Is there an impact of diet’s physical form on stomach barrier function (in vivo / in vitro) against artificially aplied E. coli (F4, STI, STII, LTI)?

It is well known that stomach barrier (acidity) acts against diverse pathogenic agents. This function is particularly influenced by particle size distribution in the diet. Diarrhoea causing E. coli is an agent of relevance in today’s pig production that can lead to weight gains up to high losses. An experimental study was conducted to evaluate the ability of a specific pathogenic E. coli to survive stomach passage, in vivo and in vitro (exposed to stomach content).

A coarsely ground meal diet (CM) and a finely ground pelleted diet (FP) being botanically and chemically identical (13.8 MJ ME, XP: 237, XF: 42 g/kg as fed) were each fed ad libitum to 9 weaned barrows housed individually. After 5 weeks the piglets were divided in two groups, 4 piglets out of each feeding group were infected artificially with an oral dose of 1.4 x 10⁹ cfu E. coli (F4, STI, STII, LTI) and euthanized two hours later to count the applied E. coli in content of stomach and small intestine. Remaining 5 piglets were euthanized and samples of stomach content were taken quartered. From these samples 10g were inoculated in vitro with 1.3 x 10⁹ cfu of the E. coli mentioned above and the counts of the agent were determined after 3, 60, 120 and 240 min of exposition in a shaking water bath (37°C). For quantitative analysis serial dilution and growing on Columbia Agar with 5% sheep blood (37°C, 24h) were used. In stomach content DM content and pH value were determined additionally. Statistical analysis was performed by procedure mixed (SAS Enterprise guide 5.1), p< 0.05.

After artificial infection the concentration of applied E. coli in the cranial small intestine differed significantly (CM: 5.40, FP: 6.94 cfu/g) but no difference was seen in stomach content. In vitro 86 to 91% of the inoculated E. coli dose was counted with no difference between the groups and the time of incubation. Stomach content was firm and layered in pigs fed CM (in the four quarters: DM: 34.4, 31.9, 27.2, 26.2%), these piglets had significantly differing pH values (pH: 4.94, 4.76, 3.74, 3.86). Piglets fed FP showed significantly lower DM content in a fluid stomach content (20.1, 21.7, 23.8, 20.1%) and no pH gradients (pH: 4.52, 4.45, 4.44, 4.41).

As known from earlier studies grinding intensity had a great impact on the quality of stomach content and with this on stomach barrier function. But the applied E. coli survives when exposed to the stomach content (in vivo, in vitro) independent of the different conditions due to the physical form of the diet so that contrary to other pathogenic agents (e.g. Salmonella) stomach barrier seems to have less impact on the defence against this distinct E. coli.

Disclosure of Interest: None Declared.