A Systematic Review of Liquid Milk Supplementation in Pre-weaned Piglets

The global pork industry has made significant genetic improvements over the last 30 years and nearly doubled the number of piglets born alive per sow; however, the percentage of pigs weaned has not increased proportionally with the number of live-born piglets. This pre-weaning loss represents a major economic and welfare challenge. While most pre-weaning mortalities are primarily attributed to crushing, it is well understood that chilling, undernutrition, and dehydration also have substantial impacts, offering a pathway to potentially mitigate pre-weaning mortalities with nutritional strategies. A systematic review was conducted of the available literature regarding the provision of liquid milk supplements to pre-weaned piglets in addition to sow milk. The review included only peer-reviewed articles in English with the full-text available and all years of publication and geographic origin were included. The search was conducted using Google Scholar and Web of Science. After screening, a total of 40 articles were selected for review, of which a subset of 21 articles pertaining specifically to milk product supplementation were included in this abstract. In the resultant literature body, supplemental milk was provided in either reconstituted liquid or powdered form. Results reported that supplying supplemental liquid milk replacer reduced pre-weaning mortality in large litters (≥15 piglets) and increased average weaning weights, with differences ranging from .2 to 2.0 kg per pig. The milk supplement may also aid in reducing incidence of diarrhea in both the pre-weaning and early post-weaning period. Liquid milk replacer improved intestinal immune function, microbiota composition, and metabolite concentrations. There were mixed effects of milk replacer on organ weights, intestinal length, and ratio of villus height to crypt depth, though no negative effects were reported. Nine of the 21 articles pertaining to milk supplementation measured post-weaning parameters. It was generally reported that there were no observed effects of pre-weaning milk supplementation on post-weaning growth performance. In conclusion, providing liquid milk replacer to pre-weaned piglets has the potential benefit of reducing pre-weaning mortality and increasing growth performance during the pre-weaning stage, resulting in more and heavier piglets weaned that will potentially be better adapted to manage the stressors of weaning.