The impact of Sarcocystis infection on lamb flavor meta bolites and its underlying molecular mechanisms

Kang Zhang ¹ Lamu DanQu ^2* Huan Teng ³ Li Zhu ³ Bin NI ¹ Jiewei Lai ¹ Shanshan Li ¹ Yunong Zhao ¹ Xiao Gou ^1*

• ¹ Foshan University, Foshan, China
• ² Institute of Animal Husbandry and Veterinary Medicine, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa, Tibet Region, China
• ³ College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan, China

Meat flavor is an important criterion for consumers to assess meat quality and a key determinant of market value. Sarcocystis spp. are a group of widely distributed parasitic protozoa, whose infection in livestock can result in reduced meat quality, fur, and fiber, leading to substantial economic losses. However, existing studies primarily focus on the pathogenic mechanisms and epidemiological features of Sarcocystis, with little research on its specific impact on meat quality and flavor, particularly its underlying molecular regulatory mechanisms. This study focused on Tibetan sheep to systematically explore the impact of Sarcocystis infection on meat flavor and its underlying molecular mechanisms using flavor metabolite analysis and transcriptomic approaches. Tibetan sheep with uniform rearing conditions were categorized into normal, low-infection, moderate-infection, and high-infection groups according to the degree of infection. Leg muscle samples were collected for flavor metabolite analysis and transcriptome sequencing. Differentially expressed metabolites (DEMs) and differentially expressed genes (DEGs) were identified, and KEGG pathway enrichment analysis was conducted to investigate how Sarcocystis infection regulates gene expression to influence lipid, amino acid, and energy metabolism, ultimately altering the production and accumulation of flavor metabolites. The findings revealed that the composition of flavor metabolites in Tibetan sheep meat underwent significant changes with increasing severity of Sarcocystis infection. Specifically, phenolic and acidic metabolites were markedly upregulated, intensifying bitterness and sourness, while ketone and lactone metabolites were downregulated, reducing fatty and creamy aromas. Transcriptomic analysis identified 574 DEGs, including upregulated genes such as MAPK12, COX6A2, and RXRA, which are involved in lipid metabolism, fatty acid oxidation, and thermogenesis, and downregulated genes such as COX2, COX3, and ADIPOQ, which are associated with mitochondrial function and energy metabolism. These gene expression changes disrupted lipid and amino acid metabolism, leading to imbalances in flavor compound synthesis and accumulation. This study systematically uncovered the significant effects of Sarcocystis infection on the meat flavor of Tibetan sheep and its underlying molecular mechanisms, providing new insights into the metabolic regulation induced by parasitic infection and offering a theoretical basis for mitigating the adverse effects of Sarcocystis infection on meat quality.