The main objective of this thesis was to evaluate the potential of various biotic strategies and the effectiveness of nanobodies designed to neutralise different virulence factors of enterotoxigenic Escherichia coli (ETEC) F4+, aiming to improve piglet response to health challenges during early stages. The thesis explores the effects of these additives on intestinal colonisation, immune response, and digestive function, shedding light on the possible mechanisms of action involved.
To achieve these objectives, four studies were conducted. The first study (Chapter 4) involved young suckling piglets fed artificial milk. This study assessed the impact of supplementing milk formulas with different additives on the development of intestinal microbiota, the animal's metabolic response, and the development of digestive function. Specifically, it evaluated the effect of a synbiotic combination of Bifidobacterium longum subsp. infantis CECT 7210, Lactobacillus rhamnosus NH001, galacto-oligosaccharides (GOS), and human milk oligosaccharides (HMO), with or without the bioactive peptide osteopontin.
In this study, 96 piglets aged 4-5 days were distributed into 32 pens over four periods (8 pens per treatment). This combination of additives successfully modified the microbial population of suckling piglets towards a more beneficial profile, achieving a greater reduction of potentially dysbiotic species such as Helicobacter and Campylobacter, and increased fermentative activity with higher concentrations of short-chain fatty acids. All three supplemented diets also promoted changes in gene expression, suggesting greater hormonal and enzymatic function, increased nutrient transport function, and reduced intestinal inflammatory tone.
The second study (Chapter 5) evaluated the potential of a synbiotic combination in newly weaned piglets challenged orally with ETEC F4+. Experimental treatments included supplementation with Saccharomyces cerevisiae Sc 47, short-chain fructo-oligosaccharides (scFOS), or their synbiotic combination.
In this study, 96 piglets aged 21 days were distributed into 32 pens (8 pens per treatment). All three supplemented diets promoted a reduction in the incidence of diarrhoea in the days following the challenge. This improvement was linked to lower pathogen counts in the different intestinal compartments, suggesting a more beneficial microbiological profile.
The third and fourth studies (Chapter 6) evaluated the effectiveness of different nanobodies specifically designed to neutralise the virulence factors F4 (fimbria), LT, and Stx2e (toxins) of ETEC through different experimental designs: an ETEC F4+ challenge model similar to that in Chapter 5, and a field trial on a commercial farm.
In the challenge model, 96 piglets aged 21 days were distributed into 32 pens and assigned to three experimental treatments: a control treatment, supplementation with nanobodies, or ZnO as a positive control (10-11 pens per treatment). Nanobodies promoted improvements in growth and clinical signs of the animals after the challenge, as well as a reduction in faecal pathogen excretion.
The field trial was conducted on a commercial farm. In this case, a total of 528 piglets aged 21 days were distributed into 32 pens and divided into three treatments: a control treatment, supplementation with nanobodies, or ZnO as a positive control (16 pens per treatment). Nanobodies reduced the incidence of diarrhoea and numerically decreased faecal toxin shedding. Additionally, the additive increased the weight of the animals, primarily due to enhanced growth in low-weight piglets.
In conclusion, all tested strategies (synbiotics and nanobodies), despite acting through different mechanisms of action, demonstrated beneficial effects on the intestinal ecosystem and the response of piglets to early-stage health challenges. For practical application, a complementary use of these strategies could prove to be an effective approach to addressing post-weaning diarrhoea issues.
Dietary supplementation strategies to enhance gut microbiota resilience and intestinal health in young pigs
Ferreres Serafini, L. (Author). 27 Sept 2024
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis