Abstract:
The poultry industry has become an important economic activity in many countries. In large scale rearing facilities, where poultry are exposed to stressful conditions, problems related to
diseases and deterioration of environmental conditions often occur and result in serious
economic losses. Prevention and control of diseases have led during recent decades to a
substantial increase in the use of veterinary medicines. However, the utility of antimicrobial
agents as a preventive measure has been questioned, given extensive documentation of the
evolution of antimicrobial resistance among pathogenic bacteria. So, the possibility of antibiotics
ceasing to be used as growth stimulants for poultry and the concern about the side-effects of
their use as therapeutic agents has produced a climate in which both consumer and
manufacturer are looking for alternatives. Probiotics are being considered to fill this gap and
already some farmers are using them in preference to antibiotics. Over the years the word
probiotic has been used in several different ways. It was originally used to describe substances
produced by one protozoan which stimulated by another, but it was later used to describe
animal feed supplements which had a beneficial effect on the host animal by affecting its gut
flora. The main sources of probiotics in poultry are strains of microorganisms such as
Lactobacillus, Enterococcus and Bacillus and fermented dairy products like yoghurt, cultured
buttermilk and cheese. A good probiotic is characterized by its ability to exert a beneficial effect
on a host, resistance to low pH and bile salts, adhere and colonizing of the intestinal epithelium,
non-pathogenic to host and produces antimicrobial substances towards pathogens. It also boosts
immune responses, improves the growth performance and productivity of poultry and increases
the quality of meat and egg. This Keynote will discuss the principles, mechanisms of action and
criteria for selection of probiotics, and to summarize their applications in the poultry industry.
