This experiment aims to investigate the impact of probiotic feed on growth
performance, carcass traits, plasma lipid biochemical parameters, intramuscular
fat and triglyceride content, fatty acid composition, mRNA expression levels of
genes related to lipid metabolism, and the activity of the enzyme in Sunit
sheep. In this experiment, 12 of 96 randomly selected Sunit sheep were assigned
to receive the basic diet or the basic diet supplemented with probiotics. The
results showed that supplementation with probiotics significantly increased the
loin eye area, and decreased plasma triglycerides and free fatty acids,
increasing the content of intramuscular fat and triglycerides in the muscle and
improving the composition of the fatty acids. The inclusion of probiotics in the
diet reduced the expression of adenosine 5’-monophosphate-activated
protein kinase alpha 2 (AMPKα2) mRNA and carnitine palmitoyltransferase
1B (CPT1B) mRNA, while increasing the expression of acetyl-CoA carboxylase alpha
(ACCα) mRNA, sterol regulatory element-binding protein-1c (SREBP-1c)
mRNA, fatty acid synthase mRNA, and stearoyl-CoA desaturase 1 mRNA. The results
of this study indicate that supplementation with probiotics can regulate fat
deposition and improves the composition of fatty acids in Sunit sheep through
the signaling pathways AMPK-ACC-CPT1B and AMPK-SREBP-1c. This regulatory
mechanism leads to an increase in intramuscular fat content, a restructuring of
muscle composition of the fatty acids, and an enhancement of the nutritional
value of meat. These findings contribute to a better understanding of the food
science of animal resources and provide valuable references for the production
of meat of higher nutritional value.