Effects of Dietary Selenium Sources on Meat Quality, Tissue Selenium Deposition, and Transcriptome Profiling of Longissimus dorsi Muscle in Tibetan Pigs

The present study evaluated the effects of dietary selenium sources on growth performance, slaughter traits, meat quality, tissue selenium deposition, and transcriptomic profiles in the longissimus dorsi muscle of Tibetan pigs. Seventy-two Tibetan pigs (initial body weight: 41.96 ± 6.91 kg) were randomly allocated to four treatment groups receiving 0.5 mg/kg selenium as either sodium selenite (SeS), selenium-enriched yeast (SeY), selenium-enriched seaweed polysaccharide (SeSP), or nano-selenium (SeN) for 60 days. Results showed that neither growth performance nor slaughter traits differed significantly among the four treatments (p > 0.05). Likewise, meat quality parameters of the longissimus dorsi remained comparable across groups, with the exception of drip loss, which was significantly increased in the SeN group compared with the SeS, SeY, and SeSP groups (p < 0.05), among which no differences were observed (p > 0.05). Importantly, selenium contents in the kidney, liver, heart, and longissimus dorsi were markedly elevated in the SeY group relative to the other three groups (p < 0.05). Longissimus dorsi transcriptome analysis identified 34 overlapping differentially expressed genes (DEGs) among the three pairwise comparisons (SeS vs. SeY, SeSP vs. SeY, and SeN vs. SeY), such as S100A1, S100A6, and COL22A1 (p < 0.05). Functional enrichment analysis revealed that response to external stimulus and extracellular region (GO terms), as well as viral protein interaction with cytokine and cytokine receptor (KEGG pathway), represented shared enriched annotations across all comparisons. In conclusion, selenium-enriched yeast at 0.5 mg/kg proved superior to the alternative selenium sources in promoting selenium bioaccumulation in longissimus dorsi of Tibetan pigs. The resultant selenium-enriched muscle tissue exhibited potential beneficial functions including external stimulus response, extracellular region homeostasis, and cytokine–cytokine receptor crosstalk.