Using Nutritional Strategies to Shape the Gastro-Intestinal Tracts of Suckling and Weaned Piglets

SIMPLE SUMMARY: Throughout the world, piglet mortality and morbidity in large litters are a major welfare concern and source of economic losses. Gastro-intestinal problems rank amongst the highest causes of morbidity, mortality and antimicrobial use. As evidenced in the recent literature, nutritional interventions before and after weaning can modulate gut development, thereby reducing the risk of gastro-intestinal problems. In particular, early-life nutrition has begun to receive increasing interest, given its potential to modulate gut health in the long-term. The literature nevertheless contains little information on how pre-weaning and post-weaning nutritional strategies can be combined to sustain optimal gut health throughout the challenging process of weaning. To address this gap in current knowledge, this review summarises a large body of literature on nutritional strategies aimed at supporting gut health in piglets, combining individual strategies into a structured nutritional approach over time, starting from a few days after birth to 5–6 weeks post-weaning. The review also contains propositions concerning potential avenues for future research that may contribute to the reduction in gastro-intestinal problems and the associated use of antimicrobials in the pig industry. ABSTRACT: This is a comprehensive review on the use of nutritional strategies to shape the functioning of the gastro-intestinal tract in suckling and weaned piglets. The progressive development of a piglet’s gut and the associated microbiota and immune system offers a unique window of opportunity for supporting gut health through dietary modulation. This is particularly relevant for large litters, for which sow colostrum and milk are insufficient. The authors have therefore proposed the use of supplemental milk and creep feed with a dual purpose. In addition to providing nutrients to piglets, supplemental milk can also serve as a gut modulator in early life by incorporating functional ingredients with potential long-term benefits. To prepare piglets for weaning, it is important to stimulate the intake of solid feed before weaning, in addition to stimulating the number of piglets eating. The use of functional ingredients in creep feed and a transition diet around the time of weaning helps to habituate piglets to solid feed in general, while also preparing the gut for the digestion and fermentation of specific ingredients. In the first days after weaning (i.e., the acute phase), it is important to maintain high levels of feed intake and focus on nutritional strategies that support good gastric (barrier) function and that avoid overloading the impaired digestion and fermentation capacity of the piglets. In the subsequent maturation phase, the ratio of lysine to energy can be increased gradually in order to stimulate piglet growth. This is because the digestive and fermentation capacity of the piglets is more mature at this stage, thus allowing the inclusion of more fermentable fibres. Taken together, the nutritional strategies addressed in this review provide a structured approach to preparing piglets for success during weaning and the period that follows. The implementation of this approach and the insights to be developed through future research can help to achieve some of the most important goals in pig production: reducing piglet mortality, morbidity and antimicrobial use.