Effect of Live Yeasts (Pichia guilliermondii) on In Vitro Fermentation of Corn Stover as a Fibrous Substrate

Round 1

Reviewer 1 Report

As antibiotic growth promoter had been forbidden in animal husbandry, alternative products research became hotspot. This study evaluated a direct-fed microbial product containing yeast strain Pichia guilliermondii using in vitro fermentation method. The study concept was clearly presented. The manuscript was well-written with nice explanations of the results, but there was still room for improvement. Listed below some comments for the authors’ consideration:

Overall comments:

1) The title of this paper should be reconsidered, because it had some logical mess as fermentation of corn stover was the method of in vitro fermentation.

2) In the manuscript, in vitro should be italic.

3) Pay more attention to the tense of the manuscript.

4) As presented in the current study, the effect of yeast product on in vitro ruminal fermentation was not remarkable, which warranted further research with gas production and microbial population.

Specific comments:

1) In the introduction part, the rationality of this study was not described clearly. Besides, what was the hypothesis of the present study?

2) What was the reason to choose corn stover as the only one in vitro substrate in this experiment? As we all know, there should be at least 10% of the concentrate in the ration for ruminant animal. I understood that yeast would be more efficient for fibrous feedstuffs, but if the experiment was not designed based on production, how would the results be applied to practice.

3) Spell mistakes in Line 113.

4) Why did authors set fermentation time as the second factorial treatment? It was common sense that in vitro fermentation was a bath method, where the substrate would be consumed and more metabolites would be accumulated with incubation, which made the current results a repeat of the exist theory.

5) Did the P-value mean interaction between treatment and time in Table 3? If so, why did P values for treatment and time not be presented?

6) As concluded by authors that yeasts should be supplied twice a day in the future in vivo study, however the forage passage rate of the ruminant was usually more 48 h. It was indicated by the current results that the yeast product had no long lasting effect on the fermentation despite the adding intervals.

Author Response

Response to Reviewer 1 Comments

 

Point 1: The title of this paper should be reconsidered, because it had some logical mess as fermentation of corn stover was the method of in vitro fermentation.

Response 1: The title has been changed from In vitro examination of yeast strain Pichia guilliermondii Levica 2 27 as ruminal additive and fermentation of corn stover to Effect of live yeasts (Pichia guilliermondii) on in vitro fermentation of corn stover as a fibrous substrate   

Point 2: In the manuscript, in vitro should be italic.

Response 2: all in vitro and in vivo changed to italic

Point 3: Pay more attention to the tense of the manuscript.

Resonse 3: already edited by MDPI

Point 4: As presented in the current study, the effect of yeast product on in vitro ruminal fermentation was not remarkable, which warranted further research with gas production and microbial population.

Response 4: We are working on that in current research

Specific comments:

• In the introduction part, the rationality of this study was not described clearly. Besides, what was the hypothesis of the present study?

Point 1: It was added: more references, hypothesis, and problem described extensively.

• What was the reason to choose corn stover as the only one in vitro substrate in this experiment? As we all know, there should be at least 10% of the concentrate in the ration for ruminant animal. I understood that yeast would be more efficient for fibrous feedstuffs, but if the experiment was not designed based on production, how would the results be applied to practice.

Point 2: The purpose of using only corn stover as a substrate to define the effect of live yeasts was because is a very important ingredient in diets for ruminants, with a rumen fill purpose. However, it is important to clarify that it is rarely used as the only ingredient in these types of diets. This was already explained in M and M.

• Spell mistakes in Line 113.

Point 3: Corrected

• Why did authors set fermentation time as the second factorial treatment? It was common sense that in vitro fermentation was a bath method, where the substrate would be consumed and more metabolites would be accumulated with incubation, which made the current results a repeat of the exist theory.

 Point 4: Commonly, during in vitro and in vivo studies, the different fermentation indicators over time are evaluated in this way, in order to know when the effect of the additive occurs and how long it lasts.

• Did the P-value mean interaction between treatment and time in Table 3? If so, why did P values for treatment and time not be presented?

Point 5: Because, when there is an effect of the interaction as occurred in this study, such effect ( treatment x time) it is not explained by separate.

