Metabolic Effects of Feeding Sow Bile to Nursery Pigs
Gallbladder bile, an underutilized-byproduct of the pork industry, is enriched with bile acids and other bioactive components. The surfactant function of bile acids is important for lipid digestion and absorption. The concentration of hyodeoxycholic acid (HDCA), a bile acid highly abundant in sow bile, has been shown to correlate positively with gestation and growth of young pigs, implying its growth-promoting function. However, the supplementation of sow bile to young pigs has not been explored in previous studies. This project examined the feasibility of feeding sow bile to nursery pigs as well as the metabolic effects of this supplementation. A total of 46 newly weaned pigs were divided into 6 groups with ad libitum access to 6 different experimental diets (one control and 5 bile treatment groups). During the 8-day feeding, feed intake was monitored daily, and pigs were weighed on days 0, 4, and 7. On day 8, serum, bile, intestinal digesta, and tissue were collected. Targeted metabolite analysis on bile acids, fatty acids, and amino acids and untargeted metabolomic analysis on nutrient and microbial metabolites in the digesta were conducted. The results showed that freeze-dried bile was well received by the nursery pigs and had dose-dependent effects on feed intake and growth. Moreover, bile supplementation dramatically increased the bile acid concentrations in all segments of the intestinal tract and improved protein digestion in the small intestine. Overall, sow bile has the potential to become a beneficial feed additive for nursery pigs.