Replacement of dietary fish meal with Clostridium autoethanogenum meal on growth performance, intestinal amino acids transporters, protein metabolism and hepatic lipid metabolism of juvenile turbot (Scophthalmus maximus L.)

Abstract

Clostridium autoethanogenum meal (CAM) is a novel single-cell protein, which is produced from bacteria using carbon monoxide (CO) as sole carbon source. To evaluate the efficiency of CAM as an alternative for dietary fish meal, a 56-days growth experiment was performed on juvenile turbot (Scophthalmus maximus L.) with initial average weight of 9.13 ± 0.02 g. Six iso-nitrogenous (crude protein, 51.0%) and iso-lipidic (crude lipid, 11.5%) diets were formulated with 0%, 15%, 30%, 45%, 60% and 80% dietary fish meal protein substituted by CAM protein, which were designated as CAM0 (the control group), CAM15, CAM30, CAM45, CAM60 and CAM80, respectively. Results showed that no significant differences were observed in survival rate (over 97.50%) among different dietary treatments (p > 0.05). The specific growth rate (SGR) was not significantly affected when replacement levels of dietary fish meal with CAM were less than 45% (p > 0.05). The feed intake (FI) was significantly linear reduced with increasing dietary CAM (p < 0.05), whereas no significant differences were observed in feed efficiency ratio (FER), protein efficiency ratio (PER) and protein retention (PR) among different dietary treatments (p > 0.05). With increasing dietary CAM, lipid retention (LR) and carcass lipid tended to be increased in both significantly linear and quadratic patterns (p < 0.05). The apparent digestibility coefficient (ADC) of crude protein and some essential amino acids, including threonine, valine, lysine, histidine and arginine, showed significantly linear increase with increasing dietary CAM (p < 0.05). Furthermore, with the increase of dietary CAM, the gene expression of intestinal peptide and amino acids transporters was first up-regulated and then down-regulated with significantly quadratic pattern (p < 0.05), peaking in fish fed with diets CAM30 or CAM45, which was similar to the expression of genes related protein degradation in muscle. For genes related to protein metabolism in liver and muscle, the expression of mammalian target of rapamycin (mtor) was not significantly affected by dietary CAM, while the general control nonderepressible 2 (gcn2) tended to be first up-regulated and then down-regulated with significantly quadratic pattern (p < 0.05). Apart from that, the lipid metabolism of turbot was also affected by high dietary CAM, evidenced by increased expression of hepatic genes related to lipogenesis as well as reduced expression of genes related to lipid oxidation and lipid transport. In conclusion, CAM can replace up to 45% fish meal protein in diet for juvenile turbot without significantly adverse effects on growth performance. But excessive dietary CAM would result in significant growth reduction, and excessive lipid deposition may also occur in fish fed diets with high levels of CAM.

Effects of Clostridium autoethanogenum protein on growth performance, intestine and liver health of turbot Scophthalmus maximus during grow-out phase

“…The present work together with previous work on juvenile turbot (Zheng et al 2022) and M. salmoides (Ma et al 2022) proved that CAP disturbed the sh lipid metabolisms. Dietary CAP decreased the plasma triglyceride and cholesterol levels in all three works.…”

“…In turbot with body weight of 9.13 g, CAP was proved to replace 45% of shmeal protein (Zheng et al 2022). Researches on L. crocea and M. salmoides showed that sh size is one of the key factors decided the optimal dietary level of CAP within the same sh species.…”

Effects of Tributyrin Supplementation on Growth Performance, Intestinal Digestive Enzyme Activity, Antioxidant Capacity, and Inflammation-Related Gene Expression of Large Yellow Croaker (Larimichthys crocea) Fed with a High Level of Clostridium autoethanogenum Protein

“…As a type of singlecell protein (SCP), CAP has pleasant quality of high protein content and balanced profile of amino acids, showing great potential to replace fish meal. The studies on largemouth bass (Micropterus salmoides) (CAP replacement level ≤ 43%) and juvenile turbot (Scophthalmus maximus L.) (CAP replacement level ≤ 45%) suggested that an appropriate level of CAP replacing fish meal did not have a significant negative effect on growth performance [4,5]. However, fish growth performance was compromised by a high level of CAP replacing fish meal in diets.…”

“…To date, extensive studies have been conducted on large yellow croaker in the nutritional requirements and replacement of fish meal [24][25][26]. Based on the research on carnivorous fish including largemouth bass [4,27], turbot [5], and large yellow croaker [7], we supposed that 45% may be a high level of CAP replacement. To make CAP more widely applied, growth performance, intestinal digestive enzyme activity, antioxidant capacity, and inflammation-related gene expression were evaluated in large yellow croaker fed with different levels of tributyrin supplementation in a high-CAP diet.…”

“…Vitamin C was supplied in the form of vitamin C polyphosphate 4. Mineral premix (mg/kg diet), MgSO4 •7H 2 O, 1200; FeSO 4 •H 2 O, 80; ZnSO 4 •H 2 O, 50; CuSO 4 •5H 2 O, 10; MnSO 4 •H 2 O, 45; CoCl 2 •6H 2 O, 50; Na 2 SeO 3 , 20; H 2 CaIO 4 , 60; zeolite powder, 13485 5. Attractant, glycine and betaine 6.…”