Effects of Different Forage Types on Rumen Fermentation, Microflora, and Production Performance in Peak-Lactation Dairy Cows

Round 1

Reviewer 1 Report

All opinion was emitted with all respect to the author's effort for the preparation of the experiment and its report

The purpose of this study was to evaluate Effects of different forage types on rumen fermentation, microflora, and production performance in peak-lactation dairy cows. In general, the topic of the study is pertinent. The antecedents and justify of the study are well described and supported. In addition, the manuscript is supported with excellent methods, techniques and procedures. The experimental design and statistical analyses are appropriate. Unfortunately, the manuscript has a fatal flaw that exclude it consideration for publication in Fermentation journal.

The central concern is about how experimental diets were planned (central point to contrast the hypothesis raised). It is well known that in medium (in this case, oat and Leymus chinensis.) -to-low quality forage (alkali-treated corn straw), due its chemical characteristics and associative factor with other components of diet, are commonly offer in high-productive animals as functional feeds. Thus, its participation in diets are restricted to 5-10% in diets.

To determine feeding value (acceptability, fermentation and digestion, and energy utilization), as well as, associative effects of tested forages with other components their inclusion must be at the limit of the maximal inclusion, or at least at average inclusion used in the industry (5 to 10%). It is very difficult (if not impossible) to determine any effects when forage participation is lower to those inclusion levels. In this case, oat and leymus chinensis hay were included at 0.5% in diets! Due to their chemical characteristics (not described in the manuscript, but well known) and feed intake of cows, those forages contributed with around 6 g of protein (0.2% of total protein intake) and 65 g of NDF (1.1% of total NDF intake).  As you note, it is very risky to attribute effects on the variables evaluated to these forages included at this level. The inclusion levels used  to OG and CW treatments are more approached to be used to evaluate nutraceutical feeds or feed additives.
Unfortunately, this flaw in the formulation of the experimental diets does not allow generating reliable data to discuss the results and reach conclusions attributing the effects to these evaluated forages.

Author Response

Dear reviewer

 

Thank you very much for your valuable comments on this paper. As you said, the content of Leymus chinensis and oat hay are restricted to 5-10% in diets. We checked the data of this test again and found that the data in Table 1 was wrong. In fact, the addition of Leymus chinensis in CW group was 5.2%, and the addition of oat hay in OG group was 5.5%. In addition, we also found that the ingredient of experimental diets of other groups in Table 1 were wrong. After verification, they have been modified and the modified Table 1 has been sent to the annex. Finally, We would like to thank the reviewers again for their valuable comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript "Effects of different forage types on rumen fermentation, microflora, and production performance in peak-lactation dairy cows" by Guo et al. aims at evaluating the utilization of silages, hays, and straw I differing proportions on the productivity and the rumen processes in dairy cows. Generally, the data is interesting and promising in terms of utilization of different forage types in dairy cow nutrition but some aspects of the manuscript must be improved. Past tense should be used throughout the manuscript and further grammar issues should be solved potentially with the help of a native speaker. The description of the Materials and Methods is often insufficient and the presentation of the results in tables and figures must be improved. Particularly a duplicated presentation of data in both table and figure must be avoided. The short description of the results concerning ruminal microflora with many non-significant differences does not justify the comparably extensive discussion section on the ruminal microflora. This should be shortened. Overall, the discussion contains a lot of repetition of a mere presentation of the results. The own finding should be better integrated in the discussion by comparing to other study results.

Detailed comments:

L19: Either "butyrate concentration" or "butyric acid concentration". Please also add the matrix, so the concentration measured in which samples?

L20: NH3-N content measured in which samples?

L21: Percentage of Oscillospira and unknown microbes in which samples?

LL24 and 25: This can be shortened to "Milk lactose and protein content in the AS group was highest among the groups".

L27: I am not sure about this wording: "of forage type from oat hay". Please rephrase.

L30: increased instead of increases.

