Spirulina Supplementation Improves Lipid Metabolism And Autophagic Activities In The Liver And Muscle Of Hu Lambs Fed A High-Energy Diet

The current study aimed to examine the effects of dietary spirulina supplementation in high-energy (HE) diets on fatty acid metabolism in sheep, and preliminarily explored the potential mechanisms underlying the associated autophagy-mediated regulation of lipid metabolism. In a 2 x 3 factorial design, including six treatment combinations of two metabolisable energy diets (10 and 11 MJ/kg DM), three spirulina supplementation levels (0, 1%, and 3%) were used. Serum alanineaminotransferase (ALT) (p= 0.003) and aspartatetransaminase (AST) (p= 0.002) activities increased, whereas total PUFA content (p< 0.001) decreased in the liver of lambs fed a HE diet. With the addition of spirulina, serum ALT (p= 0.037) and AST (p= 0.014) activities decreased, whereas EPA (p= 0.004), GLA (p= 0.019), n-6 PUFA (p= 0.005), and total PUFA contents (p= 0.019) increased. Moreover, the crude protein content in theLongissimus thoracis et lumborum(LTL) increased (p= 0.013), the expression ofPPAR alpha andPPAR gamma was up-regulated, whileELOVL2was down-regulated in liver and LTL (p< 0.05). Spirulina supplementation increased mRNA expression levels of autophagy-associated genes, including that ofBeclin-1, AMPK, andULK1(p< 0.05). In conclusion, spirulina supplementation in a HE diet exerted a protective effect on the liver, increased PUFA content, and modulated expression levels of autophagy-related genes in growing lambs.