Microbial profiling of liquid feed for pigs and the impact of strategies to optimise feed microbial quality on the feed and pig gut microbiome

Cullen, James (2024) Microbial profiling of liquid feed for pigs and the impact of strategies to optimise feed microbial quality on the feed and pig gut microbiome. Doctoral thesis, SETU Waterford.

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Abstract

The objectives of this thesis were to (1) develop an optimal methodology for simultaneous profiling of liquid feed and pig gut bacteriome and mycobiome; (2) profile the bacteriome and mycobiome of liquid feed on commercial pig farms; (3) determine the impact of different feed form and delivery methods on the feed and pig gut bacteriome; (4) determine whether intensive sanitisation of liquid feeding systems improves system hygiene and the microbiological and nutritional quality of liquid feed and if it impacts the bacteriome and mycobiome of feed and feeding system surfaces. All experiments were conducted with grow-finisher feed/pigs. The optimal method for simultaneously profiling the bacteriome and mycobiome of liquid feed and pig faeces included a 20-minute bead-beating step to minimise lysis bias. Application of this methodology on liquid feed samples from commercial pig farms revealed increased relative abundances of lactic acid bacteria (LAB) (Lactobacillus, Weissella and Leuconostoc) and yeasts (Kazachstania and Dipodascus) between liquid feed in the mixing tank and troughs, consistent with spontaneous fermentation. This was supported by moderate concentrations of biogenic amines, the products of amino acid degradation, which likely contributes to the poorer feed efficiency of liquid-fed pigs. The LAB, Leuconostoc, which was associated with spontaneous fermentation in liquid feed, was enriched in the ileal and faecal bacteriome of liquid-fed pigs and correlated with higher feed intake and poorer feed efficiency. This may, in part, explain the poorer feed efficiency of liquid-fed pigs observed in the study. Intensive sanitisation of the liquid feeding system removed pipeline biofilms, improved system hygiene and reduced concentrations of acetic acid, ethanol and biogenic amines in the liquid feed. Bacteriome and mycobiome profiling revealed differences in liquid feed post-cleaning, including predominance of fermentative Weissella and Kazachstania in the residual trough-sampled feed, however, fermentation-associated metabolites remained below pre-cleaning concentrations at 10 weeks post-cleaning.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Microbial profiling, Microbiome
Departments or Groups:	*NONE OF THESE*
Divisions:	School of Science > Department of Chemical and Life Sciences
Depositing User:	Derek Langford
Date Deposited:	25 Jul 2024 14:02
Last Modified:	25 Jul 2024 14:02
URI:	https://repository.wit.ie/id/eprint/7821

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