Effects of Monensin, Calcareous Algae, and Essential Oils on Performance, Carcass Traits, and Methane Emissions Across Different Breeds of Feedlot-Finished Beef Cattle
, Diogo F. A. Costa 1,2, Arnaldo C. Limede 3, Guilhermo F. S. Congio 1, Murillo A. P. Meschiatti 1, Priscila A. Bernardes 2 and Flavio A. Portela Santos 1
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
This study investigated the effect of three feed additives on the performance and methane emissions in two cattle breeds. The study is well-designed with interesting results presented in readable Tables. The conclusion is made based on the results of the present study.
minor comment:
lines 38-39 (abstract): the conclusion might be incorrect. Please calculate CH4/kg DM. The conclusion should be made based on any significant differences between the treatments.
In Table 4, please calculate CH4/kg DM, and discuss the effects of the additives on methane emission based on this value.
Author Response
Comments to the Editorial Board:
The authors express their gratitude to the Section Managing Editor, Ms. Crystal Zhang, and the two reviewers for their support, constructive suggestions, and comments. We believe this revised manuscript has significantly improved following your feedback. Below, we provide our responses (marked with "***") and have made the necessary changes to the manuscript accordingly. ***Line numbers (in red) mentioned in the “Responses” refer to those in the revised manuscript with tracked changes (All Markup, all revisions in-line or highlighted in yellow).
Reviewer 1
General comments:
This study investigated the effect of three feed additives on the performance and methane emissions in two cattle breeds. The study is well-designed with interesting results presented in readable Tables. The conclusion is made based on the results of the present study.
Response: ***Thank you very much. The authors really appreciate the effort and time you spent on this.
Specific comments:
lines 38-39 (abstract): the conclusion might be incorrect. Please calculate CH4/kg DM. The conclusion should be made based on any significant differences between the treatments.
In Table 4, please calculate CH4/kg DM, and discuss the effects of the additives on methane emission based on this value.
Response: ***Thank you. The methane data were calculated according to the equation proposed by Galyean & Hales (2022) and it is expressed as Mcal CH4/kg DMI, thus if converted from Mcal to g CH4/kgDMI all the values would be the same as it is a characteristic of the diet:
Mcal of CH4/kg of DMI = [0.3227 – (0.0334 × starch:NDF) – (0.00868 × %EE)]
The values of methane emission/kg DMI were then multiplied by DMI from each treatment and then expressed in the Table 4.
Authors' closing remarks
We sincerely thank the reviewers and the editorial board for their time and effort in providing corrections and valuable suggestions. Your constructive feedback has been instrumental in improving the overall quality of the manuscript, and we deeply appreciate your contributions.
Reviewer 2 Report
Comments and Suggestions for Authors
Well written manuscript. Some indications within the narrative were made regarding being more conservative within some statements, given that current experiment does not have a true control treatment (no-feed additive). Such fact does not invalidate the assessment neither removes its merits, but requires discussion to be more conservative when suggesting monensin overall expected effects outside the current experimental diet comparisons.
20: replace "higher" by "greater" (throughout the manuscript).
29: define within the abstract the experimental design used in addition to the treatment arrangement only.
35: start results by presenting simple effects (interaction), only then move to main effects.
For main effects, first characterize the feed additives, then later the breed differences (order indicated in tittle and objectives of the experiment).
107: text indicates 6 replicates, thus perhaps "pen" used as the experimental unit. If so, great, but please explicitly indicate in the narrative that "pen was used the the experimental unit".
113: replaced "fed diets" by "offered diets", throughout the narrative.
Table 4: Are FBW, ADG, and GF data presented in this table carcass adjusted? If yes, please clearly state in the text and within the table. If not, then strongly encourage authors to perform such comparison on a carcass adjusted basis FBW = (HCW/common lot DP)*0.96, then calculate related variables using such adjusted FBW.
277: search for consistency on how to report references in the text. Here, the name of authors have been written, but not in other paragraphs.
287: missing a period at the end of the sentence.
297 to 299: Please include the word "requirements" within the narrative if discussing NEm and NEg requirements.
349-357: Authors need to be more conservative on implying that monensin decreased DMI in current experiment, and that LCM was not capable to change such an effect. Simply because current experiment does not have a negative true "control" (no feed additive). It is OK to assume monensin as an industry standard, however, discussion of effects shall not assume a lack of response as a potential effect of any treatment.
381: I strongly recommend to not discuss numerical differences.
