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OCR for page 63
4
Micropigs
Most breeds of swine (Sus scrofa) are too large to
be considered microlivestock, but there are some
whose mature weight is less than 70 kg. These
micropigs it' are particularly common in West Africa,
South Asia, the East Indies, Latin America, and
oceanic islands around the world. At least one, the
Mexican Cuino, may weigh a mere 12 kg full-grown.
Many miniature swine have been developed for use in medical
research, but their agricultural potential has been largely ignored. This
is unfortunate, for micropigs of all types- native, feral, and labora-
tory deserve investigation. Swine provide more meat worldwide than
any other animal, and micropigs are potentially important sources of
food and income for poor people in many parts of the developing
world.
Smallness makes for nimble and self-sufficient pigs, in contrast to
large, lethargic breeds. Small breeds are easier to manage and cheaper
to maintain; the threat of injury from angry or frightened animals is
lessened; and the sows are less likely to crush newborn piglets, often
a major cause of mortality in large breeds. Some micropigs particu-
larly those from hot regions or wild populations also have a higher
resistance to heat, thirst, starvation, and some diseases.
Pigs adapt to a wide variety of management conditions, from
scavenging to total confinement; some are even kept indoors.2 They
gain weight quickly, mature rapidly, and help complement grazing
livestock because they relish many otherwise unused wastes from
kitchens, farms, and food industries, as well as other foods such as
small roots, leafy trash, or bitter fruits that are not consumed by
humans or ruminants.
' We use the word in its generic sense to represent all extremely small types. Charles
River Laboratories, Inc. (see Research Contacts) has trademarked the term ''micropig,''
particularly for their strain of the Yucatan miniature pig, which is becoming widely used
in medical research.
2 Small pigs are raised as indoor livestock in Vietnamese cities, for example.
63
OCR for page 64
64
MICROLIVESTOCK
For these reasons, micropigs could become useful household and
village livestock in the developing world, and they deserve greater
attention than they now receive. Although their growth may not be as
rapid as that of improved breeds raised under intensive commercial
production, with modest care and minimum investment, backyard
micropigs can produce sizable yields of meat and other products, as
well as improved income for rural and even urban populations.
AREA OF POTENTIAL USE
Worldwide, especially in warm, humid areas.
APPEARANCE AND SIZE
Like full-sized breeds, micropigs are stout-bodied, short-legged
animals with small tails and flexible snouts ending in flat discs. Examples
of some micropigs are listed at the end of the chapter.
DISTRIBUTION
Domestic pigs are found all over the world, but their concentrations
vary greatly. Africa has the fewest per capita, but in recent years they
have gained increasing favor in the sub-Saharan regions. In Latin
America, pigs have long been a major component of backyard agri-
culture. In the Middle East, an early center of domestication, pigs are
not widely kept today because of religious dietary restrictions. In the
Far East, they are the major meat source, and China has more pigs
than any other country. And in the Pacific region, pigs and chickens
are often the only meat available.
STATUS
Pigs are becoming more popular: their worldwide numbers increased
by about 20 percent in the 1970s. However, in most countries com-
mercial pig production has focused on a mere handful of breeds, and
much genetic diversity is unstudied or even threatened with extinction.
Some microbreeds have already been lost, and others are dwindling
in numbers.3 Many European breeds have been completely lost. The
Cuino and some other Latin American criollo types are threatened, as
are most of Africa's traditional breeds. China, however, has made
notable efforts to preserve its native types.
3 Because pigs breec! at an early age and can have many large litters, physical
characteristics can be lost quickly. Even within a single litter, piglets can show great
. .
c .lverslty.
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MICROPIGS
65
HABITAT AND ENVIRONMENT
Although, as previously noted, pigs are found all over the world,
they are in general adapted to warm, humid climates where many
other livestock species are more susceptible to diseases and environ-
mental stresses. They are also raised at high altitudes, such as in the
Andes and Tibet. Although there are few climatic limitations to pig
production, only about 20 percent of the world's pigs are currently
kept in the tropics.
