PONE-D-23-01772Providing environmental enrichments can reduce subclinical spondylolisthesis prevalence without affecting performance in broiler chickensPLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Generally I find this experiment to be a nice and well conducted study and well presented in the manuscript. I have only minor comments and suggestions as follows:

Line 75: "When providing diets diluted in fiber in ...". Please specify type of fiber.

Line 83: Change "favor" to improve or enhance.

Line 90: Delete "beneficial" as it means the same as "enrichments".

Line 173: Change "During recording days, only daily health checks were performed to ..." to "Health checks were only performed during recording days in order to ...".

Line 190: Change "difficulty" to difficulty in".

Line 196: Please explain why the chickens were fasted for 8 hours before killing.

Line 197: You write that "The chickens were weighed and then stunned using an electric stunner (Fluxo UFX 7, Chapecó, SC, Brazil). Are you sure that the electric stunning and muscle contractions is not the reason the deforming the cervical spines and nerves? Please add a comment on this.

Line 205 and a general comment to the study: Were the same chickens observed clinically and compared to the pathology findings after killing? This could be very valuable information and also add to the strength of the posed causal relationship between pathology of the cervical spines and affected gait. Please comment on this.

Table 2: Why is performance not stratified according to week of age? This will add better information than the not mutually exclusive grouping of 1-21, 1-35 and 1-42.

Other suggestions:

- As the authors use many abbreviations, I suggest a list of abbreviations is added to the manuscript. When reading a publication, it is always very tiring to spend time on finding (re-finding) the definitions of the abbreviations after the first presentation.

- Some of the environmental enrichments have a statistically significant effect; however, the factual improvement seems to be minor. The manuscript will benefit if the authors add a comment or some estimations of the attributable effects of these environmental enrichments; I think they will be minor, and this will be a nice contribution the manuscript to underline, that this type of "problem" (spondylolisthesis) is multifactorial and that many factors each have only a small impact, and which makes it so difficult and complex to solve such problems.

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Reviewer #1: No

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Providing environmental enrichments can reduce subclinical spondylolisthesis prevalence without affecting performance in broiler chickens

PONE-D-23-01772R1

Dear Dr. Marconi Italo Lourenço da Silva,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Ewa Tomaszewska, DVM Ph.D

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thanks for addressing all my comments and suggestions. I accept your explanation for not changing Table 2, but I still think my suggested stratification according to age, rather than the presented accumulated form, would have contributed with more knowledge, because it would have elucidated whether there is a change at a specific age interval.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

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