PS7-27. Methionine Hydroxy Analogue Bis-Chelated Trace Minerals Supplementation Results in More Diverse and Functional Fecal Microbiome Profile Compared with Inorganic Trace Minerals in Grow-Finish Pigs.

Abstract Methionine hydroxy analogue chelated trace minerals (MHAC; MINTREX® trace minerals) provides greater trace mineral availability than inorganic trace minerals (ITM). In swine, MHAC has been shown to improve nutrient retention and animal performance, including recovery from health challenges. However, MHAC effects on fecal microbiome in growing pigs are not fully characterized. This study evaluated MHAC compared with ITM on fecal microbiome composition and associated functional profiles in grow-finish pigs.A total of 80 pigs (TN70×TN Duroc; 40 barrows and 40 gilts) were used in a randomized block design. Pigs received a common nursery diet and were assigned to 1 of 2 dietary treatments during the grow-finish period: 1) ITM (ZnO, CuSO4, MnO; 100, 20, and 25 mg/kg, respectively) or 2) MHAC (Zn, Cu, Mn; 40, 10, and 20 mg/kg, respectively). Fecal samples were collected serially from the same 20 pre-identified pigs per treatment at d 0 (start of the growing phase; 31.2 ± 0.5 kg) and again on day 42 of the trial. Equal numbers of barrows and gilts were sampled across treatments. Microbiome analysis was performed using 16S rRNA sequencing. Diversity, richness, and robustness index (RI: 0 to 20 with 0 being extreme dysbiosis and 20 ideal microbiome profile; SAPIENS microbiome, Sao Paulo, Brazil) were evaluated. Microbiome data was compared against a performance-associated microbiome database to identify positive and negative biomarkers.Shannon diversity index decreased in pigs fed ITM from d 0 to d 42 (4.65 vs. 3.71; P < 0.05) whereas it numerically increased for MHAC (4.56 vs. 4.86). As a result, at d 42, pigs fed MHAC exhibited 31% greater microbial diversity (Shannon index; 4.86 vs. 3.71) compared with ITM (P = 0.011). Richness tended to be higher for MHAC compared with ITM (340 vs. 319 observed genera; P = 0.051). Although both treatment groups remained within a robust microbiome range, pigs fed ITM RI decreased from 13.56 to 11.25 whereas those fed MHAC RI remained constant (13.06 to 13.85). Further biomarker analysis showed that MHAC had lower relative abundance of negative microbial biomarkers compared with ITM (16.08% vs. 19.72%, respectively), while maintaining a more favorable positive-to-negative biomarker balance (24.85% vs. 20.31% for positive biomarkers). Functional inference indicated that MHAC supported a more balanced microbial profile, whereas ITM was associated with greater representation of inflammatory and pathogenic-related functions. In conclusion, replacing ITM with lower inclusion levels of MHAC trace minerals improved fecal microbiome diversity, stability, and overall biomarker balance in grow-finish pigs. These findings are consistent with the improved growth performance observed in the growth assay portion of this study.