Comparison of Ruminal Degradability, Indigestible Neutral Detergent Fiber, and Total-Tract Digestibility of Three Main Crop Straws with Alfalfa Hay and Corn Silage

Round 1

Reviewer 1 Report

Review of Manuscript Animals-1411537

The aim of the manuscript was to characterize crop straws in terms of ruminal degradation and intestinal digestibility of chemical constituents. I have the following few major and minor remarks:

Major comments

In the title the word “common forages” can interpreted in many manners and I think can be deleted. At the end this study is about the characterization of these 3 straw feeds

In abstract there are some topic that are not really clear (see minor comments)

The introduction is maybe too long that described well the problematic, discuss possible solutions and justify the realization of this experiment. I would just recommend to better state the objectives and state what was the expected outcome (hypothesis)

M&M were in general described with enough detail. There were just some confusing sections that can be found in “minor comments”. The description of statistic is confusing as well as some terms that are not normally used in the literature are newly here introduced or the calculation of some terms are not clearly explained and can be confounded.

The results can be reduced especially those related to DM which is not of relevance. Make emphasize on CP, NDF and ADF.

The discussion chapter has to be improved. Authors relay too much in just describing again results and comparing own results with literature. I would expect more discussion into implication of these result for nutrition of ruminants and how can be used to improve the feed evaluation. The prediction of some parameters based on chemical composition is here of relevance and are the innovative part. The latter must be better discussed and emphasized in the paper

Minor comments

L17: Top in terms of what? Specify

L18: TTD of what? OM?

L21: You use S or Str as an abbreviation for straw. Be consistent and use only one

L24: I have my doubts because these parameters are not commonly used in feed evaluation systems

L28: Delete “common”

L30: How was TTD determined? Normally this is determined in vivo. Here, this is confusing

L31: These abbreviations are not further used in the abstract, therefore, not required here. Which were the incubations times used. For the MBT, which incubation time was used to obtain the feed residues?

L31-35: this is not new and not relevant here. Delete

L36: iNDF24 and iNDF288 were not previously defined

L39: potential degradation of which chemical constituent?

L44: only based on chemical composition?

L58: Is these material really burned in the field? Is this the rule? Why just not incorporated in the

soil?

L87: degradability and digestibility, respectively

L107-109: Not really related to the feeds here evaluated. Delete.

L112-115: I think the objectives were (1) to characterize these straws based on the mentioned variables and to (1) compare them with CSil and AH

L132: The Table 1 is not really necessary. Ingredient composition and general chemical composition (e.g. CP, NDF and energy content) can be briefly given in the text

L139: Where were these samples taken from? From one field? One sample? Pooled samples?

L144: Straw was also dried?

L154: Delete “0”

L155-157: And what about the other incubation times? This is confusing

L160: NDF?

L164: For all chemical components? This is not clear

L167: For DM is not relevant

L176: How many cows?

L180: If bags were recovered from feces, then to mention that you used cows with terminal-ileum cannula is just confusing and not relevant here

L190: calculated and not estimated

L194: The other way around, the exponential equation is fitted to the data!!

L200-201: These abbreviations are confusing. Normally D and U are used in the literature

L208-216: This is somehow confusing. This equations are used under dynamic conditions for ration formulation. Are you using kind of average values for dairy cows (DMI, BW)? What was the forage intake considered for the calculations? Why 23.68 kg/d and 648 kg. Please justify

L227: Preferable use ID for intestinal digestibility. This is normally used in the literature

L230-233: What is what? This is not clear!

L234: use “intestinal digestibility”

L234-240: This term is here not clear! I think you mean “digestible CP” Please be clear and check to avoid confusions! What is the unit for IDCP. Digestible CP and Intestinal digestibility of CP are different terms and based on different units. Check!

L243: ruminal NDF digestion after how many h of incubation? Here is not clear!

L257: These should be mentioned/described before in M&M

L261: dpd288 was not mentioned before I think. Check because here is confusing. You just determined the iNDF288. Why this now?

L267: were then the ruminal degradation parameters and the equation fitted to the data using NLIN with SAS or using Graphpad prism?

L268: This was showed before! Why here again?

