Piglet Health Starts In-Utero: How to Develop Immune Competency in Piglets Before and After Birth

Swine production faces constant and evolving challenges to produce pigs more sustainably, achieve higher welfare standards to meet animals needs and consumer demands as well as being cost-effective. While demands are increasing, traditional tools used to tackle production challenges—such antibiotics and therapeutic zinc oxide—are being restricted in many parts of the world due to the threat of antibiotic resistance. At the same time, advances in genetics have led to a trend of hyper prolificacy in sows, which poses additional challenges. Higher numbers of piglets born per sow per year has resulted in larger variation in piglet birthweight more metabolic challenges on the sow which, in turn, impacts the onset of colostrum and milk production, thus increasing the risk of less robust piglets at weaning and performance losses later in life.

Figure 1. DSM’s multi-component nutritional approach to optimize piglet’s immune competency development

Immune competence has numerous development paths including vaccination programs to protect against pathogens, biosecurity to control the exposure to disease-causing agents, and nutritional support to optimize resistance and mitigate against the risk of antigens. Vaccinations are effective but are energetically costly due to the associated immune response, justifying its use only in virulent pathogens that cause high mortality rates. Therefore, balanced nutrition is a prerequisite for maintaining good health status and optimizing piglets’ own immune system.

Systemic immune competency development of a newly born piglet is highly dependent on the nutrition of the sow, starting in-utero and continuing with good quality and quantity of colostrum and milk. Therefore, a sow’s nutrition, health, and the ability to transfer it to the piglets are key to their early and robust immune system. Micronutrients including some vitamins such as D3, E, C and various B vitamins, as well as minerals are known to have immunomodulatory benefits. Piglets are born with low levels of blood vitamins and the high demands on these vitamins to support immune development and activation often result in piglets that are deficient. Considering the greater demands on the modern sow to rear a larger litter, there is a need for a more precise micro-nutrition approach to sow nutrition during late gestation and lactation to support the optimum colostrum quality and yield.

To function effectively, the systemic immune system needs to be both proficient at immune cell proliferation and regulation​ and protected from cell damage due to redox imbalance.  Vitamins E and C have long since been recognized for their ability to act as potent antioxidants that prevent oxidative damage of immune cells. Piglet viability can be enhanced through optimum vitamin E supplement of sows through gestation and into lactation (Wang et al., 2017). More recently, the role of vitamin D₃ or, more importantly, its main metabolite, 25-hydroxy (OH) vitamin D3 in immunomodulation is just starting to be understood. One of vitamin D₃ primary roles is not only to support the activation of immune cells and production of antimicrobial peptides but also to limit excess responses. Pigs are born with very low levels of blood 25-OH vitamin D3 which seldom reach the minimum much less the optimum range to support immunity. Now understanding the critical role of vitamin D₃ in immune function, piglets can be at a disadvantage without adequate vitamin levels. Konowalchuk et al. (2013) reported that supplement of vitamin D₃ and the 25-OH vitamin D₃ form in particular increased immune cell number and activation in weanling pigs.

The local gut associated lymphoid tissue (i.e., gut lumen content) has a critical role to play in the defense of the piglet’s body from the outside environment. Its development is driven by the early establishment of a diverse and stable gut microbiome whose magnitude and impact are now believed to extend even beyond the gut to the development of immune tissue in other organs such as the lungs, however these mechanisms are still poorly understood. The development of the gut microbiome of piglets begins as soon as they leave the sterile conditions of the uterus and are largely influenced by the microbiome of the sow and her immediate environment. Microbial colonization tailors gastrointestinal development and modulates epithelial barrier function which is the first line of defense. Early microbial colonization also modulates innate and adaptive immune responses, thus influencing the host’s ability to mount adequate inflammatory responses and to resist disease. Developing and maintaining a stable and diverse gut microbiome is critical to pathogen resilience and optimum functioning of the gut in an environment of reduced medication. There are numerous nutritional tools available to support the development of a balanced bacterial community in the gut. The administration of probiotics such as Enterococcus faecium appears to be most successful when administered to both the sow during the end of gestation and lactation to direct early engraftment of benefit strains in the developing but still malleable gut microbiome. Another strategy to support a healthy gut microbiome of the sows and consequently benefit the piglets is by improving fiber digestibility. Xylanases increase the supply of prebiotic fibers and energy, crucial during the negative energy balance period over lactation.

To prepare piglets to overcome challenges associated with weaning and beyond, it is vital to develop immune competency as early as possible through a multi-component nutritional approach. Before birth, optimized vitamin E, C and D nutrition of sow improves the vitamin serum status of piglets at birth as well as colostrum quality resulting in better passive immunity and litter performance​. Around birth​, shaping early microbial colonization of the piglet gut with beneficial microbes such as probiotics is crucial to boosting immune competency and avoiding diarrhea​. During lactation​, ensuring the correct levels of vitamin D in sows optimizes the vitamin supply in colostrum and milk; probiotics stimulate early piglet gut colonization and reduce the incidences of diarrhea during the suckling period; and xylanases increase net energy supply via improved fiber digestibility, producing postbiotic such as short chain fatty acids, with the result of robust and heavier piglets at weaning.