Cow Culling Rates and Causes in 12 Pasture-Based Dairy Herds in Southern Uruguay, a Pilot Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study is interesting because it describes the causes of culling in Uruguay, and this previously unavailable information is relevant for understanding dairy performance. However, the small sample size used to estimate the culling rate does not allow for inferences at the national level. Nonetheless, this pilot study could serve as a foundation for future research, extension activities, and technology transfer. I strongly suggest stating that this study is a pilot study in the title and objectives

Linea 105-106: Describe briefly the destinations and categories for slaughter. Additionally, show in the results the categories of cows for slaughter as defined by Fetrow et al. (2006).

Línea 107-108: how you can confirm that the same criteria were used in all of farms? It is crucial because a clear, precise, and consistent definition of the event is essential for accurately estimating the culling frequency

Describe in more detail in the methodology section the “sales for dairy”.

Suggest including a column in Table 3 showing the range of culling causes for herds.

Line 133: is this a mistake?

A lot of information is repeated in text and tables, you can avoid it if not necessary.

Line 189: Is reference 126 a mistake?

Author Response

Reviewer 1.

Comment. I strongly suggest stating that this study is a pilot study in the title and objectives.

RESPONSE. We accepted the suggestion. The title was changed to “Cow culling rates and causes for culling in 12 pasture-based dairy herds in Southern Uruguay, a pilot study” and the word “pilot” was added to the sentence referring to the study objective at the end of the introduction.

Comment. Line 105-106: Describe briefly the destinations and categories for slaughter. Additionally, show in the results the categories of cows for slaughter as defined by Fetrow et al. (2006).

RESPONSE. The destinations were briefly described, the categories and subcategories are defined in Table 1. The results by category are shown in Table 3.

Comment. Line 107-108: how you can confirm that the same criteria were used in all of farms?

RESPONSE. The criteria used in all farms were the same because the categories were defined by the principal investigator in conjunction with the farm’s advisors (veterinary or agronomist) and farm owners included in the study. Subsequently the categories were shared with the dairy staff. Before releasing the form, it was reviewed by the co-authors of the study. To fine-tune it, a pilot test was carried out for two months at the INIA La Estanzuela dairy farm to verify that the form was easy to complete and that the information was accurate. In addition, and more importantly, the first author participated in the classification process of dairy cow culls during the study period to assure that the same criteria were applied in all farms.

Comment. Describe in more detail in the methodology section the “sales for dairy”.

RESPONSE. The “sale for dairy” was now detailed in the context of the culling of cows in sub-section 2.2 of Materials and Methods. It represents live cows that are sold to other dairies to continue their productive life.

Comment. Suggest including a column in Table 3 showing the range of culling causes for herds.

RESPONSE. A column showing the ranges of culling causes has been added to Table 3 in the revised version of the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall I think the paper is easy to read and easy to follow. 

However, I have a major issues with how the data was analyzed.  It was just frequencies with no statistical test, no comparisons, etc.  So it is really hard to make conclusions with the data based on how the authors did the analysis.  They need to analyze the data with some statistical test accounting for herd, breed, and parity.  More on that later.

Line 24: This is too simplistic of an analysis for this data.

Line 32-38: I don't think these sentences are needed in the abstract.  They don't provide any new information about the study.

Line 131: The analysis is too simplistic.  It is very difficult to compare these results with other results because of the analysis.  The authors need to do more analysis and not make it so simplistic.

How did you account for herd, breed, parity?  I think those results could be presented.  You can either do a Chi-square test or a logistic regression account for herd, breed parity and present the data based on those factors as well. 

See a recent research on cow culling in pasture herd.  

1. Reasons for disposal and cull cow value of Holstein cows compared with Holstein, Jersey, Montbéliarde, Normande, and Viking Red crossbred cows

   Portner, S.L. et al. Journal of Dairy Science, Volume 107, Issue 11, 9656 - 9665  https://www.journalofdairyscience.org/article/S0022-0302(24)00991-3/fulltext

 

 

 

 

Table 4 and 5: I think these tables could be collapsed into a smaller table or be combined together.  There is too much detail in the table that is not needed.  I don't think that we need to know every specific condition with small frequencies.

