Accuracy of Techniques for Predicting Gas Production by Ruminants Associated with Diet

Round 1

Reviewer 1 Report

The compairson between the two different system is not really appropriate, there are some important lacks in the description of the methods. The difference between the volume of the bottles affect the pressure of the gas and the measurment. The article must be improved with those descriptions. Here, some detailed comments:

Materials and methods must be improved, it is not clear the difference between the two systems. 

abstract: line 22, delete "in the dispersion diagram"

m e m: line 89, explane what is p in the formula as you did for the other formula below.

Bachmann, Beuvink, detmann, nagadi, sudhir is not in the text. please check the references.

Author Response

Authors' general comments to reviewers.

We appreciate this very important comment. However, we emphasize that despite being different systems, the comparison between them becomes important so that we can be sure of the reproducibility and accuracy of the results when using different techniques.

In addition, despite having tested only two diets, the data are important as preliminary for further discussion about in vitro gas production techniques, given that both systems have advantages and disadvantages.

 

Comments reviewer 1:

Abstract: line 22, delete "in the dispersion diagram"

AU: We excluded.

 

Line 89

AU: We added the point as recommended.

We check all references and citations

Reviewer 2 Report

The paper is very well written, and compares the gas production profiles and nutrient degradability of two diets using automatic and semiautomatic in vitro gas production techniques. And the proposed scheme outperforms the state of the semiautomatic art can accurately detect gas production.

There are some problems, which must be solved before it is considered for publication. If the following problems are well-addressed, this reviewer believes that the essential contribution of this paper are important for gas emissions from ruminants.

1.     Problem with this paper is lack of sufficient explanation of the simulation results. You need to explain your simulation results in detail and why you got such results. Description in the results: Gas production from the fermentation of fiber carbohydrates (Vf2) was 22% higher when measured with the automatic technique than with the semiautomatic technique. However, table 1 shows that gas production is related to fiber content not measurement technology , which you did not give a reasonable explanation.

2.     Problem with this paper for the introduction part of the main text are very concise lack of enough information about different fiber content of the fermentation gas production.

3.     Another obvious problem with this paper is lack of data on fermentation products. We believe that ammonium nitrogen can not fully reflect the influence of dietary fermentation on gas production, and we are interested in knowing whether the fermentation products are more conducive to host digestion and absorption.

Author Response

Authors' general comments to reviewers.

We appreciate this very important comment. However, we emphasize that despite being different systems, the comparison between them becomes important so that we can be sure of the reproducibility and accuracy of the results when using different techniques.

In addition, despite having tested only two diets, the data are important as preliminary for further discussion about in vitro gas production techniques, given that both systems have advantages and disadvantages.

Comments reviewer 2:

1. Problem with this paper is lack of sufficient explanation of the simulation results. You need to explain your simulation results in detail and why you got such results. Description in the results: Gas production from the fermentation of fiber carbohydrates (Vf2) was 22% higher when measured with the automatic technique than with the semiautomatic technique. However, table 1 shows that gas production is related to fiber content not measurement technology, which you did not give a reasonable explanation.

 

2. Problem with this paper for the introduction part of the main text are very concise lack of enough information about different fiber content of the fermentation gas production.

 

3. Another obvious problem with this paper is lack of data on fermentation products. We believe that ammonium nitrogen can not fully reflect the influence of dietary fermentation on gas production, and we are interested in knowing whether the fermentation products are more conducive to host digestion and absorption.

 

AU: We appreciate this very important comment. However, despite some gaps that the work may have, we understand that its publication will be of great importance for the evaluation of feed for ruminants, given that there is no work comparing the semi-automatic system with the system developed by Ankom.

Reviewer 3 Report

The in vitro fermentation and gas production is an important index reflecting the rumen microorganisms’ fermentation degree of substrate nutrients. This study investigated the gas production profiles and nutrient degradability of two diets using automatic and semiautomatic in vitro gas production techniques. There are some problems with the analytical methods and tables forming in the manuscript, so major revisions are required to improve the quality of manuscript.

Abstract:

L28-29, The authors need to further describe the results of previous studies about the different potential of the two techniques for assessing the nutritional value of diets with different proportions of NFC.

Material and Methods:

Table 1, Why are there no minerals and premixes in the diet?

L76, crude protein mean PB?

L79-80, The author needs to supplement the statistical method of the total carbohydrate content and the nonfibrous carbohydrate content.

