Effects of enzymatic soybean phospholipid replacing soybean oil on growth performance, glycolipid metabolism and intestinal flora of largemouth bass (Micropterus salmoides)

Abstract

Enzymatic soybean phospholipids are single-chain fatty acyl phospholipid derivatives produced by the natural degradation of phospholipids by phospholipase enzymes by breaking the ester bond from the 1-position or 2-position, resulting in a mixture of phospholipids enriched in lysophospholipids. An 8-week feeding experiment was conducted to study the effects of enzymatic soybean phospholipid replacing soybean oil on growth performance, glycolipid metabolism and intestinal microflora of largemouth bass (Micropterus salmoides). The experiment was divided into 3 treatment groups with 3 replicates per treatment component. Each net contained 30 fish (Initial weight = 9.14 ± 0.04 g). A diet containing fish oil and soybean oil was used as the control (P0) and ESP replaced 30 % (P30) and 50 % (P50) of soybean oil in the other dietary groups. The results showed that the weight gain rate and protein efficiency ratio; amylase, lipase and trypsin in the intestine; and total antioxidant capacity, superoxide dismutase, hexokinase, glucokinase, 6-phosphate dehydrogenase and lipoprotein lipase activities in the liver were higher in the P50 group than in the P0 and P30 groups, while feeding rate, viscerosomatic index; total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol in the serum and malondialdehyde in the liver were lower than in the P0 group significantly (P < 0.05). The expressions of hormone-sensitive lipase, apolipoprotein A1 and fatty acid synthase in P50 group were higher than those in P0 and P30 groups, and the expressions of lipoprotein lipase, carnitine palmitoyl transferase, adipose triglyceride lipase and apolipoprotein B-100 in P50 group were higher than those in P0 group significantly (P < 0.05). Villi width, villi height and lamina propria thickness in P50 group were higher than those in P0 and P30 group, and lamina propria thickness in P30 group was higher than that in P0 group significantly (P < 0.05). The results of the intestinal flora showed that at the level of phylum, the relative abundance of Proteobacteria increased and that of Tenericutes and Firmicutes decreased in the P50 group compared to the P0 group. At the genus level, the relative abundance of Mycoplasma and Aeromonas decreased, and that of Plesiomonas increased in the P50 group compared to the P0 group. In conclusion, replacement of 50 % soybean oil with ESP significantly promoted the growth of largemouth bass, improved the antioxidant capacity of the organism, promoted carbohydrate utilisation and lipid metabolism, as well as enhanced the stability of the intestinal microflora.

Keywords

• Micropterus salmoides
• Enzymatic soybean phospholipid
• Lipid metabolism