BIOLOGY
Pigs are omnivores, willing and able to eat almost anything.4 Unlike
most other livestock, they eat their fill and sleep as the food digests,
allowing humans to establish a convenient eating and sleeping schedule.
Pigs are prolific; a few Chinese breeds routinely have litters of 20
or more. Micropigs are no exception; litters of ~10 are common.
Piglets gain weight rapidly and can be weaned after a few weeks.
Sexual maturity is sometimes attained as early as 4 6 months, de-
pending on breed and environment. Pigs are usually slaughtered at
7 months of age, allowing them to be produced on an annual cycle.
They can live 1~20 years.
Because of their smaller size, micropigs have a relatively greater
skin-to-weight ratio than today's commercial breeds, and therefore
they probably shed heat more effectively. Certainly they seem to
perform better in tropical heat and humidity, which normally keep the
heavier types from reaching their maximum productivity. Studies have
suggested that an optimal size for some tropical environments because
of metabolic and feed efficiency may be less than 65 kg.5
BEHAVIOR
Pigs are social animals; they enjoy companionship and ferociously
defend their young and sometimes even the humans who care for
them. They are employed as guard animals in some areas and have
been used extensively in behavioral research.
Contrary to common belief, pigs are clean and tidy if provided
adequate space. Larger breeds, however, wallow in mud to stay cool
in hot weather and require a wallow or shade (except for some Latin
American types, which seem less susceptible to heat). Some light-
colored pigs sunburn easily.
Pigs will dig up earth with their mobile snouts; some breeds do it
constantly.
4 Although pigs have some ability to ferment cellulose in their intestines, they do not
digest it as well as ruminants do, and cannot utilize large amounts of roughage.
5 Williamson and Payne, 1965.
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OCR for page 67
MICROPIGS
USES
67
Fresh pork is the major pig product in tropical areas. It usually
fetches premium prices, and in many places (such as the Pacific Islands
and China) it is the most important red meat available to rural people.
Nutritious and tasty, it is one of the easiest meats to preserve, needing
only salt or melted fat. Processed products such as bacon and sausages
can be important for both home consumption and cash sales.
Pig fat (lard) is a good source of food energy, and can substitute for
cooking fats and oils. It is easily melted and clarified, is widely used
to make soap, and is a valuable commercial product.
Pig skin, once decreased, is easily tanned into leathers that are
popular for garments, shoes, and other products demanding soft, light,
and flexible leathers.
Pig manure is a good fertilizer. Because the animals are often kept
in confinement, it can be easily collected.
HUSBANDRY
In many places, pigs are kept as free-roaming scavengers. They can
be trained (by coaxing with feed, salt, or affection) to keep close to
home, thereby helping to minimize destructive scavenging.
Herding is a higher level of management that requires more effort,
but it allows pigs to be integrated into other types of agriculture while
utilizing feeds that otherwise go to waste.
Because their exercise needs are minimal and dominance is quickly
established within litters, pigs are the easiest hoofed livestock to raise
in small enclosures (sties). However, fencing must be secure, and if
sties are small, the animals must be moved frequently to prevent
diseases and parasites from building up.
ADVANTAGES
Pigs are well-known, often traditional, animals in many areas, and
people usually do not have to be taught how to manage and use them.
Efficient scavengers, they can live, grow, and reproduce with a
minimum of investment or specialized care.
Opposite: Riverside, California. Recently, Vietnamese pot-bellied pigs have become
popular pets in the United States. They sell at high prices and are kept indoors.
Purportedly they ''love baths, never have fleas, and do not shed hair. They are also
easily housebroken and are a nonrooting variety of pig.'' Their real potential, however,
is in Third World villages. (Steve EllisonlPeople Weekly ~ 1988 Time Inc.)
