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Paper
Paper Smothering in UK free-range flocks. Part 1: incidence, location, timing and management J. Barrett, A. C. Rayner, R. Gill, T. H. Willings, A. Bright Smothering in poultry is an economic and welfare-related concern. This study presents the first results from a questionnaire addressing the incidence, location, timing and management of smothering of free-range farm managers from two commercial egg companies (representing 35 per cent of the UK free-range egg supply). Overall, nearly 60 per cent of farm mangers experienced smothering in their last flock, with an average of 25.5 birds lost per incidence, although per cent mortality due to smothering was low ( x =1.6 per cent). The majority of farm managers also reported that over 50 per cent of all their flocks placed had been affected by smothering. The location and timing of smothering (excluding smothering in nest boxes) tended to be unpredictable and varied between farms. Blocking off corners/nest boxes and walking birds more frequently were identified as popular smothering reduction measures, although there was a wide variety of reduction measures reported overall. The motivation to implement reduction measures was related to a farm manager’s previous experience of smothering. To our knowledge, this is the first study to provide a representative industry estimate on the incidence, location, timing and management of smothering. The results suggest that smothering is a common problem, unpredictable between flocks with no clear, effective reduction strategies. A follow-up study will investigate the correlations among smothering, disease and other welfare problems and may shed further light on management solutions.
Introduction
Smothering in poultry is when birds mass together, often on top of each other, resulting in death from suffocation. There is little published information on smothering incidence, cause or prevention. Avian hysteria was described by Sanger and Hamdy (1962) as unexplained extreme nervousness, followed by squawking, flight and then hiding or crowding in corners and under feeders. Mills and Faure (1990) list suffocation as an important economic and production consequence of panic and hysteria in domestic fowl. In a preliminary study, Bright and Johnson (2011) investigated the incidence of smothering and possible causal factors in 10 commercial free-range laying flocks. While only a small sample size, the evidence suggested that smothers significantly affect free-range flocks, causing both economic and animal welfare-related concern. The unpredictable nature of smothering, which makes it difficult for farm managers to address the problem by implementation of management or husbandry practices, was also confirmed. Veterinary Record (2014) J. Barrett, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX13PS, UK A. C. Rayner, BSc(Hons) A. Bright, BSc, MSc, DPhil (Oxon) FAI Farms Ltd, The Field Station, Wytham, Oxford, Oxfordshire, OX2 8QJ, UK R. Gill, The Lakes Free Range Company Ltd, Meg Bank, Stainton, Penrith, CA11 0EE, UK
doi: 10.1136/vr.102327 T. H. Willings, Noble Foods Ltd, The Moor, Bilsthorpe, Newark, NG22 8TS, UK E-mail for correspondence: [email protected] Provenance: not commissioned; externally peer reviewed Accepted April 15, 2014
Laying hens in commercial free-range systems are especially vulnerable to smothering because of the large numbers of birds kept in one area. Free-range systems are a significant component of the UK egg industry; in 2012, free-range and organic eggs accounted for 47.0 per cent of eggs packed in the UK (DEFRA 2012). Further investigation beyond the small study by Bright and Johnson (2011) in a wider commercial setting would help clarify the scale of the smothering problem. Since 2008, McDonald’s Restaurants UK has collaborated through various projects with FAI Farms (consultant) and their two UK egg supplier companies to form the McDonald’s UK Sustainable Egg Supply (SES) Group. In response to concerns over smothering, the SES group developed a questionnaire to address the incidence, location, timing and management of smothering for the free-range laying farms of the two egg supplying companies. These two companies represent 35 per cent of the UK free-range egg supply, and therefore a significant portion of the free-range egg industry. This study presents the first results of the questionnaire addressing the incidence, location, timing and management of smothering from free-range farm managers.
Methods
Questionnaire
The questionnaire related to the farm’s previous flock at the time of completing the questionnaire. The questionnaire sections addressed the three smothering categories as identified by Bright and Johnson (2011): (1) Panic smother (PS), caused by sudden disturbances such as those from predators or sudden noises, isolated incidences involving large numbers (>20 of birds); (2) Nest box smother (NBS), occurring in the nest box, when one hen visits a nest box stimulating other birds to follow; and (3) Recurring smother (RS), smothers recurring throughout lay, though usually with small (1–10) numbers of bird per July 5, 2014 | Veterinary Record
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Paper incidence. A section on concern over smothering and smothering in other previously placed flocks was also included. A first draft of the smothering questionnaire was sent to six freerange farm managers in July 2012 for feedback. Alterations were made and the final version was sent to all free-range farm managers from the two egg companies in September 2012. Questionnaires from Company 1 were filled out independently by the farm manager. Questionnaires from Company 2 were filled out by the farm manager with guidance from the field manager. A separate questionnaire was filled in for every farm, even if run by the same farm manager.