387: How do you know monensin improved G:F in current experiment? Remember that we do not have a true control (no feed additive) in current assessment. Could other treatments worsen animal's GF rather than monensin improving it?
393, 408, 471: search for consistency on how to report references in the text. Here, the name of authors have been written, but not in other paragraphs.
411: use "mg/animal-daily" (throughout the narrative)
449: Caps letter at the beginning of the sentence.
463: add at the end of the sentence "compared to the other treatments".
466: production or molar proportion? please, double check reference [77].
523: replace "higher" by "greater" throughout the narrative.
CONCLUSION: the second paragraph of the conclusion is written as a conclusion! Great job! However, the first paragraph is not a conclusion, but rather a summary. Please, re-write.
Author Response
Comments to the Editorial Board:
The authors express their gratitude to the Section Managing Editor, Ms. Crystal Zhang, and the two reviewers for their support, constructive suggestions, and comments. We believe this revised manuscript has significantly improved following your feedback. Below, we provide our responses (marked with "***") and have made the necessary changes to the manuscript accordingly. ***Line numbers (in red) mentioned in the “Responses” refer to those in the revised manuscript with tracked changes (All Markup, all revisions in-line or highlighted in yellow).
Reviewer 2
General comments:
Well written manuscript. Some indications within the narrative were made regarding being more conservative within some statements, given that current experiment does not have a true control treatment (no-feed additive). Such fact does not invalidate the assessment neither removes its merits but requires discussion to be more conservative when suggesting monensin overall expected effects outside the current experimental diet comparisons.
Response: ***We sincerely appreciate the time and effort Reviewer 1 dedicated to evaluating this manuscript. We agree with your general comments. While the absence of a true control is noted, it does not diminish the value of this work, as the use of monensin has become standard practice over the years. In the most recent feedlot survey conducted with Brazilian nutritionists by Professor Danilo Millen's group (Monsalve and Millen, 2024), this trend is evident. Your valuable input has significantly enhanced this revised version of the manuscript, and its impact can be seen throughout the revised manuscript.
Specific comments:
Line 20: replace "higher" by "greater" (throughout the manuscript).
Response: ***Modifications done throughout the manuscript as suggested.
Line 29: define within the abstract the experimental design used in addition to the treatment arrangement only.
Response: ***The following definition “in a completely randomized block design with…” was added to ***Line number 31 in the Abstract as suggested.
Line 35: start results by presenting simple effects (interaction), only then move to main effects.
Response: ***We agree and have done modifications throughout the manuscript.
Continuing (line 219): For main effects, first characterize the feed additives, then later the breed differences (order indicated in tittle and objectives of the experiment).
Response: ***As above, we agree and have modified the original manuscript. For example, in ***Lines 219-221 we have included the following statement regarding an additive interaction from the breed effect: “A breed × feed additive interaction was observed for DMI when expressed as a percentage of body weight (DMI%BW; Figure 1). Nellore bulls offered diets with LCM had the lowest DMI%BW.”
Line 107: text indicates 6 replicates, thus perhaps "pen" used as the experimental unit. If so, great, but please explicitly indicate in the narrative that "pen was used the experimental unit"
Response: ***Thank you. For clarity, “(experimental units)” has been added to ***Lines 112-113. After mentioning the number of replicates. In addition, in item 2.4, ***Lines 202-203 the following had previously been included to explain the methods “Pen was used as experimental unit for variables…”.
Line 113: replaced "fed diets" by "offered diets", throughout the narrative.
Response: ***We agree and have modified in the manuscript.
Table 4: Are FBW, ADG, and GF data presented in this table carcass adjusted? If yes, please clearly state in the text and within the table. If not, then strongly encourage authors to perform such comparison on a carcass adjusted basis FBW = (HCW/common lot DP)*0.96, then calculate related variables using such adjusted FBW.
Response: ***Thank you for your comment. While in many situations adjustments for carcass are important, the values of FBW, ADG and GF were not adjusted for carcass. As dressing percentage did not differ between breed nor feed additives, adjustments for carcass resulted in the same results. After taking into consideration the comment, FBW adjusted for carcass was calculated, however the results remained practically unaltered as well as the pattern of results and magnitude of differences between treatments, thus we opted to continue with the values as previously presented.
Line 277: search for consistency on how to report references in the text. Here, the name of authors have been written, but not in other paragraphs.
