The objective of the present research was the examination of how varying proportions of an acorn diet affects the deposition of subcutaneous fat and the composition of fatty acids (FAs) in Yuxi black pigs. Ninety pigs (with a balanced sex ratio and a similar weight 99.60 ± 2.32 kg) were stochastically assigned to the control group (CON) and the dietary acorn experimental groups (AEG). The CON was fed basal diets and the AEG1, AEG2, AEG3, and AEG4 groups were provided with dietary regimens comprising twenty, thirty, forty, and fifty per cent acorns, respectively. Each group consisted of six pigs, with three replicates. The breeding cycle was four months. The results demonstrated that, in comparison with the CON group, the lean meat rate was significantly increased in all test groups (p < 0.05), while in backfat thickness, loin eye area, carcass weight and slaughter rate was no significant difference (p > 0.05). The serum TC/HDL (total cholesterol divided by high-density lipoprotein-cholesterol) and TG/HDL (Triglyceride divided by high-density lipoprotein-cholesterol) levels in the AEG1 and AEG2 groups were significantly lower than the CON group (p < 0.05). There was no significant effect on the composition of FAs (p > 0.05). The number of fat cells in subcutaneous back fat and subcutaneous abdominal fat was significantly increased, and the area of fat cells was decreased (p < 0.05). Furthermore, the levels of ATGL and HSL expression in the subcutaneous back fat, as well as ACC, FAS, ATGL, PPARγ, and HSL expression in the subcutaneous abdominal fat, were significantly increased in the AEG2 group compared to the CON group (p < 0.05). Additionally, the expression of ACC, FAS, FABP4, PPARγ, C/EBPα, and FAS/HSL in the subcutaneous back fat, as well as FABP4, C/EBPα, and FAS/HSL in the subcutaneous abdominal fat, were significantly lower in the AEG2 group compared to the CON group (p < 0.05). In conclusion, it has been found that a 30% acorn diet can inhibit subcutaneous fat deposition and enhance the nutritional value of pork and the health of Yuxi black pigs.

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.