Speakers: Maria Florencia Bambace & Herald Wilson Ambrose

Abstract:  

Methane (CH₄) accounts for more than 90% of farmgate greenhouse gas (GHG) emissions in pig farming, with 80% being produced during manure management. In intensive pig production, slurry is stored in manure pits under the barn floor for short term storage (1 to 6 weeks) and in outside storage tanks for longer storage periods. During this time, CH₄ is emitted as a result of microbial degradation of organic substrates present in the pig feces, combined with the anaerobic conditions developed under the slurry surface, which promote the activity of methanogens. Acidification is considered a benchmark technology for mitigating CH₄ emissions from stored slurry. However, there are several associated drawbacks such as safety issues in application, soil sensitivity to increased sulphur loads during land application, and inhibitory effects on biogas production. Other chemical additives raise further environmental concerns; hence the need for a biological alternative is highly sought for CH₄ mitigation in slurry storage.  

Biological treatments studied thus far, utilizing microbial or enzymatic additives have shown little to insignificant potential for CH₄ mitigation in pig and cattle slurry storages. In this seminar talk, we will present and discuss the results of a successful biological treatment aimed at inhibiting methanogenic activity in slurry storages, conducted on a laboratory scale headspace emission setup. The biological additive involves the use of Limosilactobacillus reuteri, which in the presence of glycerol produces reuterin, a broad-spectrum antimicrobial agent. We assessed the impact of endogenously produced reuterin on CH₄ emissions from pig slurry by initially introducing both L. reuteri and glycerol into the slurry, which was then stored for a period of 26 to 30 days, during which CH₄ emissions were measured. We also optimized the dosage combination of L. reuteri and glycerol. Our results showed that endogenously produced reuterin reduced CH₄ emissions by 74-90% compared to untreated slurry. The environmental and biological aspect of our study will be further discussed, highlighting this novel approach as a promising alternative to H₂SO₄ or chemical surfactant treatments for reducing methanogenic activity in pig slurry storages.