Milk Production of Dairy Cows Fed Grass-Clover Silage Pulp

Round 1

Reviewer 1 Report

General comment I reviewed the manuscript “Lactation performance of dairy cows fed grass-clover silage pulp” and found some merits. However, author needs to improve the description of the biorefinary process, and improve methods description and discussion section. Therefore, I suggest major require major revision of the present manuscript. Specific comments:

Abstract Line 10. Biorefinary of??

Line 15: Explain better this separation of solid and liquid. Is this title correct for this abstract? Introduction The authors showed a well written introduction!

Material and methods Lines 80-82. What was organic acids concentration in the chemical additive?

Line 184. NDF digestibility was evaluated after 240 h of in vitro incubation? Why? Statistical analysis and experimental design: what were the blocks? How many blocks were used? What was the matrix of variance and covariance of each variable? I didn’t see any means test in the results. Please, remove Tukey means test description.

Results Figure 1. Add P-values for treatment comparison at each week of evaluation. Discussion.

Line 274. Why a dried diet could reduce DMI?

Line 277. It seems impossible a diet with 62% of silage (31%DM) have more than 50% of DM content. Additional comments: Fecal analysis was performed? Did you have any information of diet particle size? Did you perform any evaluation previously to treatments application?

Author Response

General comment I reviewed the manuscript “Lactation performance of dairy cows fed grass-clover silage pulp” and found some merits. However, author needs to improve the description of the biorefinary process, and improve methods description and discussion section. Therefore, I suggest major revision of the present manuscript.

AU: Dear Reviewer 1, thanks for your valuable review, we believe that our manuscript has greatly improved. We have addressed your suggestions throughout the specifics comments. The detailed description of the biorefinery process is stated on L89-94.

Specific comments:

Abstract

Line 10. Biorefinary of??

AU: Biorefinary of silage. Text reworded as suggested.

Line 15: Explain better this separation of solid and liquid. Is this title correct for this abstract?

AU: An explanation was included as suggested. Regarding the title, we changed it to “Milk production of dairy cows fed grass-clover silage pulp”. As we did not evaluate the entire lactation of the cows, we believe that the new tittle reflects the study better. Additionally, the term ‘lactation performance’ was replaced by ‘milk production’ throughout the text.

Introduction:

The authors showed a well written introduction!

AU: Thanks, we appreciate your acknowledgment.

Material and methods:

Lines 80-82. What was organic acids concentration in the chemical additive?

AU: The following statement was included on L77-80: ‘A chemical additive (Helm Gräs, Helm Scandinavien A/S, Hornslet, Denmark) containing formic acid (36.5-50%), propionic acid (10-30%) and sodium formate (10-20%) was applied at 4.0 L/t of forage on the harvester and the chopped forage was ensiled in bunker silos.’.

Line 184. NDF digestibility was evaluated after 240 h of in vitro incubation? Why?

AU: We wanted to know the potential NDF digestibility if it stays in the rumen for as long as 10 days. We also wanted to get the iNDF value, which requires such a long incubation period

Statistical analysis and experimental design:

what were the blocks? How many blocks were used? What was the matrix of variance and covariance of each variable? I didn’t see any means test in the results. Please, remove Tukey means test description.

AU: “Cows were blocked based on their breed, lactation number, DIM and ECM yield and randomly assigned to one of the two treatments within block (n = 36)”. This information is stated on L112-113. The covariance structures were unstructured (TYPE=UN) for ECM; Fat (%); Fat (kg/d); Protein (kg/d); Lactose (%); Lactose (kg/d) and autoregressive (TYPE=AR(1)) for MY; Protein (%); BW; BCS. You are correct, Tukey test description was deleted as suggested.

Results:

Figure 1. Add P-values for treatment comparison at each week of evaluation.

AU: P-values were included on both figures was suggested.

Discussion:

Line 274. Why a dried diet could reduce DMI?

AU: There is a practical consensus that high dry matter diets reduce intake of high producing dairy cows due to the difficult ingestion and the necessity of greater water consumption. Even though previous studies, as cited in the current manuscript, have shown that dietary DM concentration does not affect intake we still see farmers and nutritionists adding water to the TRM aiming to avoid intake limitation and sorting. As the SP is drier than its original silage, we decided to address this issue beforehand.

Line 277. It seems impossible a diet with 62% of silage (31%DM) have more than 50% of DM content.

