Effect of Dietary Calcium Propionate Inclusion Period on the Growth Performance, Carcass Characteristics, and Meat Quality of Feedlot Ram Lambs

Round 1

Reviewer 1 Report

Dear authors, it seems to me that this is a good manuscript and it has relevance in the scientific world. However, many points affect the quality of the manuscript.

 

The language of the study needs to be improved. Major corrections.

 

Dear authors, first of all, please do not reply to me without proofreading the manuscript. If I question the topics, it is because the text needs improvement; then change the text.

 

Abstract: Rewrite the abstract considering its parts: Introduction (if necessary), objective (mandatory), material and methods (mandatory), results (mandatory), discussion (if necessary) and conclusion (mandatory).

 

Line 13: What does CaPr mean? Describe the initials the first time they appear in the text considering the abstract and the body of the manuscript as different texts.

 

Lines 13-15: Write the objective as a concise text separate from the methodology. In the methodology describe the treatments and the initial body weight of the animals.

 

Line 18: How much longer? You studied days; describe here the days that promoted changes in fat thickness, L* and a* values.

 

Lines 19-20: 28 days is the maximum (or minimum) of the quadratic slope?

 

Lines 21-23: Ok, however, what is your indication? If you used polynomials, why didn't you use an estimated value in your conclusion?

 

Line 24: Try not to use the same keywords that were previously described in the title.

 

Line 31: Add data about it. E.g. how much is consumption reduced with the presence of ruminal acidosis? Also, avoid using subjective, non-technical words like "poor".

 

Lines 33-35: Why those non-conventional chemical sources? Why not other sources? You must describe here "why" you chose to cite these sources and not others.

 

Lines 37-39: This is repetitive with the previous text. Rewrite it.

 

Lines 43-44: This type of idea is not a necessary quality to develop a study. Many other hypotheses can be created to carry out this investigation; such as the next idea.

 

Lines 48-49: Remove this text.

 

Lines 50-52: Maybe it's the language; however, the hypothesis needs to be improved.

 

Lines 61-63: Instead of the description of the climate of the year, you can describe the average values of the climate when the study was carried out.

 

Line 70: I think that ram is not the adequate description. Add the average age of the animals. Improve language.

 

Table 1: The sum of ingredients in the diet is 100.1 and not 100. Correct it.

            What is the dry matter content of the diet?

            Add the calculated Ca:P proportion or ratio.

            Evaluate the neutral detergent fiber content of the diet.

 

Lines 79-80: Describe this calculation in the material and methods topic.

 

Line 141: Add the muscle name.

 

Results and discussion: The description of the results needs to be improved using regression equations in case of linear and quadratic effects. Add the linear or quadratic effect equation in the footnote. Improve footnotes in all tables.

The discussion is very generic. The use of comparative data is fine, but it is not specifically a discussion. I wrote some suggestions but the discussion on several points needs to be rewritten.

The discussion topic looks like a copy and paste of good ideas, but they don't directly correlate. You need to correlate the paragraphs. At the same time, some ideas do not follow a sequence.

Finally, the point of contention is that authors discuss their data and not other authors' data, unless they clearly support their data.

 

Lines 181-182: The quadratic answer is not correct. Use and footnote the regression equations generated from the quadratic tests to estimate the maximum value and days in CaPr.

 

Table 2: Change “different periods” (or similar) instead of “three inclusion periods”

 

Table 2: Change the units of ADG and DMI from Kg to grams for better observation. Using hundredths to describe p-values, here and in all tables.

 

Lines 186-188: These lines were described in the material and methods. It is not necessary to describe them here. Use the space to add the regression equations.

 

Lines 191-193: Well this is correct. However, this metabolism is a function of many parameters, mainly pH. A lot of propionate can be delivered, but how much is absorbed based on pH?

 

Lines 195-198: Remove it.

 

Lines 198-205: Ok and? This is a free idea. What is the purpose of this text?

 

Line 199 and line 208: How many days?

 

Lines 198-216: I think the problem with comparing these studies is that the animals in one study may have higher productive characteristics than the others (Criollo lambs). Also, differences in diets, days in the feedlot, etc. In order to compare studies, you should consider the factors that may influence the comparison so that you do not reach wrong conclusions.

 

Lines 217-221: These lines are a partial response to my previous comment. However, what is the importance of these texts to reach your objective? This is all very generic. Why discuss the dose if your objective is to discuss the period? Etc.

 

Lines 222-265: This is a great review; however, it is not the discussion of its results, this is a bibliographic review and discussion of this review.

 

Line 267: Remove it (Organ … table 3).

 

Line 276: Remove it.

 

Lines 298-299: What does "few variables" mean? It is better to describe those few variables. What does "inconsistent results" mean? Perhaps for me or another reader, the data is not inconsistent.

 

Lines 300-305: The manuscripts are about doses and not about periods. It is assumed that in this part, the discussion is about periods.

 

Lines 322-323: It is necessary to describe this better. How much the energy content is improved? How much net energy was added? How much of this energy was used and how much was excreted? Etc.

 

Lines 323-327: Ok and? How this is correlated with your study specifically?

 

Lines 343-350: I believe these data are more correlated with tissue deposition (specifically fatness) as a function of age than as a function of dietary energy as supported by the next lines and lines 417-419. This could be an incorrect interpretation of the results.

