Nutritional Performance of Grazing Beef Cattle Supplemented with High-Protein Distillers’ Dried Grain

Round 1

Reviewer 1 Report

Titile:　Nutritional performance of grazing beef cattle supplemented with high-protein distilled dried grain

Authors: Milene Rodrigues Dias　et al.

 Comments from a reviewer:

The authors investigated the effects of substituting SBM with HP-DDG in a study involving only five Nelore cattle in Brazil.

It is an interesting report, however, with such a small sample size and five nutrition levels, it appears insufficient for drawing definitive conclusions.

I suggest the authors provide further validation of their results.

Additionally, the frequent use of abbreviations such as HP-DDG, DOM, RAN, SUN, SBM, etc., may hinder clarity for readers. It would be beneficial for the authors to provide a list of these abbreviations for easier comprehension.

Author Response

Dear Reviewer.
We made changes throughout the text (highlighted in yellow) based on requests from reviewers and editors.

Regarding the number of animals, we agree that the number was somewhat reduced. Therefore, we highlight in the conclusion the need for more studies with a larger number of animals. However, we would just like to point out that it is not that uncommon in this type of design (Latin square) to use 5 animals (Animals 2020; https://doi.org/10.3390/ani10040662 and Animal Feed Science and Technology 2023 https:/ /doi.org/10.1016/j.anifeedsci.2023.115599) or even 4 (Animals 2023 https://doi.org/10.3390/ani13162555). Even so, our scientific team is already conducting experiments in a replicated Latin square design in an attempt to increase the power of the test.

We hope to have met the essence of what was requested by everyone. We remain at your disposal for additional corrections.

Appreciate.

Reviewer 2 Report

Line 15-16 is that per 'tropical pasture grazing' area?  I assume

In title the DDG is Distilled dried grain, in line 21 it is 'distillery' dried grain (and in other countries it is distillers' dried grain).

 Line 54 What is PM?  should be ?MP

Line 55 - 57 is an incomplete sentence ? verb ? object 

Line 80:  consider using the term 'idled' versus postponed - more appropriate term is idled in farming.

Line 85 and 86 If the experimental prior is 14 days of adaptation and 5 days of collection - then the experimental period is 19 days versus 18 days.  Note that in Line 113 the authors state the 'from the ninth to the sixteenth day of the animals' adaptation to the diet... So be consistent in your experimental days.

Table 1 - no description of superscripts 1, 2, and 3 below table for easier reading and understanding

Lines 169 to 183 Assessment of effective feed degradability - bags incubated in the rumen.  Were they animals fistulated?  Reference 18 uses bags in fistulated animals as one of the methods, but if these animals were fistulated - this is an important aspect to describe (also an IACUC issue) for the experiment.  If not fistulated, how did the bags get into the rumen because they (Line 181-182) 'were removed from the rumen'?

Lind 202 - description of commercial kit ? do you need to include city/country of Brazil?

Line 222 formula could be better explained.

Line 282-283 ... the values are higher (i.e., 800 and 710 g day-1 for RDP and RUP, respectively) than the requirement found by [27]; that is even with ...

Link 315 - 316  DDGs often contain significant sulfur acquired during processing.  In our area, often the contribution of sulfur in the DDGs can push the animals into copper deficiency and sometimes polioencephaolmalacia - therefore, be careful with the statement of completely replacing SBM because you studied this experiment over a 5 day nutritional evaluation and were not evaluating longer effects (health effects)  or evaluating trace mineral effects.  Consider a statement that based on this short-term study and evaluating nutritional responses   HP-DDG can be used to completely replace SBM, ....

See above

Author Response

Dear Reviewer.
Below are the answers to what was requested

Line 15-16 is that per 'tropical pasture grazing' area?  I assume
Yes. We added the word “tropical”

In title the DDG is Distilled dried grain, in line 21 it is 'distillery' dried grain (and in other countries it is distillers' dried grain). 
We change to distillers' dried grain

Line 54 What is PM?  should be ? MP
Yes, the correct is MP.

Line 55 - 57 is an incomplete sentence ? verb ? object
We corrected

Line 80: Consider using the term “idle” versus postponed – the more appropriate term is idle in agriculture.
Changed

Line 85 and 86 If the experimental period is 14 days of adaptation and 5 days of collection - then the experimental period is 19 days versus 18 days. Note that in line 113 the authors state the 'ninth to sixteenth day of adaptation of the animals to the diet... Therefore, be consistent in your experimental days.
Line 113 refers to the days (9 to 16) on which the external indicator was administered. It really got confusing, as it seemed like the adaptation period was 16 days. We adjusted the sentence.

Table 1 - no description of superscripts 1, 2, and 3 below table for easier reading and understanding
Added information

Lines 169 to 183 Assessment of effective feed degradability - bags incubated in the rumen.  Were they animals fistulated?  Reference 18 uses bags in fistulated animals as one of the methods, but if these animals were fistulated - this is an important aspect to describe (also an IACUC issue) for the experiment.  If not fistulated, how did the bags get into the rumen because they (Line 181-182) 'were removed from the rumen'
In fact, due to inattention, we did not inform that for these analyzes animals fistulated in the rumen were used. We correct.

Lind 202 - description of commercial kit ? do you need to include city/country of Brazil?
Information added.

Line 222 formula could be better explained.
Sentence was rewritten

Line 282-283 ... the values are higher (i.e., 800 and 710 g day-1 for RDP and RUP, respectively) than the requirement found by [27]; that is even with ...
Corrected

Link 315 - 316  DDGs often contain significant sulfur acquired during processing.  In our area, often the contribution of sulfur in the DDGs can push the animals into copper deficiency and sometimes polioencephaolmalacia - therefore, be careful with the statement of completely replacing SBM because you studied this experiment over a 5 day nutritional evaluation and were not evaluating longer effects (health effects)  or evaluating trace mineral effects.  Consider a statement that based on this short-term study and evaluating nutritional responses   HP-DDG can be used to completely replace SBM

Thank you for the valuable question. In fact, one of the limitations to the more expressive use of grains distillery in the United States is a high concentration of sulfur in these by-products due to the use of sulfuric acid in the
fermentation process, to control pH and inhibit growth of bacteria during fermentation, in addition to be an employee cleaning the tanks. In Brazil, it is used weaker acids, such as citric, in addition to hot water to cleaning of tanks, so that the sulfur content in distillers grains produced in Brazil is within a range of values much safer. The HP-DDG studied presents an average of 0.48% sulfur in dry matter and considering the quantity consumed through supplements, dietary sulfur would be below the maximum tolerable level of 0.50% DM for diets with ≥40% forage (NASEM, 2005). Therefore, if you consider it important, we can highlight these facts in the manuscript.

Round 2

Reviewer 1 Report

Accepted.

Author Response

Thank you