 

Author Response

Reviewer 2.

Comment. They need to analyze the data with some statistical test accounting for herd, breed, and parity.

RESPONSE. Unfortunately, we do not have the information of the breed at the individual (animal) level for each herd, as this information was either not recorded or not available in some herds. Thus, we are unable to explore the effect of breed on culling rates. For this reason, we followed the suggestion of Reviewer 1: to specifically indicate both in the title and in the objectives that this is a pilot study.  Future studies are required to establish comparisons according to milk production, breed, parity, lactation stage or season of the year, but evaluating the eventual effects of these on culling rates were not aims of this pilot study.

Comment. Line 32-38: I don't think these sentences are needed in the abstract.  They don't provide any new information about the study.

RESPONSE. These sentences were deleted from the abstract.

Comment. Line 24, 131: The analysis is too simplistic.  It is very difficult to compare these results with other results because of the analysis.  The authors need to do more analysis and not make it so simplistic.

RESPONSE. This answer was addressed in point 1, please consider that this is a descriptive pilot study and further properly designed studies are needed to evaluate some hypotheses that might arise from it.

Comment. Table 4 and 5: I think these tables could be collapsed into a smaller table or be combined together. There is too much detail in the table that is not needed.  I don't think that we need to know every specific condition with small frequencies

RESPONSE. We tried to join both tables, but they became confusing, so we preferred to keep them separate.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors, thank you for this interesting, insightful manuscript. There is one aspect I would like to point out, which I think should be watched and discussed more closely: it is about the dairy breeds. In the methods part you mention that two types of Holstein cows were integrated in the study. But there is no distinction between the two breeds in the results part. It would be very useful to show whether there were differences between the HOxJE-crosses and the American Holsteins. As you mention in the discussion part (lines 244 – 252) differences between the New Zealand type and the American type Holsteins have already been found concerning reproductive performance in another study in Uruguay. Since in Uruguay most dairy farms work with pasture-based systems the American Holstein breed might not be well adapted and the main reason for many health and reproductive problems is that farms don’t keep the adequate breed. I think there should be more weight on this aspect in this paper. I will propose some respective amendments.

Line 19: replace “some” by “12”.

Lines 23/24: please add which breeds were integrated in the study

Line 48: replace “silage” by “grass silage” (if that was the case)

Line 52: Please add a sentence about the mainly used dairy breeds in Uruguay.

Line 82: please add “in pasture-based systems” after “herds”

Line 89:  could you explain what that means: “by convenience”?

Line 93: Could you please indicate how many Holsteins and how many HOxJE-crossbreeds participated in the study? Were the HOxJE just on a few farms or were they on every farm? Were they New Zealand-type-Holsteins? If yes, please say it.

Table 1, line 5: “…cows without history of disease that do not reach 50% of the average milk production…” which average is meant? Of the hers or of the population of this breed in Uruguay? Please specify!

Table 2: could you please add one line after “average number of cows” where you show the breeds used on those farms (American HO or HOxJE)

Table 3: please add in the first line, 3^rd row of the table: “% of culled cows” (instead of “%”)

Line 186: replace “some” by “12”

Line 196: replace “result” by “results”

Line 208: please add “(including reproduction disorders)” after “diseases”

Lines 210/211: well, it should at least be mentioned here that unwanted culling (because of disease) is usually not profitable

Results part: would it be possible to show somewhere the culling ratesof American HO and HOxJE? That would be great. If this is not possible, please show at least the breeds on each farm in table 2 as I asked you in my remark on table 2.

Line 233: I don’t understand why those 380.9 days are an additional economic loss, because the cow was always milked within that time, maybe she even gave a little more milk, because she was not pregnant. The additional economic loss is there because of several inseminations, but not because of the 380.9 days, isn’t it?