χ2 test were violated, Yate’s correction for continuity or a Monte Carlo simulation was applied.
Data handling
The frequency of smothering incidences, number of birds lost to a smothering incidence and per cent of flock mortality in the last flock cycle due to smothering are presented in Table 1a–c. The per cent of all previous flocks placed affected by smothering and farm manager concern about smothering are presented in Table 2. Farm managers were more likely to consider smothering a problem when a higher percentage of all previous flocks had experienced smothering (z=2.17, P=0.030). In the most recently placed flock, farm managers were more likely to consider smothering a substantial problem when a higher number of smothering incidences had taken place (z=2.28, P=0.023) although this was independent of the number of birds lost to a typical smothering incidence (z=−1.43, P=0.152). There was a trend for farm managers to consider smothering a substantial problem when a higher percentage of the flock was lost to smothering in the last flock cycle (z=1.80, P=0.071). Finally, there was no difference between companies in whether or not they considered smothering a problem (z=1.53, P=0.127) and no smother category that was more likely to cause farm managers to consider smothering a problem (Company 1: χ2=0.51, P=0.500; Company 2: χ 2=1.03, P=0.674).
Farm managers from Company 1 tended to report PS and RS interchangeably (ie, they would cite multiple incidences of smothers involving one or two birds as PS, or single incidences involving more than 20 birds as RS); these two categories of smothering were therefore combined. Six Company 1 farms that reported both PS and RS were removed from the analysis of separate smothering categories. Two farm managers misinterpreted the mortality question and were removed from calculations of smothering mortality. Overall smothering incidence was calculated for each company and for each smother category. The percentage of farm managers who responded to the location, timing (day/year/age of birds), and management sections of the questionnaire was determined by company for each smother category. The location, timing and management answers were grouped into similar categories.
Statistical analysis
The statistical software package used for all analyses was ‘R’ (R Core Team 2013). A generalised linear model (‘glmmADMB’ package, Skaug and others 2012) was used to investigate whether the following factors had an effect on farm manager concern over smothering and implementation of smothering reduction measures: (a) the number of smothering incidences in the last flock cycle; (b) the number of birds lost per smothering incidence in the last flock cycle; (c) flock mortality due to smothering in the last flock cycle; and (d) the percentage of all flocks placed affected by smothering. A binomial distribution model was used, and company was included as a covariate. Interactions were investigated, but not included due to model fit. Zero inflation was accounted for in the model (‘glmmADMB’ package, Skaug and others 2012). A Pearson’s χ2 test was used to investigate whether smother category had an effect on farm manager concern over smothering and whether implementation of smothering reduction measures was dependent on farm manager concern over smothering. Pearson’s χ2 tests were also used to investigate company differences in the reporting of timing and location of smothering. Where assumptions of the
Results
Questionnaires were returned between October 2012 and April 2013. In total, 206 questionnaires were used in analyses: 162 from Company 1 and 44 from Company 2, translating to a 50 and 100 per cent response rate from the total free-range farms in each company, respectively (conventional and organic).
Incidence
Location
The locations of PS/RS reported by farm managers from each company are presented in Fig 1. Fifty-eight Company 1 farm managers (35.8 per cent) answered the question in relation to PS/RS location. Eight Company 2 farm managers (18.2 per cent) answered the question in relation to PS location and 18 (40.9 per cent) answered the question regarding RS location.
Timing Time of year
Times of year for PS and RS as reported by farm managers from each company and NBS as reported by farm managers from both companies combined are presented in Fig 2. NBS responses were combined as there was no significant difference between companies in the time of year reported (χ2=2.99, P=0.362).
