pathogens. The successful development of immune homeostasis can therefore be affected by numerous factors including gestational age, birth environment, mode of delivery, nutrition and antibiotic use. We evaluated the extent to which early-life rearing environment


in the pig affects microbial diversity of the adult gut and immune function during development. Genetically-related piglets were housed in either indoor/intensive or outdoor/extensive environments or in experimental isolators from birth to eight weeks of age. Pigs housed in indoor environments and in experimental isolators showed higher microbial diversity compared to pigs from outdoor environments. Pigs housed in the natural outdoor environment showed a dominance of Firmicutes, in particular Lactobacillus. Conversely, animals housed in a hygienic indoor environment had reduced Lactobacillus and higher numbers of potentially pathogenic phylotypes. Biomarkers associated with immune function and altered by rearing environment were identified. Significantly, indoor- housed pigs displayed increased expression of type I interferon genes, IL-22, IL-23 and Th17 pathways, MHCI and a large panel of chemokines. We thus showed that environmental exposure in early life has


a significant impact on gut microbiota composition and the immune system during development. Outdoor environments supported the establishment of a natural microbiota dominated by lactobacilli and containing low numbers of potentially pathogenic bacteria and this may be an important factor in maintaining mucosal immune homeostasis and limiting excessive inflammatory responses in the gut. More recent data showed that the outdoor environment promoted homeostatic processes of immune regulation mediated by CD4+ FoxP3+ cells, together with reduced immuno-reactivity to novel food proteins at weaning. The weaning period is a stressful time that is accompanied


by a multitude of factors (reduced feed intake, introduction of new dietary antigens from the weaning diet, removal of maternal immune protection via milk, and disruption of the microbiota) that make the piglet susceptible to infection. Transient post-weaning anorexia is followed by slower growth and a weakened immune status. The gastrointestinal tract is particularly affected by weaning, and this has dramatic functional consequences, including a reduction in barrier function against harmful antigens and pathogens. The young animal is therefore very sensitive to external influences at the time of weaning. A proper, balanced gut environment with well-established populations of commensal microbiota is of importance in protecting the animal from gut infections. Probiotic use in pigs has been reported to improve growth performance, decrease the incidence of diarrhoea and decrease morbidity/mortality rates. The mechanisms by which probiotics exert their beneficial actions involve competitive exclusion through mucosal binding, production of bacteriocins/ defensins, reduction of luminal pH, modulation of mucosal and systemic immune response and reinforcement of nonspecific intestinal barrier. Probiotics that are currently EU-approved for pigs


are based on improved animal digestive health and performance. The probiotic species most commonly investigated in pigs include Lactobacillus, Bifidobacterium, Enterococcus, and Saccharomyces. These bacterial species have direct effects on health, and are also able to direct the composition of the microbiota. In summary, while the adult established microbial ecosystem


is relatively stable, temporal stability and species richness of the microbiota are low during development. The weaning period, especially, is accompanied by a multitude of stress factors that make the piglet susceptible to infection. A proper, balanced gut environment with well-established populations of commensal bacteria can protect against infections during this time. Supplementation of probiotic bacteria during the weaning period could restore the disrupted microbiota balance. Potential probiotic species, including Lactobacillus, Enterococcus, and Saccharomyces, have provided evidence for improved animal health and performance.


FEEDING THE PIG FOR GUT HEALTH C. M. Nyachoti1


and C. F. M de Lange2 1Department of Animal Science, University of Manitoba, Winnipeg,


Manitoba, Canada R3T 2N2 2


Department of Animal and Poultry Science, University of Guelph, Guelph Ontario, Canada. N1G 2W1.


Post-weaning diarrhoea is a major cause of mortality and morbidity worldwide and has been estimated to be responsible for as much as 50% of the economic losses seen in the production of weaned pigs. In herds with this disease, up to 2% mortality in weaned pigs can be seen, but of greater economic significance is the morbidity and reduction in growth performance in pigs that survive these infections (Cutler et al., 2007). The swine industry has traditionally managed this disease by


utilizing highly digestible diets often containing sub-therapeutic level of antibiotics as growth promoters. However, the current trend is to discontinue use of in-feed antibiotics in livestock diets for fear that this practice represent a risk to human health. Consequently, there is a need for effective and safe alternative therapies for managing post-weaning diarrhoea disease in piglets raised under antibiotic- free feeding regimen. To date, several products including spray dried porcine plasma,


acidifiers, high levels of zinc and copper salts, probiotics, prebiotics, nucleotides and nucleotide-rich products, essential oils, egg yolk antibodies, lysozyme, and herbs and spices have been suggested for use in this regard. In general, there is ample evidence that many of these additives may positively influence gut health and function in weaned piglets, although much needs to be learned especially about conditions under which they work best and which combinations might act synergistically to provide the greatest benefits.


PAGE 60 JANUARY/FEBRUARY 2014 FEED COMPOUNDER


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