Influence of Perch-Provision Timing on Anxiety and Fearfulness in Laying Hens

Round 1

Reviewer 1 Report

L30: Is the result that CP and LP showed shortest TI in all tests? If so, please merge sentences.

L32: This is a very long sentence with specific results (missing dot at the end). Could you give an outlook on how we can improve laying hen rearing in terms of welfare?

 

L42: I don’t see transportation as an good example here because I doubt that flight response during catching will be reduced by positive affective states. I guess that the impact on the hen’s life is larger than in that last minute.

L53: Indeed, three-dimensional structures improve welfare, maybe switch with previous sentence as in the study cited here perches are not the only difference between treatments (group size, pen size etc.).

 

Methods in general: please add a short definition of the variables e.g., birds resume feeding = , birds begin feeding etc. so no other reference has to be looked up for clearer understanding

Are there any pictures of the perches? If not, please provide detailed size measurement such as height, distance, diameter, material etc.

L144/155: please add authors before citation.

L163: was the center area in the middle of all pens so birds were able to hear and see each other during the test?

 

Results in general. Do you think it would add to the comparison of single variables of the same test, if figures are presented as templates e.g., A to D next to each other?

Table 1: As NS is similar to NP, please indicate lacking significance otherwise. Please also add a more detailed description including abbreviations to the table caption for a possible stand-alone understanding. Please also shift to results part.

Could you provide performance data (maybe only percentage of lay) at the age of testing? Fear and anxiety might also be influenced by performance.

 

Discussion in general: It is very hard to follow the combination of results and weeks. Is there an overarching impression that you could communicate instead of giving single week numbers for you argumentation? Maybe a short, medium and long-term effects of changes in the environment or the general provision of perches already during rearing? Same with the discussion of age effects, please correlate to onset of lay, peak etc..

I would suggest adding literature to the discussion on the effect of three-dimensional structures to poultry welfare (L343). In the context of three-dimensionality, perching motivation is among the most know behaviors but there might be others that we did not identify so far. Many studies not only provide 3D but also a lot of other enrichments, this might make a difference.

L317: Is is a short period of increase anxiety/fear due to new objects in the environment?

 

L552: As you did not test in-between, I would doubt the exclusive 16-week period for adaptation.

L562: What about the positive effect during rearing/ontogeny?

L564 and following have not been edited!

Author Response

Thank you editors and reviewers for your helpful comments on our manuscript! We have incorporated the following changes below. One extra item to note is that our back matter was not incorporated into the downloadable manuscript document. We have added this information into the current manuscript.

 

Reviewer 1:

L30: Is the result that CP and LP showed shortest TI in all tests? If so, please merge sentences.

AU: This has been amended in L31-32.

L32: This is a very long sentence with specific results (missing dot at the end). Could you give an outlook on how we can improve laying hen rearing in terms of welfare?

AU: Thank you for the suggestion! The current sentence has been broken up and a concluding sentence has been added (L32-37).

L42: I don’t see transportation as an good example here because I doubt that flight response during catching will be reduced by positive affective states. I guess that the impact on the hen’s life is larger than in that last minute.

AU: We totally agree, and a more suitable example with a citation was inserted.

L53: Indeed, three-dimensional structures improve welfare, maybe switch with previous sentence as in the study cited here perches are not the only difference between treatments (group size, pen size etc.). 

AU: Thank you so much for your comment, but we were not able to locate this statement in the provided line number.

Methods in general: please add a short definition of the variables e.g., birds resume feeding = , birds begin feeding etc. so no other reference has to be looked up for clearer understanding.

AU: A table summarizing the AB methods has been added in L154.

Are there any pictures of the perches? If not, please provide detailed size measurement such as height, distance, diameter, material etc.

AU: Thank you for catching this missed detail! L133-136 now contains this information.

L144/155: please add authors before citation.

AU: This has been added in L139.

L163: was the center area in the middle of all pens so birds were able to hear and see each other during the test?

AU: For TI, the cradle used was placed on a high table in the middle of the pen so most birds could not see the bird being tested. 

Results in general. Do you think it would add to the comparison of single variables of the same test, if figures are presented as templates e.g., A to D next to each other?

AU: Thank you so much for your valuable suggestion, we wanted to address possible differences across treatments and within the age category side by side, for each variable of the testing and then discuss them both separately and collectively to give the readers the opportunity to acknowledge both views.