AU: This calculation can be done using the information stated in Tables 1, 2 and 1A by simply multiplying the DM content of each ingredient by its inclusion in the diet. E.g.: Silage (310 g/kg DM) at 62.2% inclusion in the diet, contributed to 192.8 g/kg DM. Mix of cereals (896 g/kg DM) at 17% inclusion in the diet, contributed to 152.3 g/kg DM. Faba bean (916 g/kg DM) at 5.74% inclusion in the diet, contributed to 52.6 g/kg DM. Pellets (912 g/kg DM) at 14.9% inclusion in the diet, contributed to 135.9 g/kg DM. Then, the sum of each ingredient contribution to the dietary DM (192.8 + 152.3 + 52.6 + 135.9) is equal to 533 g/kg DM.

Additional comments: Fecal analysis was performed? Did you have any information of diet particle size? Did you perform any evaluation previously to treatments application?

AU: Fecal analysis and particle size of the diets were not performed. Interesting point. We will consider it to the next trial on biorefined forage. At the end of the adaptation period, all the variables (MY, ECM, milk components, BW and BCS) were evaluated to ensure that cows were properly blocked. There was no difference between treatments on d1 of the study.

Author Response File: Author Response.pdf

Reviewer 2 Report

Lines 38-39: check references and punctuation.

Lines 63-68: please reword the aim of the study; in my opinion the hypothesis must come first.

Lines 80-82: please specify the concentration of the formic, propionic acid and sodium formate in the chemical additive.

Lines 87-90: please rewrite properly the dates and explain better how silages were mixed together.

Lines 91-94: since the paper focuses on organic dairy production, more information on the biorefinery process would be advisable.

Lines 288: “not” must replace “no”.

This manuscript submitted as “communication” is, on average, well-written and clearly described. However, as for its originality, I am afraid that some aspects could have been expected on the basis of the two treatments compared (silage-based diet vs silage pulp diet) such as milk yield and ECM that were (almost) always greater following the silage-based diet. Furthermore, cows receiving the silage-based diet had also greater yields of milk protein and fat in comparison with those receiving the SP-based diet. The mechanical pressing process did not increase fibre digestibility in SP, thus, it is easily imaginable that the complete substitution of silage for SP would reduce the lactation performance of dairy cows over time. Anyway, a positive result was that, notwithstanding the SP diet, there were no significant effects on the cows’ BCS and BW.

Therefore, it might be useful to specify in the aim of the study the preliminary character of the trial that could be part of a larger project.

Author Response

AU: Dear Reviewer 2, thanks for your detailed review. We firmly believe that our manuscript has improved after this revision.

Lines 38-39: check references and punctuation.

AU: Thanks for noticing that. References and punctuation were reorganized.

Lines 63-68: please reword the aim of the study; in my opinion the hypothesis must come first.

AU: We agree. Indeed it reads better. Thanks for your suggestion.

Lines 80-82: please specify the concentration of the formic, propionic acid and sodium formate in the chemical additive.

AU: The following statement was included on L77-80: ‘A chemical additive (Helm Gräs, Helm Scandinavien A/S, Hornslet, Denmark) containing formic acid (36.5-50%), propionic acid (10-30%) and sodium formate (10-20%) was applied at 4.0 L/t of forage on the harvester and the chopped forage was ensiled in bunker silos.’.

Lines 87-90: please rewrite properly the dates and explain better how silages were mixed together.

AU: Dates were rewritten and a more detailed explanation was included as suggested.

Lines 91-94: since the paper focuses on organic dairy production, more information on the biorefinery process would be advisable.

AU: A more detailed description of the biorefinery process was included on L89-94.

Lines 288: “not” must replace “no”.

AU: Replaced. Thanks for noticing that.

This manuscript submitted as “communication” is, on average, well-written and clearly described. However, as for its originality, I am afraid that some aspects could have been expected on the basis of the two treatments compared (silage-based diet vs silage pulp diet) such as milk yield and ECM that were (almost) always greater following the silage-based diet. Furthermore, cows receiving the silage-based diet had also greater yields of milk protein and fat in comparison with those receiving the SP-based diet. The mechanical pressing process did not increase fibre digestibility in SP, thus, it is easily imaginable that the complete substitution of silage for SP would reduce the lactation performance of dairy cows over time. Anyway, a positive result was that, notwithstanding the SP diet, there were no significant effects on the cows’ BCS and BW. Therefore, it might be useful to specify in the aim of the study the preliminary character of the trial that could be part of a larger project.

AU: We appreciate your suggestion, however, the novelty of our study is the complete replacement of silage for SP, which is a valuable information for the growing use of fibrous pulp in ruminant nutrition. Therefore, the magnitude of the difference between the two treatments is new information. The study is already part of a larger project.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report