 

Lines 369-370: What are those values?

 

Lines 374-375: I don't understand this idea, it's confusing.

 

Line 429: Remove it.

 

Table 6: Are you sure "instrumental color" is the correct description?

 

Lines 451-455: ok and?

 

Lines 456-487: Improve the discussion.

 

Line 489: How much CaPr?

 

Lines 491-492: Two optimal levels? You need to conclude considering one value obtained from regression equations.

 

Lines 494-496: This is a compilation of results, no need to describe this here. Improve it.

 

Many references used in the discussion are very old. Comparison of current data with previous studies can lead to misleading comparisons.

Extensive editing of English language required

Author Response

Authors appreciate your comments and observations, which are very valuable to improve the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Agriculture

 Review – Comments on the scientific contribution

Effect of dietary calcium propionate inclusion period on the 2 growth performance, carcass characteristics, and meat quality 3 of feedlot ram lambs

 

The revised contribution is within the scope and theme of the Agriculture journal, it is relevant and there is interest from the scientific community and society, with some additives novelty for this product meat and provides important technical information, however, the manuscript presents some   deficiencies and omissions in the materials and methodology used, especially in the experimental design and statistical analysis, which influence the results, discussion and conclusions.

The main observations found in the manuscript are indicated below, in an effort to improve its technical, scientific and presentation quality.

1. Summary

The authors must include in the summary the breed of the experimental sheep, the treatments applied, the experimental design used and the statistical analyzes of the information collected, as well as the days of the fattening period.

2. Introduction

P1L43-44. Clarify what characteristics of sheep are referring to?

The review made by the authors on the use of calcium propionate in feedlot sheep is very simple and short (it only considers the productive response), it does not include the results of its effect on the carcass and meat quality, likewise, I consider that they should discuss, for the justification of the study, how many days it has been supplied in other studies with fattening sheep and from there justify the dose and treatments (supply times) applied in the present study. Why is it hypothesized that the inclusion of calcium propionate will influence carcass characteristics and meat quality; what is its function, how does it work? In other words, what is the biological justification?

3. Materials and methods

Table 1. I suggest using absolute values (g kg^-1 DM) in the diet and nutritional composition.

¿ Finishing sheep with 40 kg of LW require that protein content (16.3%) in the diet ?. Its alot. Review (NRC, 2007).

Indicate in the manuscript the energy contribution of calcium propionate.

Statistic analysis.

I think that the authors should consider a mixed model in the study and in the analysis of repeated measures in the productive response variables.

I do not quite understand why the initial weight was used as a covariate to adjust the analysis of the productive response data?. It is not different between treatments from the beginning.

In the case of the weight of the hot carcass, for the rest of the characteristics of the carcass it is fine. And it would be better to use the weight of the cold carcass as a covariate.

It is indicated that the linear and quadratic effects of the applied treatments, calcium propionate supplementation times, were analyzed by orthogonal contrasts. It should be indicated as follows:

Suggestion. “Levels of CaPr supplementation were partitioned into linear and quadratic orthogonal polynomials for four equally spaced levels with the statements LSMEANS and ESTIMATE”.

4. Results and discussion

Separate into different sections as indicated by the magazine.

Reviewing the data in table 2 does not coincide when calculating the weight gain:food intake ratio. This variable refers to feed efficiency and not to feed conversion, therefore the units are not kg/kg.

Example: 0.22/1.67=0.131; 0.27/1.69=0.159; 0.28/1.69=0.165; 0.25/1.60=0.156

ADG, kg/day 0.22 0.27 0.28 0.25

DMI, kg/day 1.67 1.69 1.69 1.6

G:F, kg/kg?? 0.14 0.15 0.18 0.16

Note: I suggest putting the feed conversion values (ratio of kg of food consumed for each kg of weight gain.

In the following paragraph, if a trend is indicated, it should be placed (P<0.10 instead of P<0.05):

“Former studies conducted in lambs have not considered the length period of CaPr  supplementation nevertheless, the changes observed through periods in this study suggest a modification of the growth response over time (P<0.05)”. Correct the same in other paragraphs of the manuscript where a trend is indicated (results description in Table 4).

P5L197 to P6L226. In the previous studies, to which the authors of this manuscript refer, on the use of calcium propionate, it would be more important to indicate the energy content rather than crude protein in the diets supplied to sheep, either growing or finishing.

Note: The paragraph of P6L227-236 that refers to dairy cattle in production does not contribute to the discussion of this study that deals with growth, production and quality of sheep meat with a high grain diet. Similarly the following paragraph was done on pre-ruminant calves.

In fattening sheep with a diet high in grain and low in forage, it is more important from the meat quality point of view to evaluate the color of the meat than the fat itself.

 

Author Response

The authors appreciate your comments and observations, which are very valuable to improve the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors, congratulations, the manuscript was improved.

 Line 15: Change “male” instead of “ram”.

 Line 28: Change “quality” instead of “characteristics”.

 Line 493: Change “quality” instead of “characteristics”.

 The language of the study needs to be improved.

Author Response

Authors appreciate your valuable comments and corrections for the improvement of the manuscript. These corrections have been made following their recommendations.
Thank you.

Author Response File: Author Response.pdf