113 An organic acid blend containing the Ca salt of 2-hydroxy,4-methylthiobutanoic acid fed mid gestation through lactation may improve sow nutrient utilization and reduce offspring immune challenge.

Abstract A dry organic acid blend (DOA) containing the Ca salt of 2-hydroxy,4-methylthiobutanoic acid fed at 0% (Control), 0.3% (0.3% DOA) or 0.5% (0.5% DOA) from 50-d of gestation through lactation was evaluated. Initially, 100 sows were allotted to each treatment. Parities 1 through 6 were used with similar parity distribution across treatments. Average parity was 2.8, with 26% parity 1 sows and 67% being parity 1 to 3. Sow body weight, body weight change, litter size, and performance were measured. Plasma samples were taken from 20 sows per treatment across parities at gestation days 80 and 110 and on day 20 of lactation. Plasma samples were taken from 1 male and 1 female pig from the sow used for plasma sampling. Diets were corn-soybean meal-based with 0.66% SID Lys in gestation and 1.06% SID lysine in lactation. The 0.3% DOA and 0.5% DOA were fed as a top dress calculated based on individual sow intake. Sows averaged 1.85kg/d of intake day minus 50 – 85 and 2.6kg/d from day 85 to farrowing. Lactation intake began at 2 kg/d starting at +1-d post-farrow, reaching 8 kg/d by 7-d post-farrow. There were 11 removals prior to farrowing for the Control compared with 6 for the 0.3% DOA and 5 for the 0.5% DOA groups. DOA inclusion was associated with a reduction in bacterial causes of removal, including MMA and abortions. There was no effect of DOA dose on sow body weight change nor total born, born alive, or number weaned. Sows averaged 16.4 total born and 15.2 born alive. A lower litter (P=0.03) and piglet (P=0.05) ADG for the 0.3% DOA litters was observed compared with the other treatments, resulting in a lower (P=0.03) calculated milk yield. The wean-service interval for Control sows was 5-d, while 0.3% and 0.5% sows had a wean-service interval of 4.4 and 4.3-d, respectively (P=0.16). Lactation feed intake did not differ (P >0.10). DOA inclusion at 0.5% resulted in 16% lower (P< 0.01) plasma urea nitrogen (PUN) at d-110 of gestation, with 0.5% DOA also resulting in 12% lower (P=0.15) PUN at gestation d-80 and 14% lower PUN at lactation d-20 (P=0.24). The treatment did not affect NEFA, IGF-1, glucose, and measures of oxidative stress. For Control offspring, blood samples at day 18 had higher (P< 0.05) IL-12/IL-23p40 concentrations than 0.5% DOA offspring, indicative of higher macrophage and dendritic cell response to microbial infections. The higher IL-12/IL-12p40 concentration was reinforced by numerically higher (P >0.10) IFN-α and IFN-γ concentrations in the Control offspring. These results suggest that inclusion of a DOA containing the Ca salt of 2-hydroxy, 4-methylthiobutanoic acid may improve nitrogen utilization, particularly late gestation, as well as alter the level of immune challenge near weaning.