• As concluded by authors that yeasts should be supplied twice a day in the future in vivo study, however the forage passage rate of the ruminant was usually more 48 h. It was indicated by the current results that the yeast product had no long lasting effect on the fermentation despite the adding intervals.
• Point 6: If it is decided to carry out an in vivo study, we consider important adjusting the supplementation conditions, trying to maintain a more constant supply of additive. However, this paragraph was deleted from the text, but we will take care of that in future experiments.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors reported the effects of supplementing yeast on ruminal fermentation of corn stover. The study design is moderate however, the introduction, method description, results and discussion need to be thoroughly improve as it hard to follow. Extensive grammar editing is required before resubmission. Please see comments to help improve the manuscript.

 

Line 6 please delete “1;”

Line 8 include utilization after potential

Line 12 -13 consider deleting “fiber degradation indicators”. Also can you rewrite these “

 fiber degradation indicators percentages of neutral detergent fiber and acid detergent fiber, digestibility” in a better way?

Line 12 please define N-NH. All abbreviations should be define in abstract

Line 15 consider deleting “the concentration of”

Line 20 please add some of the keywords

Line 23 which century? Please specify

Line 26 antibiotics, growth promoters

Line 25-28 this out of order. Doesn’t make sense….please improve

 

The introduction needs more literature and flow in logical order. At present the introduction lacks a story.

 

Line 47 please fix the full stop after 2.2

Line 51-52 Yeast strain sample of should be deleted

Line 57 cfu should be CFU

line 64-65 Please rephrase and improve. Doesn’t look scientific

Line 69 The Table 1 is result so please move to results section

Line 70-85 please improve the method descriptions. Doesn’t flow well

Line 83 please add city and country

Line 86 the sub title is not appropriate please replace with something good

Line 89 (1980) [18]????

Line 90 delete In addition,

Line 98=100 please improve

Line 101 needs improvement

Line 111 As can be seen???? Grammar. The line 111-114 needs to be fix. Also p value should be small letters and italised

Line 115-117 what message are you trying to say here? Doesn’t flow well

The results and discussion need to be rewritten in concise, clear manner. Currently it lacks logic.

Author Response

Response to Reviewer 2 Comments

Point 1: Line 6 please delete “1;”

Corrected

Point 2: Line 8 include utilization after potential

Corrected

Point 3: Line 12 -13 consider deleting “fiber degradation indicators”. Also can you rewrite these “

fiber degradation indicators percentages of neutral detergent fiber and acid detergent fiber, digestibility” in a better way?

Corrected

Point 4: Line 12 please define N-NH. All abbreviations should be define in abstract

Added definition

Point 5: Line 15 consider deleting “the concentration of”

Deleted

Point 6: Line 20 please add some of the keywords

Added

Point 7: Line 23 which century? Please specify

Corrected

Point 8: Line 26 antibiotics, growth promoters

Corrected

Point 9: Line 25-28 this out of order. Doesn’t make sense….please improve!

Improved

 Point 10: The introduction needs more literature and flow in logical order. At present the introduction lacks a story.

It was added: more references, hypothesis, and problem described extensively. Edition was improved.

 Point 11: Line 47 please fix the full stop after 2.2

Corrected

Point 12: Line 51-52 Yeast strain sample of should be deleted

Corrected

Point 13: Line 57 cfu should be CFU

Yes

Point 14: line 64-65 Please rephrase and improve. Doesn’t look scientific

It was edited by professionals (MDPI EDITOR)

Point 15: Line 69 The Table 1 is result so please move to results section

That table shows the chemical composition of the ingredient utilized in the experiment and generally belongs to the Materials and Methods, not to the results.

Point 16: Line 70-85 please improve the method descriptions. Doesn’t flow well

Improved

Point 17: Line 83 please add city and country

Added

Point 18: Line 86 the sub title is not appropriate please replace with something good

Replaced

Point 19: Line 89 (1980) [18]????

Corrected

Point 20: Line 90 delete In addition,

Deleted

Point 21: Line 98=100 please improve

Improved by the edition

Point 22: Line 101 needs improvement

Improved

Point 23: Line 111 As can be seen???? Grammar. The line 111-114 needs to be fix. Also p value should be small letters and italised

Corrected

Point 24: Line 115-117 what message are you trying to say here? Doesn’t flow well

Corrected

Point 25: The results and discussion need to be rewritten in concise, clear manner. Currently it lacks logic.

Edited properly

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have made little improvement. Please accept it in the present form.

 

Thank you