OCR for page 68
68
MICROLIVESTOCK
Pigs are highly efficient converters of feed to meat. They can provide
the greatest return for the least investment of any hoofed livestock
because of their fecundity, low management costs, broad food pref-
erences, and rapid growth.
Pigs normally accumulate fat during adolescent growth (making
"finishing" feeds less necessary). Some micropigs (especially those
from feral ancestors) have the ability to quickly mobilize and store
these body-fat reserves; in times of extreme scarcity, it aids their
survival.6
Pigs work well in multiple-cropping schemes. They are often used
to help clear small plots by uprooting weeds, shrubs, and even small
trees. In Southeast Asia, they are frequently raised in conjunction
with aquaculture, their manure providing food for the fish.
LIMITATIONS
If improperly managed or maintained in filthy conditions, pigs may
quickly succumb to disease and parasite epidemics. Most diseases are
communicated only among pigs, but some can be transmitted to
humans. For this reason, pork should always be fully cooked.
Some cultures never eat pork. Others do, but nonetheless accord
pigs and their keepers low status.
Young pigs are vulnerable to many predators.
RESEARCH AND CONSERVATION NEEDS
A major survey of small pig breeds is needed. They have the potential
to be valuable producers in their own right, as well as to improve
other pig breeds. For instance, they represent a little-known reservoir
of disease resistance and climatic adaptation. Governments, research
stations, universities, and individuals should make special efforts to
preserve types that have outstanding or unusual qualities.
When it is necessary to eradicate feral pig populations (as is common
on Pacific islands), representative stocks should be preserved. These
rugged animals have been genetically isolated for decades or even
centuries and are likely to carry valuable traits for survival under
adversity.
Large breeds may be promising candidates for genetic ''downsizing,''
which has already produced the many types of miniature pigs that are
used in medical research.
h Information from I. Lo. Brisbin.
OCR for page 69
MICROPIGS
69
THE LITTLEST PIG
Although this chapter highlights the world 's smallest breeds,
there exists a pig that is even smaller. It is, however, an entirely
different species and it Is on the brick of extinction
The pigmy hog (Sus salvanius) is a shy and retiring wild
creature of northeastern India. It is merely 60 cm long with a
shoulder height of 25 cm, and weighs less than 10 kg. It was
once found widely along the southern foothills of the
Himalayas. Today, however, it apparently occurs in only one
area, the Manas IYational Park in Assam. Despite this protection
and the fact that it is listed among the 12 most endangered
species on earth, it still falls victim to hunters and to habitat
destruction-especially illegal grass fires.
If saved from extinction, this minute species-barely reach-
ing a person's calf might become useful throughout the
world. Its chromosome number is the same as that of the
common pig and its physiological processes are probably also
similar. Therefore, were its numbers to be built up, it might
become a valued and well-known resource for laboratories and
small farms. Its daily food intake and its space requirements
are only a fraction of a normal pig's. It probably has exceptional
tolerance to heat, humidity, and disease.
This is not a domesticated species, and there is therefore
much to learn before its usefulness can be clearly seen. Indeed,
whether it can be reared in captivity is uncertain. Some attempts
have ended in disaster, but this seems to have been the result
of mismanagement.
Before there is any possibility of developing it, however, the
pigmy hog must be preserved from ultimate loss. The last
specimen could go into a villager's pot at any time now.
at- ''~
/ ~
/ _ _
If, ~
'an,
``':
\~`'5
/ / i\
/~1 i,
Adult male of the common pig (wild boar) and pigmy hog drawn to
same scale. (W. L. R. Oliver)
OCR for page 70
70
REPRESENTATIVE EXAMPLES OF MICROPIGS
West African Dwarf (Nigerian Black, Ashanti)
MICROLIVESTOCK
West Africa. Mature weights of 25~5 kg are reported. In the humid
lowland forests of West Africa this breed has long been kept by
villagers, often as a scavenger. Indigenous to the hot, humid tsetse
zones of West Africa, it seems resistant to trypanosomiasis.
