Most active AMPs are able to interact with bacterial membranes.

Knowledge on the structures of AMPs will greatly help in the understanding of the mechanisms of action employed by AMPs and accelerate the generation of novel AMPs more suitable for pharmaceutical applications.Д¬urrently, the best-studied class of AMPs are those with antibacterial activity. The loop AMPs, including bactenecin, form loop structures owing to a disulfide bridge. The extended AMPs, which are rich in proline, tryptophan, arginine or histidine, do not fold into regular secondary structure (for example, indolicidin). ОІ-sheet AMPs are stabilized by two to four disulfide bridges and form relatively rigid structures, such as human О±- and ОІ-defensins, plectasin, and protegrins. The О±-helical AMPs, including cecropins, magainins, and LL-37, are characterized by their structure, an extremely high propensity for the formation of О±-helix. Based on their secondary structure, AMPs fit into four major classesвЂ“namely, О±-helical peptides, ОІ-sheet peptides, extended peptides, and loop peptides. They are small molecules (12вЂ“50 amino acids) containing positive charge and an amphipathic structure. The potential applications of AMPs in swine and broiler production are also reviewed.ДЄntimicrobial peptides have certain common features. In this article, we discuss the potential of AMPs as alternatives to conventional antibiotics, including their broad-spectrum of activity, low level of induced resistance, and immunomodulatory properties. Antimicrobial peptides are attractive candidates for the design of new antimicrobial agents for specific application because of their natural antimicrobial properties and a low propensity for the development of bacterial resistance. As an important component of the innate immune system, AMPs provide immediately effective, non-specific defenses against infections. Produced by all organisms, from prokaryotes to human beings, AMPs serve a fundamental role in innate immunity. ДЄntimicrobial peptides (AMPs) have been described as evolutionarily ancient weapons against microbial infections. For this reason, there is an urgent need to develop novel antimicrobial agents, including alterative drugs based on antimicrobial peptides. In addition, the number of approvals of new antibiotics has significantly and steadily decreased in the past three decades. Antibiotic resistance has become an increasingly serious problem with global human deaths due to antibiotic resistant infections predicted to reach 10 million by 2050, more than the current death toll associated with different forms of cancer. Concurrent with the success of antibiotics for treating infections, the emergence and rapid dissemination of antibiotic-resistant bacteria poses substantial risks for human health. In 2010, the global antibiotic consumption in food animal production was conservatively estimated at 63,151 tons.

Therefore, AMPs have good potential as suitable alternatives to conventional antibiotics used in swine and poultry industries.ДЄntibiotics are widely used for disease prevention and growth promotion in conventional livestock and poultry production. In addition, AMPs have beneficial effects on growth performance, nutrient digestibility, intestinal morphology and gut microbiota in pigs and broilers. Antimicrobial peptides not only have broad-spectrum activity against bacteria, fungi, and viruses but also have the ability to bypass the common resistance mechanisms that are placing standard antibiotics in jeopardy. This manuscript reviews the current knowledge of the basic biology of AMPs and their applications in non-ruminant nutrition.

Antimicrobial peptides (AMPs), produced by bacteria, insects, amphibians and mammals, as well as by chemical synthesis, are possible candidates for the design of new antimicrobial agents because of their natural antimicrobial properties and a low propensity for development of resistance by microorganisms. Over the last decade, the rapid emergence of multidrug-resistant pathogens has become a global concern, which has prompted the search for alternative antibacterial agents for use in food animals.

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