PS4-6. Effects of Water-based Yeast Bioactive Supplementation on Wean Pig Growth Performance and Health During the Nursery

Abstract Yeast-bioactive supplements are a promising alternative to antibiotics in the nursery stage, with research showing improved growth and health when given to piglets through the sow or in feed. This study aimed to determine if supplementing liquid yeast bioactives (LYB) via water medicator improves the health of weaned pigs during the nursery period based on blood markers of immune and general health. A total of 220 weaned pigs (PIC 1050 sow x DNA Duroc boar; 19 ± 2 d of age) were weighed and allocated to 44 pens, assigned to one of four treatments: 0 mL/L (control), 2.5 mL/L, 5 mL/L, 7.5 mL/L of LYB in a randomized complete block design. One pig per pen was euthanized via captive bolt on day 10. Before euthanasia, one plasma and one serum vacutainer of blood were collected for analysis of plasma urea nitrogen (PUN) and immunoglobulin A (IgA), respectively. After euthanasia, a jejunum sample was taken at the midpoint of the small intestine (2 cm in 40 mL of formalin). The samples were placed in wax blocks and H&E slides were prepared to determine villus height and crypt depth. Data was analyzed as a randomized complete block with pen location as the block. There was a quadratic response in serum concentration of IgA (445, 394, 347, 365 ± 33 μL/L in order of increasing LYB concentration, P = 0.06), villus height (326, 283, 256, 304 ± 22 μm, P = 0.01), and crypt depth (220, 185, 167, 202 ± 17 μm, P = 0.01), where CON pigs had the greatest values and the 5 mL/L group had the lowest. There was no difference in villus/crypt ratio (1.5 ± 0.2) or PUN concentration (6.6 ± 0.7 mL/L) between the groups. The general pattern of response in markers of immune and intestinal health followed a similar quadratic pattern, with CON pigs having the highest value and the 5 mL/L group having the lowest. The higher IgA concentration in combination with the greater villi and crypt values in the CON pigs may indicate greater intestinal stress or greater effort to manage antigens or pressure on the intestinal structure, supporting the hypothesis that LYB supplementation could improve the health of piglets in the nursery stage, particularly at a dose of 5 mL/L.