The impact of beak tissue sloughing and beak shape variation on the behavior and welfare of infrared beak-treated layer pullets and hens

The impact of beak tissue sloughing and beak shape variation on the behavior and welfare of infrared beak-treated layer pullets and hens

∗

†

Department and Animal and Poultry Science, University of Saskatchewan, Saskatoon S7N 5A8, Canada; Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon S7N 5B4, Canada; and ‡ Department of Mechanical Engineering, University of Saskatchewan, Saskatoon S7N 5A9, Canada Data collected for Experiment 2 included behavioral expression, feather cover, comb damage, and mortalR ity. Data were analyzed using PROC MIXED (SAS 9.4) with Tukey’s test to separate means. Differences were significant when P ≤ 0.05. IRBT and sloughing had no effect on pecking force or mortality throughout rearing. The variations in post-IRBT beak shape had minor effects on behavior. During rearing, STAN pullets were more active than C pullets but STP and STAN pullets performed less exploratory pecking. During the laying period, SHV and STP hens preened more than C hens. The IRBT treatments, regardless of beak shape, reduced feather loss, comb damage, and cannibalismrelated mortality during the laying period. Overall, the results indicate that LW and LB pullets and hens can cope with the change in beak shape that occurs with IRBT, and that welfare is not negatively impacted if some variation in beak shape occurs.

ABSTRACT This research examined how infrared beak treatment (IRBT), sloughing of the treated beak tissue, and the variations in beak shape that can occur post-IRBT impact the welfare and mortality of Lohmann LSL-Lite (LW) and Lohmann Brown (LB) pullets and hens. Two experiments were conducted and birds for both experiments were treated on the day of hatch. IRBT equipment settings were adjusted to create 4 specific beak shapes: shovel (SHV), step (STP), standard (STAN), and an untreated sham control (C). Experiment 1 pullets (n = 80 per strain) were reared in bioassay cages from 1 to 29 D of age (4 replicates per treatment). Data collected included time and presence of beak sloughing, pecking force, behavioral expression, and mortality. Experiment 2 pullets (n = 320 per strain) were reared in floor pens from 1 D to 18 wk of age (2 replicates per treatment) and then conventional cages from 18 to 60 wk of age (6 replicates per treatment).

Key words: Lohmann, cannibalism, shovel beak, beak shape 2019 Poultry Science 0:1–13 http://dx.doi.org/10.3382/ps/pez274

INTRODUCTION

the treated beak tissue sloughs off. Because the loss of the treated beak tissue is gradual, the bird is able to use its beak normally during the critical first few days of life post-treatment. The gradual loss of the tissue also allows the bird time to adapt to the change in beak shape and length. The PSP is programmable and has components that can be adjusted to create different treatment settings. The most common treatment that is applied results in a symmetrical beak shape where the top and bottom beak lengths are approximately equal. However, variations in beak shape can occur with beak regrowth, if the PSP is damaged or if a quality control program is not in place and followed at the hatchery. This can result in beak shapes such as shovel (SHV) or step (STP) beaks where the bottom beak extends out beyond the top. Although variation is less common with IRBT than HBT (Carruthers et al., 2012), it is still important to understand how variations in beak shape affect layer pullets and hens as it has been suggested that any variation or elongation of the lower beak could be a welfare concern (Prescott and Bonser, 2004; Kajlich et al., 2016).

Although controversial, beak treatment remains one of the most effective methods of controlling and preventing cannibalism in egg production flocks (Glatz, 2000). Infrared beak treatment (IRBT) differs from other methods, such as hot-blade trimming (HBT), because it does not physically cut or result in the immediate loss of the beak tissue. During IRBT, day of hatch chicks are placed into head-holding fixtures on the Poultry Services Processor (PSP; Nova-Tech Engineering LLC, Willmar, MN, USA) and their beak tips are exposed to an infrared light (Glatz, 2005). The light penetrates the outer layer of the beak and damages the underlying tissue, thereby inhibiting further growth of the beak. Post treatment, the outermost layer of the beak remains intact and after a period of 1 to 2 wk,  C 2019 Poultry Science Association Inc. Received February 9, 2019. Accepted April 25, 2019. 1 Corresponding author: [email protected]

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S. Struthers,∗ H. L. Classen,∗ S. Gomis,† T. G. Crowe,‡ and K. Schwean-Lardner∗,1

