Assessment of Influential Factors for Scours Associated with Cryptosporidium sp., Rotavirus and Coronavirus in Calves from Argentinean Dairy Farms

Round 1

Reviewer 1 Report

Manuscript ID: animals-1244470

Title: Assessment of risk factors for scours associated with Cryptosporidium sp., rotavirus and coronavirus in calves from Argentinean dairy farms

 

The authors report a very straightforward and well-designed study, however, there are some issues in the manuscript that in this reviewer’s opinion prevent publication in current form.

Major issues:

Line 118: A standard voluntary and anonymously multiple-choice survey was developed to collect information about pre-weaned calf management practices in the participant farms.

The correct term here would be anonymous, however, I do not see in what form this survey could be anonymous at all? Obviously, the results from the survey must be matched to the farms and the calves, and the veterinarians filling in the survey were known to the researchers. Please explain in more detail how this data was created and what exactly the veterinarians role was on the farms.

Line 161: The variables with a significant P < 0.2 [9,10] were selected for performing a Multivariable Logistic Regression (MLR) model where calf within farm was included in the model as a random effect.

In the tables of the supplement farm size is the only parameter with p<0.2. Please explain.

The discussion is poor. Mainly there are comparisons of the parameters to other studies, but discussion of the reasons, why certain parameters could have an influence are mostly missing. If the attempt is made on a discussion of causal relationship of the results it is done poorly or false, for example:

Line 244: General recommendations in modern dairy systems are that newborn calves should be moved from the calving pen as soon as possible to decrease the risk of injury and avoid disease transmission from the dam to the offspring [53].

This is only part of what the cited paper says. The subject is more complicated and should be discussed more thoroughly. See also: https://www.journalofdairyscience.org/article/S0022-0302(19)30417-5/fulltext

Line 260: Scours incidence in calves that were fed with milk replacers was higher than calves fed with raw milk. When feeding with milk replacers, it is necessary to take numerous variables into accounts such as temperature, nutritional qualities, digestibility, and solubility. However, the major difference is the lack of antibodies in the milk replacer, by which the intestinal local protection is lost, given more opportunity to pathogens to cause infection and disease [12,30,56].

The lack of antibodies would only play a major role, if calves were fed milk replacer from birth. This seems unlikely, but should be specified more clearly. It is by far more likely that the lower energy content of milk replacer is the reason. Also, citation 30 is clearly not a correct source for the statement, since there it is said: “On most of the visited farms (84%), whole milk was fed. Waste milk was offered to the calves on 82% of the farms. Whole milk may have advantages over milk replacer in terms of greater energy content and a better balance of nutrients (Davis and Drackley, 1998; Godden et al., 2005). This might therefore improve calf immunity and lead to a decreased disease rate (Godden et al., 2005).” Citations should be re-checked for correctness.

The high incidence of diarrhea and the low level of milk feeding should also be discussed, see for example: https://irishvetjournal.biomedcentral.com/articles/10.1186/s13620-021-00185-3

 

 

Minor issues:

Some examples for language/editorial issues that need addressing:

Line 174: In table 1 and Figure 1 the results of this section are detailed and represented (either always lower or upper case)

Table 1:

Númber of studied farms

Satandard desviatio (SD).

Line 204: Contrasting the findings scours, calves were moved from the maternity pen 6 that remained less than 6 h after calving had lower odds (OR=0.3; P=0.02) of becoming infected with RVA.

Table 4.

Tabla 4: Predicción de la regresión logística para la variable dependiente 215 “Cryptosporidium sp. infection”. Log-likelihood = -208.3219 AIC = 426.64.

Calostrum bank, No

Line 228: reported in studies performed in Brazil and Argelia [39,40], but lower than other studies

Line 250: Therefore, further research is needed to identify is this practice is beneficial or not in preventing scours and RVA infection

 

 

 

Author Response

Thank you very much for all your suggestions. We hope we have improved the manuscript and you like it. Best regards. 

Emiliano Bertoni

Author Response File: Author Response.docx

Reviewer 2 Report

Please replace the term "risk" with "chance" throughout the paper because you use odds ratio. Therefore the right terminology is "chance".

Please standardize the number of decimal places, see for example line 39 (84.2%)  and line 40 (63%).

Please discuss the bias by using a voluntary questionnaire. Further, please discuss intensively your result with these both currently published worldwide prevalence studies for Rotavirus, Coronavirus, Cryptosporidium.  https://doi.org/10.3390/ani11041014.  and https://doi.org/10.3390/ani11061786

The following aspects would enhance the discussion: Do these two studies come to the same conclusions as yours? If not, why? Where are the differences? What is the advantage of these two studies compared to yours? What are the benefits of your study compared to both above-mentioned studies? A significant improvement of the discussion is necessary. 

Line 49: Please provide some references in the discussion that colostrum influence the prevalence of C.sp. I don't think that colostrum influences the occurrence of C. sp. 

Line 63: The Reference should be a running number.

Line 84: Why the season is not included in the logistic model because it's well known that the season will have an effect on the prevalence

Line 108 and 130: Please define the abbreviation: SOP and INTA

Line 156: It's not clear why dispersion statistic was conducted in Excel and not directly in the Logistic regression model.

In general, the statistic analysis part needs a major improvement because for me it's not clear, what the authors did. Additionally, the Akaike information criterion is not correct. You should use the Akaike information criterion corrected for a small sample size but maybe a likelihood ratio test would be more appropriate. Further, describe in detail the selection process, check of correlation of preditor variables and provide the stepwise selection process in the supplement for the reader with all relevant statistics meta-data including checking of normal distribution and show the reader of the journal that the statical model which you use is appropraite. 

Line 157: please describe which variables were analyzed with Fisher and which were analyzed with the Chi-square test and why. 

Line 162: Please describe also the fixed effects.

Table 2: Please explain why significant P-values are presented when the 95% Confidence iNterval includes the value 1 for the variables "Time in calving,....., age under 20 days).

Table 4 the title is not understandable. Its in a different language than English. 

Author Response

Thank you very much for all your suggestions. We hope we have improved the manuscript and you like it.

Best regards. 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I do not agree with all of the authors revisions, see file attached

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Thank you for incorporating my comments. The manuscript was significantly improved and will be valuable for the readers of the journal. 

Author Response

Thank you very much for your suggestions. The manuscript has improved substantially.

 Best regards