TABLE 1: (a) Frequency of smothering reported in the last flock cycle; (b) Number of birds lost to a typical smothering incidence; and (c) Smothering flock mortality (panic smother (PS), nest box smother (NBS), recurring smother (RS)) Company 1 (%) PS/RS (a) Incidences 0 1–5 6–10 >10 x number of incidences (±sd) (b) Number of birds lost 1–25 26–50 51–100 >100
x number of birds lost (±sd) (c) Mortality (%) 0.01–0.1 0.11–1.0 1.1–5.0 >5 x Mortality (%) (±sd) Veterinary Record | July 5, 2014
NBS
PS
Company 2 (%) NBS
RS
Total (%)
62.2 30.2 5.8 1.9 1.5 (±3.3)
67.9 14.7 9.0 8.4 4.2 (±14.3)
84.1 15.9 0 0 0.20 (±0.5)
72.7 15.9 9.1 2.3 1.6 (±3.2)
56.8 27.3 6.8 9.0% 5.7 (±17.5)
38.8 34.5 14.1 12.6 6.2 (±15.5)
67.8 20.3 8.5 3.4 41.2 (±112.9)
93.0 3.5 1.8 1.8 9.1 (±21.4)
42.9 14.3 28.6 14.3 52.1 (±46.7)
83.3 16.7 0 0 13.8 (±14.6)
61.1 16.7 11.1 11.1 33.7 (±42.2)
73.2 17.9 4.1 4.9 25.5 (±51.0)
12.2 53.7 29.3 4.9 1.7 (±2.7)
21.7 56.5 21.7 0 1.0 (±1.1)
70.0 15.0 15.0 0 0.3 (±0.7)
60.0 40.0 0 0 0.2 (±0.2)
5.3 73.7 21.2 0 0.7 (±0.7)
11.1 55.6 29.3 4.0 1.4 (±2.0)
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Paper 80
TABLE 2: (a) Per cent of all flocks placed affected by smothering and (b) per cent of farm managers reporting smothering as a substantial problem (a) Flocks affected (%) 0 0–25 25–50 >50
x flocks affected (%) (±sd)
(b) Substantial problem (%) Yes No
60
Total (%)
17.8 23.3 13.2 45.7 52.3 (±42.6)
17.9 17.9 5.1 19.0 12.8 13.1 64.1 50.0 69.2 (±40.9) 56.3 (±42.7)
21.3 78.7
42.9 57.1
Number of responses
Company 1 (%) Company 2 (%)
70
26.0 74.0
50 40 30 20 10 0
30
Morning
Midday
Afternoon
Evening
Time of year
No specified time
Number of responses
25
20
Company 1 PS/RS
Company 2 RS
Company 2 PS
Company Combined NBS
FIG 3: Smother category and time of day for Company 1 and Company 2
15 10
60
5
0 Litter
Corners
Slats
Range At divisions Centre
Nests
Location Company 1 PS/RS
Company 2 PS
Company 2 RS
FIG 1: Smother category and location for Company 1 and Company 2
Number of responses
50 40
30 20
10 80 0
70
< 20 weeks
Number of responses
20 -28 weeks
29 - 45 weeks
> 45 weeks
Age of birds
60 50
Company 1PS/RS
Company 2 PS
Company 2 RS
Companies NBS combined
40
FIG 4: Smother category and age of birds at last smothering incidence for Company 1 and Company 2
30 20
Time of day
10 0 Spring
Summer
Autumn
Winter
No specified time
Time of year Company 1 PS/RS
Company 2 PS
Company 2 RS
Companies Combined NBS
FIG 2: Smother category and time of year for Company 1 and Company 2
Seventy-six Company 1 farm managers (46.9 per cent) answered the question regarding time of year in relation to PS/RS. Only 6 (13.6 per cent) Company 2 farm managers answered the question regarding typical time of year for PS. Nineteen (43.2 per cent) Company 2 farm managers reported on time of year for RS. Seventy-four farm managers (35.9 per cent) from both companies responded to the question regarding time of year for NBS.
Times of day for PS and RS as reported by farm managers from each company and NBS as reported by farm managers from both companies combined are presented in Fig 3. NBS responses were combined as there was no significant difference between companies in the time of day reported (χ2=2.15, P=0.188). Seventy-seven Company 1 farm managers (47.5 per cent) answered the question in relation to PS/RS time of day. Six farm managers (13.6 per cent) from Company 2 answered the question regarding PS time of day and 19 (43.2 per cent) answered the question regarding RS time of day. Eighty-one farm managers overall (39.3 per cent) answered the question regarding NBS time of day.
