Feed additives

Background

Dietary immunomodulation directs immune cells in the body

Activated immune cells can be sent through specific food components to a specific location in the body, like the upper respiratory tract or the skin. All About Feed covers current research that extends these findings and proves the hypothesis that immune cells can be directed towards certain organs or body parts.

The research project ‘Nutrition-based gastro-intestinal health promotion in agricultural animal husbandry’ began in 2014 and headed by Huub Savelkoul, professor and head of the Cell Biology and Immunology group of the department of Animal ­Sciences of Wageningen University.

Photo: Dick van Doorn
Photo: Dick van Doorn

More to feed than just nutrition

Just last year Prof Savelkoul and colleagues published findings in the prestigious global scientific journal Mucosal Immunology. Prof Savelkoul: “Our study is based on extensive studies of food allergies in humans that evolved into a research programme called ‘Immune modulation through diet’.” He continued: “Immunomodulation by food and feed provides the industry with a new concept. So, since then we are actively communicating to the food industry and compound feed industry that there could be more to their feed than just nutrition. The relationship between gut, nutrition and resilience to infection and therefore general health is of relevance for humans and animals alike. Maintenance of health and prevention of infectious disease in the respiratory and the gastro-intestinal tracts are critically dependent on a proper functioning of the immune system in relation to intestinal homeostasis. Therefore, when this homeostasis is compromised by the presence of infectious organisms, toxic compounds, bacterial dysbiosis, stress-related conditions, and exposure to particular dietary components, the health status of the individual is at risk. Often this condition will not directly result in overt clinical disease but in the development of a chronic low-grade, subclinical inflammation which can result in chronic diseases.”

Directing immune cells

During a meeting with the Dutch compound feed company MulderAgro from Kollumerzwaag, the model of natural disease resistance and immune modulation by feed was presented for the first time. “What we communicated was mainly based on literature studies and already some own research,” Prof Savelkoul explained. After the publication of 2 dissertations in 2018 by Dr Marloes van Splunter and Dr Olaf Perdijk it became clear that in e.g. (raw) milk the immunity can be held by this immunomodulation. Prof Savelkoul: “We found out how to positively change the immunity-promoting activity in milk with a particular treatment.” The research proposal for immune modulation was approved and Prof Savelkoul could launch his research activities.

He is currently investigating immunomodulation in poultry and pigs, and performs specific research into diet-induced alterations in intestinal bacteria. The results of this research will be presented to the sector through scientific publications and by presentations in courses provided by Wageningen Academy and called ‘Gut Health in pigs and poultry’. During Gut Health 2019 which was held earlier this year, Prof Savelkoul spoke about the remarkable results. Prof Savelkoul: “We have discovered that we can send immune cells, activated by interaction with infections or vaccines, through specific food components to a particular place in the body such as into the airways or to the skin. Some nutritional components with proven immunomodulatory activity, like vitamin A and certain fatty acids, we can programme to stay in the intestines. With a precise dosage of vitamin D3 we can send them to the skin or, with just a slightly different vitamin A to D ratio, to the upper airways.”

Clearly measurable

But that’s not all, the researchers were also able to ensure that the activated immune cells stayed in the intestine to fight infection. That happened by administering a particular vitamin A in a very precise dose. Prof Savelkoul: “So, now we know exactly how we can send the activated immune cells to a specific part of the body and measure it.” According to the professor, the immune system of humans and animals can be much more efficient and thus respond faster and more effectively by providing precise doses of selected nutritional compounds that possess immunomodulatory activity. When the activated immune cells cannot reach the right spot (in time), then obviously valuable energy is wasted. This holds especially true for adequate protection against upper respiratory infections in young animals. Prof Savelkoul: “This new knowledge is therefore crucial.”

Another discovery that the professor has great expectations for, is the positive effect of probiotics on immune competence by poultry as well as by pigs.” Because the research on underlying immune mechanisms are still in progress, it will take some time before the fruits can be harvested in practice. But given its influence on the immune system the interest in this probiotic will be greatly intensified.

Upcomming presentations

According to Prof Savelkoul the influence of the immune system by immune modulation is based on another important concept, namely genetic imprinting. Prof Savelkoul: “Transgenerational changes in the genetics of the animal run through epigenetic changes rather than through mutation in coding sequences in the DNA. A big advantage of this genetic imprinting is that we can temporarily change the transcriptional rate of coding genes resulting in a more optimised immune competence. Because of our discoveries we can precisely adjust the husbandry conditions, like infection pressure, breeding, feeding, etc., and this will lead to animals who are more resilient or robust during every generation.”

This is the reason Wageningen Academy is organising the course ’How Mother can Influence Offspring’. During this course the importance of the epigenetic influences on the phenotype of offspring will be discussed. Also the latest knowledge and insights on transgenerational (nutritional) effects will be presented. A diversity of inspiring examples seen in livestock will be presented. The goal is to promote a better understanding of the nutritional and environmental maternal influences on the expression of the genome of offspring. The more practical implications for the pig and poultry sectors will be presented at the ’Gut Health in pigs and poultry’ course 2020, which takes place on Tuesday 4 February 2020.

Dick van Doorn