Table 1: As NS is similar to NP, please indicate lacking significance otherwise. Please also add a more detailed description including abbreviations to the table caption for a possible stand-alone understanding. Please also shift to results part.

AU: Thank you for this suggestion. The table has been moved to the results section (L296).

Could you provide performance data (maybe only percentage of lay) at the age of testing? Fear and anxiety might also be influenced by performance.

AU: Performance data: hen-day% ± SD were added as per your suggestion.

Discussion in general: It is very hard to follow the combination of results and weeks. Is there an overarching impression that you could communicate instead of giving single week numbers for you argumentation? Maybe a short, medium and long-term effects of changes in the environment or the general provision of perches already during rearing? Same with the discussion of age effects, please correlate to onset of lay, peak etc..

AU: Thank you so much for your valuable comment; the following terms were used to describe the age effects and POSSIBLY correlate with production as per your suggestion (Onset of lay = weeks 20 and 21, early lay = week 25, and peak lay = week 37). Also, the average hen-day% with SD was added to reflect the production level and flock variation. We preferred to mention both the describing terms alongside the corresponding week of age and/or use them alternatively on different occasions to avoid any possible confusion and remind the readers throughout the results and discussion.    

I would suggest adding literature to the discussion on the effect of three-dimensional structures to poultry welfare (L343). In the context of three-dimensionality, perching motivation is among the most known behaviors but there might be others that we did not identify so far. Many studies not only provide 3D but also a lot of other enrichments, this might make a difference.

AU: We totally agree with you, however since we did not test or relate to the concept, we did not want to expand further in discussing this concept.

L317: Is is a short period of increase anxiety/fear due to new objects in the environment?

AU: This may be the case, we discuss this explanation in L392-396.

L552: As you did not test in-between, I would doubt the exclusive 16-week period for adaptation.

AU: This is a good consideration, we have added this caveat to the discussion in L385-387.

L562: What about the positive effect during rearing/ontogeny?

AU: Of course, this part was discussed earlier

L564 and the following have not been edited!

AU: The back matter has been added, thank you for bringing this to our attention!

 

Reviewer 2 Report

The topic of importance of perches is not new, however, the authors confirmed this in a nice, straightforward experiment. The authors focus entirely on fear and anxiety. Therefore I assume presented data are part of larger study, where other variables such as health, production and welfare are presented. The paper is written in clear and concise way.

Specific questions about the manuscript:

• No information, other than multi-tier perches were provided, is given about the perches. What were the dimensions, shape, perch space per bird, were different perches provided to match the age?

• How the birds were captured for both AB and TI test could affect the outcome. Please provide the description of the procedure.

• Were the hens habituated to the AB test arena?

• How was the ground predator alarm call obtained?

• Why the interobserver reliability for tonic immobility test was calculated using Cohen's kappa? Shouldn't it be used for nominal variables? 

• Two experimenters performed TI tests on different birds. Can you compare at all such data for inter-observer reliability?  Inter-observer reliability requires the observers to assess the same set of subjects in order to compare their measurements.

• Did any of the birds reach the 300s duration limit? If yes, was this considered in statistical evaluation and how?

 

Author Response

Thank you editors and reviewers for your helpful comments on our manuscript! We have incorporated the following changes below. One extra item to note is that our back matter was not incorporated into the downloadable manuscript document. We have added this information into the current manuscript.

 

 

Reviewer 2:

The topic of importance of perches is not new, however, the authors confirmed this in a nice, straightforward experiment. The authors focus entirely on fear and anxiety. Therefore I assume presented data are part of larger study, where other variables such as health, production and welfare are presented. The paper is written in clear and concise way.

AU: Thank you for taking the time to provide us with insightful comments to better our manuscript.

Specific questions about the manuscript:

• No information, other than multi-tier perches were provided, is given about the perches. What were the dimensions, shape, perch space per bird, were different perches provided to match the age?

AU: Thank you for pointing this missing detail out. We have added information about the perches in L133-136.

• How the birds were captured for both AB and TI test could affect the outcome. Please provide the description of the procedure.

AU: The birds were randomly selected. The handlers walked into the pen and gently picked up a random individual bird for testing. Caution was taken to keep noise/talking to a bare minimum.

• Were the hens habituated to the AB test arena?