L299: Improve the quality of figure 1. Make it bigger

L314: Based on what is this p-value? Specify

L315-316: that degradability increases is of course expected and logic and does not need to be mentioned. Same comment for L311 (increased)

L316: Which degradability’s? Be clear what are you referring to!

L318: This cannot be stated just based on the figures! Delete

L321: This statement is not valid for the variable “c”. For Csil was similar to WS

L322: Of DM or CP. be clear.

L324: EDs of which component?

L326: Results from Dm are not relevant and can be deleted! The Ed values calculated with different kp results in the same ranking of feeds. I would recommend to just use one kp to reduce the information presented and to better follow

L340: I do not understand the reason to correlated ED and ruminal degraded (RD) values. Both terms are theoretically the same. I would recommend to skip this topic. Less is more!

L365: Delte values of DM. They are not relevant. In table just show the undegradable fraction e.g. RUP and not RDP. Use CP and not P. As mentioned before differentiate clearly between digestibility of CP (%) and digestible CP (g/kg DM)

L393: Not all abbreviations are defined in the footnote. Check. I assume variables included in the multiple linear regression are also significant. I would recommend to highlight the significance with ***. The equations for dpd’s are not of relevance and cannot be used in the practice. Can be deleted

L405: Feed type

L406: Delete etc. Neve use it

L408: I think there exist no plural for digestibility. Check

L422-423: Delete this sentence. This is logic and is always expected

L424-425: But in terms of what specifically?

L425-427: In the forage or in the total diet? A forage can be supplemented

L427: All kind of discussion for DM can be skipped. Not relevant

L433: What do you mean with degradabilities? This is too general. Be specific

L438: Not agree! A high r cannot let to conclude that. Delete

L460-461: TTD is the same as digestibility. What do you mean here? Rewrite

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This is an overall good paper and I recommend it for publication. Please carefully check correctness of English. In Simple Summary, Abstract and Conclusions you state that "potential" NDF degradation was higher in straws than e.g., in alfalfa hay. Please be careful with such a "hypothetical" measure and consider what can be expected to realistic to achieve by the animal within a realistic retention time. L492-493, I disbelieve that you optimize milk production in cows with straw diets.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors present an interesting outlook on the use of crop straws. However, even more interesting is the use of the iNDF technique for comparisons. There are several sentences and phrases that do not conform to standard English usage. I would recommend moderate English language editing prior to publication.

The introduction is very well thought out and comprehensive in its review. Again, English language editing is recommended to straighten out some of the more confusing sentences.

L131 Where did the last percent go? By my math, 60.1 plus 38.9 is 99.

L140 This sentence is awkwardly structured and does not make sense as currently worded.

L159 Why was 65C chosen to dry the bags prior to laboratory assays? Going back to the writings of Van Soest, drying at this temperature can lead to artificially high values for fiber as Maillard products tend to form.

L288 Starch and ether extract are expressed in the chemical composition table, but these were not discussed in the chemical analysis section.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Review of Manuscript Animals-1411537.R1

I reviewed the revised version of the manuscript that aimed to characterize crop straws in terms of ruminal degradation and intestinal digestibility of chemical constituents. First, thanks a lot to the authors for the clear, very detailed and kindly answers to my questions, and for considering most of my suggestions. In general authors have improved the quality of the paper and is clearer. I have no more remarks to the paper

Author Response

Dear Editor,

    Thank you very much for your comments and recommendations on improving the manuscript. We have responded to your concerns in the last version. Meanwhile, you suggested that English language and style are fine/minor spell check required.  My native English-speaking colleagues have re-checked the manuscript very carefully again. 

    All authors have agreed to change the corresponding author from Prof. Shengli Li to Wei Wang. We have made corresponding changes in the revised manuscript. 

    We hope that the revised manuscript is now acceptable for publication in Animals. Thank you and your staff for assisting in this manuscript. If you have any questions, please do not hesitate to contact me.

 

Sincerely,

 

Wei Wang, Ph.D.,

China Agricultural University

No. 2 Yuanmingyuan West Road, Haidian

Beijing 100193, China

Tel.: +86-010-62731254

E-mail: wei.wang@cau.edu.cn