Milk Yield, Composition, and Fatty Acid Profile in Milk of Dairy Cows Supplemented with Microalgae Schizochytrium sp.: A Meta-Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled “Milk Yield and Composition, and Fatty Acid Profile in Milk of Dairy Cows Supplemented with Microalgae Schizochytrium sp: Meta-Analysis” presented the effects of Microalgae Schizochytrium inclusion in dairy cows’ diets on yield and composition of milk. The paper has well-defined objectives, it is well-organized, and it has a logical flow of information. However, a minor revision of some aspects is needed.

Abstract

Line 19: Correct the phrase to “…on the yield, composition, and fatty acid profile of milk”.

Introduction

Line 51: The full explanation of the MIAs abbreviation should be provided in the text before used it.

Line 53: Correct the phrase to “at the same time, to reduce the amount…”

Lines 53-55: The author provided a broad range of values for the protein, carbohydrate, and lipid content in MIAs composition. It might be necessary to include an explanation for these varied values.

Materials and methods

Table 1: The authors have to include an explanation of “NR” in the table's footer.

Table 1: Please review reference [24]; the authors have reported the days in milk as 0.

Results

Table 2, Table 3: Please present the references selected for these parameters.

Author Response

Response to Reviewer #1:

We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Our response follows:

Comments and Suggestions for Authors

The manuscript entitled “Milk Yield and Composition, and Fatty Acid Profile in Milk of Dairy Cows Supplemented with Microalgae Schizochytrium sp: Meta-Analysis” presented the effects of Microalgae Schizochytrium inclusion in dairy cows’ diets on yield and composition of milk. The paper has well-defined objectives, it is well-organized, and it has a logical flow of information. However, a minor revision of some aspects is needed. 

Abstract

Comment 1: Line 19: Correct the phrase to “…on the yield, composition, and fatty acid profile of milk”.

Response 1: This change has been made on line 19.

Introduction

Comment 2: Line 51: The full explanation of the MIAs abbreviation should be provided in the text before used it.

Response 2: The full explanation of the abbreviation MIAs has been added before it was used for the first time on line 51.

Comment 3: Line 53: Correct the phrase to “at the same time, to reduce the amount…”

Response 3: This change has been made on line 53.

Comment 4: Lines 53-55: The author provided a broad range of values for the protein, carbohydrate, and lipid content in MIAs composition. It might be necessary to include an explanation for these varied values.

Response 4: This variation has been explained and clarified with the following information: “This variation in the chemical composition of MIAs depends on the cultivation and growth conditions, as well as their physical and chemical processing before being included in diets (Saadaoui et al., 2021). Lines 56-58.

Materials and methods

Comment 5: Table 1: The authors have to include an explanation of “NR” in the table's footer.

Response 5: The abbreviation NR has been explained in the footer of Table 1.

Comment 6: Table 1: Please review reference [24]; the authors have reported the days in milk as 0.

Response 6: This information has been double-checked and is correct. Therefore, it should not be changed. The authors of the reference [24] reported 0 days in milk because the experiment began just on the day of delivery.

Results

Comment 7: Table 2, Table 3: Please present the references selected for these parameters.

Response 7: All references selected for these parameters were previously listed in Table 1.

Reviewer 2 Report

Comments and Suggestions for Authors

In the study titled „Milk Yield and Composition, and Fatty Acid Profile in Milk of 2 Dairy Cows Supplemented with Microalgae Schizochytrium sp: 3 Meta-Analysis”, the authors (Orzuna-Orzuna et al.,) used a meta-analytic approach to test the hypothesis that a dietary addition of MIAs Schizochytrium sp. for dairy cows will positively impact milk yield and the profile of fatty acids in milk. The comparison was between diets with and without MIAs Schizochytrium sp.), and the outcomes were considered as the response to the treatments with regard to milk yield, milk composition, and milk fatty acid profile.

The paper is well written, structured, and the methods and results are quite well described.

The number of articles included in this study is quite small (n = 11), but we accepted the authors' explanations, which is why we consider it reasonable.

The references are relevant.

Mirror correction or checking:

3.2. Milk Fatty Acid Profile

I recommend the authors emphasize only the significant effects of the dietary supplement (lines 196–197).

Please check the P value of the butyric acid (C4:0) in Table 3 because P = 0.029 is not higher than P = 0.05, as you mention on Line 197.