L30: Why "tended to increase milk protein"? In LL24-26 it was stated that this was a significant effect and not just a tendency.

L33: I think this sentence misses an "of".

LL37/38: Ruminants do not produce fiber. Please rephrase.

The introduction is a bit repetitive and should be revised to remove repetitions and provide some more background information. Hypotheses are missing.

LL40/41: This sentence is a repetitive to what was written before. Please integrate with previous sentences.

L44: optimizing instead of optimize. Also, before it is only stated that forage per se is important. Now it says that the forage type is important but no explanation is given why/how forage types differ in their nutritional value. Please add.

L46: Spelling mistake in dairy.

L46-48: The beneficial effect of forage on cow productivity and health was already mentioned before. Please delete.

L56: This sentence seems incomplete. Alfalfa silage was used to replace which component of the diet of dairy cows?

L69/70. This sentence starts with a lowercase letter and is unclear both in terms of vocabulary and grammar used.  Please adjust.

LL83/84: It is mentioned that cows were selected for "similar parity, lactation days, milk yield and milk somatic cell count" but baseline data is only provided for days in milk and body weight. Please add the missing information.

LL87-89: This is not a complete sentence. Please rephrase.

L90: Define abbreviation NRC.

LL92/93: Incomplete sentence.

LL96-98: There is a lack of information about the feeding management. How was access to the experimental feed provided? Did cows have collars and accessed the troughs via transponders, having access to only one trough? Please clarify.

LL100-103: It is also unclear in which order the animal received the diets. Was the order randomized? Were always two animals receiving the same feed at the same time? So that all four diets were always tested in parallel? Was there a washout period between experimental periods? How did you account/correct for potential carry over effects?

L101: Pre-fed instead of pre feed.

LL101/102: Sentence is unclear. What is the pre-test period? When (time of the day) were samples collected?

L106: This should be period instead of trial, I assume? Also: 100 mL of rumen fluid instead of rumen fluid 100mL.

L107/108: It is stated that the rumen fluid was collected at five times points: before feeding(0 h), after feeding(3 h, 6 h, 9 h, 9 h and 12 h). The 9 h are duplicated. Please remove. Also, when feeding was performed two times per day at 7.30 and 15.30, how was it possible to collect samples 9 and 12 h after feeding? This would again be 1 and 4 h after feeding. Or was the sampling relative to the afternoon and not the morning feeding? Please clarify.

L110: What is r/min? Do you mean g/min? Please check the unit.

L119/120: The primer was designed to bind to which gene/sequence? The table shows details on the PCR but not on the sequencing. Please provide details on the sequencing conditions. How many reads etc.

L127/128: What is the ruminant counter? Please provide more details.

L129: Indicate the total time that samples were dried.

L138: What does this mean: morning: noon: evening = 4: 3: 3 ? Were samples pooled in this proportion? If so, why and why not in proportion to milk yield proportion at each milking relative to total daily milk yield?

LL139/140: How was the analysis of milk components performed?

LL141/142: Please provide kit/company name, city and country.

L143: Why 300 g/500 g. When were 300 g and when 500 g sampled?

L145: What does this mean "6V, 11v, 1700 and 22v"? How were feces samples collected?

L146: What does "evenly mixed" mean? In proportion to what? How does this relate to the 300 g and 500 g sampled?

L147: This sentence reads like an instruction and not like a description. Please rephrase.

LL156/157: What is the platform and what is the software? Please specify.

LL165-172: The description of the statistical analysis is incomplete. Please describe how you tested if all assumptions for the GLM were met. Please also indicate at which P value a statistical significance was assumed.

L174: The parameters in this heading do not match the parameters given in the following subheadings. Is this header level actually required? I would think that the precise subheadings are sufficient.

LL178-180: There is no need to repeat the p values in the text when they are given in the table and the text already states "significant" and "not significant". Please remove p values from text (also in the following sentences).

LL180-182: Do not repeat mean values from table in text.

L196: There are four and not three experimental groups.

