The demand for pork products has increased over the last decades, leading to a doubling of pig production in the last 20 years. Asia now accounts for more than 60 percent of global pig production with China alone raising around 50 percent of the pigs on the planet. While the global increase in the number of pigs between 2002 and 2012 has been estimated as 11.9 percent, most of the countries from East and Southeast Asia experience a much faster growth with some countries experiencing growth rates of more than 100 percent over that time period.Pig production systems are heterogeneous across the region. Whilst most pigs are raised in intensive and large production units in countries such as China, Japan or Thailand, small, extensive and often free-ranging backyard herds are responsible for most of the production in countries such as Cambodia, Myanmar or Lao PDR. The level and the pace of intensification of pig production is also very diverse between higher and lower income countries. While production is heavily intensified in the former, it is only starting to shift from traditional subsistence farming to specialised household operations in the latter. The intensification of pig production and the objective to produce more at reduced cost raise important questions regarding disease management. In Asia, control of infectious diseases is often based on the use of antibiotics, without appropriate supervision by veterinary authorities. In many countries, antibiotics can be obtained without prescription. Therefore, the development of antimicrobial resistance and the presence of antimicrobial residues in meat is an important issue in this region.
Antibiotic use and alternatives for prophylaxis and growth promotion:
As in many places in the world, antibiotics are used in East and Southeast Asia for three purposes: therapeutic, preventive and growth promotion. For therapy, antibiotics are generally used at high doses for short periods of time on individual animals, in order to treat a specific disease. For prophylaxis, antibiotics are generally administered at high doses for short periods of time (for example after weaning or during transport) to groups of animals in order to prevent the occurrence of specific diseases. For growth promotion, they are also used for groups of animals but at low dose and for long periods of time in order to reduce bacterial competition in the gut and improve feed conversion. Whilst the use of antibiotics for promoting growth has been banned in Europe since 2006, it is still commonly practiced in East and Southeast Asia.
To restrict the use of antibiotics for growth promotion, and to a lesser extent for disease prevention, many alternative disease management approaches have been studied, including vaccination against specific bacterial diseases, feed supplementation with probiotics, with herb extracts, with clays or minerals, etc. Two studies reported that vaccination of sows with a locally produced vaccine against Escherichia coli and Clostridium perfringens results in a significant reduction of the occurrence of neonatal diarrhoea. A review of some studies carried on in East and Southeast Asia indicates that some probiotics such as Lactobacillus spp., Bacillus spp., Enterococcus spp. or yeast culture, when added to pig feed at specific concentrations, can improve growth rates and prevent the occurrence of enteric diseases such as post weaning diarrhoea. Some studies even showed that they produce similar rates of growth to piglets given antibiotics and therefore may be used in addition or as a substitute to antibiotics.