Health and Growth Performance During the Pre-Weaning Phase of Angus × Holstein Crossbred and Holstein Calves Managed Under the Same Conditions
Katherine C. Creutzinger
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis study takes an important step to compare dairy and dairy-beef calves in the pre-weaning setting. The study was well done and the results are nicely reported. Thank you for your contribution to the research on pre-weaned dairy-beef calves. A few comments and suggestions are below for you to consider.
26-27: Consider explaining what the ‘beef-on-dairy” strategy is instead of assuming the readers know
81-83: What does “whenever possible” mean? Were there calves who received <10% body weight colostrum or colostrum <22 Brix degrees?
98: At what age were calves fully weaned?
104: Were calves housed with their cohort (Holsteins pairs and cross-bred pairs) or mixed?
129-135: How were variables selected for inclusion in the multivariable models and for final variable retention (e.g., univariable analysis and backwards stepwise regression)?
128-167: Please include the fixed effects included for each model and final model distribution selections (lines 153-156)
164-167: Were any steps taken to investigate model fit? (E.g., residuals for average daily gain)
193, 217-221: Make sure to include the units
Figures 1 and 3: Consider reordering the x-axis labels so the crossbreds are grouped together instead of Holsteins being in the middle of the 2 crossbred groups
Figure 2: Not in the body of the paper
239-244: Only probability or relative risk should be included in the analysis. One should be removed
248-253: How is this different from cases of diarrhea and BRD? The definitions should be provided more clearly and it would be helpful for the # of animals treated for each disease within their respective categories should be provided. E.g., X out of X calves with diarrhea were treated for the disease.
342-358: It might be interesting to compare the prevalence of diarrhea and BRD to other common industry standards for pre-weaned dairy calves and surplus calves in calf raiser settings. For example, did the crossbred calves in your study have lower, equivalent, or greater disease prevalence than reported in veal/dairy-beef production settings?
Author Response
Thank you for your comments; they were very helpful throughout the revision process. All modifications made to the manuscript have been highlighted in yellow.
Reviewer 1:
This study takes an important step to compare dairy and dairy-beef calves in the pre-weaning setting. The study was well done and the results are nicely reported. Thank you for your contribution to the research on pre-weaned dairy-beef calves. A few comments and suggestions are below for you to consider.
AU: Thank you for your comments. We have carefully revised the manuscript according to your suggestions and feedback.
26-27: Consider explaining what the ‘beef-on-dairy” strategy is instead of assuming the readers know
AU: Thank you for your comment. We have updated the text at line L27-37: “The term "beef-on-dairy" refers to a breeding strategy that involves the use of beef cattle semen in dairy cows, aiming to produce offspring for meat production from dairy herds [1]. This increasingly popular approach is viewed as a potential solution to mitigate the issue of surplus male dairy calves [2]. Additionally, improvements in reproductive performance among dairy herds—coupled with a slowdown in herd expansion in many developed countries—have led to a reduced demand for dairy heifers. As a result, the need to maintain cash flow through the sale of surplus calves for meat production, along with the often negligible market value of male dairy calves, supports the adoption of this strategy on dairy farms [1,3]. However, few studies have compared the performance and health of crossbred (beef-on-dairy) and purebred dairy calves during the pre-weaning phase”.
81-83: What does “whenever possible” mean? Were there calves who received <10% body weight colostrum or colostrum <22 Brix degrees?
AU: Thank you for your comment. Removed to avoid ambiguity. This meant that some calves received colostrum with Brix values below 22%, as presented in the descriptive results (L205-7): “Descriptively, a total of 12 calves (3.44% of Holstein, 0% of Ang x Hol crossbred females, and 2.17% of Ang x Hol crossbred males) received colostrum with < 22% Brix.”
98: At what age were calves fully weaned?
AU: Information added in line L106-7: “All calves were completely weaned at 77 ± 2 days of age.”
104: Were calves housed with their cohort (Holsteins pairs and cross-bred pairs) or mixed?
AU: Thank you for your comment. Calves were preferably housed in homogeneous pairs, except in situations where homogeneous and contemporary animals were not available for pairing. However, this was not measured or recorded in the present study. Our research group is currently conducting an experiment specifically addressing this aspect, and the results will be submitted for publication in the near future. Thank you for your comment.
129-135: How were variables selected for inclusion in the multivariable models and for final variable retention (e.g., univariable analysis and backwards stepwise regression)?