L106, Are there only two donor animals? Additionally, why are different feed sources included in the diet of the donor animals and the fermentation substrate?

L162-165, The author needs to supplement the statistical model for the data of gas composition and fermentation kinetics parameters. How to determine the significance of the main effects and interaction?

Results:

Table 2 and 3, The expression of main effects and interactions is complex in table, and the content of which is difficult for readers to understand.

Fig. 1D-F, Why analyze the correlation between two methods? Instead of chi-square test and degree of dispersion?

Fig. 2, Why analyze the knowledge that everyone knows? What is its purpose?

Discussion

The discussion includes a lot about gas pressure affecting the results of study, but no relevant data in the results.

Author Response

Authors' general comments to reviewers.

We appreciate this very important comment. However, we emphasize that despite being different systems, the comparison between them becomes important so that we can be sure of the reproducibility and accuracy of the results when using different techniques.

In addition, despite having tested only two diets, the data are important as preliminary for further discussion about in vitro gas production techniques, given that both systems have advantages and disadvantages.

Comments reviewer 3:

Table 1: Why are there no minerals and premixes in the diet?

AU: Dear reviewer, the idea of this work was not to test complete diets, but high and low fibrous carbohydrate diets, which is why we did not insert minerals and premixes in the diets.

Line 76.

AU: We added the point as recommended.

 

Line 106. Are there only two donor animals? Additionally, why are different feed sources included in the diet of the donor animals and the fermentation substrate?

AU: As we worked with animals with rumen fistula, the use of only two animals was given to comply with the ethics and animal welfare committee of the Federal University of Paraíba (UFPB) (CEUA nº 9866190719), authorizing only these.

 

Fig. 1D-F, Why analyze the correlation between two methods? Instead of chi-square test and degree of dispersion?

AU: We chose to use correlation between the two systems (automatic and semiautomatic) to verify any relationship within a wide class of statistical relationships that involves dependence between the two systems, indicating by the correlation coefficient (R) and by the P value obtained in the comparison between the two systems. It is possible to highlight the low relationship in both systems in Figure 1E, with low correlation. This low ratio is also confirmed in the dispersion of the two systems visualized in the boxplot (Figure 1H). We understand that the X² test can also be applied considering the data, but the response trend, even following another statistical approach, would be similar to what is already shown in the figures, for this reason, we chose to keep it that way, understanding that there will be no mistakes in the interpretation of results.

 

Fig. 2, Why analyze the knowledge that everyone knows? What is its purpose?

AU: We decided to present figure 2 to observe from what time the gas production from the different sources of carbohydrates would be significantly different.

Round 2

Reviewer 1 Report

M & M: please provide a better description of the two systems.

Author Response

In this response letter, we kept the reviewer's comments, and we presented our reply, immediately after. In the revised version of the manuscript, highlighted red text refers to the changes made.

 

Comments reviewer 1:

M & M: please provide a better description of the two systems.

AU: We added the point as recommended.

Reviewer 3 Report

After the author revised the manuscript, the quality of the manuscript was improved. However, there are still some questions in the manuscript which have not been replied.

Table 2 and 3, The expression of main effects and interactions is complex in table, and the content of which is difficult for readers to understand. The form does not meet the requirements of the "three-line form". In particular, the expression of interactions.

Authors provide literature on comparative methods using correlation analysis. The reasons provided by the author are hard to convince me.

Author Response

In this response letter, we kept the reviewer's comments, and we presented our reply, immediately after. In the revised version of the manuscript, highlighted red text refers to the changes made.

Comments reviewer 3:

1. Table 2 and 3, The expression of main effects and interactions is complex in table, and the content of which is difficult for readers to understand. The form does not meet the requirements of the "three-line form". In particular, the expression of interactions.

AU: In order to facilitate the visualization and understanding of the information regarding the significant interactions, we present it in the form of a figure (Figure 1A, 1B) which facilitates the visualization and interpretation by the readers and changes were also made in the results, lines 208 to 221.

 

2. Authors provide literature on comparative methods using correlation analysis. The reasons provided by the author are hard to convince me.

AU: The authors are grateful for the suggestions and information that, we complement the information present in Figure 2D, 2E, 2F, inserting the value of the chi-square test (X²) between the automatic and semi-automatic system, the value of the significance of the test from X² and then, the strength of the association was established using the Cramer's test, which ranges from 0 to 1.

We complement the description of the analyzes in the data analysis item (lines 182 to 189) and in the results of each figure lines 226, 228, 236.