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HEALTHYPIGUT
Defining and validating gut health criteria in young pigs, based on digestive physiology, microbiology and mucosal immunology investigations for testing alternative strategies to in-feed antibiotics

Considerable efforts have been devoted to the understanding of infectious diseases, including the biology of pathogens, host resistance and therapy in animals and humans. By contrast, very little is known about the prevention of diseases in pigs through dietary and non-dietary strategies because these problems have been overcome by adding sub-therapeutic doses of antibiotics and elevated levels of metal trace elements (zinc and copper) in feed. This prophylaxis was highly effective in the newly weaned piglet, which is particularly prone to infection. However, the European Union has recently put a ban on such practices, encouraging alternatives with claimed effectiveness to invade the market prior to being fully evaluated. The purpose of this project is to provide a scientific basis for understanding the functional disturbances of the gut, which favour enteric infections. It has now become urgent to investigate the mechanisms of gut health and dysfunction thoroughly in order to provide relevant, scientifically founded health criteria.

Objectives
The main objective is to provide a scientific basis for understanding the early disturbances of animal gut leading to enteric infections, to define relevant gut health criteria, and to evaluate the socio-economic consequences of the ban and of tested alternatives.
This main objective will be met by working towards four other complementary objectives, as follows:
1) Based on a common model of newly weaned pig, the first objective is to apply appropriate challenges and create disturbed gut models that will serve for characterising the major changes occurring in digestive physiology and digestion, microbiology and mucosal immunity
2) The second subsidiary objective is to develop, or adapt to the pig, three complementary in vitro systems for investigating these interactions in young pigs, at the level of the gut mucosa (Ussing chambers), microbial populations (molecular taxonomy, cultures and metabolic activities), and immune cells and cytokines (enterocyte culture and/or enterocyte-lymphocyte co-culture).
3) The third subsidiary objective is to validate the in vitro selection of novel feed additives and rearing strategies through animal health and performance observations in vivo. This will be made in large-scale production trials in which the relevance of selected digestive physiology, microbiology and immunology criteria will be checked.
4) The fourth subsidiary objective is to evaluate the economic effect of the ban by a) developing an analytical model using classical public and industrial economics, and b) characterising the alternative technologies by integrating the experimental data of the partners in animal sciences.

Progress to Date
Most activities and work packages are progressing broadly as anticipated in the technical annex work plan. However, it is important to note that the Foot and Mouth disease outbreak in March 2001 in the UK caused a major delay (approximately 10-12 months) for the British partner at the start of the project. This has and will have a negative impact on the progress of the overall project through the work package on gut immunology involving this partner, and the work packages dedicated to data integration and dissemination.

Results
New data confirmed the stronger influence of time post-weaning compared to dietary and environmental factors, on intestinal architecture and functions. In contrast, abrupt changes from milk- to plant-based diets appeared to influence gastric emptying rate and to decrease the sensitivity of duodenal neurones in stimulated situations. Increasing the weaning age had favourable effects on creep feed consumption but it also increased piglet sensitivity to stress as evaluated through plasma cortisol.
Fermentable carbohydrates supported the growth of lactobacilli, which may potentially have a protective effect on the gut of piglets through increased colonisation resistance by pathogenic bacteria. First data on the type of environment (clean vs. dirty) do not suggest so many differences in the numbers of bacteria and composition of bacterial community throughout age. Available data tend to suggest that the developmental programme (age) has a greater influence on immunological parameters than fasting and dietary factors. Cytokine gene expression (RT-PCR) was strongly influenced by weaning.
The in vitro fermentation system made it possible to demonstrate the influence of dietary substrates used in the project and of the piglet GIT inoculum (ileum vs. faeces) on the fermentation kinetics and end products.
A pig intestinal epithelial cell model was set up and confirmed the protective effect of ZnO on membrane integrity. Thus, cell cultures provide information on in-feed alternatives and some mechanisms of action.
From in vitro data generated, in vivo experiments with experimental E. coli challenge were set up to evaluate the protective effects of ZnO (various forms) and two probiotics in piglets post-weaning.
A first (static) assessment of the antibiotic ban at farm level (micro economy) has been conducted after the integration of different information, including technical references and data on antibiotic alternatives.

Classified in ANIMALS, HUMAN HEALTH AND WELLBEING

Scientist responsible for the project

Dr JEAN-PAUL LALLES
Domaine de la Prise
35590 Saint-Gilles
France - FR

Phone: +33 2 99 23 48 52 00
Fax: +33 2 99 23 48 50 80
E-mail: lalles@rennes.inra.fr

References

Project ID QLRT-1999-30522
Organisation Institut National de la Recherche Agronomique
Area 5.1.1
Start date 01 January 2001
Duration (months) 42
Total cost 5 532 475 €
Total EC contribution   3 853 156 €
Status Completed

The partners

  • Institute for Animal Science and Health (ID-Lelystad), Netherlands (The) - NL
    zmroz@id.dlo.nl
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