Investigating the impact of sanitisation of a liquid feeding system for pigs on the bacterial and fungal microbiota of the liquid feed and liquid feeding system surfaces
The aim of this study was to investigate the effect of implementing an intensive liquid feeding system sanitisation programme on the bacterial and fungal microbiota of liquid feed and the feeding system surfaces. The results confirm previous findings that the resident microbial biofilms on the feed pipeline internal surfaces were disrupted post-cleaning (PC). Before cleaning, the feed pipeline biofilm was dominated by a low diversity microbial community, comprised mainly of Lactobacillus, Leuconostoc and Chryseobacterium and the yeast Alternaria. Microbial diversity increased on the pipeline surface PC, but relative abundances were unstable throughout the 10-week PC period and never returned to baseline values, likely due to the nightly acid rinse circulated through the feed pipeline, preventing re-colonisation. Sanitisation also impacted the bacterial and fungal communities in the liquid feed. For example, Weissella and the yeast Kazachstania both became predominant in the trough-sampled liquid feed PC. However, despite the cleaning, spontaneous fermentation was still observed in the feed, as evidenced by decreased abundance of Pantoea and Pseudomonas between the mixing tank and troughs, with a concurrent increase in Lactobacillus. Nonetheless, previous analysis revealed only minimal losses in gross energy in the liquid feed. Additionally, organic acid, ethanol and biogenic amine concentrations were lower PC, indicating that spontaneous fermentation was reduced, thereby improving the chemical quality of the liquid feed. Overall, although microbes began to re-colonise the feeding system PC, hygiene was still improved at the end of the 10-week grow-finisher period, compared to baseline, as evidenced by disruption of surface microbial communities.