces where they are mostly found, reward hunters for killing this "pest." However, the numbers are so reduced that now there is no need for a bounty system.
HABITAT AND ENVIRONMENT
Vizcachas live in flat, dry, steppelike plains; in dry woodland (Chaco), and in low mountains.
The fact that these rodents eat their own droppings (coprophagy) augments their ability to utilize natural forages, and allows them to abound in degraded zones. They feed on any plant materials they can find near their colonies, particularly grasses. In feeding trials, their daily dry matter intake was 2-5 percent of the body weight. The metabolic efficiency (dry matter per kg) was 33-56 percent; the digestive efficiency was 50-60 percent.2
Male vizcachas become sexually mature at about seven months of age and remain fertile throughout the year. The gestation period is long: 154 days. Litters contain one or two young. Newborns are well developed, fully furred, and open eyed, although they cannot fend for themselves for at least three weeks. In the wild, one or two litters are reared each year.
Vizcachas are nocturnal and are active year-round. They inhabit underground burrows, living in colonies often containing many individuals. They collect a variety of materials (for example, bones, sticks, and stones), and heap them in piles above the entrances to their burrows.
Their hearing and sense of smell are acute.
Vizcachas have long been hunted for food as well as for their fur. Their meat is often consumed in pickled form in southern South America.
The skins are fabricated into table runners, rugs, bedspreads, slippers, and belts. The skins are also popular for overcoats.
Vizcachas can be kept in captivity without major difficulty.
In zoos, vizcachas are fed the typical diets furnished for vegetarian rodents: rolled oats, green vegetables, bananas, apples, and bread. They are usually kept indoors in wire-fronted cages, about 1 x 2 m in size, and provided with sleeping boxes.
Little is known about vizcacha husbandry, but in one trial, weight rose most rapidly in males until age 18 months (the average size was then 5.3 kg) and subsequently slowed. The heaviest male was 7.3 kg at 30-32 months. The female's weight gain was greatest until 16-18 months (average size 3.3 kg).3
The animals seem well adapted to harsh sites where the climate and forage make raising conventional livestock difficult.
The meat is white and has a good nutritive value because of its high digestibility, low levels of saturated fats, and high levels of proteins.
In marginal zones of the pampas, these rodents appear far more productive than traditional livestock.4
Vizcachas may do considerable damage by foraging in cultivated crops. As noted, ranchers claim that they take grazing away from domestic animals, 10 vizcachas eating as much as a sheep. In addition, they claim, vizcachas destroy pasture with their acidic urine. And the large burrow systems sometimes create a hazard.
Because their reproductive rate is low and their growth rate is only moderate, their commercial breeding might not be profitable except in well-designed projects with clear markets.
Vizcachas require sturdy pens, which implies a high initial cost for materials such as concrete and brick.
Vizcachas can be aggressive to one another, especially in captivity.
RESEARCH AND CONSERVATION NEEDS
There are several possible research projects, including:
- Gathering specimens from different regions for comparative evaluation of characters such as biology, chromosome type, reproductive physiology, social behavior (both in its wild state and under controlled conditions);
- Attempting captive rearing and small-scale husbandry;
- Assessing performance under various environments; and
- Quantifying productivity and population dynamics in relation to rangeland use and improvement practices.
A rational cropping program based on wild stocks is perhaps more viable than captive breeding. This could be organized so as to keep vizcacha numbers in check while sustaining a small chain of processing plants by providing a constant supply of meat and skins.