Age of birds
The age of birds at the last incidence of PS, RS and NBS reported by farm managers from each company, and NBS as reported by farm managers from both companies combined are presented in Fig 4. NBS responses were combined as there was no significant difference between companies in ages reported (χ2=10.63, P=0.684). Fifty-five Company 1 farm managers (33.9 per cent) answered the question in relation to the age of birds at the last PS/RS incidence. Five July 5, 2014 | Veterinary Record
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Company 1 PS/RS
Company 2 RS
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Company 2 NBS
FIG 5: (a) Panic smother (PS) and recurring smother (RS) reduction measures implemented by Company 1 and Company 2. (b) Nest box smother (NBS) reduction measures implemented by Company 1 and Company 2
farm managers from Company 2 (11.4 per cent) answered the question in relation to age of birds at the last PS incidence and 14 answered the question in relation to the age of birds at the last incidence of RS. Sixty-five farm managers (31.5 per cent) responded to the question in relation to age of birds at last NBS incidence.
Management
The PS and RS reduction measures reported by farm managers for each company are presented in Fig 5a. Forty-one Company 1 farm managers (25.3 per cent) answered the question in relation to management of PS/RS and there were a large number of measures employed (Fig 5a). Veterinary Record | July 5, 2014
Three farm managers (6.8 per cent) from Company 2 answered the question in relation to reduction measures for PS (Fig 5a). All three suggested reducing noise/stress. The NBS reduction measures for each company are presented in Fig 5b (significant difference between companies for NBS reduction measures (χ2=14.65, P=0.035)). A total of 49 farm managers from Company 1 (32.7 per cent) and 11 farm managers from Company 2 (25.0 per cent) implemented NBS reduction measures. Farm managers were significantly more likely to implement smothering reduction measures when there were more smothering incidences in the last flock cycle (z=2.23, P=0.026). Farm managers with a higher percentage of flocks placed affected by smothering were also more likely to implement smothering reduction measures (z=1.73, P=0.084). However, the number of birds lost per smothering incidence (z=0.72, P=0.471) and flock mortality due to smothering (z=−0.79, P=0.430) did not influence the farm managers’ decisions to implement smothering reduction measures. There was no difference in the decision to implement reduction measures between companies (z=−0.62, P=0.533). Farm managers from both Company 1 (χ2=11.48, P=
Paper
Paper Smothering in UK free-range flocks. Part 1: incidence, location, timing and management J. Barrett, A. C. Rayner, R. Gill, T. H. Willings, A. Bright Smothering in poultry is an economic and welfare-related concern. This study presents the first results from a questionnaire addressing the incidence, location, timing and management of smothering of free-range farm managers from two commercial egg companies (representing 35 per cent of the UK free-range egg supply). Overall, nearly 60 per cent of farm mangers experienced smothering in their last flock, with an average of 25.5 birds lost per incidence, although per cent mortality due to smothering was low ( x =1.6 per cent). The majority of farm managers also reported that over 50 per cent of all their flocks placed had been affected by smothering. The location and timing of smothering (excluding smothering in nest boxes) tended to be unpredictable and varied between farms. Blocking off corners/nest boxes and walking birds more frequently were identified as popular smothering reduction measures, although there was a wide variety of reduction measures reported overall. The motivation to implement reduction measures was related to a farm manager’s previous experience of smothering. To our knowledge, this is the first study to provide a representative industry estimate on the incidence, location, timing and management of smothering. The results suggest that smothering is a common problem, unpredictable between flocks with no clear, effective reduction strategies. A follow-up study will investigate the correlations among smothering, disease and other welfare problems and may shed further light on management solutions.
