Effects of Dietary Glutamate on the Growth Performance and Antioxidant Capacity of Juvenile Chinese Mitten Crab (Eriocheir sinensis)
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsI have carried out the revision of the manuscript assigned to me. In general terms, it seems to me that the study fulfills its purpose and is of interest to the scientific community related to the thematic area.
The methodology seems detailed and appropriate for the type of research carried out. In general, all methods used (dietary treatments, food preparation, experimental conditions and analysis) are well described. It would be good to include an argument about the sample size that could strengthen the statistics of the study. Regarding the results, they are clearly presented. There are contradictions regarding the effects of glutamate, which are presented as beneficial, but also without effect or negative. Although the above is discussed, this could be further explored. The discussion correctly carries out the analysis of the results with already published works. However, more detail could be given, including studies in which negative effects of glutamate have been observed.
I consider that it would be desirable to include more references that address the molecular mechanisms in which glutamate affects metabolism and antioxidant capacity, especially in crustaceans (if such exist). The above, because comparisons are made with works published mainly on fish. This would give stronger support to arguments about how glutamate can influence metabolic pathways in crustaceans.
Author Response
Responses to Reviewers' comments:
We thank the editor and reviewers to take their time to read and provide critical comments, which have improved greatly our manuscript. Kindly, find the point-point responses to reviewers’ comments for your action.
Comment 1: It would be good to include an argument about the sample size that could strengthen the statistics of the study.
Response 1: We thank the reviewer for this comment. We have supplemented the relevant information in the Lines 119, 127-128, 138-139, which reads “Four duplicate samples were analyzed for each treatment (n = 4).”
Comment 2: However, more detail could be given, including studies in which negative effects of glutamate have been observed.
Response 2: We thank the reviewer for this suggestion. We have supplemented this information in Line 226-232, which reads “Moreover, a previous study in the weaned piglet reported that diets supplementation with more than 3.2% glutamate reduced the growth performance of piglet and presented a toxicity effect [30]. On the other hand, dietary excessive concentrations of sodium glutamate caused the intestinal mucosa stress in fish [31]. The differences may be caused by species specificity. Unfortunately, it is difficult to find an article on glutamate toxicity effects in crustaceans. Therefore, it is necessary to further study the toxic effect of glutamate in shrimp and crab.”
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Dr Ye
Thank you for submitting your manuscript to Fishes. In this study, 0%, 1% and 2% glutamic acid were added to low protein (30%) and normal protein (35%) diets, respectively, to investigate the effects of glutamic acid on growth performance, antioxidant capacity and protein metabolism of juvenile Chinese crabs. It was found that dietary glutamate could not significantly improve the growth of Chinese mitten crab, but could improve the antioxidant capacity under low protein conditions. The experimental design of this paper is reasonable and beneficial to the actual production practice of Chinese mitten crab. However, the manuscript was subject to the following modifications before publication:
1. The experimental results in the manuscript should correspond to the pictures one by one. For example, add “(Figure 1)” on line 176.
2. The 180-line description of the manuscript “But At 30% protein level, dietary glutamate did not significantly affect the SOD of crabs (P > 0.05).” , should the 30% be changed to 35%?"
3. Lines 219-221 of the manuscript describe ”However, in the present study, dietary glutamate did not significantly affect the weight gain and specific growth rate. Moreover, dietary glutamate significantly decreased the growth of Chinese mitten crab.”Dietary glutamate had no significant effect on weight gain and specific growth rate. So why does dietary glutamate significantly reduce the growth of Chinese mitten crabs? On what basis?
In conclusion, we believe that your paper has the potential to make a good contribution to our journal. Therefore, we recommend that you revise your manuscript accordingly and resubmit it for further consideration. We appreciate your hard work and look forward to receiving your revised manuscript.
Author Response
Responses to Reviewers' comments:
We thank the editor and reviewers to take their time to read and provide critical comments, which have improved greatly our manuscript. Kindly, find the point-point responses to reviewers’ comments for your action.
Comment 1: The experimental results in the manuscript should correspond to the pictures one by one. For example, add “(Figure 1)” on line 176.
Response 1: We thank the reviewer for this comment. We have revised all these errors in the RESULTS SECTION.
Comment 2: The 180-line description of the manuscript “But At 30% protein level, dietary glutamate did not significantly affect the SOD of crabs (P > 0.05).”, should the 30% be changed to 35%?"
Response 1: We thank the reviewer for pointing out this minor error. We have revised this error.
Comment 3: Lines 219-221 of the manuscript describe” However, in the present study, dietary glutamate did not significantly affect the weight gain and specific growth rate. Moreover, dietary glutamate significantly decreased the growth of Chinese mitten crab.” Dietary glutamate had no significant effect on weight gain and specific growth rate. So why does dietary glutamate significantly reduce the growth of Chinese mitten crabs? On what basis?
Response 1: We suspect that the excessive glutamate can result toxicity effects. A similar previous study in the weaned piglet reported that diets supplementation with more than 3.2% glutamate reduced the growth performance of piglet and presented a toxicity effect [1]. On the other hand, dietary excessive concentrations of sodium glutamate caused the intestinal mucosa stress in fish [2]. Unfortunately, it is difficult to find an article on glutamate toxicity effects in crustaceans. Therefore, it is necessary to further study the toxic effect of glutamate in shrimp and crab.
References
[1] LI Y, HAN H, YIN J, et al. Effects of glutamate and aspartate on growth performance, serum amino acids, and amino acid transporters in piglets [J]. Food & Agricultural Immunology, 2018, 54(7): 1-13.
[2] LADEIRA A L F, RUSTH R C T, CARNEIRO C L D S, et al. Dietary monosodium glutamate supplementation during the feed training of pacamã (Lophiosilurus alexandri): Growth performance and intestinal histomorphometry [J]. Aquaculture Research, 2021, 52(1): 356-363.
