Stimulating immune responses to defend against pathogenic bacteria

The weaning period is a precarious phase of pig production. Piglets’ digestive and immune systems are still developing, and they can no longer access the immunity protection supplied in sow milk. This situation can make it easier for harmful bacteria to colonise in the digestive tract, leading to enteric issues such as diarrhoea. Including specialty ingredients like short- and medium-chain fatty acids and B-glucans in the piglet diet can help stimulate the immune response in the face of a pathogen pressure such as gram-negative bacteria.

Considering immunity and defence strategies

Farm management is an essential element in a pathogen mitigation strategy. For example, implementing and maintaining biosecurity practices and improving piglets’ access to colostrum can help support young animals in the face of gram-positive and gram-negative bacteria. Science-based nutrition can also help protect piglets from threatening bacteria. Feeding a diet enriched with elements like short- and medium-chain fatty acids (SCFA, MCFA) known to support the immune response can create conditions that make it harder for pathogenic bacteria to survive in the gastrointestinal tract.

Piglets are born with an innate immunity and develop adaptive immunity as they mature. The innate immune response generates a fast, non-specific reaction to pathogens and other potentially threatening agents, but retains no “memory” of the pathogens it attacks. In contrast, the adaptive immune response can “remember” pathogen threats (vaccination makes use of this ability) and target attacks on specific antigens. Antigen-presenting cells help send signals to the immune system to activate appropriate defences. Because the adaptive immune system is immature at weaning, piglets cannot fully access its protection against problematic bacteria.

Strategies to mitigate harmful bacteria can also leverage cellular activities involved in the animal’s immune response. Specialty ingredients supplemented in the piglet diet can defend against threatening bacteria. Innate and adaptive immune responses rely on phagocyte cells to help find, “eat,” and kill pathogens. Supplementing specific elements – like beta-glucans – that support phagocyte function may help improve the immune response against harmful bacteria. SCFAs are known to help control unwanted gram-negative bacteria like E. coli and S. typhimurium. Supplementing precise levels of these acids in the diet can help support the development of piglets’ immune systems.

Stimulating macrophages

Macrophages, cells of the innate immune system, can stimulate a more alert and effective immune response. Enhancing the diet with specialty ingredients known to support immune system functions provides an interesting approach to activate or strengthen piglets’ immune system response.

A feeding trial tracked the inclusion of scientifically selected specialty ingredients in a piglet diet designed to support immune system function in the face of a gram-negative pathogen challenge. A total of 180 piglets received one of three diets – negative control (NC) incorporating an optimised diet with a feed additive blend and no post weaning E. coli challenge; a positive control (PC) the same diet and feed additive blend with an E. coli challenge; and the trial diet (NEW) the same feed with a new fatty additive blend, and an E.coli challenge that was applied on day seven post weaning. The experimental diets were fed in the first 2 weeks post weaning, then all piglets were switched to a diet optimised for efficient production. Piglets were tracked for 34 days.

Researchers tracked mortality, treatment days, and occurrence of diarrhoea during the first two weeks (Table 1). Mortality rates tended to be lowest for pigs on the NEW diet (0%) and highest (6.7%) for those in the PC group. Treatment days tended to be slightly higher for those on the NEW diet. There was a significant difference between occurrences of diarrhoea during the first two weeks. The NC group had the fewest (0.1) followed by the pigs receiving the NEW diet (1.5), with piglets eating the PC feed having the highest occurrences of diarrhoea (2.6).

Through day 14 post weaning, piglets receiving the NC and NEW diets had higher body weights and average daily feed intake than pigs in the positive control group (Table 2). Animals on the NEW feed also tended to have higher ADG than piglets on the positive control diet. The new feed additive was shown to improve the performance and support the health of piglets following an E. coli challenge compared to a diet with a previously formulated feed additive blend.

Another study compared the performance of piglets receiving a diet with or without the blend of specialty ingredients while facing a S. typhimurium challenge. Piglets receiving the specialty ingredient blend had a reduced incidence of diarrhoea and a lower prevalence of salmonella colonisation, so supplementing the feed additive blend in the diet offered a tool to support animal health and performance and farm profitability (Figure 1).

Figure 1-Supporting immune function in piglets facing a salmonella challenge can reduce incidence of diarrhoea.

Discerning the data

Gut health, immunity, and economics are critical factors to manage on health-challenged farms. The Milkiwean Vital Start feeding programme includes specialty ingredients that nurture gut health and support immune system functions. Scientific research findings led formulators to enrich a tailored feeding program with a blend of specialty ingredients selected to support immune system functioning in the face of a gram-negative disease challenge. Trial findings show that supplementing piglet diets with these ingredients helped piglets retain gut function and faecal consistency. The data suggests that this specialty ingredient package and optimised diet may reduce bacterial colonisation, helping to prevent incidence of severe diarrhoea, reduce mortality rates, and support profitable pig production.

As part of a strategy to defend piglets from pathogenic bacteria, science-based nutrition can help support resilient pigs and efficient production.