Effect of Fermented Cottonseed Meal on the Lipid-Related Indices and Serum Metabolic Profiles in Broiler Chickens

Simple Summary: Excessive fat deposition in broiler chickens is detrimental for both producers and consumers. Fermented cottonseed meal (FCSM) was proposed as a potential method to relieve fat deposition in broilers' rearing, while the physiological and metabolic mechanisms behind that still remain unclear. This study showed that both abdominal fat content and subcutaneous fat thickness significantly decreased in response to dietary FCSM supplementation at the age of 21 d, and altered the lipid-related metabolites index in serum, liver, and abdominal fat. Moreover, serum metabolic pathways were clustered into organic acid metabolism, fatty acid metabolism, and amino acid metabolism. Abstract: This study aimed to investigate the changes of lipid-related gene and serum metabolites in broiler chickens fed with fermented cottonseed meal (FCSM) diet, through quantitative real-time PCR and metabolomics analysis. Totally, 180 1-day-old Cobb broilers were randomly assigned to two groups with six replicates of 15 birds in each. The two diets consisted of a control diet supplemented with 0% FCSM (CON group) and an experimental diet with 6% FCSM (fermented by Candida tropicalis) replacing the soybean meal (FCSM group). The results showed that both abdominal fat content and subcutaneous fat thickness significantly reduced (p < 0.05) in response to dietary FCSM supplementation at the age of 21 d. Serum concentrations of glucose, triglyceride, and low-density lipoprotein cholesterol decreased (p < 0.05) in FCSM fed broilers compared with CON fed broilers, while the levels of epinephrine and growth hormone in serum, liver and abdominal fat tissue were higher (p < 0.05) in FCSM than in CON fed broilers. The activity of hormone-sensitive esterase and lipoprotein lipase (LPL) in the liver and abdominal fat were higher (p < 0.05) in FCSM than CON group. Additionally, compared with the CON group (p < 0.05), the expression of peroxisomeproliferator-activated receptor alpha and LPL genes were upregulated in the livers of FCSM group broilers. Gene expressions of hormone-sensitive lipase and LPL in the abdominal fat tissue were also upregulated (p < 0.05) with the broilers fed with FCSM diets. A total of 20 significantly different metabolites were obtained in the serum of different dietary FCSM supplemented fed broilers. The mainly altered pathways were clustered into organic acid metabolism, fatty acid metabolism, and amino acid metabolism. These results not only provide a better understanding of broilers' lipid metabolism with FCSM but also can be helpful in further improvement of the broilers' healthy production and utilization of FCSM.