A Sustainable Approach to Managing Invasive Macroalgae: Assessment of the Nutritional Profile and the Potential for Enteric Methane Mitigation of Rugulopteryx okamurae

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Manuscript oceans-3164727, entitled “A Sustainable Approach to Managing Invasive Macroalgae: Assessment Nutritional Profile and the Potential for Enteric Methane Mitigation of Rugulopteryx okamurae”

 

Recommendation:       The above paper is not suitable for publication in its present form.

 

 

This article provides information about the nutritional profile of Rugulopteryx okamurae and its potency to act as an agent for enteric methane mitigation in dairy cows. It is in general appropriately organized, carried out and written, however there are some points that should be corrected or clarified.

 

Title: I suggest “A Sustainable Approach of Managing Invasive Macroalgae: Assessment of the Nutritional Profile…”

L12: “of managing”

L17-18: How were these percentages calculated? Please check

L20: When? After 24?

L23: “could serve” instead of “has potential”

L26: In vitro or in vivo tests?

L34, 40, 42: “feed” instead of “food”

L46: “by 12-95%” instead of “by 12 percent to 95 percent”

L70: “…added to the diets of the ruminants. Therefore…”

L73: “basal diet”

L81: “cattle diet”

L82: “basal diet” instead of “base feed”

L84: “diet” instead of “base feed”

L85: “…presented in Table 1.”

Table 1: Calculated or analyzed composition?

L96, 97: “basal diet”

L122: “…by Borba et al. [28].”

L153: “…was 43.28±1.59%, with both parameters…”

L165: 9.47±2.36% or 9.47±0.93%?

L172: “The differences were statistically…”

L181: Not at 12h

L185: “Regarding the methane production, results are shown in Table 4. The control had…”

L187-188: “It should be noted that in treatment A5%, methane was not produced in the first…”

L194: How was “98%” calculated?

L207: “based on” instead of “according to the in”

L214: “showed minimum variation” instead of “varied little”

L223: “could serve” instead of “has potential”

L227: “originated” instead of “come”

L229: “…according to Campbell et al. [38], the…”

L244: “…is also limited due to the low digestibility of this macroalgae [36]. Vizcaíno et al. [41]…”

L259: “intense” instead of “pronounced”

L260: “…suggesting that this…”

L266: “when” instead of “with”

L267: “previous” instead of “other”

L281: “observed” instead of “found”

L287: “showed” instead of “has revealed”

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

Dear Reviewer 1

We would like to express our deepest gratitude to the reviewers for the valuable corrections and suggestions provided. Your insightful and detailed observations have significantly contributed to the improvement of this scientific paper. The proposed revisions not only addressed critical aspects but also enhanced the overall quality of the work, strengthening the clarity and consistency of our arguments. We sincerely appreciate the time and dedication you invested in the thorough review of the manuscript. Your contributions have been crucial in elevating the quality of this study. 

Attached, I answer each of your questions point by point.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Comments to the Authors of manuscript number oceans-3164727 entitled “A Sustainable Approach to Managing Invasive Macroalgae: Assessment Nutritional Profile and the Potential for Enteric Methane Mitigation of Rugulopteryx okamurae”

The study examines the use of the invasive Asian macroalgae Rugulopteryx okamurae as a feed ingredient to reduce methane production in cattle. Incorporating 5% of this alga in feed decreased methane by 98%, while 1% reduced it by 38%. The algae's nutritional content includes 18.68% crude protein and 55.71% fiber, but also high ash content.

1. The introduction is well written. The problem is well presented.

2. the collection of algae is well presented.

3. Collection of rumen fluids from healthy cows immediately after slaughter is standard practice, but the description of the Borba method should be more detailed

4. Conducting in vitro tests with three different variants (control, 1% algae, 5% algae) and repeating the tests three times ensure the reliability of the data and enable accurate statistical analysis.

5. The reasons for the high ash variability, which may influence further analyses, should be described in more detail.

6. The NDF (55.71%) and ADF (43.28%) values ​​are consistent with the literature data for other brown algae, confirming the stability of the results.

7. High lignin content (ADL) may limit digestibility, which is consistent with general observations for algae. There is a need for further research on the specificity of marine fibers compared to terrestrial plants.