L203: In 12 h what? In rumen fluid collected 12 h after feeding? Please adjust.

L204: Please use abbreviation TMR.

LL207/208 and the remaining results text: Do not repeat mean values from table in text.

L215: Unclear what "after the morning feeding (9h)" means. See one of my previous questions about definition of the timings.

L222: Please rephrase to clarify "change trend".

LL231-244: These three sections should be combined into a single one to avoid extremely short sections with sometimes only one sentence.

LL242-244: This can be shortened to " The distribution of rumen microorganisms in each group did not differ before and after feeding."

LL246-248: This should be moved to the Material and Methods section.

LL248-251: This should be moved to the figure caption.

LL251/252: The current figure 5 does not support this statement. As individual data per animal is shown (this should be changed to group means as commented below), this does not allow for a description on dietary treatment level. Please adjust figure 5 and then adjust the description accordingly. It seems that table 9 is presenting the means of figure 5? In that case, delete figure 5 completely and present the data of table 9 in the same bar format as the current figure 5.

LL261/262: How was the test done to state that these differed "significantly"? I suggest to remove the word.

LL315-317: Do not refer to tables/figures in the discussion.

LL319-321: Do not repeat the presentation of results.

L324: "several studies" but only one reference is provided. Please adjust.

L330: "as raw"? Please rephrase.

L348: There were four and not three groups.

L361: "histone yield", what is this about? Please correct.

LL552-560: This is just a summary of results and no conclusion. Please remove.

Figure 1 and Table 5 are showing the same data. This is not acceptable. Please remove one of the two. I would suggest to keep the table.

Figure 2 and Table 7 are showing the same data. This is not acceptable. Please remove one of the two. I would suggest to keep the figure and add letters to indicate significant differences just like in the table. Figure caption is insufficient. Figures should be self-explanatory. Please add information on matrix, treatments (abbreviations), etc.

Figure 3: Font size must be increased. Figure caption is insufficient. Figures should be self-explanatory. Please add information on matrix, treatments, etc.

Figure 4: Explanation for scale is missing. Figure caption is insufficient. Figures should be self-explanatory. Please add information on matrix, treatments (abbreviations), etc.

Figure 5: Figure caption is insufficient. Figures should be self-explanatory. Please add information on matrix, treatments (abbreviations), etc. "Up one and down one" is insufficient. Please add letters e.g. as in Figures 2 and 3 and/or write sampling time directly next to the figures. Also, no individual sample data should be presented. Please modify graph to show means per treatment group.

Figure 6: Font size should be increased. Figure caption is insufficient. Figures should be self-explanatory. Please add information on matrix, treatments (abbreviations), etc.

Table 1: Provide the composition of "premix". Unit for DM is missing. Explain all abbreviations used in the table in the footnote of the table.

Table 2: To save space, I recommend to integrate the information given in Table 2 in two sentences in the Materials and Methods section and remove Table 2.

Table 3 and following tables: SEM should always have one decimal place more than the mean. What is "a murc"? Please remove "extremely significant" from the footnotes. Providing significance levels in the footnotes is unnecessary since P values are given in the tables. Table caption is insufficient. Tables should be self-explanatory. Please add information on matrix, treatments (abbreviations), etc.

Author Response

Dear reviewer

 

Thank you very much for your valuable comments on this paper. Your suggestions on the manuscript are essential to us. We have revised the manuscript according to your suggestions. We also further improved the manuscript according to the suggestions of another reviewer. We have uploaded the revised results to the attachment. In order to more clearly express the difference significance and data, we have retained Table 7. In addition, this manuscript has been revised by a professional English editing agency, and the editing certificate has been uploaded to the attachment.Finally, We would like to thank the reviewers again for their valuable comments.

 

Best wishes to you！

Yours

Cheng Guo

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors corrected all observations and suggestions, and the main concern about dietary treatments was corrected and clarified.  In my opinion, now the paper has the scientific sustain to be published in Fermentation journal