Piglets need better immune competence

Swine producers are facing legislative issues such as reducing pharmacological levels of zinc oxide post-weaning as well as an overall reduction of the use of antimicrobial growth promoters. These demands will increase the challenge for weaned piglets. However, there are nutritional solutions available to increase the immune competence of these piglets.

Until weaning, the piglet’s immune status is driven by the sow through colostrum and milk (passive immunity). It is only after weaning that the pig starts building up its own active immunity. Inevitably there will be a period after weaning where immune status of the piglet is low as passive immunity is fading out and active immunity has not been fully developed yet – this is the so-called immunological gap.

IgG in colostrum will give the piglets a good start and increase their immune competence. Photo: Zinpro
IgG in colostrum will give the piglets a good start and increase their immune competence. Photo: Zinpro

The challenge is to overcome this gap without using high levels of zinc and medication. By reducing this gap, the challenge becomes smaller and successful weaning in the future, when provision of zinc and medication will be more limited, is achievable with minimal compromise to performance, see Figure 1.

Figure 1 – Reducing the immunological gap: organic trace minerals* can help from 2 sides.

Not one single solution

The recent Zero Zinc Summit in Copenhagen, Denmark in June 2019 gave some clear messages. There will not be a single solution to add to the feed for replacing pharmacological levels of zinc oxide. There is a need to focus on management, diet formulation and different additives. It’s also clear that this focus should already start in lactation to ensure that heavier and more robust piglets can be weaned.

Improved feeding of the lactating sow is an economically efficient way to improve the quality of piglets. First of all, the amount and quality of colostrum should be in focus. It is important that all piglets within a litter receive the required amount of colostrum. This is particularly true for herds with large litters (highly prolific sows).

Research has shown that feeding certain feedstuffs will increase the amount of colostrum, and that feeding organic performance minerals (Availa Sow, Zinpro) increases the level of IgG in colostrum. This will give the piglets a good start and increase their immune competence.

Secondly, there should be a focus on weaning heavier piglets. This requires that the sow produces more milk. In this context, that same feed ingredient has shown good results as five comparative studies yielded on average 200g more weaning weight per piglet and, also interestingly, a reduced number of light-weight piglets at weaning, see Figure 2.

Figure 2 – Organic trace minerals* increase IgG in colostrum and increase weaning weight.

Thirdly, it is possible to increase antioxidative capacity of weaned piglets. This has been practised for a long time with vitamin E. Feeding organic selenium (Availa Se, Zinpro) will boost antioxidant defence as well. When feeding organic selenium the muscle selenium content increases and then piglets after weaning, when feed intake is low and demand for selenium is high, can mobilise these reserves.

Better gut integrity to decrease inflammation

It has been demonstrated that weaning increases leaky gut. In particular, early weaning combined with stress has a negative impact on gut integrity. As a result of leaky gut, more endotoxins and other undesirable substances will pass from the intestinal lumen into the blood stream. This will increase inflammation and more reactive oxygen metabolites will be generated. This means that in a period with low feed intake and reduced nutrient digestibility, which weakens the pig, it also has to fight inflammation and the reactive oxygen metabolites.

Research has shown that organic zinc (Availa Zn, Zinpro) improves gut integrity. This is important for the weaned pig and as such an important part of the solution to replace high dosages of zinc oxide post-weaning. Given that tight junctions, which are holding the epithelial cells knitted together and ensure gut barrier function, are depending on zinc, it makes perfect sense that using this highly absorbable zinc source makes a difference.

Increase active immunity

Looking into the economics, increasing expenditure on vaccination will help reduce the need for antibiotics. Vaccinating pigs is the right way to boost their immune response and make them more resilient against diseases. While vaccinations have been used for a long time, they will become even more important in the future. In the context of improving the immune response of weaned pigs, two very interesting studies were conducted. Both studies involved pigs that were ­infected with Lawsonia intracellularis.

The first study showed that pigs responded faster to the Lawsonia challenge when they were fed highly absorbable organic zinc, as indicated by an increased percentage of pigs having antibodies. A quick immune response is critical to minimise the negative impact of an infection. This first study also showed significantly fewer intestinal lesions – both in number and severity – when pigs were supplemented with an organic zinc source, see Figure 3.

The second study combined vaccination and adding organic zinc to the diet. This combination resulted in improved growth performance compared to vaccination in combination with supplementing inorganic zinc.

Looking to the future, where an increasing amount of money will be spent on vaccination, supplementing with highly absorbable organic zinc in pig diets becomes highly interesting as it makes vaccinations more effective.

Focus on increasing immune competence

The reduced use of antibiotics and pharmacological levels of zinc oxide in the future makes it more difficult for pigs to overcome the immunological gap. Decreasing the gap by making piglets more immune competent is part of future solutions aimed at maintaining good growth performance and health. Organic performance minerals have been shown in controlled research studies and practical tests to be a part of such solutions.

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