Effect of Management on the Bacterial Community Present in Poultry Litter
Type of Degreedissertation
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An unwanted byproduct of commercial broiler chicken grow out is thousands of tons of litter. This litter is the material on which the broiler chicken spends its entire life. Litter consists of a starting material, in the southeast United States normally pine shavings, plus excreta, feathers, feed, litter beetles, parasites and bacteria. While some litter is used for other applications, such as plant fertilizer or livestock feed, most of it is reused from one flock to the next. With proper management, the litter can be maintained in good condition for several years. A problem associated with litter is the high number of bacteria that survive in the litter environment. Most of these bacteria are not harmful, but some such as Salmonella enterica, can cause serious illness in humans through contaminated meat. Other bacteria, such as Clostridium perfringens, can cause illness in both chickens and humans. In both instances, the economical impact of such illness is substantial, reaching into the millions of dollars in losses. The majority of previous research into litter bacterial makeup has utilized the hand grab method of sampling that simply removes the top inch or two of litter. From this sampling, researchers have extrapolated the bacterial makeup of the entire litter bed. However, most commercial broiler houses have more than two inches of litter. It is the author’s belief that previous findings concerning the amount of bacteria present in litter could be erroneous. Therefore the first phase of this dissertation is to identify the concentrations of several pathogenic bacteria, their stratification from top to bottom of iii the litter and location of the bacteria within the house. Sampling would include the entire depth of the litter bed, including the hard dirt pad underneath. This would be achieved utilizing traditional culture and second generation high throughput sequencing methods. The second phase aims to discover any litter management techniques that would reduce the pathogenic bacteria load in litter, specifically Salmonella. In recent years, the emphasis on controlling this pathogen has switched from processing plant to more on farm control methods. The methodology to be examined will be the application of several commercial and novel litter amendments that would normally be used for ammonia reduction on a commercial poultry farm. These amendments consist of several acid salts, a liquid acid and several nonpathogenic bacteria. The acidic amendments function by lowering the pH of litter from its normal basic pH, around 8 to 9, to an acidic pH of 5 or less. This reduction in litter pH not only traps ammonia, but could reduce the concentration of pathogenic bacteria present in litter.