Increased Sulphur Amino Acids Consumption as OH-Methionine or DL-Methionine Improves Growth Performance and Carcass Traits of Growing-Finishing Pigs Fed under Hot Conditions

Round 1

Reviewer 1 Report

This manuscript targets to evaluate the OH-Met and DL-Met on growth and carcass traits of growing-finishing pigs under a heat stress. The English expression is odd and need to improve by native experts. And there are many flaws in this article, especially the introduction and discussion.

Comments to the Author

1.       The manuscript could be improved by sending to a technical writing assistance in English. In many cases the wording is odd, and corrections is beyond what a reviewer should do. For example, in Line 269-272, it’s better to change the sentence to ‘The LD muscle depth in the OH-Met group was greater than the DL-Met and an increase in the dietary Met level caused positive effects on the boy weight and the lean meant percentage (or weight?)’.

2.       Line 59-63, this is not related to your study on growth performance and carcass traits

3.       I suggest the author should make the introduction more clear. For example, there are some citation that was not related to the present study. It will be more clear to focus on the effects of Met on growth and carcass rather than other parameters.

4.       Table 3: the a and b should be superscripts.

5.       Line212-216: better to give the results of the PIC

6.       Line228-230, I did not get your point, what is your hypothesis or expectation?

7.       Line 232-237, when you mentioned the influence of the OH-methionine in animals under heat stress. I think you need to give some explanation about the mechanism.

8.       In the introduction and discussion part, please use the past tense when you cite previous studies.

9.       Line 250-253, do you mean Met acts as anti-inflammatory and antioxidant modulator, so that the performance of pigs get improved?

10.    Line 264-265, In the finishing phase, the pigs often did not need a lot of AA since they can take much more feed than in the growing phase, right? Can you give more recent citation about the negative effects of a standard AA level on feed intake of finishing pigs?

11.    I suggest the author reorganize the discussion part. For example, from line 273 to 287, there are some explanation about why the OH-Met was more effective or caused more positive effects on performance and carcass. It’s better to give your results firstly, then compare with previous findings and give the explanation or discussion about your results.

12.    Line 293-302, The author list some previous studies on carcass traits, but I hope to see some explanations about your results or your findings.

13. Change the presentation style of results in table 4-6,specifically, change the horizontal and vertial indexes.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is quite well written, the aim is clearly stated and also material and method is adequate. I have following suggestions and recommendations.

 

Introduction

All abbreviation must be explained at its first use.

Line 60, 64 – HMTBA (no explanation, line 55 different abbreviations – OH-Met)

Line 60 - DLM (no explanation, used only one time)

Line 73-74 – for oxidised glutathione use abbreviation GSSG

 

Materials and Methods

Line 10-105 – “At the beginning of the trial, animals were distributed in five blocks (according to the initial body weight and sex), with 10 replicates each. A replicate was a floor pen of five pigs of the same sex (barrows or females)“  It is probably a mistake, because altogether there were 200 pigs (5 x 10 x 5 = 250). Number of animals per individual groups should be stated also in tables.

How was evaluated feed intake?

Line 114 – DDGS - abbreviation without explanation

Line108 – “DL-Met (99% powder) and OH-Met (88%, liquid)“ – specify the sources of Methionine in more details

It would be also useful to show the tables value /recommended values according Brazil tables, which you used for the calculation.

Table 1 – This table show only calculated values, thus it is redundant to show all parameters for two groups, by this way you have two times the same numbers. There should be stated separately only values which differ between groups (Met source, SID Met equivalent, SID Met+Cys equivalent).

The explanation of SID is missing.

Please modify the table to be more clear and without repetition of the same numbers.

 

Results

Table 2 – The units in the table are not clear. You show “Total AA %”, but it is not clear % from what (dry matter, fresh matter..)? Similarly, for individual AA (Lys, Thr, Val, Met) it is not clear % of what. You should also show the intended values and compare them with analytical values. I am not sure with units, but your calculated values for Met equivalent differ from analytical values quite a lot (i.e. finisher II – calculated values 0.24/0.29 and analytical values 0.42/0.55-0.51…). Your commentary is not clear and did not explain these differences: “Also, the levels of synthetic methionine added are similar, independent of the sources used, as well as the other amino acids.“

Table 3 –the importance of this table is not clear. Is it really surprising that pigs eating diet with 120% Met have higher Met intake than pigs eating diet with 100%? How was the data calculated when two different forms of Met were used? There is also no comment on this table in the text. Is this table important?

Repeatedly you used “highest dose of methionine” however, there were only two doses. Thus, it should be higher dose. Or did you consider different analytical values?

You display the data in Tables 4, 5, 6 with three decimal places, which is redundant. There is the rule that it is enough to show only three significant numbers, which means for example 1.23 or 12.3. There is a similar problem also in the text, where you repeatedly use three decimal places even for body weight (e.g. lines 198-200)

Line 190-191: you used a comma instead of a dot  (“were heaviest at 112 days (P=0,051), at 140 days of age (P=0,055) and at the 190 end of the trial (P=0,055; 163 days of age)“).

 

Discussion

Line 277 – MHA – abbreviation not explained

Line 255 – 260 – You should be more precise, compare recommended values and suggestion for the new genetics.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I have no more recommendation, only some editorial.

Line 32-35 – You display the data with three decimal places, which is redundant. There is the rule that it is enough to show only three significant numbers.

Line 196 – “were heaviest at 112 days (P=0.051)“  replace „were heavier at 112 days“

Line 205-208 - replace “best results” with “better results”

Author Response

Thank you for your recommendations. All corrections indicated were made in the manuscript.