AU: Thank you for your comment. We include this point at L-138-9: “Initial models included all potential measured confounders (e.g., Birth weight, dam parity) and were reduced through manual backwards elimination”. The R scripts and datasets used for these analyses will be made available as supplementary material (see Notes section).
128-167: Please include the fixed effects included for each model and final model distribution selections (lines 153-156)
AU: Thank you for your comment. The information has been added in line L163-7: For the analysis of diarrhea case counts, the linear regression model demonstrated the best fit based on the lowest AIC and included the following fixed effects: breed composition and sex, transfer of passive immunity, and birth weight. In contrast, for the analysis of bovine respiratory disease (BRD) case counts, the negative binomial regression model yielded the lowest AIC and was fitted using the same set of fixed effects.”
164-167: Were any steps taken to investigate model fit? (E.g., residuals for average daily gain)
AU: Yes, this is now added at L174-6: "Goodness-of-fit of the logistic regression models were assessed via Hosmer-Lemeshow goodness-of-fit test [31]. Linear regression models assumptions were assessed graphically. Assumptions were not violated in all models." Please note that model fit for the negative binomial was assessed via the comparison against the poission model as there is no gold standard test for assessing negative binomail model fit.
193, 217-221: Make sure to include the units
AU: Thank you for your comment. Updated.
Figures 1 and 3: Consider reordering the x-axis labels so the crossbreds are grouped together instead of Holsteins being in the middle of the 2 crossbred groups
AU: We appreciate your suggestion. However our main point is the comparison against Hol calves. That is why we opted to maintain the current formatting.
Figure 2: Not in the body of the paper
AU: Sorry. This has been included in the text at line L-217-8: “Holstein calves showed a higher probability of occurrence of diarrhea compared to both male and female crossbred calves (P < 0.01, Figure 2).”
239-244: Only probability or relative risk should be included in the analysis. One should be removed
AU: Thank you for your comment. The probability value was removed from the BRD outcome, in accordance with the use of a negative binomial model to evaluate this variable.
248-253: How is this different from cases of diarrhea and BRD? The definitions should be provided more clearly and it would be helpful for the # of animals treated for each disease within their respective categories should be provided. E.g., X out of X calves with diarrhea were treated for the disease.
AU: Thank you for your comment. This variable represents the sum of diarrhea and BRD cases. To improve clarity and avoid potential misinterpretation by readers, we decided to remove the data regarding the total number of treatments from the manuscript.
342-358: It might be interesting to compare the prevalence of diarrhea and BRD to other common industry standards for pre-weaned dairy calves and surplus calves in calf raiser settings. For example, did the crossbred calves in your study have lower, equivalent, or greater disease prevalence than reported in veal/dairy-beef production settings?
AU: Thank you for your comment. This has been included in the text at line L380-90: The occurrence of BRD in our study ranged from 11% to 14%, which is lower than the values reported by Fernandes et al. [63], who observed 26% of beef-on-dairy calves with lung consolidation at 61 days of age, and by Pereira et al. [21], who reported an incidence of approximately 55% in crossbred calves. Additionally, a study conducted on veal farms in the Netherlands showed that at least 38% of calves were clinically affected by BRD [64]. The occurrence of diarrhea was comparable to that reported by Pereira et al., who observed over 60% of affected calves, and by Pharo et al. [65], who reported that 63.8% of crossbred calves were treated for diarrhea. In terms of performance, the ADG in our study exceeded 1000 g/day, whereas Pereira et al. [21] reported gains below 600 g/day. These discrepancies may reflect differences in the management practices employed or differences on how the data were collected in each study.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript investigates differences between Holstein and crossbred calves during the pre-weaning period while they are subjected to the same management conditions. While the study has some limitations, these are properly acknowledged and overall this work contributes to a body of evidence suggesting that the beef-on-dairy strategy -when calves are appropriately managed- could offer a solution to deal with the surplus dairy calf issue.
The paper is generally well-written, I have a few points that should be addressed to improve the clarity and interpretability of the results:
L16: Brix is not used again in the abstract as abbreviation
L21: BRD should be explained upon first appearance in the abstract
L27: A brief definition of the phrase “beef-on-dairy strategy” would be helpful for readers
L28: Unclear what “reduction in the necessity for dairy breeding “ refers to - please rephrase
L32: crossbred and purebread
L35: explain BRD upon first appearance
L47: comparing how
L59: entered in Excel
L82: Do you have any estimates on how often this was not possible? Were these events randomly distributed among Holstein and crossbred calves?
L125: at weaning
L165: these
L205-226: The descriptive data in Figure 1 tells a different story compared to the full model where confounders are included (Table 2). I think it would help readers to briefly acknowledge and discuss the reasons behind this.
