The researchers said their study showed that YL yeast could be used in compound feeds for piglets interchangeably with SC yeast. The combined application of YL or SC with a probiotic had a more favorable effect on the gut microbiota than the use of yeast alone.
However, the effect of YL on haematological blood parameters and the microbes colonizing the gut proved to be more beneficial than the effect of SC yeast. Supplementation of the compound feed with YL in combination with a probiotic reduced the multiplication of coliform bacteria and Escherichia coli in the intestinal contents, while the feed containing SC together with a probiotic did not, they added.
They published their findings in Research in Veterinary Science.
The team said the aim of their work was to evaluate the efficacy of two species of yeast, Yarrowia lipolytica (YL), and Saccharomyces cerevisiae (SC), with or without a probiotic supplement, when added to feed for piglets, relying on haematological blood indices and the gut microbiota.
They said, typically, it is brewer's yeast, Saccharomyces cerevisiae, that would be used in the diet of farmed animals currently. However, they noted growing interest in Yarrowia lipolytica as a feed additive for monogastric animals (Czech et al., 2016; Fickers et al., 2005; Merska et al., 2015).
Yarrowia lipolytica is produced on a substrate of waste glycerol derived from biodiesel production, they explained.
The effect of yeast in feed could be enhanced by applying it together with live cultures of probiotic and prebiotic microbes, to obtain a symbiotic with a different mechanism of action on the digestive system, said the Polish scientists.
“Probiotics act mostly in the upper compartments of the gastrointestinal tract, while prebiotics are intended as a substrate for potentially beneficial bacteria in the hindgut of monogastric animals. Research has shown a synergistic connection between probiotics and prebiotics, which has a beneficial effect on the microbiological profile of the digestive tract.”
The experiment involved 360 piglets from 36 litters of line 990 sows, weaned at 21 days of age. The team said the piglets were divided into six feeding groups according to their body weight and sex. Each feeding group comprised 60 piglets, distributed in six pens with ten piglets each. The mean age of the piglets at weaning, when the experiment was begun, was 28 days. The experiment lasted 56 days.
Animals from groups C (control) and P were fed standard feed compounds with no yeast supplements, and in group P the probiotic (a mixture of Bacillus licheniformis and Bacillus subtilis) was added in the amount of 2 × 109 CFU/kg of feed, said the authors.
The animals in groups Y and YP were fed standard feed compounds with dried Yarrowia lipolytica, and group YP additionally received the probiotic, they said. In groups S and SP, the piglets received the standard feed with dried Saccharomyces cerevisiae fodder yeast, and group SP additionally received the probiotic. The optimal dosage of the yeasts (3%) was based on the results of a previous study (Czech et al., 2016), added the researchers.
Blood was drawn for analysis on days 14, 35 and 56 of the experiment from 6 piglets from each group for a total of 36 samples. The material for microbiological analysis consisted of the contents of the jejunum intestine and feces of the piglets, they said.
Fodder yeast, particularly Yarrowia lipolytica, is a valuable source of easily digestible micronutrients, including iron and copper (Czech et al., 2016), i.e. elements taking part in synthesis of red blood cells (Andrews et al., 1999).
“For this reason, we can expect it to exert a beneficial effect by stimulating erythropoiesis processes, which are particularly important in young animals (Kumar et al., 2012). This was confirmed in the present study, which showed that in the blood of piglets receiving feed supplemented with Yarrowia lipolytica there was a significant increase in the erythrocyte count and other indicators of erythropoiesis, i.e. haematocrit and haemoglobin content.”
Their results showed the addition of Saccharomyces cerevisiae yeast was a factor determining an increase in the number of neutrophil granulocytes, while in the piglets receiving feed supplemented with Yarrowia lipolytica and/or the probiotic, an increase was noted in the lymphocyte count.
Stimulation of the immune system caused by both the probiotic and the yeasts was also demonstrated by an increase in IgG, whose most important function is to defend the body against pathogens and mycotoxins through the secondary immune response (Adewole et al., 2016; Czech et al., 2010; Fessele and Lindhorst, 2013; Murphy et al., 2008), they added.
The researchers said the stable and complex cell wall of yeasts and the presence of mannans cause strong binding of pathogenic bacteria and mycotoxins, which are thereby rendered harmless or excreted from the body (Giannenas et al., 2016; Flickinger et al., 2003; Pettigrew, 2000). This significantly reduces the number of pathogenic microbes, and thus increases the number of beneficial lactic acid bacteria (Adewole et al., 2016; Broad et al., 2006).
“This reaction makes it possible to reduce the pH of the contents of the gastrointestinal tract, which additionally eliminates pathogens sensitive to low pH. This was confirmed in our experiment.”
Source: Research in Veterinary Science
Published online ahead of print: https://doi.org/10.1016/j.rvsc.2018.06.007
Title: Effect of dietary supplementation with Yarrowia lipolytica or Saccharomyces cerevisiae yeast and probiotic additives on haematological parameters and the gut microbiota in piglets
Authors: A Czech, A Smolczyk, K Ognik, Ł Wlazło, B Nowakowicz-Dębekc, M Kiesz