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MATERIALS AND METHODS The experimental protocols for these experiments were approved by the University of Saskatchewan Animal Research Ethics Board, and all birds were cared for as specified in the Guide to the Care and Use of Experimental Animals by the Canadian Council of An-

imal Care (2009). The 2 experiments conducted for this study were part of a larger study, which examined the effects of IRBT and post-treatment beak shape on the productivity and welfare of layer pullets and hens. While this study’s focus is primarily on behavior and welfare, the data pertaining to productivity has been previously reported (Struthers et al., in press). Experiment 1 examined the effects of IRBT treatments and bird strain (LW, LB) on the welfare and mortality of pullets reared in cages from 1 to 29 D of age and floor pens from 29 to 113 D of age. Experiment 2 examined the effects of IRBT treatments and bird strain (LW, LB) on the welfare and mortality of pullets reared in floor pens until 18 wk of age and hens housed in conventional cages from 18 to 60 wk of age.

Beak Treatments Newly hatched LW and LB female pullets for each experiment were randomly assigned to 1 of the 4 beak treatments. Four specific beak shapes were used in this study (Figure 1). IRBT settings (guard-plate, mirror design, and power) were adjusted to create 3 of these beak shapes: SHV, STP, and STAN (Table 1). The fourth shape was a sham untreated control (C). All treatments were applied post-hatch at a commercial hatchery using the PSP (Nova-Tech Engineering LLC, Willmar, MN, USA) prior to the pullets being transported to the research facility. Pullets in the C treatment were handled and loaded onto the PSP to mimic conditions experienced by the IRBT treated pullets; however, their beak tips were not exposed to the infrared light. Definitions for each beak shape created by IRBT were established based on the difference in length between the top and bottom beaks. An SHV beak was defined as a large difference in top and bottom beak length (average difference of 1.65 mm), with a severe elongation of the bottom beak relative to the top. An STP beak was defined as an intermediate difference in length (average difference of 0.69 mm), with a slight elongation of the bottom beak relative to the top. Finally, an STAN beak was defined as a small difference in length (average difference of 0.03 mm), with the top and bottom beaks being flush.

Housing and Management Experiment 1 and 2 pullets had ad libitum access to water and nutritionally balanced age-appropriate commercial diets. During Experiment 1, feed was provided via chick feeders for the first 14 D and then in trough feeders for the remaining time. Feed for Experiment 2 was provided via tube feeders (diameter of 36 cm for the first 5 wk and 44 cm thereafter) with supplemental feeders added for the first 7 D. Water for both experiments was provided through 360◦ nipple drinkers (Lubing EasyLineTM ), with supplemental waterers

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The viewpoint that any detectable difference between the top and bottom beak lengths is “abnormal” or a welfare concern may question the value of any amount of beak treatment, particularly as the classification has primarily been based on the physical appearance of the beak. Very little research has studied the relationship between variations in beak shape and the effect on production and welfare parameters. It has been suggested that birds with an SHV beak may not be able to effectively grasp and consume feed (Prescott and Bonser, 2004). However, other research has found that IRBTtreated hens with SHV beaks of varying lengths had no differences in production and only minor differences in behavior as compared to IRBT-treated hens that had symmetrical beaks (Hughes et al., 2017). It has been suggested that IRBT may affect behavior during early life, particularly time spent at the feeder and drinker; however, these effects were shortterm (Marchant-Forde et al., 2008). One of the primary criticisms of beak treatment is that it may cause acute and/or chronic pain (Glatz, 2000). Pecking force can be used as an indicator of pain as birds will use less force when pecking at food post-beak treatment if they are in pain (Freire et al., 2008). Freire et al. (2008) reported that IRBT-treated pullets did not show a reduction in pecking force suggesting that the pullets were not in pain. Birds with intact beaks may be better able to grasp and remove feathers, which can result in pain and exposed skin as well as increases the risk of cannibalism (Gentle and Hunter, 1990; Lambton et al., 2010; Riber and Hinrichsen, 2017). It has been found that IRBT results in better feather cover during the laying period compared to untreated hens (Damme and Urselmans, 2013) and HBT-treated hens (Dennis et al., 2009). Although considerable research has been conducted on the effects of IRBT on the welfare of egg production birds, many studies do not report the treatment settings used or the beak shapes that were observed posttreatment. This makes it difficult to understand how IRBT and the variations in beak shape impact layer pullets during early life, particularly during the time that the beak tissue is sloughing. Therefore, the objectives of this study were to (1) examine the effects of 4 beak shapes (3 IRBT-created and 1 sham untreated control) on the welfare and mortality of Lohmann LSLLite (LW) and Lohmann Brown (LB) pullets and hens and (2) assess beak sloughing and its impact on the behavior and pecking force of LW and LB pullets during early life. Two of the IRBT-created beak shapes (SHV and STP) represent the most variations from the standard (STAN) treatment applied.

