The Impact of Thermal Treatments up to 140 °C on Amino Acid Digestibility of Fish Meal in Rainbow Trout (Oncorhynchus mykiss)
, Judith Ringel 3, Carsten Schulz 4,5 and Martin Gierus 1,2,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsCould you please explain why the basal diet has the same protein level as the other diets but a lower lipid content?
I noticed that the vitamin/mineral mix and TiO2 levels differ between the basal diet and the other tested diets. Could you please clarify the reason for this difference?
What is the purpose of adding TiO2 in the diet?
Could you please explain the reason for the increase in crude protein levels in the various thermally treated fish meals?
Could you please explain why the dry matter content of fish meal increases at very high temperatures?
Could you please explain why the n 3 fatty acid content of fish meal increases at very high temperatures?
The conclusion section contains too many abbreviations. The authors are advised to write them out in full for better clarity.
Author, please justify this procedure "Faecal material was collected once a day (at 1:30 pm) by manual stripping of each fish for 28 days. Therefore, fish were transferred to a separate tank and anesthetized using clove oil (1 ml per 40 L of water). Subsequently, gentle pressure on the abdomen was applied to strip faeces out of the posterior intestinal area". This is completely unethical, as it will cause significant stress to the fish and could lead to biased results. It is concerning that the fish were anesthetized daily and then recovered to be used again in the experiment.
The authors are advised to provide a complete methodology for the determination of titanium rather than merely citing a reference, as it forms the basis of the digestibility study.
The authors have provided the methodology for the estimation of fatty acids but have not included the methodology for amino acids. They are requested to provide the complete methodology for amino acid analysis in the manuscript as well.
The abstract should be rewritten to include background information, followed by the hypothesis, results, and conclusion.
The title of the manuscript is not clear, and authors are suggested to revise the title of the manuscript.
Author Response
Please see attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authorsline 89 due to their ,,, sensitivity.....
line 122 with 150 l water capacity each.
line 126 mean weight one decimal , the accuracy is in the SD
line 134 the salinity 4.2% ??? means 42 %o , is this relevant for rainbow trout?
I have some major task, the stripping of fecal material every day has been tested before? no reference to a similar routine is presented.
No final weight is ever mentioned, which means fish lost weight?
does this result in skin lesions or stress response where the trial is not giving the expected results with longer treatment.
An experiment on duration of such routine should be performed .
Author Response
Please see attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsManuscript ID: fishes-3174195
The impact of thermal treatments on macro nutrient and amino acid digestibility of fish meal in rainbow trout (Oncorhynchus mykiss)
Authors: Pedro Henrique Sessegolo Ferzola, Judith Ringel, Carsten Schulz,Martin Gierus *
This paper deals with the effect of different temperature treatments on digestibility values.
Major comments.
1. The starting material of this experiment is freeze dried fish meal
I wonder why they examined using dried fishmeal instead of wet ingredients.
In a practical situation, fishmeal is processed from wet material, so there is great interest in how thermal treatment affects the nutritional value, such as digestibility of the material.
Conversely, how can current research findings be used in practical field?
2 The dry matter of 140C is higher than that of others. This variation could have influenced the calculation of ATTD (%).
Did the authors use dry matter basis values to calculate ATTD (%)?
Minor comments
l L. 105 …titanium dioxide (TiO2) as inert marker (Table1).
Ø Since it is noted as chemical formula in Table 1, it would be better to indicate chemical formula in the text as well.
l L. 229 …0.05) among FM…, and energy GE did not differ (p>0.05) in FM
Ø “GE” is used in the L144 instead of energy. Please be consistency in the terminology throughout the manuscript.
l L. 231 …140℃in comparison to FM 0℃ and 70℃ (Table 4).
Ø Should insert Table 4.
l L. 239-240 (Table 6)
Ø The significant notation of “a-b (p<0.10) “may not necessary because the authors did not mention ATTD of non-essential amino acids in Table6.
l L. 259 We observed a CP, and gross energy GE in FM.
Ø Same as L.229.
l It seems that following parts are missing a subject.
Ø L107 …protocol of *** (15) .
Ø L263 *** (16) reported…
Ø L270 *** (9) reported…
Author Response
Please see attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAuthors are suggested to revise the title of the MS as it is not reflecting anything that is present in the MS.
Still the conclusion section is not depicting the clear finding of this study. Authors are also advised not to exaggerate their finding in this section.
I see that authors have not included the methodology for TiO2 estimation in feed and feacal matter. Author must incorporate the same for better understanding by the readers.
Author Response
Reviewer 1
Authors are suggested to revise the title of the MS as it is not reflecting anything that is present in the MS.
Dear reviewer, we appreciate your suggestion, nonetheless the authors disagree with it. During the elaboration of the manuscript, the authors opted for this title – The impact of thermal treatments up to 140°C on amino acid digestibility of fish meal in rainbow trout (Oncorhynchus mykiss) – as thermal treatment refers to the main effect evaluated; amino acids to reflect the nutrients evaluated; and digestibility as the focus of the study. As ATTD is a methodology to evaluate the digestibility, we opted to write only digestibility to keep the title shorter, but maintaining the focus of the study.
Still the conclusion section is not depicting the clear finding of this study. Authors are also advised not to exaggerate their finding in this section.
Dear reviewer, we appreciate your suggestion. The authors have adjusted the conclusion section by rewriting the sentences and connection between paragraphs.
I see that authors have not included the methodology for TiO2 estimation in feed and feacal matter. Author must incorporate the same for better understanding by the readers.
Dear reviewer, we appreciate your suggestion. The methodology for TiO2 was added on the manuscript (from Line 149 to Line 161).
Reviewer 2 Report
Comments and Suggestions for Authorsyou dont obviously understand my salinity comment
1 % is 10 promille 0.1 vs 0.01
4.2% is 42 promille - more than Atlantic ocean salinity ! Please correct
the DHA % has to be investigated, there are most likely some inpurities in the peak. Could be an idea to rerun sample, including methylation
Thank you for the explanation on the fish status
Author Response
Reviewer 2
you dont obviously understand my salinity comment
1 % is 10 promille 0.1 vs 0.01
4.2% is 42 promille - more than Atlantic ocean salinity ! Please correct
Dear reviewer, thank you for your comment. Indeed, we have made a mistake during the description of the salinity and wrote the wrong unity. We have measured the salinity in ppt using HI 96822 Seawater Refractometer, Hanna Instruments Inc., Woonsocket-RI-USA. We have corrected this information in the text.
the DHA % has to be investigated, there are most likely some impurities in the peak. Could be an idea to rerun sample, including methylation
Dear reviewer, we appreciate your comment. Following your suggestion, we asked the lab to reevaluate the samples, and the results were consistent. Indeed, it is an intriguing result and we will organize new trials to deeper investigate this effect.
Thank you for the explanation on the fish status
Reviewer 3 Report
Comments and Suggestions for Authors The author has provided a reasonable explanation for the comments and considered it appropriate to accept the manuscript in its current form.
Author Response
comment: The author has provided a reasonable explanation for the comments and considered it appropriate to accept the manuscript in its current form.
answer: dear reviewer, thank you for your time to review this manuscript.
Round 3
Reviewer 2 Report
Comments and Suggestions for Authorsplease delete second decimal in Table 1 and 2
the accuracy is not relevant for the analytical data , the uncertainity is shown by the SD
Author Response
Reviewer 2
Comment: please delete second decimal in Table 1 and 2 the accuracy is not relevant for the analytical data , the uncertainity is shown by the SD.
Answer: Dear reviewer, thank you for the suggestion. Both tables have been corrected.
