Narasin as a manure additive to reduce methane production from swine manure

Authors: ANDERSEN, DANIEL - Iowa State University; YANG, FAN - Iowa State University; Trabue, Steven - Steve; Kerr, Brian; HOWE, ADINA - Iowa State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2018
Publication Date: 6/1/2018
Citation: Andersen, D.S., Yang, F., Trabue, S.L., Kerr, B.J., Howe, A.S. 2018. Narasin as manure additive to reduce methane production from swine manure. Transactions of the ASABE. 61(3):943-953. https://doi.org/10.13031/trans.12568.
DOI: https://doi.org/10.13031/trans.12568

Interpretive Summary: Foam accumulation in swine manure deep-pits has been linked to increased methane production rates resulting in flash fire incidents that pose safety concerns for both animals and humans. This study investigated the use of narasin, a swine feed additive, for its potential to reduce pit foaming. Narasin addition to manure reduced methane production rates by close to 10% for each unit increase in narasin fed to pigs. The effectiveness of a single dose of narasin was close to 25 days. Narasin use not only affected methane production rates, but it reduced processing of the organic waste and changed the composition of the microbial community. Information in this report will be of value to growers, engineers, and scientist developing foam mitigation practices and technologies since this report will assist in evaluating the use of anti-microbial products to reduce methane production rates to control foam formation.

Technical Abstract: High levels of methane production from swine operations have been associated with foam accumulation in deep-pit storage systems since excessive foaming poses both a safety concern (i.e., flash fires), and operational challenges in managing stored waste. Mitigating methane production is one approach in controlling foam accumulation. In this study, swine manures obtained from three deep pit storage barns in Central Iowa were dosed with narasin to evaluate its inhibitory effects on methane and biogas production. Dose rates ranged between 0 to 3.0 mg narasin kg-1 manure. Overall, methane rates were reduced by 9% for each mg narasin added kg-1 manure and this reduction was effective for up to 25 days. However, the inhibitory effect weakened with time such that after 120 days of incubation there was no statistical difference in cumulative methane production between samples dosed with narasin and undosed controls. In addition to methane rates, narasin addition reduced degradation of total solids and volatile solids in the manure by 1.9% and 2.6%, respectively, for each mg of narasin kg-1 manure added. Additional study treatments included sugar (10 g kg-1 manure) with and without narasin (15 mg narasin kg-1 manure). Results from this treatment show that methane production was initially increased by the sugar addition, but the effect lasted for less than 6 days, at which point cumulative methane production was similar to the control. When treated with both narasin and sugar the inhibitory effect did not impact gas production during the sugar digestion phase but did reduce methane and biogas production thereafter. The addition of sugar and the rate of narasin addition caused changes to the microbial community as compared to the control. Overall the results indicated that narasin can be an effective pit additive for reducing methane emission, but further study is needed to recommend dosing frequency and to evaluate how the continuous addition of manure impacts narasin effectiveness.