How to train the first line of defence for better immunity in pigs

We are more familiar with the importance of, and terminology around, immunity than ever. During the global Covid-19 pandemic, virologists, epidemiologists and politicians continuously talk about herd immunity, vaccins, and – most of all – the importance of, and vulnerability, of our health and wellbeing. And whether we are talking about human or farm animal health, having a strong immune defence system is the basis of good health and resilience. In pig production, during different phases of production, animals can need a little bit of support. Think of piglets that are being weaned and relocated or when gilts arrive on a new farm for example. A strong immune system will make sure these processes will go as smoothly as possible.

So, let’s first refresh our brain about what immunity entails. The immune system protects us against invasive pathogens and consists of several parts. First we have the inner and outer layers of the body such as the skin. When a pathogen breaks through these barriers, the innate immunity is activated and releases a non-specific immune response (through activation of phagocytes and natural killer cells amongst others). This is a quick reaction. When the pathogens can break through this first line of barriers, they need support from the second part of the immune system, the adaptive (acquired) immunity, to make sure the infection gets under control and pathogens are removed. This immune response takes longer than the innate immune response. The adaptive immunity creates immunological memory after an initial response to a specific pathogen to create a bigger and faster response to future encounters with that same pathogen. Vaccines utilise this adaptive immunity and memory by exposing the body to small doses of the pathogen or inactivated virus (without causing disease) to prepare the body to train a strong and fast adaptive immune response when there is an actual pathogen invasion.

It has been found that beta-glucans (polymers of glucose) with specific beta-1.3/1.6 ramifications, are known to be excellent immune trainers. Beta-glucans can be extracted from several natural sources, such as yeasts, algae, cereals and fungi. Beta-glucans from yeast, and with specific β-1.3/1.6 ramifications, are highly potent in including trained immunity. So what if we can use these beta-glucans to boost the first line of defence of animals, and with that, may help to improve animal health and performance?

Safglucan^®, a product of Phileo by Lesaffre, is composed of a purified fraction with a minimum of 50% of 1.3/1.6 beta-glucans. The beta-glucans are extracted from a naturally selected proprietary yeast strain Saccharomyces cerevisiae and achieved through a unique and controlled manufacturing process. This guarantees a high and stable level of beta-glucans, batch after batch. So, what does this mean in practice? Trials showed that Safglucan^® is able to induce a small immune response to train the innate immune cells for an actual challenge (Figure 1). Safglucan^® has been shown to do this more effectively than several other commercially available beta-glucans. Trials in live pigs show a range of health benefits when Safglucan^® was added to the diet. When fed to sows, it resulted in colostrum with a superior mitogenic activity (regeneration of cells). When consumed by piglets, it can help to increase villus height and gut development.

The ability to mitigate the risk of infection or the proliferation rate of pathogens of Safglucan^® was tested in several trials. In nursery pigs, challenged with Mycoplasma hyopneumaniae. On day 21, the pigs supplemented with the beta-glucans showed an improved body weight, compared to the non-supplemented group (17kg versus 13kg) and decreased lung lesions (0.51% versus 14.43%). Another trial was done with Salmonella typhimurium UK1 strain in weaned piglets. The group that received the beta-glucans on top of the bacteria challenge had a lower Salmonella typhimurium load in the cecum, compared to the control group (Figure 2). This results in a reduced bacterial translation in the gastrointestinal tract of pigs and a lower Salmonella typhimurium load in the Peyer’s patch (lymphatic tissue found throughout the ileum region of the small intestine).

Because immune training allows the innate immune cells to respond quicker and stronger, it has also an effect on the adaptive immune system and can hence potentiate the vaccine response. To test the effect of Safglucan^® on a vaccine response, a trial was set up in which piglets received 2 doses of the Parvovirus vaccine (one at day 0 and one at day 21). The Safglucan^® group was supplemented 4 days before and after each vaccine. It was shown that at day 42, the beta-glucan supplement had 55% more antibody titres against Parvovirus, compared to the control group. The beta-glucans were also put to the test in weaned piglets that received an influenza vaccine on day 14 and day 28, followed by an influenza virus challenge on day 42. The antibody titers were significantly higher in the Safglucan^® group, compared to the control group and the vaccinated group (without supplementation) (Figure 3). Also lung lesions were significantly decreased in the Safglucan^® group.

The supplementation of Safglucan^® increases the capacity of the innate (first line) immune system to deal with a pathogen and vaccine challenge. It also helps to increase colostrum quality and has an effect on the performance of piglets. All of these benefits will reduce the need for antibiotics and increase animal production and performance. Application of Safglucan^® is beneficial for different stages in pig production, such as preparing the gilts before relocation and be stronger against the pathogens they face at the new farm or preparing piglets to relocate or be mixed after weaning. Ideally, pigs should be supplemented, with Safglucan^®, at least during 10 to 15 days to gain the benefits of the boosted immune response. The recommended dosage is 125 to 500 g/t and has benefits for all stages of pig production. The duration and dose will depend on the expected results depending on the animals and the challenges (short term or long term).