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INFRARED BEAK TREATMENT OF LAYER PULLETS

(b)

(c)

(d)

: ( Figure 1. The 4 beak shapes created for the present study: (a) shovel beak, (b) step beak, (c) standard beak, and (d) sham untreated control.

provided for the first 7 D. The photoperiod during rearing for both experiments was 23L:1D (20 lux) for the first 7 D and then 8L:16D (10 lux) from 8 D onwards using incandescent light bulbs as the light source, and included dawn and dusk periods of 15 min each. Heat for both experiments was provided via hot water pipes running along the walls of the rooms. Experiment 1 LB and LW pullets (n = 160; 20 pullets per treatment) were housed in bioassay cages (n = 32; 500 cm2 per pullet; 4 replicates per treatment) within an environmentally controlled room from 1 to 29 D of age with 5 pullets per cage. Room temperature started at 32◦ C at 1 D and decreased by approximately 2◦ C every week to reach a final room temperature of 23◦ C at 29 D of age. After the 28 D period, 80 pullets (10 pullets per treatment) were moved to 2 floor pens. Each pen was allocated to 1 strain and housed pullets from the 4 IRBT treatments together (40 pullets per pen; 1,150 cm2 per pullet). Pullets were kept until 113 D of age to continue monitoring pecking force. Experiment 2 A total of 320 LB and 320 LW pullets (80 pullets per IRBT treatment) were housed in floor pens (n = 16; 1,150 cm2 per pullet; 2 replicates per treatment) within 2 environmentally controlled rooms from 1 D to 18 wk of age with 40 pullets per pen. Room

temperature started at 32◦ C at 1 D and decreased to 29◦ C by 7 D. After 7 D, temperature decreased by 2.0◦ C every week to reach a temperature of 21◦ C at 5 wk of age, which was maintained for the remainder of rearing. At 18 wk of age, pullets (n = 576) were transferred to the research laying facility and housed in Layer Specht conventional cages (n = 48; 6 replicates per treatment) Table 1. Infrared beak treatments applied on day of hatch to Lohmann LSL-Lite and Lohmann Brown chicks to create 4 specific beak shapes by adjusting the guard plate, mirror, and power settings. Strain LB

LW

Treatment

Guard plate

Mirror

Power

SHV STP STAN C SHV STP STAN C

27/23C 27/23C 27/23C 27/23C 26/23 26/23 26/23 26/23

Flat Glass Aluminum Curve Glass Flat Glass Curve Glass Mid Wrap -

42 42 44 41 41 41 -

SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite.

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(a)

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Data Collection Beak Sloughing Starting at 7 D of age, the IRBTtreated pullets from Experiment 1 were individually examined daily to determine initiation and completion of beak sloughing. To perform this assessment, pullets were removed from the cage one at a time and their top and bottom beaks were examined and identified as either intact, partially sloughed, or completely sloughed. Pecking Force The force with which Experiment 1 pullets used to peck at nutritive food objects was measured at 4, 11, 18, 25, 53, 81, and 109 D of age (same pullets tested at each age; 4 replicate birds per treatment). Feed was removed 1 h prior to testing to encourage pullets to peck at feed placed on top of the force plate. Two pullets were tested at a time and 1 pullet of the pair was marked with non-toxic ink to distinguish it from the other. Pullets were weighed to determine body weight and then placed onto a wooden platform with a force plate connected to a load cell, which was connected to a P-3500 Portable Strain Indicator unit (Vishay Measurements Group, Raleigh, NC, USA) and visualized on a TDS1002R oscilloscope (Tektronix Inc., Beaverton, OR, USA). Three pecks per pullet were recorded and averaged. A peck was considered any hit from the beak onto the force plate (load cell). Once a pullet had successfully pecked the force plate, the maximum force (measured in millivolts (mV)) was recorded and converted to newtons (N) by multiplying the mV value by the sensitivity reciprocal (see below). Pecking force was equalized for body weight (calculated at N per 100 g of BW) and then averaged per bird. Sensitivity reciprocal =

=

(m/1000) ∗ 9.81 System output (1000/1000) 640

∗

9.81

= 0.01532815 m = known mass = 1,000 gSystem output = 640 mV.