Response: ***Thank you. We have thoroughly reviewed the manuscript to ensure consistency in how references are reported in the text and have confirmed that all citations adhere to the Journal's guidelines.
Line 287: missing a period at the end of the sentence.
Response: ***Thank you. Subtitles do not require a period at the end, as they are not considered full sentences.
Line 297 to 299: Please include the word "requirements" within the narrative if discussing NEm and NEg requirements.
Response: ***Thank you. Now ***Lines 39-40 read: “greater net energy (NE) requirements for maintenance (NEm) and gain (NEg)…”
Lines 349 to 357: Authors need to be more conservative on implying that monensin decreased DMI in current experiment, and that LCM was not capable to change such an effect. Simply because current experiment does not have a negative true "control" (no feed additive). It is OK to assume monensin as an industry standard, however, discussion of effects shall not assume a lack of response as a potential effect of any treatment.
Response: ***We agree with Reviewer one and now on ***Lines 365-366 we have stated the following: “changes observed on DMI in this trial were not enough to result in significant differences on ADG.”
Line 381: I strongly recommend to not discuss numerical differences.
Response: ***We agree. The following statement has been added to ***Lines 363-364: “It is important to note that numerical differences are reported; however, they are not considered statistically significant.”
Line 387: How do you know monensin improved G:F in current experiment? Remember that we do not have a true control (no feed additive) in current assessment. Could other treatments worsen animal's GF rather than monensin improving it?
Response: ***Your rationale is correct. Despite being well reported the effects of monensin decreasing DMI while maintaining ADG and thus increasing G:F (Tedeschi et al., 2003, Duffield et al., 2012), it is important to maintain the discussion to what was measured within the current work. The statement on now ***Line 388 is adequate as it is comparing MON to BEO only.
Lines 393, 408, 471: search for consistency on how to report references in the text. Here, the name of authors have been written, but not in other paragraphs.
Response: ***Thank you. The inconsistency have been addressed to adhere to Journal’s guidelines.
Line 411: use "mg/animal-daily" (throughout the narrative).
Response: ***We have modified throughout the manuscript as suggested.
Line 449: Caps letter at the beginning of the sentence.
Response: ***Thank you. We could not find a sentence that had begun with no caps letter.
Line 463: add at the end of the sentence "compared to the other treatments".
Response: ***Thank you. We have added at the end of the sentence as suggested.
Line 466: production or molar proportion? please, double check reference [77].
Response: ***Thank you. We have added the following on now ***Lines 447-448: “Bergen and Bates [77] pointed out that monensin alters the route of ruminal fer-mentation for a greater molar proportion of propionate and lower molar proportion.”
Line 523: replace "higher" by "greater" throughout the narrative.
Response: ***We have modified throughout the manuscript as suggested.
CONCLUSION: the second paragraph of the conclusion is written as a conclusion! Great job! However, the first paragraph is not a conclusion, but rather a summary. Please, re-write.
Response: ***Thank you. The CONCLUSION on now ***Lines 556-572 read: “Crossbred bulls outperformed Nellore bulls presenting greater final body weight, hot carcass weight, average daily gain likely due to greater dry matter intake, both daily and expressed in percentage of body weight, which also supports the same observed feed efficiency. Nevertheless, when comparing dietary net energy, the concentrations for maintenance and gain were greater for crossbreds which may suggest that they were more efficient in energy utilization. The higher energy utilization indicated by the observed energy concentrations did not reflect in lower methane emission per daily weight gain. Methane emissions estimates were driven by dry matter intakeCrossbred bulls emitted more methane than Nellore bulls and animals offered the essential oils had greater daily methane emissions than bulls offered the seaweed and monensin.
In the present trial the utilization of the seaweed buffer Lithothamnium calcareum associated with monensin brought no advantages over the single use of monensin on performance of cattle finished offered a high concentrate diet in a feedlot. The blend of essential oil composed by castor beans, cashew nuts and copaiba at the inclusion of 3g/kg DM was not as efficient as monensin on feed efficiency and nutrient utilization.”
Authors' closing remarks
We sincerely thank the reviewers and the editorial board for their time and effort in providing corrections and valuable suggestions. Your constructive feedback has been instrumental in improving the overall quality of the manuscript, and we deeply appreciate your contributions.
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
no more comments
Reviewer 2 Report
Comments and Suggestions for Authors
Clarity and cohesion of the document were improved by given modifications performed by the authors. Suggestions were incorporated, and if not, they were well justified in the response.