3.3. Publication Bias and Meta-Regression

Line 223: None of the covariates used had a significant relationship (p > 0.05) with MFC, MPC, total MUFA, and total PUFA. Please check, for significant relationship, the p value must be < 0.05.

I liked the way the authors explained the mechanisms in the Discussion chapter.

Congratulations on your work!

Author Response

Response to Reviewer #2:

We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Our response follows:

Comments and Suggestions for Authors

In the study titled „Milk Yield and Composition, and Fatty Acid Profile in Milk of Dairy Cows Supplemented with Microalgae Schizochytrium sp: Meta-Analysis”, the authors (Orzuna-Orzuna et al.,) used a meta-analytic approach to test the hypothesis that a dietary addition of MIAs Schizochytrium sp. for dairy cows will positively impact milk yield and the profile of fatty acids in milk. The comparison was between diets with and without MIAs Schizochytrium sp.), and the outcomes were considered as the response to the treatments with regard to milk yield, milk composition, and milk fatty acid profile.

The paper is well written, structured, and the methods and results are quite well described.

The number of articles included in this study is quite small (n = 11), but we accepted the authors' explanations, which is why we consider it reasonable.

The references are relevant.

Mirror correction or checking:

Comment 1: 3.2. Milk Fatty Acid Profile

I recommend the authors emphasize only the significant effects of the dietary supplement (lines 196–197).

Response 1: We do not agree with this comment. It is also important to mention which fatty acids are not modified by dietary supplementation with MIAs Schizochytrium sp. Therefore, we think it is not necessary to delete lines 196-197.

Comment 2: Please check the P value of the butyric acid (C4:0) in Table 3 because P = 0.029 is not higher than P = 0.05, as you mention on Line 197.

Response 2: We apologize, it was a typo and has been corrected on lines 204 and 206.

Comment 3:  3.3. Publication Bias and Meta-Regression

Line 223: None of the covariates used had a significant relationship (p > 0.05) with MFC, MPC, total MUFA, and total PUFA. Please check, for significant relationship, the p value must be < 0.05.

Response 3: Thanks for the comment, this error has been corrected and “p > 0.05” has been changed to “p < 0.05”. Line 230.

Comment 4:    I liked the way the authors explained the mechanisms in the Discussion chapter. 

Congratulations on your work!

Response 4: Dear reviewer, thank you very much for your good comments.

Reviewer 3 Report

Comments and Suggestions for Authors

Please follow suggestions from attached document.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer #3:

We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Our response follows:

Comments and Suggestions for Authors

Please follow suggestions from attached document. 

Comment 1: Keywords: I recommend also use of Schizochytrium word as keyword together with Aurantiochytrium. Although similar, further search of both names can be directed here.

Response 1: This change has been made. Line 32

Introduction

Comment 2: Rows 51 – 55: Sometimes mislabeled as MIA, Thraustochytrids are not algae. Are single celled saprophytes who recycling dead matter. Some clarifications are needed here.

 Response 2: Dear reviewer. Although some scientific sources consider Schizochytrium sp. as Thraustochytrids, most scientific articles consider Schizochytrium sp. as microalgae. The use of Schizochytrium as a microalgae is more widespread and approved worldwide (Chi et al., 2022; Saadaoui et al., 2021). Therefore, we do not agree with your suggestion, and correcting these lines is unnecessary.

 Chi, G.; Xu, Y.; Cao, X.; Li, Z.; Cao, M.; Chisti, Y.; He, H. Production of polyunsaturated fatty acids by Schizochytrium (Auranti- 463 ochytrium) spp. Biotechnol. Adv. 2022, 55, 107897. https://doi.org/10.1016/j.biotechadv.2021.107897

Saadaoui, I.; Rasheed, R.; Aguilar, A. Microalgal-based feed: Promising alternative feedstocks for livestock and poultry produc- 418 tion. J. Animal Sci. Biotechnol. 2021, 12, 76. https://doi.org/10.1186/s40104-021-00593-z

Materials and methods

Comment 3: Very well explained selection of meta regression analysis. Nothing to recommend.

Response 3: Thank you so much.

