Origin of pig breeds

All current pig breeds are generally considered to have originated from the wild boar. However, given that two domestication processes are known, one in the Middle East dating back 12,500 years and the other in Asia dating back 7,000 years, it is considered that the European wild boar (sus scrofa ferus) could have given rise to the European pig while the Asian wild boar (sus indicus) would be the origin of the Asian pig breeds.

However, other researchers consider that the Asian wild boar evolved into the European wild boar, and therefore, according to them, the Asian wild boar is the origin of all wild boars and all breeds of pigs.

A recent finding seems to support the latter. The trend of keeping Vietnamese pigs has led to a growing population of wild Vietnamese pigs in Europe and to hybridisations with European wild boars, either through abandonment or escape. These hybrids of Asian pigs with European wild boar are fertile, which is unquestionable evidence that the Asian and European wild boar are the same species.

Concept of breed

So far, we have talked about a species (wild boar) and derived breeds of pigs.

It is necessary to clarify these terms by referring to taxonomic concepts.

It is considered that nature can be divided into three kingdoms: mineral, plant, and animal.

The animal kingdom is divided into classes, orders, families, genera, species, subspecies, and finally into breeds.

Although some taxonomists say that subspecies and breeds are the same, pig taxonomy disproves this claim.

A breed is a set of individuals phenotypically equal to their ancestors, equal to each other and that by inheritance transmit the same characteristics to their descendants.

The European wild boar is a species that gave rise to three subspecies of pigs:

1. White-skinned Celtic pigs with large, drooping ears, including breeds such as Galician Celtic
2. White-skinned Celtic pigs with small, vertical ears
3. Dark-skinned or coloured Atlantic pigs with medium-sized horizontal ears, which some call the Mediterranean and include breeds such as the Iberian pig and the Murcian chato.

The Asian wild boar is a species that has given rise to pig breeds in several countries, such as China, Vietnam, Indonesia, and Korea. Although there is a lack of information, we can say that there are two subspecies:
Taihu (omnivorous) and Jinhua (vegetarian). The first one is composed of 4 breeds (Meishan, Fengjing, Black Jiaxing and Erhualian) and the second one of 5 breeds (Daweizi, Hang, Leping, Qingping and Rongchang).

Pig farming and pig characteristics

• Currently, pig farms differ considerably from traditional farms, where the breed was linked to the predominant feed in the area, or the suitability of the type of meat for the prevailing culinary customs.

• Pigs are now the second largest source of food for humans (140 billion tonnes of meat), which has made it necessary to work on the genetics, breeding, nutrition and management of the pig breeds that producers consider the most suitable.
• Currently, the Celtic white breeds, such as Yorkshire/Large White and Landrace, are the most important breeds due to their prolificacy, their meat production suitable for the production of processed food (sausages) and their adaptation to genetic improvement programmes.
• Other pig breeds of the Atlantic trunk, such as Duroc and Iberian pigs, are important in the production of meat for cooking or for the production of cured meat such as ham. In this group, the Duroc breed, due to its better prolificacy, is used as an improver in Iberian pig farms in genetic absorption programmes (f1 50% Duroc and 50% Iberian; f2 25% Duroc and 75% Iberian) with a notable increase in meat production and the number of piglets born.
• Asian breeds are very prolific, and sometimes, except the Chinese breeds, little studied.

The Chinese Meishan breed of pigs has been used in European countries to improve the prolificacy of Atlantic breeds (Iberian pigs).

Industrial crossbreeding

• Industrial pig production requires suitable business structure and industrial infrastructure so that the entire production chain, including piglets, is supplied promptly.
• For this purpose, specialised selection farms have been set up, which work with purebred pigs and other breeding farms which crossbreed selected breeds to take advantage of the inheritable characteristics of mothers, fathers, and grandparents.
  Piglets obtained from these multiple hybridisations cannot be considered pig breeds as their offspring would be different from their parents. They are considered commercial hybrids and are usually destined for slaughter.
• Another crossbreeding practice, usually carried out on family farms, consists of keeping the females that meet the appropriate morphology, passing them from the pre-breeding phase to the rebreeding phase. When they reach the age of 6 months and 110 kpv, they are covered or inseminated with males of another breed. This practice has a positive sanitary effect, as no new animals are introduced, and improves the vitality of the piglets as they come from mothers with hybrid vigour and purebred fathers.