8. The high variability in ash content (31.86%) may be due to sand contamination or the presence of organisms. This indicates the need for more rigorous sample cleanup methods in future studies.

9. Protein content may vary with season, with literature suggesting that January to April is optimal. Further research into seasonal changes in protein content may be warranted, as it may impact its use in animal diets.

10. The addition of R. okamurae to the diet leads to a significant reduction in gas production. Although the reduction in fermentation activity may suggest a negative impact on the rumen microbiota, which may reduce the efficiency of digestion, it is worth investigating whether such a reduction in gas is beneficial to the health of the animals or whether it may affect other aspects of their diet.

11. The reduction in methane production, especially at higher concentrations (5%), is promising but requires further analysis. The results are consistent with the literature, suggesting that polyphenols such as phlorotannins may be responsible for this reduction. However, it is worth exploring the mechanism of action of these compounds and their potential impact on other components of the diet.

12. It is important that future studies focus on assessing the toxicity of Rugulopteryx okamurae and developing processing methods that improve digestibility. Further research is needed on the long-term use of this supplement and its impact on ruminant health.

13. Rugulopteryx okamurae has promising potential as a dietary supplement, but issues related to its digestibility and toxicity need to be addressed. Further research is warranted to fully assess its usefulness and safety for long-term use.

Author Response

Dear Reviewer 2

We would like to express our deepest gratitude to the reviewers for the valuable corrections and suggestions provided. Your insightful and detailed observations have significantly contributed to the improvement of this scientific paper. The proposed revisions not only addressed critical aspects but also enhanced the overall quality of the work, strengthening the clarity and consistency of our arguments. We sincerely appreciate the time and dedication you invested in the thorough review of the manuscript. Your contributions have been crucial in elevating the quality of this study. Attached, we respond point by point to each of the comments, with the author’s responses identified as (AR). 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 

- The study aimed to investigate the nutritional value and digestibility of the brown macroalgae Rugulopteryx okamurae, and Asian invasive macroalgae species along the costs of the Azores, and the in vitro effect of the addition of this macroalgae in two concentrations (1% and 5%) in a substrate simulation a tyical basal diet for dairy cattle in the Azores.

Introduction:

-       Ln 35: The authors state that ruminants are responsible for 40% of total methane emissions!. This sentence needs to be revised for a precise and correct information to the reader.

-        Ln 45: Reference nr. 6 (Molina-Alcaide & Carro, 1996) is wrong in this context. Please, use right reference.

 Materials and Methods:

-        Description of methodology for nutritional composition of basal diet is lacking.

-        Ln 102-106: Description of the collected samples and more detailed description of how the biomass was handled after collection is lacking.

-        Ln 117-122: A description of the donor animals, diets of the animals, and sampling and storage procedures for collected ruminal fluid are lacking. These are important factors for understanding and the repeatability of results. Therefore just referring to another publication is not sufficient. Please, write more detailed description of this. Further, the reference Borba (28) doesn’t describe this either, but refers again to another publication. Please, find good strong publications as references.

Discussion:

-        Ln 212-213: How do the authors know that the collected macroalgae were at the same growth phase? These samples are collected from washed out biomass? Biomass attached to hard substrate? These descriptions lack in M&M section, among other information about the sampled material and conservation method, etc.

 Overall comments:

This is an interesting study in the search for new sustainable sources for antimethanogenic feed ingredients for livestock. The paper is easy to understand. However, I have the following main concerns about the paper:

-  The descriptions of M&M should be more extensive to give the reader a better understanding of the different procedures. 

- The paper reports results from a very limited number of parameters from the in vitro fermentation trial (total gas and methane production), what limits the possible conclusions that can be done from this work. 

- The use of refences should be reviewed.

 

 

Author Response

Dear Reviewer 3

We would like to express our deepest gratitude to the reviewers for the valuable corrections and suggestions provided. Your insightful and detailed observations have significantly contributed to the improvement of this scientific paper. The proposed revisions not only addressed critical aspects but also enhanced the overall quality of the work, strengthening the clarity and consistency of our arguments. We sincerely appreciate the time and dedication you invested in the thorough review of the manuscript. Your contributions have been crucial in elevating the quality of this study. Attached, we respond point by point to each of the comments, with the author’s responses identified as (AR). 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for the revised manuscript. The manuscript has now been sufficiently improved.