L234-237: Figure 2 is not cited in the text. Please refer to it or omit.
L245: did not show
L254-255: How can the overall mortality be the same as the % of Holstein calf death?
L255: delete “pre-weaning phase”
Author Response
Thank you for your comments; they were very helpful throughout the revision process. All modifications made to the manuscript have been highlighted in yellow.
Reviewer 2:
This manuscript investigates differences between Holstein and crossbred calves during the pre-weaning period while they are subjected to the same management conditions. While the study has some limitations, these are properly acknowledged and overall this work contributes to a body of evidence suggesting that the beef-on-dairy strategy -when calves are appropriately managed- could offer a solution to deal with the surplus dairy calf issue.
AU: Thank you for your comments. We have carefully revised the manuscript according to your suggestions and feedback.
The paper is generally well-written, I have a few points that should be addressed to improve the clarity and interpretability of the results:
L16: Brix is not used again in the abstract as abbreviation
AU: Thank you for your comment. Updated.
L21: BRD should be explained upon first appearance in the abstract
AU: Thank you for your comment. Updated.
L27: A brief definition of the phrase “beef-on-dairy strategy” would be helpful for readers.
AU: Thank you for your comment. We have updated the text at line L27-37: “The term "beef-on-dairy" refers to a breeding strategy that involves the use of beef cattle semen in dairy cows, aiming to produce offspring for meat production from dairy herds [1]. This increasingly popular approach is viewed as a potential solution to mitigate the issue of surplus male dairy calves [2]. Additionally, improvements in reproductive performance among dairy herds—coupled with a slowdown in herd expansion in many developed countries—have led to a reduced demand for dairy heifers. As a result, the need to maintain cash flow through the sale of surplus calves for meat production, along with the often negligible market value of male dairy calves, supports the adoption of this strategy on dairy farms [1,3]. However, few studies have compared the performance and health of crossbred (beef-on-dairy) and purebred dairy calves during the pre-weaning phase”.
L28: Unclear what “reduction in the necessity for dairy breeding “ refers to - please rephrase
AU: Thank you for your comment. The correct phrasing is: L30-2: “Additionally, improvements in reproductive performance among dairy herds—coupled with a slowdown in herd expansion in many developed countries—have led to a reduced demand for dairy heifers”
L32: crossbred and purebread
AU: Thank you for your comment. Updated.
L35: explain BRD upon first appearance
AU: Thank you for your comment. Updated.
L47: comparing how
AU: Thank you for your comment. Updated.
L59: entered in Excel
AU: Thank you for your comment. Updated.
L82: Do you have any estimates on how often this was not possible? Were these events randomly distributed among Holstein and crossbred calves?
AU: Thank you for your comment. In response to Reviewer 1, we updated the term “whenever possible” to “with a set minimum of 22 Brix degrees administered.” This term refers to colostrum Brix values. The information regarding calves that received colostrum with <22% Brix is provided in lines L-205–207: “Descriptively, a total of 12 calves (3.44% of Holstein, 0% of Ang x Hol crossbred females, and 2.17% of Ang x Hol crossbred males) received colostrum with <22% Brix.” When considering the total number of animals in each group, it becomes evident that this was a rare occurrence.
L125: at weaning
AU: Thank you for your comment. Updated.
L165: these
AU: Thank you for your comment. Updated.
L205-226: The descriptive data in Figure 1 tells a different story compared to the full model where confounders are included (Table 2). I think it would help readers to briefly acknowledge and discuss the reasons behind this.
AU: Thank you for your suggestion. The reason why figure 1 shows that there is "more" diarrhea in male AngxHol is due to the lower number of animals in this category. Such apparent effect goes away when taking into account other variables and the probability of diarrhea in the studied animals. To avoid misleading the readers to an non-existing effect we opted to no disscuss it but added the n for each category in the figure legend. That given, we assume the reader can promptly take the n into consideration.
L234-237: Figure 2 is not cited in the text. Please refer to it or omit.
AU: Thank you for your comment. Updated at L217-8: “Holstein calves showed a higher probability of occurrence of diarrhea compared to both male and female crossbred calves (P < 0.01, Figure 2).”
L245: did not show
AU: Thank you for your comment. Updated.
L254-255: How can the overall mortality be the same as the % of Holstein calf death?
AU: Thank you for your comment. Updated at L262: “The overall mortality in the study was 2.8%”.
L255: delete “pre-weaning phase”
AU: Thank you for your comment. Updated.
