Effect of starter culture inoculation on feed hygiene and microbial population development in fermented pig feed composed of a cereal grain mix with wet wheat distillers’ grain

Abstract

Aims: Investigating the influence of an added starter culture on the properties of fermented liquid pig feed. Methods and Results: Diets of cereal grain blended with wet wheat distillers’ grain that were either not inoculated (WWDG), inoculated with a silage starter culture at start (WWDGsc1) or at start and at each backslopping (replacement of 80% the content with fresh mixture, simulating feed outtake, WWDGsc5) were fermented for 5 days, followed by 5 days of daily backslopping. Numbers of undesirable micro‐organisms (enterobacteria, moulds) were reduced in all fermentations; particularly enterobacteria in the starter culture inoculated diets. Lactobacillus plantarum present in the starter culture became dominant in diets WWDGsc1 and WWDGsc5. However, Lactobacillus panis that was dominating WWDG was also abundant in WWDGsc1 and WWDGsc5. Yeast populations were not influenced by the starter culture, with Pichia fermentans dominating all fermentations. All diets had similar chemical characteristics with the exception of a significant increase of all tested organic acids in WWDGsc5. Conclusions: The addition of a starter culture influences the bacterial population in fermented liquid feed, but there is also a strong impact of the flora already present in the feed ingredients. The yeast population is not influenced by adding a lactic acid bacteria (LAB) starter culture. A consortium of LAB and yeast strains adapted to the fermentation should be used as starter culture. Significance and Impact of the Study: The results suggest that it is possible to influence the current unpredictable and spontaneous process of feed fermentation when appropriate starter cultures are used. For this purpose, LAB and yeasts with desirable characteristics should be isolated.

Controlling fungal growth and mycotoxins in animal feed

“…The microbial and chemical characteristics of fermented liquid feed differ among fermentations (Scholten et al 2001a, b;Beal et al 2005;Moran et al 2006;Lyberg et al 2008;Olstorpe et al 2008Olstorpe et al , 2010c. The microorganisms involved in fermentation produce organic acids, which may reduce the pH to approximately 3.5-4.5.…”

“…Thus, most liquid diets are affected by microbial activity to varying extents. Mould growth is seldom a problem in these liquid feeding systems, as they do not proliferate during the biopreservation process Olstorpe et al 2010c). Thus, any mycotoxins present in bioprocessed liquid feed most certainly entered with the raw feed material.…”

Pichia anomala in grain biopreservation

“…Due to its negative charge, this major grain phosphorus storage compound binds minerals and proteins, resulting in insoluble complexes that are unavailable for absorption in the intestine of monogastric animals (BrinchPedersen and Hatzack 2006;Kies et al 2006;Sandberg and Andlid 2002). The phytate content may be reduced by phytase enzymes, supplied by supplementing the feed with pure enzymes or with phytase-producing microorganisms, and/or through activation of endogenous phytase present in the cereal grain (Bergman et al 1999;Fageer et al 2004;Lyberg et al 2008;Olstorpe et al 2009Olstorpe et al , 2010aSandberg and Andlid 2002). During storage of moist crimped cereal grain a reduction in phytate content was detected.…”

Cryptococcus cerealis sp. nov. a psychrophilic yeast species isolated from fermented cereals

“…Under Swedish farming conditions, it can frequently happen that such fermentations run at 10°C or even lower temperatures. Due to the spontaneous character of the fermentation, different microbial interactions occur in such systems Olstorpe et al 2008Olstorpe et al , 2009.…”