Effect of the combination of three yeast strains on post weaning piglets after an experimental E. coli infection

Weaning imposes stress on the piglets, which may affect their general health, therefore, it is necessary to keep a well balanced microflora to protect against colonisation of pathogenic microorganisms in the gastrointestinal tract (Jensen 1998). Yeast fractions have been shown to have a positive effect on gut health in weaning piglets. A blend of three inactivated yeasts strains (YANG^®; Lallemand SAS, comprising two complementary species of Saccharomyces cerevisiae and one strain of Cyberlindnera jadinii) has shown positive antibacterial effects in vitro (Dunière et al. 2016). The objective of this trial was to evaluate the effect of the yeast blend on E. coli faecal counts and IgG blood concentration of weaned piglets with an E. coli challenge. It was hypothesised that both the E. coli excretion and the immunoglobulin G (IgG) concentration will be lower, as an effect of counteracting the effects of the challenge given by E. coli inoculation.

The trial was run at Schothorst Feed Research (SFR), and 36 male piglets (Topigs Tempo × (Great Yorkshire × Finnish Landrace)) aged 25 ± 0.91 days and weighing 6.83 ± 0.51 kg at weaning, were housed in pairs in 1 m² pens. Pens were allocated to one of the experimental treatments: negative control (NC), positive control (PC), and YANG (Y, 800 g/ton). The test product was offered in feed for the entire experiment. In PC treatment, piglets were daily treated with colistin (100 000 IU Coliplus, Bimeda, Llangefni, UK^®) via drinking water at a dose of 2 000 000 IU/mL per kg of bodyweight. During the first 3 days, all piglets received colistin to reduce the presence of E. coli in the gut. On d 10, all the piglets were challenged orally with 5 mL of 8.80 ± 0.07 log CFU E. coli/mL. The E. coli strain was isolated from an SFR herd and made resistant to nalidixin to facilitate its identification. Faecal samples were taken on d 8, 11, 15, and 22 and blood samples on d 8, 15 and 22. The experimental data were analysed using the mixed model (repeated-measurements) using Genstat 18 (VSN International, Hemel Hempstead, UK), with dietary treatment and day as fixed effects. Significance was set at P < 0.05., with pen being the experimental unit. Before challenge, faecal excretion of E. coli in all the piglets was lower than detectable levels. Piglets fed diet Y had lower faecal E. coli excretion than piglets fed NC (P < 0.001). Piglets treated with colistin showed the lowest E. coli excretion in the faeces. Piglets fed diet Y tended to have lower IgG blood concentration (P < 0.10) than piglets on the PC diet. The study design did not allow detection of growth performance between dietary treatments. Results are shown in Table 1.

Table 1.  E. coli excretion (log CFU/g faeces) in faeces and IgG concentration in blood (mg/mL) before (d 8) and after (d 11 to 22) E. coli challenge

It was concluded that the inclusion of YANG^® at a dose of 800 g/ton decreased faecal E. coli excretion by ~0.5 log CFU compared with piglets in NC treatment. An effect on the humoral immune response was suggested, but needs further investigation.