Line 228 and Lines 244-252: Those are important sentences. The breed aspect should also be mentioned for the feet and limbs part and the digestion part.

Line 265: This result is interesting, but it can not be found in the results part. There should be no new results in the discussion part. Here the results should just be discussed! You can add a line on reproductive problems / abortion in table 2.

Line 267: Preventing abortion is actually not just an “alternative” to reduce cow culling rates due to reproductive problems, but it is additionally necessary. Please replace “an alternative to reducing” by “necessary to reduce”

Line 288: do YOU recommend that? That is fine, but please say it. Or is there a reference?; so please mention it.

Line 297: this result can also not be seen in the results part (you could add a line in table 2 with “other diseases”)

Line 303: please replace “some” by “12”

Line 343: I don’t really see the similarity to those data from Denmark

Line 354: please replace “optimal” by “reasonable” (because actually optimal would be no culling because of health problems…)

Lines 364 to 369: I don’t understand this calculation: you say farmers need all their heifer calves for replacement and there are not many cos sold for further production, but a significant number of animals is sold (exported) for production in other countries. So those heifers are really sold for production; therefore it can’t be true that they need to keep all their heifer calves for replacement… . Please write that clearly!

Lines 380 to382: Please add a sentence that it may be necessary to change breeds: to use well adapted breeds for pasture-based systems.

Author Response

Reviewer 3

Comment. I would like to point out, which I think should be watched and discussed more closely: it is about the dairy breeds.

RESPONSE. This is an interesting suggestion; unfortunately, this data was not always available at the individual (animal) level for many cows included in the study. The herds included in the study had lower Holstein-Jersey crossbred cow populations than pure Holsteins, and not all herds used crossbreeds. The comparison of New Zealand-type Holsteins and American-type Holsteins was carried out at one of the farms, but the sample size was too small to draw reliable conclusions. This pilot work on culling was carried out under the conditions of the Uruguayan dairy production system with the aim of having an overview of culling rates and causes. Based on the results, future studies should be conducted to investigate eventual effects of the breed and/or biotypes on culling rates.

Comment. Line 19: replace “some” by “12”.

RESPONSE This has been addressed.

Comment. Lines 23/24: please add which breeds were integrated in the study.

RESPONSE The breeds had been added to this line.

Comment. Line 48: replace “silage” by “grass silage” (if that was the case).

RESPONSE. Most of the silage used in Uruguayan dairies in general and in the 12 ones included in our study is corn or sorghum silage. Grass silage is mentioned in the same line as haylage. This line has been edited in the revised version of the manuscript to address your suggestion.

Comment. Line 52: Please add a sentence about the mainly used dairy breeds in Uruguay.

RESPONSE. The suggestion was included. In Uruguay, 83.6% of the dairy herd belongs to the American and Canadian biotypes of the Holstein breed, 6.3% to the New Zealand Holstein biotype, 0.9% to Jersey, 0.8% to Normande, and 8.4% are crossbreeds.

Comment. Line 82: please add “in pasture-based systems” after “herds”.

RESPONSE. The suggestion was included.

Comment. Line 89: could you explain what that means: “by convenience”?

RESPONSE. Convenience sampling is a non-probabilistic sampling type that implies sampling part of the population that is close to hand based on for instance location and/or accessibility of data. The word was deleted to avoid potential confusion in the readership. The study included representative herds of the Uruguayan dairy system. The following sentence was also added: In Uruguay, 75% of dairy herds are (<200 cows), 17% are medium-sized (199-500 cows), and 8% are large (>500 cows).

Comment. Line 93: Could you please indicate how many Holsteins and how many HOxJE-crossbreeds participated in the study? Were the HOxJE just on a few farms or were they on every farm? Were they New Zealand-type-Holsteins? If yes, please say it.

RESPONSE. The number of cows of different breeds was not included because this information was not recorded/available in all dairy herds included in the study.