Behavior (Experiment 1) Pullets housed in 2 replicate cages per treatment were video recorded for 8 continuous hours every second day from 10 to 28 D of age for behavior analyses. Videos were recorded using Canon Vixia HFR700 Camcorders (Canon Canada, Mississauga, ON, Canada) that captured the entire cage. Data were later observed for behavioral expression. The percent of time pullets spent performing nutritive, active, resting, preening, comfort, exploratory, and aggressive behaviors as described in Table 2 was evaluated using scan sampling at 15-min intervals. Behavioral expression was analyzed and presented as an average of the entire period (10 to 28 D of age). Behavior (Experiment 2) During the rearing period, pullet behavior was recorded in all pens for 24 continuous h at 5, 9, 13, and 17 wk of age. Ceilingmounting infrared video camera systems (Panasonic WV-CF224FX, Panasonic Corporation of North America, Secaucus, NJ, USA) captured the entire pen, and recorded to a computer system in continuous real-time mode. Nutritive, comfort, active, resting, exploratory, and aggressive behaviors as described in Table 2 were evaluated using scan sampling at 15-min intervals. During the laying period, hen behavior was recorded using 3 replicate cages per treatment for 24 continuous h at 23 and 39 wk of age. Behavior was recorded using tripod-mounted infrared video cameras (Panasonic WV-CF224FX, Panasonic Corporation of North America, Secaucus, NJ, USA) placed in front of the cages which captured the entire 2 cages (1 replicate). The cameras recorded to a computer system in continuous real-time mode. The same behaviors as during the rearing period were evaluated using scan sampling at 15-min intervals.

Feather Cover and Comb Damage Experiment 2 hens were individually scored for feather cover and comb damage at 18 and 42 wk of age by the 2 same independently working individuals. Because of the removal of LB hens from the trial at 42 wk of age, only LW hens were feather and comb scored at the end of the laying period (60 wk of age). Each bird was scored for 5 areas: neck, back, breast, wings, and tail. These areas were given a score ranging from 1 (no feather cover) to 4 (full plumage) using a scale adapted from Davami et al. (1987) and Sarica et al. (2008) as described in Table 3. Comb damage (fresh and/or scabbed) was given a score ranging from 0 (no damage) to 4 (extensive damage) using a scale adapted from Ali and Cheng (1985) as described in Table 3. Feather cover and comb damage scores were calculated as an average of the scores given by each individual scorer for statistical analyses. Mortality and Cause of Mortality Birds for both experiments were monitored daily for mortality or morbidity and were humanely euthanized using manual cervical dislocation when culling was necessary. All

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with 12 birds housed in 2 cages for each replication, until 60 wk of age. Bird density during the laying period was 489 cm2 per bird and met the minimum requirements set by the National Farm Animal Care Council Codes of Practice for the Care and Handling of Pullets and Laying Hens (NFACC, 2016). All hens had ad libitum access to water (1 Lubing EasyLineTM 360◦ nipple per cage) and a nutritionally balanced commercial layer diet. Light was provided by incandescent bulbs and was kept at 14L:10D (10 lux) from 18 wk of age onwards with the same dawn and dusk periods as during the rearing period. Barn temperature was maintained at approximately 20◦ C. At 42 wk of age, all LB hens from all treatments were removed from the trial due to high mortality from cannibalism and injurious pecking.

