Effects of Acorns on Subcutaneous Fat Deposition in Yuxi Black Pigs by Transcriptomic Analysis

Background/Objectives: The backfat thickness of pigs is closely related to dorsal subcutaneous fat deposition and meat quality, and appropriate reduction in backfat thickness is important for improving pork quality. The present study investigated the effect of acorn diet on the backfat thickness and lipase activity of Yuxi black pigs and to gain further insight into the molecular mechanism of the acorn diet on the dorsal subcutaneous fat deposition of Yuxi black pigs by transcriptome sequencing (RNA-seq). Methods: Thirty-six Yuxi black pigs with an initial body weight of 99.60 ± 2.32 kg (three replicates per group and six pigs per replicate) were randomly divided into two groups (CON group was fed a basic diet and AEG group was fed 30% acorn diets). Pigs were individually fed twice daily and had access to water ad libitum throughout the experiment. The test period was 4 months. Results: Results showed that backfat thickness and ACC, MDH, and LPL lipase activities were significantly reduced in the AEG group than in the CON group (p < 0.05). In addition, RNA-seq identified 826 differentially expressed genes (DEGs), with 505 up-regulated and 321 down-regulated. The DEGs were significantly enriched in the lipid metabolism process and lipid catabolic process, fatty acid (FA) catabolic process, and FA β-oxidation according to GO enrichment analysis. LEP, CHPT1, UCP3, ACOX1, SCD5, and ACAA1 were screened as key differential genes regulating dorsal subcutaneous fat deposition. Conclusions: The above results indicated that feeding the 30% acorn diet could regulate the expression of genes involved in fat deposition and reduce lipase activity, thereby decreasing the backfat thickness, inhibiting the deposition of dorsal subcutaneous fat, and improving the pork quality. The findings of this experiment established a basis for subsequent research into the molecular mechanisms underlying the impact of acorn diets on fat deposition in Yuxi black pigs and provided the scientific evidence to promote the exploitation and industrialization of acorns.