Effect of Litter Amendments on Poultry Litter Microbial Communities and the Subsequent Effect on Nitrogen Dynamics.

Ammonia production in poultry houses has serious implications for flock health and performance, nutrient value of poultry litter, and energy costs for running poultry operations. Numerous amendments are available for reducing ammonia volatilization, with acidifier-types being the most prevalent due to their ability to convert the volatile NH₃-N to the mineralized NH₄-N form. While the effects of litter amendments on the physiochemical makeup of poultry litter has been previously studied, little work has been done to determine their microbiological effects. The microbiological effect is considered significant considering the role that microbial enzymes have on the nutrient cycling in poultry litter, specifically in terms of the N cycle. In a laboratory scale study, triplicate poultry litters were incubated at 25 °C for 16 weeks under varying amendment strategies. Various acidifier type amendments (i.e. Alum), biological inhibitor amendments (i.e. Clinifarm^®), and chemical inhibitors/adsorbers (i.e. Agrotain Plus^®) were used. To determine the effect of amendment strategy on the poultry litter microbiology, 16S (specific for bacteria) and 18S (specific for fungi) rDNA was quantified using quantitative real-time PCR (QRT-PCR). In addition, denaturing gradient gel electrophoresis (DGGE) was used to analyze the bacterial and fungal community fingerprints to determine what community shifts were observed as a result of the different amendment strategies. Acidification of the litter led to a significantly greater reduction (>90%) in the concentration of bacteria in the litter as compared to the normal litter (72.9% reduction). Conversely, litter acidification led to a greater than 2-log increase in fungal concentrations, while the normal litter exhibited a greater than 50% decrease in fungal numbers. The addition of Clinifarm^® to the alum treatment did not result in significantly lower fungal numbers.