INFRARED BEAK TREATMENT OF LAYER PULLETS

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Table 2. Ethogram of behaviors commonly performed by commercial layer pullets and hens. Category

Behavior Feeding Drinking Wing stretch Leg stretch

Comfort

Sham dustbathing

Comfort Comfort Active Active Active Exploratory Exploratory Aggressive Low incidence Low incidence

Preening Feather ruffling Standing Walking Resting Gentle pecking Object pecking Aggressive pecking Perching Wing flapping

Low Low Low Low

Head scratching Head shaking Beak wiping Unknown

incidence incidence incidence incidence

Head extended into feeder; manipulating or ingesting feed1 Head extended to water line; manipulating water nipple1 Extension of wings away from body without flapping or walking3 Stretching leg out to the side or behind body and returning leg back under body without taking a step forward3 Trying to perform dustbathing behavior (wing shaking, scratching ground with one leg) on cage/pen floor3 Grooming own feathers with beak while standing or laying3 Feathers of wings and body are raised/shaken out4 Standing and idle; eyes may be open or closed2 Taking at least 2 successive steps1,4 Crouching with breast on floor of cage, otherwise inactive, with eyes open or closed3 Pecking at plumage of other birds; does not cause harm or damage5 Pecking at inedible objects (floor, water hose, bars, feeder)2 Pecking which causes damage and causes birds to flinch and/or vocalize5 Sitting or standing on an elevated object3 Extension of wings away from body and flapping up and down rapidly but without flight/walking4 Using leg to scratch at head3 Head is moved side to side/up and down rapidly3 Rapid stroking of alternate sides of the beak on the walls and/or floor of cage/pen4 Behavior cannot be discerned because bird is not visible or is being blocked by other birds

Definitions adapted from 1 Dennis et al. (2009), 2 Gentle and McKeegan (2007), 3 Hurnik et al. (1995), 4 Marchant-Forde et al. (2008), and 5 Savory (1995).

Table 3. Scoring criteria for feather cover1 and comb damage2 of hens.

Feather cover

Comb damage

1 2

Score

Description

1 2 3 4 0 1 2 3 4

No feather cover More than 50% of the plumage is missing 50% or less of the plumage is missing Full, intact plumage No sign of pecking damage A single mark of pecking damage 2 to 3 marks of pecking injuries on either side of the comb More than 3 marks of pecking on the comb Severe injuries, bleeding, extensive damage to the comb

Adapted from Davami et al. (1987) and Sarica et al. (2008). Adapated from Ali and Cheng (1985).

found-dead and euthanized birds were recorded, weighed, and submitted for necropsy to an independent diagnostic laboratory. For Experiment 2, during the laying period, any hen that was being actively pecked as evident by the presence of blood and/or minor tissue damage was removed from the trial and placed into a non-experimental cage. Birds that were removed from the experiment (live cull) and placed into nonexperimental cages were considered mortalities.

Statistical Analyses Experiment 1 The experiment was designed as a 4 × 2 factorial arrangement of IRBT treatment and bird strain, in a completely randomized design with 4 replicates per treatment (cage as replicate unit for behavior and mortality and bird as replicate unit for pecking force). Data were anaR 9.4, Cary, NC) lyzed using PROC MIXED (SAS with Tukey’s range test to separate means. Peck-

ing force data was correlated with body weight usR 9.4, Cary, NC). Percenting PROC CORR (SAS age data was checked for normality using PROC R 9.4, Cary, NC) and log transUNIVARIATE (SAS formed (data log + 1) when necessary. Differences were considered significant when P ≤ 0.05 and a trend was noted when 0.05 < P ≤ 0.10. Experiment 2 The experiment was designed as a 4 × 2 factorial arrangement of IRBT treatment and bird strain, in a randomized complete block design with 2 (pullets) or 6 (hens) replicates per treatment and blocked by either room (pullets) or row (hens). After LB hens were removed from the trial at 42 wk of age, the experimental design was a one-way analysis of variance, in a randomized complete block design with 6 replicates per IRBT treatment and blocked by row. Data were analyzed using PROC MIXED (pen as replicate unit R for pullets and cage as replicate unit for hens) (SAS 9.4, Cary, NC) with Tukey’s range test to separate means. Percentage data was checked for normality using

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Nutritive Nutritive Comfort Comfort

Definition

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R 9.4, Cary, NC) and log PROC UNIVARIATE (SAS transformed (data log + 1) when necessary. Differences were considered significant when P ≤ 0.05 and a trend was noted when 0.05 < P ≤ 0.10.

ing period (Table 4). Differences in pecking force were found between the 2 strains from 11 to 109 D of age. From 11 to 25 D of age, LB pullets pecked with more force but at 53 and 109 D, LW pullets pecked with more force.