AU: Hens were not habituated to the AB testing arena, however, the arena was set up similar to their home pen with litter and a feeder and was not far away from their home pens. They were also tested in groups to minimize the effect of a new environment on responses during the AB test.

• How was the ground predator alarm call obtained?

AU: The alarm predator call used in the current study is one of many recordings used for teaching domestic animal behavior courses in the home institutes of coauthors. All the recordings including the alarm call were tested by several animal behavior professors before they were used as educational materials.  

• Why the interobserver reliability for tonic immobility test was calculated using Cohen's kappa? Shouldn't it be used for nominal variables? 

AU: Thank you so much for such a great question. We have consulted with the statistician (SMCC - Statistics and Mathematics Consulting) who conducted the analysis of the current study, and he provided us with the following explanation; Although Cohen-Kappa is a coefficient of agreement, that is used predominately with nominal data, it can also be used to measure agreement of different types of data; simply by comparing the outcome (X) of one event to the outcome of another event (Y), and report if they are different or the same, then calculate the ratio of agreement across observations (k = 100, mean 100% agreement) or different (k = 0 or 0% agreement).

• Two experimenters performed TI tests on different birds. Can you compare at all such data for inter-observer reliability?  Inter-observer reliability requires the observers to assess the same set of subjects in order to compare their measurements.

AU: Thank you so much for catching this, the 2 observers had a 3-day training period when they tested 40 birds and their results were tested for interobserver agreement, details were added to the manuscript. 

• Did any of the birds reach the 300s duration limit? If yes, was this considered in statistical evaluation and how?

AU: Thank you so much, this is a very good point. Luckily none of the tested birds exceeded the 300s test limit, and we totally agree this would totally change our approach of data analysis.

 

Reviewer 3 Report

Dear Authors, 

The manuscript contains very interesting findings relevant to laying hen research but also to practical implementation in the field.

Some questions came up while reading the manuscript:

1. What about AB and TI tests in pullets? Do you have experience, knowledge in performing this? Could be interesting to know before the transfer to a hen house.

2. Did you also collect addition data or perform measurements outside the AB and TI test moments? Production data, feather cover evaulation, (unwanted) pecking behaviour? The link between this data and AB en TI could be very interesting for pullet/laying hen farmers. 

3. line 127: what was the light intensity during rearing and after 17 weeks? 

4. line 510: You describe the effect of exposure to humans during  the laying period, how were the pullets reared? Did they also have 17weeks of exposure to humans? Do you think there is a difference between rearing/ production?

 

Author Response

 

Thank you editors and reviewers for your helpful comments on our manuscript! We have incorporated the following changes below. One extra item to note is that our back matter was not incorporated into the downloadable manuscript document. We have added this information into the current manuscript.

 

 

Reviewer 3:

The manuscript contains very interesting findings relevant to laying hen research but also to practical implementation in the field.

AU: Thank you very much for your questions and comments.

Some questions came up while reading the manuscript:

1. What about AB and TI tests in pullets? Do you have experience, knowledge in performing this? Could be interesting to know before the transfer to a hen house.

AU: Yes, absolutely, this point would be very interesting, however, as this manuscript tested adult birds, we don’t have results on AB and TI in our pullets.

2. Did you also collect addition data or perform measurements outside the AB and TI test moments? Production data, feather cover evaulation, (unwanted) pecking behaviour? The link between this data and AB en TI could be very interesting for pullet/laying hen farmers.

AU: Yes, we categorize the data based on the research questions and will publish them accordingly  

3. line 127: what was the light intensity during rearing and after 17 weeks? 

AU: The light intensity started with 40 lux at 0-3 days and then reduced gradually to 25 lux at 2 weeks of age, to reach 10 lux at 6 weeks of age and to the end of the trial, following the standard guidelines of the breed. https://www.hyline.com/filesimages/Hy-Line-Products/Hy-Line-Product-PDFs/Brown/Brown%20Alt/BRN%20ALT%20COM%20AUS.pdf

4. line 510: You describe the effect of exposure to humans during the laying period, how were the pullets reared? Did they also have 17 weeks of exposure to humans? Do you think there is a difference between rearing/ production?

AU: Thank you so much for your comment, the question is very interesting. Birds were reared in the same facility and the same pens, however before the onset of lay at week 17 hens were moved to another pen but similar to what they were reared at. Overall, the level of human exposure was the same throughout the trial, both rearing and laying phases.