Impact of High-Moisture Ear Corn on Antioxidant Capacity, Immunity, Rumen Fermentation, and Microbial Diversity in Pluriparous Dairy Cows

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a well thought out and well written report describing the results of an experiment where dairy cows were fed diets that included either steam flaked corn or high-moisture ear corn as part of a 60-day feeding trial. the objective was to see if there were differences in the digestion, metabolism, milk yield responses and rumen microbes, and subsequent improvement in immune function. It was hypothesized that the group receiving high moisture corn would have improved positive milk and immune function response due to the increased content of NDF and preserved B-carotene in the high moisture corn.

The experiment was well documented, and results presented clearly, though some improvement could be achieved on the support for b-carotene in the HMEC diet? 

A few places for edit:

line 34- K is missing on kernel.

Line 49- replace few with little.

Line 76- in Table 1, please place a dash where the ingredient was not included (a dash to show there was 0 HMEC in the SFC diet, and vice versa).

Line 85- please include how often forage samples were taken- were individual forage samples analyzed each week/month/ etc, or were samples combined and only one sample analyzed? Would be ideal to include the standard deviation or range of values for each nutrient, if they are known.

Also, if available, please add NDF digestibility to the table of nutrients. The difference in NDF digestibility would help explain why the HMEC diet had improved results, but hard to know without the data included.

One main reason HMEC should improve cow health is the increased b-carotene levels in the diet, however, this was not measured so why would there have been expected any difference in immune markers? I think this value should be added and further discussed or all immune function theory taken out of the paper. It is just a supposition, and no evidence was found to support that B-carotene is increased in HMEC.

Line 96- needs a space between week and and.

In line 278- please include comments about the HMEC had increased NDF, which allowed more fiber to be used as substrate for fiber-digesting bacteria which enhanced the overall VFA profile and also mention that HMEC is a "wet" feed that allows a quicker bacterial attachment and therefore more extensive digestion compared to drier SFC that would require "wetting" by rumen fluid before the bacteria could attach and culture the SFC surfaces. These are important and basic points that should not be overlooked, since the two diets had very little other differences between them to explain the differences in overall results. 

Line 312- 318; I feel there is not enough direct evidence in this paper to really link improved immunity factors to your results.  The references for b-carotene are not related to dairy cows (3, 25, 26). Can you find a more direct reference? or show that you actually have b carotene in your HMEC? If not, take out this portion. I find this all very interesting but not strongly supported. perhaps there could be a follow- up study where Vitamin A is supplemented and theses same samples taken from the participating cows to see if there were similar results in IGg's due to Vit A supplementation> the improved IgA, IgG, and Ig M could also be attributed to reduction of cytokines, but this was not measured in the current study. 

Figure 2- I don't understand how the bars are showing a difference in the two feeding groups. Which data belong to which group? this figure is confusing, maybe needs some extra description in the title or the legends. 

 

Figure 3- Are the heat maps that include stars some sort of significance? it needs to be explained in the description. I applaud the efforts and work it takes to arrive at these kinds of data, but it is useless if it can't be clearly described so the educated reader can interpret what they mean. I have a PhD is Dairy Science- I know cows well. The rumen microbes- I am familiar with several- but I don't use OTU and related analyses on a regular basis, so to improve the usefulness of the data presented here, it needs to be better explained how these data are important and how they really show what is being claimed in an understandable way. 

Line 415- please cite references for Mogibacterium and and Prevotella, Eubacterium nodatum group and no rank-f-Lachnospiraceae and their functions - these strains are rarely noted in literature, and I would like to know where the roles have been previously identified as I am not as familiar with these strains and their functions in rumen fluid. I think your claims make sense, but you need more references of previous work identifying these roles to support your statements here.

Lines 438-442- I'm not sure you can make these claims without more cited references, or more direct evidence, but neither are reported in this study, please take this out until there is more clear and direct evidence to link HMEC to immune function. I am not sure that increased b-carotene- which content was not reported- could help the immune system as described without having actual evidence that it did this. Otherwise, the paper was very good and presented interesting results.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors studied replacing steam-flaked corn with high moisture ear corn in the diary feed and evaluated effects of the treatment on the performance of the diary cow. The study demonstrated that the feed with HMEC was more beneficial to the cow with significant improvement in feed intake, milk yield, physiochemical indexes, and ruminant microbiota. The methods used for the study are reliable and relavent to the objectives of the study. The conclusions are supported by the results. Please consider resolving the comments below before publication in the journal. 

Please give one or two sentences in the Abstract section as to why conducting this study.

L 34, "Produced by corn corb and ernal fermentation" This is confusing. Is this how the HMEC produced? If so, please describe more in detail.

L 45, Please add a reference to this sentence. 

L46-47, Can you add more information about the "challenges, including highe-feed cost, limited forage energy " and also add reference to these.

L65, Please explain what is "LAB fermentation additives".

Please give justification of why replacing HMEC with SFC, not others (e.g. DDGS, brewer grain, corn grain, etc.) in the feed formulation. Also why was this study choosing 6.58% replacement of HMEC? Why not testing higher inclusion rate of HMEC such as 10%, 20%, 30% etc?

The authors should highlight the significance of replacing HMEC with SFC, would HMEC have lower cost, or be more easier to obtain? How is the current dairy cow feeding in the area and would incorporating HMEC a future solution to improve dairy cow production. These should be discussed in the sections of Discussion and Conclusion. Otherwise, this manuscript would be just an technical report.

Comments on the Quality of English Language

English language is fine with minor spelling errors.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf