Suckling Induces Differential Gut Enzyme Activity and Body Composition Compared to Feeding Milk Replacer in Piglets

SIMPLE SUMMARY: Large litters have resulted in a surplus of piglets, and there is therefore a need for alternative management tools. Currently, nurse sows (i.e., sows rearing surplus piglets) are the primary solution; however, this means that the sows are contained for a longer period. In addition, a larger proportion of small piglets are born with special needs i.e., extra warmth, energy, etc. This makes it important to investigate alternatives to normal rearing practices in order to ensure piglet welfare to decrease mortality and morbidity in the farrowing unit, as well as in the weaner unit to assure the optimal welfare in pig production. The study showed that piglets could be artificially reared without detrimental effects on the immune system and growth; however, there is a need for further research on optimizing the nutrient composition for artificially reared piglets and the subsequent consequences at weaning. ABSTRACT: The aim of this study was to investigate differences in growth, hematology, metabolism, small intestine (SI) morphology, and enzyme activity of sow-reared piglets (SOW) compared to artificially reared piglets (MILK) given milk replacers in two different environments. Thirty-six piglets were selected at birth based on their birth weight; eighteen were kept on a commercial farm, another eighteen transferred to an animal research facility for artificial rearing. Differences were observed in enzymatic activity, with a larger amount of sucrase in the SOW compared with MILK group across the SI. SOW piglets also had a body composition with a larger amount of fat, muscle, and bone mass content. Differences in hematology were observed, suggesting environmental influences, biochemistry differences reflective of the diets given, and finally, an increased dry matter (DM) intake in SOW piglets was estimated. No differences were observed in immune function and only small differences in the gut integrity were found between the two groups. It can be concluded that body composition and enzyme activity can be manipulated through dietary intervention and that an increase in DM during lactation is beneficial for gut function. The study warrants further investigation into what this means for the subsequent weaning period.