Results

Comment 4: For a better explanation of the results, I highly recommend use of forest plot (forestplot package in R https://bookdown.org/MathiasHarrer/Doing_Meta_Analysis_in_R/forest.html - ) for analyzed traits (milk quality and fatty acid profile) - (I hope the editor will understand that forestplots request an increased number of pages)

Response 4: Dear reviewer. We do not agree with his suggestion. Forest plots are useful when evaluating a few response variables (e.g., less than 10), but in studies with a large number of response variables (such as the current study), the use of forest plots causes reader confusion. Furthermore, forest plots can only be interpreted by highly specialized readers using the meta-analysis methodology. In contrast, a table of results such as those used in the current study is easy to interpret even by non-specialized readers.

Last but not least, the current study contains 38 response variables, which indicates that the use of graphs would more than double the pages of the manuscript. An excessive number of pages is also not attractive to readers. Considering all the previous arguments, we consider that the use of forest plot graphs is not scientifically justified. On the other hand, several recent meta-analyses published in MDPI journals and other prestigious publishers do not use forest plots for the reasons mentioned above. Below, we mention some examples:

Orzuna-Orzuna, J. F., Godina-Rodríguez, J. E., Garay-Martínez, J. R., Granados-Rivera, L. D., Maldonado-Jáquez, J. A., & Lara-Bueno, A. (2024). A Meta-Analysis of 3-Nitrooxypropanol Dietary Supplementation on Growth Performance, Ruminal Fermentation, and Enteric Methane Emissions of Beef Cattle. Fermentation, 10(6), 273. https://doi.org/10.3390/fermentation10060273

Orzuna-Orzuna, J. F., Godina-Rodríguez, J. E., Garay-Martínez, J. R., & Lara-Bueno, A. (2024). Capsaicin as a Dietary Additive for Dairy Cows: A Meta-Analysis on Performance, Milk Composition, Digestibility, Rumen Fermentation, and Serum Metabolites. Animals, 14(7), 1075. https://doi.org/10.3390/ani14071075

Hernández-García, P. A., Orzuna-Orzuna, J. F., Chay-Canul, A. J., Silva, G. V., Galván, C. D., & Ortíz, P. B. R. (2024). Meta-analysis of organic chromium dietary supplementation on growth performance, carcass traits, and serum metabolites of lambs. Small Ruminant Research, 107254. https://doi.org/10.1016/j.smallrumres.2024.107254

Mendoza-Martínez, G. D., Orzuna-Orzuna, J. F., Roque-Jiménez, J. A., Gloria-Trujillo, A., Martínez-García, J. A., Sánchez-López, N., ... & Lee-Rangel, H. A. (2024). A Polyherbal Mixture with Nutraceutical Properties for Ruminants: A Meta-Analysis and Review of BioCholine Powder. Animals, 14(5), 667. https://doi.org/10.3390/ani14050667

Hernández-García, P. A., Orzuna-Orzuna, J. F., Godina-Rodríguez, J. E., Chay-Canul, A. J., & Silva, G. V. (2024). A meta-analysis of essential oils as a dietary additive for weaned piglets: Growth performance, antioxidant status, immune response, and intestinal morphology. Research in Veterinary Science, 105181. https://doi.org/10.1016/j.rvsc.2024.105181

Comment 5:  3.3. Publication Bias and Meta-Regression

In table 4, is missing milk yield meta-regression. Also, as a recommendation, maybe is better to introduce meta-regression of Conjugated linoleic acid (LCA). MIA have an important increasing effect in LCA (table 3).

Response 5: Milk yield is not missing from Table 4. As mentioned in the materials and methods section (lines 177-179), meta-regression was only applied to response variables that had significant heterogeneity and were reported in at least ten different scientific articles. Milk yield did not have significant heterogeneity, which justifies its exclusion from the meta-regression analyses. Likewise, conjugated linoleic acid also did not meet the requirements to apply meta-regression, so it cannot be added to Table 4.

Comment 6:  3.4. Subgroup Analysis

As a recommendation, follow the table 4 setup for a more complete image of the study. Thereby, if data is available, analyze also MY, MFC, MPC, SFA, MUFA, PUFA and LCA.

Response 6: Dear reviewer, in the materials and methods section (lines 184-186), the requirements that a response variable must have to be able to perform subgroup analysis were indicated. The variables you mention were not analyzed in subgroups due to a lack of sufficient data and because they did not meet all established scientific requirements.