Introduction
Smothering in poultry is when birds mass together, often on top of each other, resulting in death from suffocation. There is little published information on smothering incidence, cause or prevention. Avian hysteria was described by Sanger and Hamdy (1962) as unexplained extreme nervousness, followed by squawking, flight and then hiding or crowding in corners and under feeders. Mills and Faure (1990) list suffocation as an important economic and production consequence of panic and hysteria in domestic fowl. In a preliminary study, Bright and Johnson (2011) investigated the incidence of smothering and possible causal factors in 10 commercial free-range laying flocks. While only a small sample size, the evidence suggested that smothers significantly affect free-range flocks, causing both economic and animal welfare-related concern. The unpredictable nature of smothering, which makes it difficult for farm managers to address the problem by implementation of management or husbandry practices, was also confirmed. Veterinary Record (2014) J. Barrett, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX13PS, UK A. C. Rayner, BSc(Hons) A. Bright, BSc, MSc, DPhil (Oxon) FAI Farms Ltd, The Field Station, Wytham, Oxford, Oxfordshire, OX2 8QJ, UK R. Gill, The Lakes Free Range Company Ltd, Meg Bank, Stainton, Penrith, CA11 0EE, UK
doi: 10.1136/vr.102327 T. H. Willings, Noble Foods Ltd, The Moor, Bilsthorpe, Newark, NG22 8TS, UK E-mail for correspondence: [email protected] Provenance: not commissioned; externally peer reviewed Accepted April 15, 2014
Laying hens in commercial free-range systems are especially vulnerable to smothering because of the large numbers of birds kept in one area. Free-range systems are a significant component of the UK egg industry; in 2012, free-range and organic eggs accounted for 47.0 per cent of eggs packed in the UK (DEFRA 2012). Further investigation beyond the small study by Bright and Johnson (2011) in a wider commercial setting would help clarify the scale of the smothering problem. Since 2008, McDonald’s Restaurants UK has collaborated through various projects with FAI Farms (consultant) and their two UK egg supplier companies to form the McDonald’s UK Sustainable Egg Supply (SES) Group. In response to concerns over smothering, the SES group developed a questionnaire to address the incidence, location, timing and management of smothering for the free-range laying farms of the two egg supplying companies. These two companies represent 35 per cent of the UK free-range egg supply, and therefore a significant portion of the free-range egg industry. This study presents the first results of the questionnaire addressing the incidence, location, timing and management of smothering from free-range farm managers.
Methods
Questionnaire
The questionnaire related to the farm’s previous flock at the time of completing the questionnaire. The questionnaire sections addressed the three smothering categories as identified by Bright and Johnson (2011): (1) Panic smother (PS), caused by sudden disturbances such as those from predators or sudden noises, isolated incidences involving large numbers (>20 of birds); (2) Nest box smother (NBS), occurring in the nest box, when one hen visits a nest box stimulating other birds to follow; and (3) Recurring smother (RS), smothers recurring throughout lay, though usually with small (1–10) numbers of bird per July 5, 2014 | Veterinary Record
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Paper incidence. A section on concern over smothering and smothering in other previously placed flocks was also included. A first draft of the smothering questionnaire was sent to six freerange farm managers in July 2012 for feedback. Alterations were made and the final version was sent to all free-range farm managers from the two egg companies in September 2012. Questionnaires from Company 1 were filled out independently by the farm manager. Questionnaires from Company 2 were filled out by the farm manager with guidance from the field manager. A separate questionnaire was filled in for every farm, even if run by the same farm manager.
χ2 test were violated, Yate’s correction for continuity or a Monte Carlo simulation was applied.
Data handling
The frequency of smothering incidences, number of birds lost to a smothering incidence and per cent of flock mortality in the last flock cycle due to smothering are presented in Table 1a–c. The per cent of all previous flocks placed affected by smothering and farm manager concern about smothering are presented in Table 2. Farm managers were more likely to consider smothering a problem when a higher percentage of all previous flocks had experienced smothering (z=2.17, P=0.030). In the most recently placed flock, farm managers were more likely to consider smothering a substantial problem when a higher number of smothering incidences had taken place (z=2.28, P=0.023) although this was independent of the number of birds lost to a typical smothering incidence (z=−1.43, P=0.152). There was a trend for farm managers to consider smothering a substantial problem when a higher percentage of the flock was lost to smothering in the last flock cycle (z=1.80, P=0.071). Finally, there was no difference between companies in whether or not they considered smothering a problem (z=1.53, P=0.127) and no smother category that was more likely to cause farm managers to consider smothering a problem (Company 1: χ2=0.51, P=0.500; Company 2: χ 2=1.03, P=0.674).
Farm managers from Company 1 tended to report PS and RS interchangeably (ie, they would cite multiple incidences of smothers involving one or two birds as PS, or single incidences involving more than 20 birds as RS); these two categories of smothering were therefore combined. Six Company 1 farms that reported both PS and RS were removed from the analysis of separate smothering categories. Two farm managers misinterpreted the mortality question and were removed from calculations of smothering mortality. Overall smothering incidence was calculated for each company and for each smother category. The percentage of farm managers who responded to the location, timing (day/year/age of birds), and management sections of the questionnaire was determined by company for each smother category. The location, timing and management answers were grouped into similar categories.