Comment. Table 1, line 5: “…cows without history of disease that do not reach 50% of the average milk production…” which average is meant? Of the herds or of the population of this breed in Uruguay? Please specify!

RESPONSE. The average here corresponds to the average production of multiparous cows in the same at similar stage of lactation herd. Appropriate modifications were included in Table 1.

Comment. Table 2: could you please add one line after “average number of cows” where you show the breeds used on those farms (American HO or HOxJE).

RESPONSE. As we had stated previously, the information about the number of cows from each breed was not recorded or available on all herds/farms.

Comment. Table 3: please add in the first line, 3^rd row of the table: “% of culled cows” (instead of “%”). AR. The suggestion was added to Table 3.

Comment. Line 186: replace “some” by “12”.

RESPONSE. The word was changed to number 12.

Comment. Line 196: replace “result” by “results”.

RESPONSE. The word was changed to plural.

Comment. Line 208: please add “(including reproduction disorders)” after “diseases”.

RESPONSE. The suggestion was added.

Comment. Lines 210/211: well, it should at least be mentioned here that unwanted culling (because of disease) is usually not profitable.

RESPONSE. Thank you for the suggestion, the sentence was added.

Comment. Results part: would it be possible to show somewhere the culling rate sof American HO and HOxJE? That would be great. R/. If this is not possible, please show at least the breeds on each farm in table 2 as I asked you in my remark on table 2.

RESPONSE. This is not possible because this information was not recorded or was not available for all farms.

Comment. Line 233: I don’t understand why those 380.9 days are an additional economic loss, because the cow was always milked within that time, maybe she even gave a little more milk, because she was not pregnant. The additional economic loss is there because of several inseminations, but not because of the 380.9 days, isn’t it?

RESPONSE. To avoid confusion Line 243 was deleted.

Comment. Line 228 and Lines 244-252: Those are important sentences. The breed aspect should also be mentioned for the feet and limbs part and the digestion part.

RESPONSE. These sections were not included because the study design and available data did not allow us to identify this outcome.

Comment. Line 265: This result is interesting, but it can not be found in the results part. There should be no new results in the discussion part. Here the results should just be discussed! You can add a line on reproductive problems / abortion in table 2.

RESPONSE. A column was added to the culling causes with the percentage ranges between herds in Table 3.

Comment. Line 267: Preventing abortion is actually not just an “alternative” to reduce cow culling rates due to reproductive problems, but it is additionally necessary. Please replace “an alternative to reducing” by “necessary to reduce”.

RESPONSE. We agree and the sentence has been modified.

Comment. Line 288: do YOU recommend that? That is fine, but please say it. Or is there a reference?; so please mention it.

RESPONSE. The suggestion was included, and the sentence was modified.

Comment. Line 297: this result can also not be seen in the results part (you could add a line in table 2 with “other diseases”).

RESPONSE. Same answer as in number 19. In addition, the abortion rate was corrected as we identified an error in it.

Comment. Line 303: please replace “some” by “12”.

RESPONSE. The word was changed to the number 12.

Comment. Line 343: I don’t really see the similarity to those data from Denmark.

RESPONSE. Traumatic reticuloperitonitis was a frequent cause of death in both countries.

Comment. Line 354: please replace “optimal” by “reasonable” (because actually optimal would be no culling because of health problems…).

RESPONSE. The suggestion was included, and the wording was modified.

Comment. Lines 364 to 369: I don’t understand this calculation: you say farmers need all their heifer calves for replacement and there are not many cos sold for further production, but a significant number of animals is sold (exported) for production in other countries. So those heifers are really sold for production; therefore it can’t be true that they need to keep all their heifer calves for replacement…. Please write that clearly!

RESPONSE. The paragraph was rewritten.

Comment. Lines 380 to 382: Please add a sentence that it may be necessary to change breeds: to use well adapted breeds for pasture-based systems.

RESPONSE. The suggestion was accepted, and a sentence was added.

 

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have satisfactorily responded to my comments.