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Acellular vaccines are typically associated with pertussis, commonly known as whooping cough. These vaccines were created in response to the adverse side effects relating to whole cell vaccines. These adverse reactions often include redness and swelling at the site of injection and fever.

The use of antibiotics to increase the growth of pigs is most studied of all livestock. This use for growth rather than disease prevention is referred to as subtherapeutic antibiotic use. Studies have shown that administering low doses of antibiotics in livestock feed improves growth rate, reduces mortality and morbidity, and improves reproductive performance. It is estimated that over one-half of the antibiotics produced and sold in the United States is used as a feed additive. Although it is still not completely understood why and how antibiotics increase the growth rate of pigs, possibilities include metabolic effects, disease control effects, and nutritional effects. While subtherapeutic use has many benefits for raising swine, there is growing concern that this practice leads to increased antibiotic resistance in bacteria. Antibiotic resistance occurs when bacteria are resistant to one or more microbial agents that are usually used to treat infection. There are three stages in the possible emergence and continuation of antibiotic resistance: genetic change, antibiotic selection, and spread of antibiotic resistance.

Alternatives
Increasing concern due to the emergence of antibiotic resistant bacteria has led researchers to look for alternatives to using antibiotics in livestock. In addition, with current consumer trends leaning more towards purchasing organic products, meaning livestock raised without antibiotics, there is a big push to find alternative treatments. Some developments for disease prevention without using antibiotics are by modulating the gut microbial community through feed additives or fecal transplantation and use of pro and prebiotics. Forms of disease treatment include phage therapy, phage lysins, bacteriocins, and predatory bacteria.

Probiotics
Probiotics are cultures of a single bacteria strain or mixture of different strains that have been used historically to improve both human and animal health. Lactic acid bacteria are the core of probiotic health supplements for humans, and the health benefits of these bacteria in yogurt have been extensively studied for years. Currently, probiotics can be used in livestock as a production enhancer to positively affect the digestive microflora to increase performance as well as protect the gut against colonization by harmful bacteria.

Prebiotics
Prebiotics are non-digestible carbohydrates. The carbohydrates are mainly made up of oligosaccharides which are short chains of monosaccharides. Prebiotics are more recent compared to probiotics, but like probiotics they are believed to benefit the gut and help the growth of beneficial organisms. The two most commonly studied prebiotics are fructooligosaccharides (FOS) and mannanoligosaccharides (MOS). FOS has been used in chicken feed and studies have shown that diets containing FOS helped prevent chickens from contracting Salmonella. MOS works as a competitive binding site, as bacteria bind to it rather than the intestine and are carried out. A study put MOS in the drinking water of broilers and the results showed a reduced ''Salmonella typhimurium" intestine colonization compared to the control broilers.

Bacteriophages
Bacteriophages or phage therapy is one alternative to antibiotics for disease treatment. Bacteriophages are able to infect most bacteria and are easily found in most environments colonized by bacteria. They can be used for disease treatment because bacteriophages target specific bacteria and mixtures of multiple phages can be used to limit the emergence of resistance.