Understanding intestinal physiology of weaning piglets helps understand the mechanism of action of gut pathogens. A recent paper by Dr A Moeser, North Carolina State University, College of Veterinary Medicine has highlighted factors influencing the critical defence mechanisms of protection in the gut and precisely how weaning-associated pathology negatively affects the integrity of the gastrointestinal barrier.

At over 300m², the gut is the largest interface between the host and the environment. The intestinal epithelium has cells called enterocytes which are orientated adjacently to the lumen of the gut. These cells have continual exposure to pathogenic micro-organisms, toxins, enzymes and dietary antigens. The intracellular structure of these aligning cells forms a membrane of “tight junctions” which serves as a secure barrier function to these unwanted biochemical molecules and micro-organisms. Nutrient absorption is driven by intracellular apical ionic transportation due to an electrolyte gradient formed by Na⁺, K⁺ and the Adenosine Tri-Phosphate (ATP) cycle. The crypt and villus regions are divided by a dynamically transitional secretory and absorptive epithelium. Aging cells migrate from the crypt to the villus, eventually becoming sloughed off into the lumen. The function of younger cells is to secrete mucus whilst older cells in contact with the lumen absorb nutrients. Paneth cells stay at the base of the crypt and don’t migrate to the surface.

There are three barriers between the gut and the blood and organs of the pig. These are (1) the mucus, antimicrobial peptides and antibodies (2) Tight junctions of the enterocytes (3) immunological barrier of innate and adaptive immunity associated with lymphoid tissues. The tight junctions of the enterocytes adjacent to the lumen prevent large molecules including toxins and antigens penetrating further. However, infectious disease agents including Escherichia coli, Clostridium perfringens, Isospora suis and Rotavirus as well as other acute or chronic stressors can increase permeability of the intestine either by protein degradation, inflammation or excess mucous production. Piglets that are weaned at a younger age are also more susceptible to the detrimental effects of long term increased intestinal permeability.

There are many physiological factors which affect whether the barrier function of the gut against pathogens is working as it should do. Meriden Animal Health Limited has some of the longest standing research into nutritional additives in this area, specifically with regard to their plant based feed additive range of products – Orego-Stim.

Orego-Stim has a multi-action function which works by modifying the population of gut bacteria with preferential antibacterial action against pathogenic bacteria rather than lactobacilli or bifidobacter. Orego-Stim also acts directly on the gut lining by increasing the rate of enterocyte turnover and cellular exfoliation. This provides an optimal absorption surface area for nutrients, with lower energy and nutrient losses to luminal bacteria, resulting in better feed conversion ratios and faster growth. The combination of these modes of action effectively prevents diarrhoea and gastrointestinal tract diseases in livestock animals by stabilising intestinal epithelial tight junctions. In comparison to conventional routine antibacterial growth promoter treatments, it has been shown that piglets with Orego-Stim in their diet had 12.5% lower mortality rates and 10% higher body weight gain.

Orego-Stim optimally prepares piglets for the inevitable stress of weaning. A smooth transition from milk to solid feed reduces problems and ensures a healthy start. Improvement of feed palatability attracts nursing pigs to dry feed and stimulates feed intake. Phenols are aromatic substances commonly used in flavourings. Natural phenols in Orego-Stim enhance feed palatability by stimulating smell, taste and the olfactory and glossopharyngeal pathways of the cranial nerves which stimulates saliva production. Piglets are consequently stimulated to consume solid feed.

Summary

The intestinal physiology of weaning piglets is complex but Orego-Stim protects during this vulnerable time. Orego-Stim Liquid can be administered directly into milk based piglet feeds for diarrhoea control, and Orego-Stim Powder can be included in creep feed to enhance palatability and maintain optimal gut microflora balance.

Moeser A. (2010). Weaning: What’s going on at gut level? Allen D. Leman Swine Conference September 18-21, 2010, RiverCentre, St Paul, MN, USA

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