Dietary carbohydrate to lipid ratio affects growth, reproductive performance and health of female yellow catfish (Pelteobagrus fulvidragrus): A lipidomics analysis

This study aimed to examine the impact of dietary carbohydrate to lipid (CHO/L) ratio on the growth, reproductive, and offspring performance of broodstock yellow catfish, and to elucidate the metabolic differences between mothers and offspring using lipidomics. Five isonitrogenous and isoenergetic diets with varying CHO/L ratios (0.65, 1.44, 2.11, 3.13, and 5.36) were fed to five groups of female broodfish with three replicates per group and 35 female broodfish per replocate in a pond-cage culture system. After an eight-week feeding trial, the dietary CHO/L ratio had a significant impact on the growth and reproductive performance of female yellow catfish. The weight gain ratio (WGR) and specific growth rate (SGR) in the CHO/L0.65 and CHO/L2.11 groups were significantly higher than those in the CHO/L5.36 group (P < 0.05). The fertilization and hatching rates were the highest when the dietary CHO/L ratio was 0.65 and 2.11, respectively. When the dietary CHO/L ratio was 3.13 and 5.36, the plasma contents of testosterone (T) was significantly lower than those of other groups (P = 0.013), and the plasma vitellogenin (VTG) content was the lowest when the CHO/L ratio was 5.36. The plasma contents of estradiol (E2) significantly decreased with increasing dietary CHO/L ratio (PL = 0.012). Lipidomic analysis revealed that the ovary primarily consisted of five subclasses in terms of lipid composition, namely triglyceride, fatty acyl, sterol, glycerophospholipid, and sphingolipid; however, sphingolipids were not detected in the larvae. The relative expression levels of the ovarian lipid metabolism-related genes sterol regulatory element binding protein 1 (srebp1), acetyl-CoA carboxylase (acc), delta (12)-oleate desaturase (fad2), and elongation of very long chain fatty acids protein 5 (elvol5) significantly increased with increasing dietary CHO/L ratio (P < 0.05). The relative expression levels of lipid metabolism-related genes srebp 1, peroxisome proliferator activated receptor α (pparα), carnitine palmitoyl transferase 1 isoform (cpt), adipose triglyceride lipase (atgl), fad2, and elvol5 in offspring larvae were initially increased and then decreased with increasing dietary CHO/L ratios until reaching a maximum at a ratio of 2.11 (P < 0.05). In conclusion, based on the broken-line regression of the dietary CHO/L ratio and egg diameter, the optimal dietary CHO/L ratio was 1.91 for broodfish yellow catfish. A high CHO/L ratio diet results in increased lipogenesis and hepatic lipid accumulation in maternal organisms, leading to impaired reproductive performance and reduced offspring quality.