Adding Condensed Tannins to High-Concentrate Diets: Effects on Rumen Fermentation and Tympanism in Goats

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title: The Effects of Adding Condensed Tannins to High-Concentrate Diets on Rumen Fermentation and Rumen Bloat in Goats

By: Wang et al.

ID: fermentation-3507129

General Comments

The manuscript presents a valuable study on the effects of condensed tannins (CT) in reducing rumen bloat in goats fed high-concentrate diets (HCD). It is well-structured, incorporating both in vitro and in vivo experiments, and offers important insights into ruminal fermentation dynamics and bloat prevention. The methodology is sound, featuring appropriate statistical analyses and a thorough discussion of findings. However, several aspects need refinement to improve clarity, scientific rigor, and overall impact. Addressing these issues will strengthen the manuscript’s scientific contribution and practical relevance. A major revision is recommended, particularly to enhance the justification of experimental design, clarify mechanistic explanations, and provide a more detailed microbial analysis. Improving the discussion and methodology sections will significantly enhance the study’s impact.

Major Concerns and Suggested Revisions

1. The introduction does not explicitly state the hypothesis. Clearly defining the expected outcomes (e.g., reduction in bloat incidence, improvement in fermentation efficiency) would enhance the study’s scientific rigor.
2. The selection of 1%, 2%, and 3% CT levels is reasonable, but the manuscript lacks justification based on prior studies or preliminary experiments. Why were these specific concentrations chosen?
3. The discussion mentions that 2% CT was the most effective, but it remains unclear whether higher levels (e.g., 3%) have diminishing or adverse effects. Additional discussion on why 3% CT did not further reduce foam retention would be beneficial.
4. The manuscript attributes foam stability to proteins in the 38-52 kDa range but does not explore whether these proteins originate from microbial activity or dietary sources.
5. Could alternative mechanisms, such as CT’s impact on surface tension or microbial exopolysaccharides, contribute to the observed effects? More discussion is needed on potential physicochemical interactions.
6. The 16S rRNA sequencing data indicate no significant changes in microbial diversity, yet CT affected fermentation parameters (e.g., VFA production). Were there changes in specific microbial populations (e.g., fibrolytic bacteria, methanogens)?
7. A deeper analysis of microbial shifts and their metabolic implications would strengthen the findings.
8. While bloat scoring was performed, details on observer consistency and validation of the scoring system are missing.
9. Was the scoring method subjective, or was an objective measurement (e.g., rumen pressure, ultrasound) considered?
10. The study concludes that CT supplementation is safe, but longer-term effects on feed efficiency, metabolic health, and animal performance are not addressed.
11. Could CT interact with other dietary components or cause anti-nutritional effects over time?

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript ID : Fermentation-3185785
Title: The Effects of Adding Condensed Tannins to High-Concentrated Diets on Rumen Fermentation and Rumen Bloat in Goats
This manuscript brings an approach to an important issue for the ruminant production system. The inclusion of high levels of concentrate is being increasingly in the diets of these animals and solutions/ understanding for problems caused by these high levels of grains in the rumen, especially tympanism, are necessary.

Requests and suggestions to authors:
Correct the title "High-Concentrate " to "High-Concentrated".
I suggest changing the word "Rumen Bloat" to "Tympanism".
Abstract, lines 7 and 8 I suggest integrating the objectives presented in one only because the objective represents the article as a whole and to achieve the goal there yes we can have one or more experiments in trying to reach such goals.
I suggest not to use T1, T2 or T3 but to use the acronyms presented to refer to treatments. For example: CON; 1%CT; 2%CT; and 3%CT. This is easier for the reader.
Keywords, line 32, repeat words that appear in the title, I suggest to exchange.
Line 51-57 “To achieve this aim, two experiments were conducted: (1) a trial examining the relationship between protein concentration and foam characteristics—specifically foaming production and retention—in ruminal fluid; and (2) another trial assessing how varying doses of CT incorporated into HCD influence rumen bloat incidence, overall health status, fermentation processes within the rumen, and structural composition of microbial communities present in the rumen.”, suggest to rewrite this passage, since regardless of having been carried out two experiments, first if there is an objective that leads the development of these two researches, it is expected from the writing order.
Line 61-62, “The study involved 15 healthy, 4-6 month-old 61 black goats weighing approximately 24 kg ± 2.5 kg.” adjust to “The study involved 15 healthy black goats, 4-6 month-old and weighing approximately 24 kg ± 2.5 kg. ” 
Trial 1. I did not find in the text that the goats were fistulated and cannulated in the rumen or how the rumen fluid was removed and the rumen was observed to be given notes. This information needs to be entered. How was the ruminal fluid removed?
Table 1 and Table 2 do not show what the antioxidants are as components of the concentrate.
Table 4 and Table 5, “Potein fraction”corrigir o texto para “protein fraction”.
The figures need to be improved in terms of presentation.
Figure 4 may not be necessary and a brief description of the effects observed due to the levels of inclusion of concentrated tannin that affected the results of the tympanism score according to the day observed, especially for 2% CT would be sufficient. As it is presented, only with the average values I understand that it is necessary.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article presents an interesting and relevant topic; however, it contains some errors that need to be corrected to improve clarity and compliance with the journal’s guidelines. We have identified areas that can be refined to enhance the scientific quality and presentation of the results. Attached, you will find a detailed document with suggested revisions to assist you in the review process.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The manuscript is well-structured and covers a relevant topic, but there are minor language issues that need to be reviewed to improve the fluency and clarity of the text. We recommend a language revision to ensure greater precision in scientific communication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors addressed my comments, and the manuscript is greatly improved. Thanks

Author Response

Heartfelt thanks for the reviewers' hard work.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors kindly accepted all suggestions and made adjustments, but two cases persist in the text:
1 - The expression "Rumen Bloat" being replaced by "Tympanism" was not carried out by total and is repeated many times in all manuscript.
2 - The non-use of T1, T2 or T3 and yes the acronyms were not carried out by total and is in several points of the manuscript and needs to be corrected.

Author Response

Comments 1: 1 - The expression "Rumen Bloat" being replaced by "Tympanism" was not carried out by total and is repeated many times in all manuscript.

Response 1: We respect the rigorous attitude of the reviewer. We have corrected them.

Comments 2: The non-use of T1, T2 or T3 and yes the acronyms were not carried out by total and is in several points of the manuscript and needs to be corrected.

Response 2: We respect the rigorous attitude of the reviewer. We have corrected them.

 

Reviewer 3 Report

Comments and Suggestions for Authors

After the changes were made, the work improved a lot. However, the graphics are of low quality. If possible, we will improve.

Comments on the Quality of English Language

Its good

Author Response

Comments: the graphics are of low quality. If possible, we will improve.

Response: We respect the rigorous attitude of the reviewer. We have increased the resolution of all the images to 300dpi and readjusted them accordingly.