Statistical analysis
The statistical software package used for all analyses was ‘R’ (R Core Team 2013). A generalised linear model (‘glmmADMB’ package, Skaug and others 2012) was used to investigate whether the following factors had an effect on farm manager concern over smothering and implementation of smothering reduction measures: (a) the number of smothering incidences in the last flock cycle; (b) the number of birds lost per smothering incidence in the last flock cycle; (c) flock mortality due to smothering in the last flock cycle; and (d) the percentage of all flocks placed affected by smothering. A binomial distribution model was used, and company was included as a covariate. Interactions were investigated, but not included due to model fit. Zero inflation was accounted for in the model (‘glmmADMB’ package, Skaug and others 2012). A Pearson’s χ2 test was used to investigate whether smother category had an effect on farm manager concern over smothering and whether implementation of smothering reduction measures was dependent on farm manager concern over smothering. Pearson’s χ2 tests were also used to investigate company differences in the reporting of timing and location of smothering. Where assumptions of the
Results
Questionnaires were returned between October 2012 and April 2013. In total, 206 questionnaires were used in analyses: 162 from Company 1 and 44 from Company 2, translating to a 50 and 100 per cent response rate from the total free-range farms in each company, respectively (conventional and organic).
Incidence
Location
The locations of PS/RS reported by farm managers from each company are presented in Fig 1. Fifty-eight Company 1 farm managers (35.8 per cent) answered the question in relation to PS/RS location. Eight Company 2 farm managers (18.2 per cent) answered the question in relation to PS location and 18 (40.9 per cent) answered the question regarding RS location.
Timing Time of year
Times of year for PS and RS as reported by farm managers from each company and NBS as reported by farm managers from both companies combined are presented in Fig 2. NBS responses were combined as there was no significant difference between companies in the time of year reported (χ2=2.99, P=0.362).
TABLE 1: (a) Frequency of smothering reported in the last flock cycle; (b) Number of birds lost to a typical smothering incidence; and (c) Smothering flock mortality (panic smother (PS), nest box smother (NBS), recurring smother (RS)) Company 1 (%) PS/RS (a) Incidences 0 1–5 6–10 >10 x number of incidences (±sd) (b) Number of birds lost 1–25 26–50 51–100 >100
x number of birds lost (±sd) (c) Mortality (%) 0.01–0.1 0.11–1.0 1.1–5.0 >5 x Mortality (%) (±sd) Veterinary Record | July 5, 2014
NBS
PS
Company 2 (%) NBS
RS
Total (%)
62.2 30.2 5.8 1.9 1.5 (±3.3)
67.9 14.7 9.0 8.4 4.2 (±14.3)
84.1 15.9 0 0 0.20 (±0.5)
72.7 15.9 9.1 2.3 1.6 (±3.2)
56.8 27.3 6.8 9.0% 5.7 (±17.5)
38.8 34.5 14.1 12.6 6.2 (±15.5)
67.8 20.3 8.5 3.4 41.2 (±112.9)
93.0 3.5 1.8 1.8 9.1 (±21.4)
42.9 14.3 28.6 14.3 52.1 (±46.7)
83.3 16.7 0 0 13.8 (±14.6)
61.1 16.7 11.1 11.1 33.7 (±42.2)
73.2 17.9 4.1 4.9 25.5 (±51.0)
12.2 53.7 29.3 4.9 1.7 (±2.7)
21.7 56.5 21.7 0 1.0 (±1.1)
70.0 15.0 15.0 0 0.3 (±0.7)
60.0 40.0 0 0 0.2 (±0.2)
5.3 73.7 21.2 0 0.7 (±0.7)
11.1 55.6 29.3 4.0 1.4 (±2.0)
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Paper 80
TABLE 2: (a) Per cent of all flocks placed affected by smothering and (b) per cent of farm managers reporting smothering as a substantial problem (a) Flocks affected (%) 0 0–25 25–50 >50
x flocks affected (%) (±sd)
(b) Substantial problem (%) Yes No
60
Total (%)
17.8 23.3 13.2 45.7 52.3 (±42.6)
17.9 17.9 5.1 19.0 12.8 13.1 64.1 50.0 69.2 (±40.9) 56.3 (±42.7)
21.3 78.7
42.9 57.1
Number of responses
Company 1 (%) Company 2 (%)
70
26.0 74.0
50 40 30 20 10 0
30
Morning
Midday
Afternoon
Evening
Time of year
No specified time
Number of responses
25
20
Company 1 PS/RS
Company 2 RS
Company 2 PS
Company Combined NBS
FIG 3: Smother category and time of day for Company 1 and Company 2
15 10
60
5
0 Litter
Corners
Slats
Range At divisions Centre
Nests
Location Company 1 PS/RS
Company 2 PS
Company 2 RS
FIG 1: Smother category and location for Company 1 and Company 2
