Yeasts and Their Derivatives as Functional Feed Additives in Poultry Nutrition

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

After careful review, I have determined that your manuscript requires major revision before it can be considered for publication. I strongly recommend that the English quality be thoroughly reviewed and corrected by a native English speaker or a professional language editing service before resubmission. Additionally, some technical statements should be clarified to ensure scientific accuracy as below:

1. Title should be considered to reword for conciseness: "Yeasts and Their Derivatives as Functional Feed Additives in Poultry Nutrition"
2. Line 29-30: "Showed great restrictions" It is not the antibiotics themselves but government regulations and consumer concerns that have restricted antibiotic use.
3. Line 31: "Investigations on the role of functional feed ingredients are still promising." It is unclear; should specify what is promising.
4. Line 43: The “40 µm” claim is uncommon and needs reference.
5. Line 47: "role" is singular, so "have" should be "has."
6. Line 50-51: "They are used as an alternative protein source to soybean and fish meals in the poultry diet." Needs evidence or more reference to justify the comparison with soybean and fish meals.
7. Line 56: "Yeast containing feed ingredients" should be "yeast-containing feed ingredients."
8. Line 113-115: "Broiler" should be "broilers" (plural) to match "diets." "Has a potential" is incorrect. It should be "has the potential" or "can potentially" for better flow. "Reduction of mortalities" should be "Reduction in mortality".
9. Line 127: "MOS" is singular here (referring to "Mannan oligosaccharides"), so "are" should be "is."
10. Line 136: "This" should be "These".
11. Line 168: "FI" is not immediately defined, making it unclear for some readers.
12. Line 183-186: How much did cholesterol decrease? It needs quantification.
13. Line 199: "Have hypolipidemic factors" is unclear. Does it mean they exhibit hypolipidemic properties or contain specific compounds that reduce fat?
14. Line 229-231: "it is could" is incorrect; "is" or "could" should be removed. Also, "support in the production" should be "support the production."
15. Line 232: "yeast’s prebiotics" should be "yeast-derived prebiotics."
16. Line 308: The sentence mixes present and past tense. "Show" is in present tense, while "modified" is past tense.
17. Line 309-310: "In ovo dietary incorporation" sounds unclear. It should specify that prebiotics are administered in ovo (before hatching). Also, "broilers diets" should be "broilers' diets" (possessive form).
18. Line 313: "Supplementation" is singular, so it should be "has" instead of "have."

Author Response

Dear respected reviewer 

Please, find the attached response letter

Best regards

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper reviewed the yeasts and their derivatives in poultry nutrition. The topic and results are interesting and beneficial, but there are some revisions should be made as follows:

1. In the section of “Introduction”, the author introduced the application of yeasts in animal and poultry nutrition, such as antibiotic-free ingredients, alternative protein source to soybean and fish meal, production performance, immune response and gut health. But it the followed introduction, suitable addition amount should be presented.
2. In the section “Productivity”, “broilers”, “layers and breeders”…were separately listed and clarified. However, in the followed subheadings, “Carcass traits”, “immune response” …were listed. The expression of subheadings is not standardized. Therefore, it should be revised as “growth performance”, “production performance”, “carcass traits”….
3. In the section of “Carcass traits”, the author listed the effects of yeasts supplementation on carcass traits, but the added amounts were not presented. The addition amount was important, so it should be presented. Similar results should be revised in the other parts.
4. The author only stacked the results of previous researches, but lacked the condensation on the effects of yeasts. Therefore, relevant conclusions or inferences should be added.

 

Author Response

Dear respected reviewer 

Please, find the attached response letter

Best regards

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript summarizes the applications of yeasts as supplements in poultry. It processes a large number of publications, which are also organized into tables. It is not yet possible to run a meta-analysis from this much data, but we already have enough information to consider the effects of yeast.

The manuscript meets its own objectives, but I would suggest changes in some areas.

The first is yeast and its derivatives. These two should be distinguished more sharply from each other. A living yeast cell is capable of proliferation, can have metabolic and other interactions with other microorganisms, but its derivatives are not. Derivatives are utilized as nutrients or modulator substances. Because of this, their effects may also be different, and this should be discussed separately.

The next remark is the two tables. They contain a lot of useful information, but their content should be reorganized so that the different derivatives are below each other. They contain a lot of useful information, but their content should be reorganized so that the same derivatives are in the same group under each other.

In the case of the gastrointestinal tract, the effects should also be distinguished according to the place of effect. It makes a difference whether something happens in the small intestine or the caecum, different processes take place in the two places, and microbes also have different roles.

At the end of the sub-chapters, there is a short paragraph in several places, which mentions in connection with the positive effects that precede it, that these effects do not always appear. The explanation is quite short and schematic („could be associated to differences in the breed of bird used, ingredient/ diet composition, form or type, as well as the level of yeast product inclusion in poultry diet”). It would be worth expanding and explaining it more deeply. For practice, it would be fundamental to know when and under what circumstances it is worth using yeasts.

In chapter 2.3, in connection with the immune response, it would be useful to have a few paragraphs about the immunological parameters that are usually measured. And a brief description of what the changes in these parameters mean. When it comes to the immune system, it is usually thought that the stronger it is, the better. However, the immune response is a cost to the host. If the costs are high, the production parameters will decrease. It means that not the maximum, but a closely adapted immune system is favourable for animal husbandry. Therefore, it is important to know what immunological parameters mean.

The chapter on pathogens can be separated from Chapter 2.3 (but this is optional).

In Chapter 2.4, it is also important to divide the gastrointestinal tract into at least the small intestine and caecum.

Chapter 2.5 is short. It should be mentioned whether it is related to production parameters and also what causes it. Reducing the causative factors is perhaps more effective than the yeast supplementation.

On the basis of the above, I propose to accept the manuscript with minor modifications.

Best regards,

Author Response

Dear respected reviewer 

Please, find the attached response letter

Best regards

Author Response File: Author Response.pdf