This study was conducted to assess whether shifts in manure microbial populations could explain foam production in deep-pits manure storages. To make the study relevant and practical, swine sites with similar genetic stock, same feed source, and similar barn design were selected for sampling to reduce site-to-site variability. Additional samples were provided from farms in Iowa and Minnesota to include in the analysis. Samples were collected over time to determine if foam production or shifts in microbial communities occur in the manure of these facilities. Twenty-six barns were sampled four times during a six-month period from April 2012 through September 2012. The results indicate that microbial communities do indeed differ between foaming and non-foaming manure samples. We noted that some deep-pits were consistently stable in their foam or non-foam status and also the microbial communities associated with each of them. Other deep-pits shifted from foaming to crusting (or vice-versa) during the study and their microbial communities changed over time.
These results support the idea that foam production in deep-pit manure storages is correlated with distinct bacterial populations present in the manure; however we are conducting additional research to determine if the bacterial communities are the cause of foaming, or merely an indicator of the foaming condition. This NPB funded study was a key first step to discovering the cause of foaming and developing a solution for foam production in deep-pit manure storages. Additional funding has been secured to further investigate this problem on a much larger scale. Industry support has been obtained by major swine integrators to help identify and correlate environmental and management factors related to this foaming phenomenon.