Circadian Lying Behaviour Assessed in a Commercial Mixed Horned Dairy Goat Herd
Round 1
Reviewer 1 Report
The study investigates the activity patters of dairy goats in a commercial setting. In particular, the authors focus on lying down; the frequency of lying bouts and their duration. The authors state that this is important to investigate as lying behaviour can be an indicator of health, performance and welfare. Hence, they argue that their results could ultimately improve goat management, but do not discuss this in greater detail based on their findings. This could be improved in the discussion. Overall, the study offers some interesting results. Its novelty is not quite clear, which could be highlighted more strongly. Another shortcoming is that the authors are interested in seasonal and age affects since they are discussed, but they are not analysing their data along those lines. Nevertheless, the authors could do that, since they have the relevant information.
Introduction:
In L44 the authors state “(…) lying times serves as an indicator for health, performance and welfare of dairy goats”. This statement appears to be the motivation for the current study. However, the authors do not elaborate further on those mentioned relationships. Some more context, and elaboration of the current knowledge in this area would improve the introduction.
L49. The authors write that some previous work has been done, but do not mention the findings. It would be helpful for the reader to know the current state of knowledge that relates to the study.
Methods:
L99. It is not clear what the authors mean by “false reading”. Why a ten second time interval when the recording was done in five second intervals? Please elaborate on the method of removing false readings. This should be standalone without the reader having to refer to the cited paper.
L100. More detail is needed here. How was lying behaviour deduced from the 3-axial reading of the accelerometers. Was this done by the authors or is this based on an inbuild algorithm by the supplier of the accelerometer. If so, this needs some more detail. If the latter, is this algorithm specific to goats etc. Please elaborate. Further, please provide more detail how the start and end of a lying bout was identified, which would provide the basis to calculate the duration of the lying bout.
The authors state later that horn status and age co-vary. Please clarify why horn status was chosen to be included in the analysis over age. Although horn status was chosen in the discussion age is discussed. If this is the important variable, then including it the analysis (instead of horn status) may be better.
Results
L133. The authors state “A seasonal progression can be seen for lying times and LBD, with higher ones in spring and lower ones in summer, whereas for FLB it is exactly the opposite way.” However, no statistical analysis in relation to season was done. “Months” was included in the analysis (based on the method section) but those results are not shown. Some better alignment of text and methods/results would be helpful and improve the MS.
Fig1. Would it be possible to add error bars to the figure?
Discussion
L179 and further below. The discussion starts with a statement on season and age. However, as mentioned above neither season nor age was actually analysed. If these are the variables of interest the authors should restructure their analysis and provide statistical outcomes that support those statements. Both, age or season, could be analysed since the authors have that information.
L243. The authors state “Nevertheless, no data – to our knowledge – is available, to which extent lying times can be interpreted as affecting health in dairy goats.” This was confusing since the authors wrote in line 44 “lying times serves as an indicator for health, performance and welfare of dairy goats”. These two statements are not consistent with each other and need clarification. Furthermore, the link to health seemed to be the motivation to actually conduct the present study. Hence, it is not clear anymore, what the motivation and novelty of the study actually is. It would be great for the reader if this was highlighted more (incl in the introduction).
Author Response
Dear reviewer 1,
thank you for your supportive comments. We have tried to answer all your comments and performed changes in the manuscript. We hope this meets your expectations.
With our best regards,
Ines Maurmann & Maren Bernau
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper has major weaknesses. This starts with the fact that neither hypotheses nor objectives have been formulated. One can guess that the aim is to analyse the daily rhythm of lying behaviour over the course of a year. In this study, however, the daily and seasonal lying behaviour is completely overlaid by the given group structure. Here, younger dehorned goats meet older ones that wear horns. In my opinion, this fact has a decisive influence on group dynamics. Another weak point is the imprecise definition of fixed and variable effects: For example, the frequency of lying is defined as " n/time and goat ". Furthermore, interaction between horn status and time, for example, is written. There is no question of interaction. One can only speak of an influence. The presentation of the results is very sparing. It is not clear which and how much measurement data has been included in the evaluation.
Author Response
Dear reviewer 2,
we would like to thank you for your time you put in our manuscript. Thank you for the comments, we tried to answer them and hope this makes it clearer for you.
With our best regards,
Ines Maurmann & Maren Bernau
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper describes a nice experiment on the use of accelerometers on dairy goats. The application is rather new and can be interesting for other researchers in this field. Interesting results on the FLB and LBD are found with many significant effects, but unfortunately these are not explored.
