Abstract: 【Objective】 This study aimed to investigate the effects of curcumin and its primary metabolite,tetrahydrocurcumin,on growth performance,backfat thickness,and transcriptomic gene expression in finishing pigs,and to compare their regulatory mechanisms in backfat deposition.【Method】 Thirty Duroc×Landrace×Yorkshire fattening pigs were selected and divided into the control group (basal diet),the curcumin group (with 300 mg/kg curcumin added to the basal diet),and the tetrahydrocurcumin group (with 300 mg/kg tetrahydrocurcumin added to the basal diet) based on the principle of consistent body weight.There were 10 pigs in each treatment group,and the experimental period was 28 d.After the experiment,the initial body weight,final body weight and feed intake of pigs in each group were counted.Blood was collected through the anterior vena cava to detect blood lipid levels,the backfat thickness of carcasses was measured,and backfat samples were collected for morphological analysis and counting the size of dorsal adipocyte area.Western blotting was used to analyze the expression of fat metabolis-related proteins.High-abundance genes and DEGs were analyzed by transcriptome sequencing,and the molecular mechanism of back fat deposition was explored by combining GO functional enrichment and protein-protein interaction analysis.【Result】 Compared with the control group,the addition of tetrahydrocurcumin in the diet significantly reduced the average daily feed intake,backfat thickness,and the size of back adipocytes of fattening pigs (P＜0.05).Western blotting analysis showed that the expression of FASN in the back fat of fattening pigs in both the curcumin group and the tetrahydrocurcumin group decreased significantly (P＜0.05).The transcriptomic results showed that the DEGs of dorsal fat in the curcumin group were mainly enriched in regulating metabolic pathways such as hydrogen peroxide reaction and cell migration. The DEGs of dorsal fat genes in the tetrahydrocurcumin group were mainly enriched in regulating pathways such as protein catabolism and cholesterol excretion.The genes significantly upregulated in the tetrahydrocurcumin group were mainly enriched in fat metabolism-related pathways such as mitochondrial electron transport-cytochrome C to oxygen,and proton-driven ATP synthesis.Further GO functional enrichment and protein-protein interaction network analysis were conducted on the DEGs，the genes that were significantly elevated in the dorsal fat of the tetrahydrocurcumin group were mainly enriched in fat metabolic-related pathways such as oxidative phosphorylation and thermogenesis.The top-ranked genes in the protein-protein interaction network nodes were the mitochondrial electron transport chain-related genes：COX5B,COX7A1,COX6C,NDUFA7,and NDUFA1.【Conclusion】 At the same dose,tetrahydrocurcumin was more effective than curcumin in reducing fat deposition in fattening pigs.Adding 300 mg/kg of tetrahydrocurcumin to the diet of fattening pigs significantly reduced backfat thickness by enhancing the oxidative phosphorylation ability of dorsal fat mitochondria in fattening pigs,reducing the size of adipocytes.

Key words: finishing pigs; curcumin; tetrahydrocurcumin; backfat thickness; transcriptome