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Title: Effects of nitrocompounds on uric acid-utilizing microorganisms, nitrogen retention, and microbial community in laying hen manure

item KIM, WOO - Texas A&M University
item WEEKS, LAUREN - Texas A&M University
item Anderson, Robin
item Nisbet, David
item DUNKLEY, KINGSLEY - Texas A&M University
item RICKE, STEVEN - Texas A&M University

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2009
Publication Date: 5/1/2009
Citation: Kim, W.K., Weeks, L.J., Anderson, R.C., Nisbet, D.J., Dunkley, K., Ricke, S.C. 2009. Effects of nitrocompounds on uric acid-utilizing microorganisms, nitrogen retention, and microbial community in laying hen manure. Journal of Environmental Science and Health Part B. 44:403-406.

Interpretive Summary: Modern poultry farms are trying to find ways to reduce the amount of ammonia produced by microorganisms in chicken manure. The present study was conducted to test if two chemicals nitropropanol and nitropropionic acid known to have inhibitory activity against certain food borne pathogens such as Salmonella and Campylobacter could inhibit the uric-acid-degrading microorganisms predominantly responsible for ammonia production in poultry manure. We found that when administered individually, both nitrocompounds significantly inhibited the growth of uric acid-degrading bacteria by approximately 1000-fold and further found that the amount of nitrogen retained in the treated manure was greater than that retained in untreated control manure. This later finding indicates that less nitrogen was lost in the treated manure than in the untreated manure. An assessment of the overall microbial community presented in the poultry manure indicated that the nitrocompounds moderately changed the community structure. These results indicate that nitropropanol and nitropropionic acid may be chemicals that can be used by poultry farmers to reduce ammonia emissions from their poultry manure while at the same time reducing pathogen levels on their chickens. Ultimately, these results may help poultry producers to continue to produce safe, wholesome and environmentally friendly products for the American consumer.

Technical Abstract: A study was conducted to evaluate the effects of nitrocompounds on the growth of uric acid-utilizing microorganisms, nitrogen retention, and microbial community in laying hen manure. There were three treatments: control, 100 mM nitropropanol (NPL), and 100 mM nitropropionic acid (NPC). The mixed laying hen manure was divided into 3 groups and incubated at 23C for 7 days. On days 0, 3 and 7, samples were collected to measure the quantity of uric acid-utilizing microorganisms, total nitrogen retention, and microbial community changes. Both nitrocompounds significantly reduced growth of the uric acid-utilizing microorganisms on day 3 (P < 0.05). Inhibitory effects of both nitrocompounds remained until day 7 when the experiment was terminated. NPL treatment retained significantly more manure nitrogen compared to the control on both days 3 and 7. Manure nitrogen levels of NPC treatment were also significantly higher than the control on day 7. We further investigated the effects of NPL and NPC on microbial community changes during a 7-day incubation. NPC treatment and control on day 7 exhibited 94% community similarity. NPC on day 3 and NPL on day 7 also showed high community similarity (approximately 94%). Control on day 0 and day 7 yielded less than 80% community similarity. Control and NPL treatment groups on day 3 gave the lowest community similarity (approximately 64%) compared to the other groups. This indicated that the incubation time and treatment moderately influenced microbial community changes. In summary, these results indicate that both nitrocompounds increased manure nitrogen retention by inhibiting the growth of uric acid-utilizing microorganisms, and that NPL and NPC could be used as manure treatments in order to reduce ammonia volatilization and nitrogen retention in poultry manure. Moreover, nitrocompounds may have potential as feed additives to reduce ammonia volatilization.