Chinese Dwarfs
China (and Southeast Asian countries such as Vietnam) has long
had small pigs-often characterized by numerous teats and large
litters associated with traditional intensive agriculture as well as
scavenging conditions. Some Chinese pigs weighing less than 70 kg
are adapted to tropical and subtropical conditions, but the smallest
(2() 35 kg) live in the cold climates and high altitudes of Gansu,
Sichuan, and Tibet. Small black Chinese pigs were crossed with
European types in the early 1800s and produced the foundation stock
of many modern Western breeds.
Criollo
There are a number of "native" breeds throughout Latin America
commonly known as "criollo." Many are quite small. Although,
apparently, they are slow to mature and bear small litters, they adapt
well to environmental extremes and are widely kept by rural inhabitants
for food and income. Criollos are little studied and are being replaced
by imported breeds before their possibly outstanding qualities can be
quantified.
Cuino This micropig from the highlands of central Mexico may be
descended from small Chinese types and is the smallest domestic pig,
weighing as little as 1~12 kg fully grown. Hardy and an efficient
scavenger, it can grow quickly when feed especially corn- is abun-
dant. A century ago the cuing was a widespread household animal and
was used for a time for experimental work in central Mexico. It is
now little known and could be threatened with extinction.
Black Hairless (felon, Tubasqueno, Birish) These small pigs of
central and northern South America survive in hot, humid, adverse
climates. They are adapted to bulkier feeds than most pigs and can
thrive on fruit wastes. Many local types exist.
OCR for page 71
MICROPIGS
71
Nilo (Macao, Tatu, Canastrinha) This small, widespread, black,
hairless pig of Brazil is often kept inside the house.
Yucatan Miniature Swine A subtype of the black hairless from
Mexico's hot, arid Yucatan Peninsula, it was imported into the United
States in 1960. It has been downsized for laboratory use in the United
States and is known as the Yucatan Micropig~. Weight at sexual
maturity has been lowered through selective breeding from 75 kg to,
currently, between 30 and 50 kg, with an ultimate goal of 2~25 kg.
There is no evidence of "dwarfism," stunting, or loss of reproductive
performance, and it appears to hold notable promise as microlivestock
for developing countries. The parent stock, used for meat and lard
production in Yucatan, is renowned for gentleness, intelligence, re-
sistance to disease, and relative lack of odor. Exceptional docility,
even in older boars and sows with litters, makes them easy to handle
without the need for specialized housing or equipment.7
Other Laboratory Breeds
Other miniature laboratory pigs have potential for tropical use. These
include the Goettingen, Hanford, Kangaroo Island, Ohmini, Pitman-
Moore, and Sinclair (Hormel). In general they weigh 3~50 kg when
ready for slaughter and mature at less than 70 kg.
Ossabaw
United States. 2() 30 kg. Feral on Ossabaw Island, South Carolina,
for more than 300 years, this pig is well adapted to environmental
extremes. Unlike most domestic animals, it can maintain itself in
coastal salt marshes. It has perhaps the highest percentage of fat of
any pig. The piglets are very precocious, self-reliant, and robust.8
Kunekune (Pua'a, Poaka)
New Zealand. Female 40 kg; male 50 kg. Perhaps of Chinese origin,
these black-and-white spotted pigs are docile, slow, and easy to contain.
Although late maturing, they can fatten on grass alone. Like other
native breeds throughout the Pacific region (for example, the Pau'a of
Hawaii), stock is being lost through crossbreeding, displacement by
other breeds, and eradication efforts.
7 Information from L. Panepinto.
Information from I. L. Brisbin. Small feral pigs are established on many islands
worldwide, often left by seafarers as a future source of meat.
OCR for page 72
72
~ICROLIVES1OCK
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1
Representative terms from entire chapter:
pigmy hog