Major remarks:
· "Diurnal" behaviour/progression might be confusing, I would prefer "circadian".
· Paragraph 2.3: I would like more information on the lactation stage of the herd and the involved goats in the experiment (days in milk an extra factor?). April is beginning of lactation (Line 183) and October is end of lactation (Line 185)?
· Paragraph 2.4: Are these accelerometers validated for this application? If yes, add reference. If no, discussion point.
· Table 1: Why is the number of evaluated accelerometers sometimes lower than 20: not attached, defects or lost?
· Line 99/100: I do not understand how the method to remove false readings works (and can not find a better description in the reference). How many readings were false?
· Days are divided into 2-hour periods, but evening milking is in a 4-hour period. I would have chosen to divide a day in six 4-hour periods (starting at 2/6/10/14/18/22 h).
· Paragraph 3.1: Results for April/June and October are similar in 2019 and 2020, but the result in May/August 2020 do not fit in this pattern. This is neglected by the authors (Line 186/187) but is a least a point for discussion.
Differences might be explained by climate conditions. Local climate data were not available (Line 232/233), but climate data from any regional station might be useful for this?
· Paragraph 3.2: Many variables and interactions are very significant, but only graphs with overall means are used for explanation (Figure 1). Please add more results on the differences per variable and interactions.
· Line 193: I can not see month effects in Figure 1?!
· Line 212/213: Not true, highest FLB is in 18:00-19:59 = during milking time?!
Minor remarks:
· Line 19: "Highest" frequencies
· Line 31: "setups"
· Line 44: "serve"
· Line 80: "offered"
· Line 100-101 is similar to Line 112-116
· Figure 1 can be improved by using boxplots?
· Line 267: "frequency in FLB" = frequency in frequency?
· Line 296: These results should not be part of Conclusions.
Author Response
Dear reviewer 3,
thank you for your supportive comments. We have tried to answer your comments and performed changes in the manuscript. We hope this meets your expectations.
With our best regards,
Ines Maurmann & Maren Bernau
Author Response File: Author Response.pdf
Reviewer 4 Report
This paper is well written and interesting. It addresses the study of the lying behavior of goats, using an methodology that lacks information to evaluate if it was properly implemented. However, assuming that everything will be correct, the objectives consist only in evaluating the number and lying time of the goats, without relating them to production or welfare indicators. The presentation of the results and their discussion are coherent. Also the conclusions presented are in agreement with the results and discussion. The bibliography is current and appropriate to the paper.
I leave some suggestions:
Line 44-45: In this paper no relationship was made with these indicators, which would be quite positive for the value of the paper
Line 54: I suggest the authors incorporate, if possible, indicators that demonstrate the usefulness of determining lying states in this paper
Line 84: The methodology used to calibrate the accelerometers, and then to detect and validate the lying state should be mentioned (or refer to the article where it has already been published, if applicable)
Line 100: I think it is better characterized than defined, not to be confused with the well-known definition of this species' lying behavior
Line 112: To be consistent with the following definition, I suggest: Frequency of lying bouts (n/time) (FLB), representing mean number of all lying bouts that occurred in a two-hour-section by goat.
Author Response
Dear reviewer 4,
thank you for your supportive comments. We have tried to answer your comments and performed changes in the manuscript. We hope this meets your expectations.
With our best regards,
Ines Maurmann & Maren Bernau
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The revisions have improved the paper.
Author Response
Thank you very much for your comments. The changes have strengthened our manuscript. Thank you very much for that!
Reviewer 4 Report
The authors have changed the text according to the suggested revisions, improving the paper, but the text must still be revised.
A few suggestions:
Line 30: circadian animal or with circadian rhythms or cycles?
Line 46: “Ruminants need time for ruminating to prevent acidosis”, this is not the main reason why they ruminate
Line 54-56: I am sorry but I do not understand what is intended
Author Response
Dear reviewer 4,
thank you very much for your suggestions. We changed or altered the sentences in the manuscript. I hope that it meets your expectations.
A few suggestions:
Line 30: circadian animal or with circadian rhythms or cycles?
- Thank you. Of course it is “animals with circadian rythms”.
Line 46: “Ruminants need time for ruminating to prevent acidosis”, this is not the main reason why they ruminate
- Thank you. Of course you are right. We deleted this sentence.
Line 54-56: I am sorry but I do not understand what is intended
- We are sorry; maybe we just made the sentence worse with that addition. We tried again and structured the sentence in two parts. I hope that it is clearer now.
