Short- and medium-chain fatty acids as feed alternatives for the promotion of gut health in challenged weaning piglets
- Autores: Paola López
- Directores de la Tesis: Susana María Martín Orúe (dir. tes.), Lorena Castillejos (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Manuel Fondevila Camps (presid.), Joaquín Morales Peñaloba (secret.), Paolo Trevisi (voc.)
- Programa de doctorado: Programa de Doctorado en Producción Animal por la Universidad Autónoma de Barcelona
- Materias:
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- Resumen
The control of opportunistic pathogens during weaning of piglets can comprise the prophylactic use of in-feed antibiotics. Alternatively, new in-feed protected forms of short- and medium-chain fatty acids (SCFA and MCFA, respectively) are purposed in this Thesis to enhance the gut health of early-weaned piglets and face intestinal pathogens. To accomplish these objectives, three studies with weaning piglets were performed. In a first study, two fat-protected forms of sodium butyrate or sodium heptanoate were evaluated under an oral challenge with enterotoxigenic Escherichia coli (ETEC) F4. In a second study, sodium salts of a coconut distilled MCFA mixture were tested under two different pathogen oral challenges, Salmonella Typhimurium and ETEC F4. Finally, in a third study, new forms of sodium butyrate or sodium heptanoate, protected with these coconut distilled MCFA salts, were tested under two oral challenges with ETEC F4. A similar protocol was used in all the experiments. Briefly, weaning piglets were transported from commercial farms to the experimental facilities. Each treatment included 8 pens (replicates) with three piglets each. After a week of adaptation to diets and facilities, animals were orally challenged with the corresponding pathogen and one animal per pen was euthanised on days 4 and 8 post-inoculation (PI). For all experiments, main parameters assessed were animal performance, clinical signs, pathogen excretion, fermentation profile, immune response, intestinal morphology, and intestinal microbiota through 16S rRNA gene high-throughput sequencing (HTS). In the first study, no increases of butyric nor heptanoic acids were detected in the lower gastrointestinal tract with butyrate nor heptanoate supplementation. Nonetheless, in stomach, lactic fermentation was depressed with butyrate and fermentative profile altered with heptanoate. Both additives reduced SCFA in colon and increased enterobacteria and coliforms in ileum without affecting E. coli F4. Colonic populations were affected by both additives. Butyrate promoted Prevotella genus and tended (P=0.11) to reduce Firmicutes:Bacteroidetes (F/B) ratio, whereas heptanoate increased Actinobacteria and some members of Clostridiales and Bacteroidales. In the second study, with the coconut distilled MCFA salts, consistent reductions of Salmonella spp. and enterobacteria counts were observed in the hindgut of piglets after Salmonella or ETEC F4 challenges, respectively. Depending on the pathogen, the numbers of ileal intraepithelial lymphocytes differed, being reduced by the MCFA salts after the Salmonella challenge or increased after the ETEC F4 one. Furthermore, this additive tended (P=0.13) to reduce the F/B ratio and enriched Fibrobacteres after the Salmonella challenge, whereas after the ETEC F4 challenge it modified the entire microbial structure with increases in Dialister, and also a trend (P=0.14) to increase the Veillonellaceae family. In the third study, MCFA-protected butyrate was not able to reduce E. coli F4 colonisation and increased enterobacteria, despite the colonic F/B ratio was higher with this additive. Goblet cell counts in ileum were elevated as well as serum TNF-α boosted. Regarding MCFA-protected heptanoate, it was capable of reducing E. coli F4 colonisation as well as Enterobacteriaceae numbers in colon (by 16S rRNA gene HTS), also showing lower colonic SCFA concentrations and goblet cells in ileum. Summarising, the new functional forms of butyrate or heptanoate, protected with MCFA salts, combined partially the effects observed with the individual compounds. Protected forms of sodium butyrate would benefit of combining positive effects seen with MCFA on the microbiota structure and potential trophic effects of butyrate on intestinal epithelium that could help the animals to better recovery from the pathogen damage. MCFA-protected sodium heptanoate demonstrates efficacy in reducing gut colonisation by ETEC F4 and could contribute to prevent post-weaning colibacillosis. Taken together, different strategies might be suggested with the preliminary results from this Thesis, however, more studies would be required to further validate these hypotheses.