Number of responses
50 40
30 20
10 80 0
70
< 20 weeks
Number of responses
20 -28 weeks
29 - 45 weeks
> 45 weeks
Age of birds
60 50
Company 1PS/RS
Company 2 PS
Company 2 RS
Companies NBS combined
40
FIG 4: Smother category and age of birds at last smothering incidence for Company 1 and Company 2
30 20
Time of day
10 0 Spring
Summer
Autumn
Winter
No specified time
Time of year Company 1 PS/RS
Company 2 PS
Company 2 RS
Companies Combined NBS
FIG 2: Smother category and time of year for Company 1 and Company 2
Seventy-six Company 1 farm managers (46.9 per cent) answered the question regarding time of year in relation to PS/RS. Only 6 (13.6 per cent) Company 2 farm managers answered the question regarding typical time of year for PS. Nineteen (43.2 per cent) Company 2 farm managers reported on time of year for RS. Seventy-four farm managers (35.9 per cent) from both companies responded to the question regarding time of year for NBS.
Times of day for PS and RS as reported by farm managers from each company and NBS as reported by farm managers from both companies combined are presented in Fig 3. NBS responses were combined as there was no significant difference between companies in the time of day reported (χ2=2.15, P=0.188). Seventy-seven Company 1 farm managers (47.5 per cent) answered the question in relation to PS/RS time of day. Six farm managers (13.6 per cent) from Company 2 answered the question regarding PS time of day and 19 (43.2 per cent) answered the question regarding RS time of day. Eighty-one farm managers overall (39.3 per cent) answered the question regarding NBS time of day.
Age of birds
The age of birds at the last incidence of PS, RS and NBS reported by farm managers from each company, and NBS as reported by farm managers from both companies combined are presented in Fig 4. NBS responses were combined as there was no significant difference between companies in ages reported (χ2=10.63, P=0.684). Fifty-five Company 1 farm managers (33.9 per cent) answered the question in relation to the age of birds at the last PS/RS incidence. Five July 5, 2014 | Veterinary Record
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FIG 5: (a) Panic smother (PS) and recurring smother (RS) reduction measures implemented by Company 1 and Company 2. (b) Nest box smother (NBS) reduction measures implemented by Company 1 and Company 2
farm managers from Company 2 (11.4 per cent) answered the question in relation to age of birds at the last PS incidence and 14 answered the question in relation to the age of birds at the last incidence of RS. Sixty-five farm managers (31.5 per cent) responded to the question in relation to age of birds at last NBS incidence.
Management
The PS and RS reduction measures reported by farm managers for each company are presented in Fig 5a. Forty-one Company 1 farm managers (25.3 per cent) answered the question in relation to management of PS/RS and there were a large number of measures employed (Fig 5a). Veterinary Record | July 5, 2014
Three farm managers (6.8 per cent) from Company 2 answered the question in relation to reduction measures for PS (Fig 5a). All three suggested reducing noise/stress. The NBS reduction measures for each company are presented in Fig 5b (significant difference between companies for NBS reduction measures (χ2=14.65, P=0.035)). A total of 49 farm managers from Company 1 (32.7 per cent) and 11 farm managers from Company 2 (25.0 per cent) implemented NBS reduction measures. Farm managers were significantly more likely to implement smothering reduction measures when there were more smothering incidences in the last flock cycle (z=2.23, P=0.026). Farm managers with a higher percentage of flocks placed affected by smothering were also more likely to implement smothering reduction measures (z=1.73, P=0.084). However, the number of birds lost per smothering incidence (z=0.72, P=0.471) and flock mortality due to smothering (z=−0.79, P=0.430) did not influence the farm managers’ decisions to implement smothering reduction measures. There was no difference in the decision to implement reduction measures between companies (z=−0.62, P=0.533). Farm managers from both Company 1 (χ2=11.48, P=
