ADDITIVES ; BETTER ALTERNATIVES TO ANTIMICROBIAL GROWTH PROMOTERS IN POULTRY.

The demand for healthier safety-proven production methods and the trend to reduce antibiotic uses is undeniable, and is steadily expanding. Simultaneously, the increasing ineffectiveness of antibiotics due to resistance 
development is another concern. The concern about antibiotic residues in meat products is solved in many countries, but the bacterial resistance to antibiotics is a much more complex problem, involving the entire medical profession. In animal production—poultry production in particular :ceasing the use of antibiotics as growth promoters has changed the technical approaches used to counter the removal or reduction of these products. Without antibiotics, the microbiota in the birds’ gastrointestinal tract must be viewed as an entity to implant, develop and control to ensure that the animals are healthy and can grow according to their genetic potential. The removal of antibiotic growth promoters has revealed that it is crucial to manage the makeup of the birds' intestinal microbiota to avoid or at least limit the risks of health problems inherent to intensive production, hence alternatives are necessary to ensure health of birds and food safety. The main strategies can be outlined as follows: Selectively introduce favourable bacterial populations from a very young age; Provide a regular supply of nutrients specific to the beneficial bacteria; Act directly on pathogenic bacteria. Different methods are available, such as the dietary supplementation with probiotics, prebiotics, organic acids and essential oils. These products act either avoiding bacterial adhesion to the intestinal cells or through bactericidal or bacteriostatic effects. The goal is to achieve the most stable balance on the microbiota in order to avoid the trouble caused by bacteria like E. coli, Clostridium and Salmonella. The gastrointestinal microbiota profile depends on numerous factors such as the health of the breeding stock, production system, stressors (vaccination, viral episodes, etc.), nutrition and stocking densities. The first bacteria to colonise the animals’ digestive tract will shape the intestinal ecosystem for the introduction of global intestinal microbiota. Selectively colonising the gastointestinal tract with beneficial bacteria can modulate the expression of certain genes in the tract’s epithelium, creating conditions for establishing beneficial microbiota. Since the first micro-organisms that come into contact with a newly hatched chick’s gastrointestinal tract are from the breeding stock, controlling the microbiota in the parents would be ideal. Studies have demonstrated that the use of beneficial bacteria in low doses in the hatchery improves chicks’ resistance to pathogens. Other studies have validated that an in-ovo injection of FOS (fructooligosaccharide) helps maintaining higher levels of bifidobacters, with positive effects on zootechnical performance and mortality rate. Most of the microbial strains in probiotics are of the genus Bifidobacterium or Lactobacillus. In certain conditions, lactobacilli can produce metabolites that limit the growth of Salmonella by modulating immunity and avoiding bacterial binding to the epithelial cells of the intestine. However, according to some publications, this type of effect is limited. In poultry production, interactions between the birds’ feed and their intestinal health have been amply demonstrated. In the past, the use of antibiotic growth enhancers had the potential to mask a number of problems. In the field, functional diet-based strategies need to be adapted to the different sanitary and production contexts for each production system. Selectively introducing favourable bacterial populations for young chicks, providing a regular supply of nutritious substrates specific to the beneficial bacteria and effectively controlling pathogenic bacteria are important courses of action to ensure the intestinal health of the birds via their feed. Prebiotics, enzymes, and combinations of organic acids and essential oils can be viable alternatives to antimicrobials. story credit; world poultry.