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Leaky gut – Old fact in a new light

Healthy weaned piglets as they should be. Often, however, the shift from easily digestible sow milk to more complex weaner diets creates difficulties for the digestive system

The gut wall can be considered as a ‘first line defence’ for example against bacteria, toxins and endotoxins. If this defence is reduced, piglets are more susceptible to infections, which may lead to a leaky gut and consequently diarrhoea. Feeding combination of organic and inorganic minerals decreases leaky gut at weaning and lowers pig mortality while keeping growth rate at a high level.

By Hans Aae, director, Vitfoss/ Vilofoss, Denmark

When trying to google ‘Leaky Gut’, a lot of hits can be found, however mainly directed towards humans. Wikipedia makes a definition, saying: “It is hypothesised to be caused by increased permeability of the gut wall resulting from toxins, poor diet, parasites, infection or medications.” This is a very interesting approach, when discussing diarrhoea in piglets, as it is legitimate to wonder whether it is possible that there is a link in relation to gut wall permeability and diarrhoea.

Zinc plays a role
Researchers at Iowa State University, led by Dr Lance Baumgard, have demonstrated that it is possible to improve gut wall integrity by feeding a zinc amino acid complex (Availa Zn) to pigs. They used heat stress as a model to provoke leaky (permeable) gut, and showed that feeding this zinc amino acid complex to stressed pigs improved gut wall integrity, thereby also reducing leakiness of the gut (Table 1). Consequently, when looking at causes for leaky gut for piglets after weaning, it is possible to name several causes, e.g.:
• Poor diet – or poorly digestible diets
• Toxins or endotoxins
• Stress

Leaky gut and diarrhoea
When talking about diarrhoea in piglets, most of the time weaning diarrhoea is meant. Weaning is probably the most problematic and very stressful period in a piglet’s life. The shift from easily digestible sow milk to more complex and less digestible weaner diets triggers the digestive system. If no preventive steps are taken piglets, in nearly all farms, will suffer from weaning diarrhoea. Therefore in this period it makes sense to think about the leaky gut syndrome and the finding of Dr Baumgard. He provides scientific background for the fact that zinc is working effectively against weaning diarrhoea.

Two ways to go
It is well-known in the industry that high dosage of zinc oxide in weaning feed has a very good effect on diarrhoea. However, within the EU feed legislation the use of high levels of zinc are not allowed and only few countries allow it within the frames of a special permission in a short period of the animal’s life (often first two weeks after weaning).

Not only the weaning phase can cause troubles for the pig’s digestive system - this is also possible when changing to a more economical starter feed.

To work within legislation and to have beneficial effects of zinc, it is an option to start using organic zinc. Organic zinc has a better absorption in piglets and the zinc is more efficiently used. Dr Baumgard’s lab at Iowa State University underlined this effect. Ten years ago Vitfoss/Vilofoss already demonstrated this beneficial effect. At that time it proved that feeding 250 ppm zinc from zinc amino acid complex (Availa Zn) to weaners had nearly the same effect as 2,500 ppm zinc from zinc oxide. Unfortunately, within the EU feed legislation, 250 ppm also exceeds the maximum zinc level and adding 125 ppm organic zinc is not enough to control diarrhoea.

This stimulated Vitfoss/Vilofoss to look for an alternative. Over the last years it worked on combining various organic micro-minerals in order to minimise diarrhoea in piglets. There is evidence that organic iron reduces diarrhoea, and that organic copper increases growth and feed conversion. The result of various trials is a combination of organic and inorganic minerals, called Pig-Omic, which aims at:
• Improving gut integrity
• Reducing diarrhoea
• Stimulating growth and improving feed efficiency

Focus on starter period as well
Apart from leaky gut and weaning diarrhoea, this solution seems to be of relevance at a later stage in nursery – more precisely, when changing from high quality weaner feed towards more economical starter feed with a lower digestibility. In many farms this change is observed to cause problems like E. coli and/ or Lawsonia diarrhoea or in more severe cases, oedema disease.

In this period high dosage of zinc oxide is not permitted; further it would probably also cause lower performance due to the negative impact of high dosage zinc over longer periods on feed intake. At this stage the use of organic trace mineral sources makes very good sense, and we see some good results from practice, especially regarding oedema disease. Pigs at a French farm had clear symptoms of oedema disease, which stimulated the farmer to allow a test on using the aforementioned combination of organic and inorganic minerals. The results showed that this combination of organic and inorganic minerals significantly reduced mortality and maintained growth performance despite a lower start weight. This once again proved that adding organic micro minerals to the feed of nursing piglets decreases leaky gut at weaning, which in turn seems to lower pig mortality and keep growth rate at a high level