RESULTS Beak Sloughing Experiment 1 Sloughing of the affected beak tissue was first noted at 11 D of age and was complete by 25 D of age (Figure 2a). Within the treated pullets, sloughing began at 11 D of age for the SHV treatment, 15 D of age for the STP, and 12 D of age for the STAN treatment. Sloughing was completed by 24 D of age for the SHV and STP treatments and 25 D of age for the STAN treatment. LW pullets began to slough sooner and were faster at sloughing throughout than LB (Figure 2b). Sloughing was first observed for LW at 11 D of age and LB at 14 D of age. By 25 D of age, 100% of the treated LB and LW pullets had sloughed beaks.

Pecking Force Experiment 1 Pecking force was found to be strongly, positively correlated with body weight (r = 0.79). Altering the beak shape did not alter the force with which pullets used to peck at food over the test-

Behavior Experiment 1 The IRBT treatments had minimal impacts on early pullet behavior when monitored every second day from 10 to 28 D of age. Pullets in the STAN treatment spent a greater percent of time being active as compared to C pullets (41.7 vs. 36.5%, respectively). Strain had a larger impact on behavior during early life than the IRBT treatments. LB pullets spent a greater percent of time performing active (41.8 vs. 38.3%, LB and LW respectively), resting (11.0 vs. 9.8%, LB and LW respectively), and low incidence behaviors (14.8 vs. 11.6%, LB and LW respectively) while LW pullets spent a greater percent of time performing exploratory behaviors (5.4 vs. 2.4%, LW and LB respectively). Experiment 2 The IRBT treatments did not influence behavior at any age during the rearing period, with the exception of exploratory behavior (Table 5). At 5 wk, C pullet spent a greater percent of time exploring their environment as compared to STP and STAN pullets (8.1 vs. 6.6 and 6.5%, respectively). The bird strains

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Figure 2. Effect of infrared beak treatment (a) and strain (b) on beak sloughing, expressed as a percent of birds showing complete (top and bottom beak) sloughing. SHV = shovel beak, STP = step beak, STAN = standard beak, and C = sham untreated control. LB = Lohmann Brown and LW = Lohmann LSL-Lite.

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INFRARED BEAK TREATMENT OF LAYER PULLETS

Table 4. Effect of infrared beak treatments and strain on the pecking force per 100 g of body weight (N/100 g BW) of Experiment 1 Lohmann LSL-Lite and Lohmann Brown pullets housed in cages from 1 to 29 D and floor pens from 29 to 113 D of age. Beak Treatment

Strain

Interaction

SHV

STP

STAN

C

P value

LB

LW

P value

P value

SEM

4 11 18 25 53 81 109

14.1 12.7 7.5 7.2 3.3 3.1 3.0

14.8 14.2 6.9 7.9 3.1 2.9 2.5

16.9 14.2 8.3 8.0 3.4 3.2 3.0

15.1 11.5 7.4 7.2 3.2 3.9 2.8

0.79 0.09 0.50 0.14 0.39 0.14 0.27

16.1 15.8a 8.3a 8.1a 3.0b 3.0 2.6b

14.2 10.6b 6.8b 7.0b 3.5a 3.6 3.1a

0.25 < 0.01 0.02 < 0.01 0.01 0.08 < 0.01

0.94 0.25 0.38 0.19 0.19 0.69 0.50

0.67 0.65 0.33 0.18 0.09 0.16 0.10

Means within a main effect with different superscripts are significantly different (P ≤ 0.05). SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite

a,b

in general presented a slightly different behavioral profile (Table 5). LB pullets spent a greater percent of time in active behaviors at 5, 9, and 17 wk of age as compared to LW. Expression of low incidence behaviors (perching, head shaking, head scratching, beak wiping, wing flapping, and unknown behavior) also differed between the two strains at multiple ages with LW pullets spending a greater percentage of time performing these behaviors than LB pullets. At 5 wk of age, an interaction occurred, as IRBT treatments affected how each strain responded with respect to the percent of time spent performing low incidence behaviors. LW STAN pullets performed these behaviors more than LB regardless of treatment (3.6 vs. 2.7, 2.3, 2.6, and 2.4%, LW STAN, LB SHV, LB STP, LB STAN, and LB C, respectively) and more than LW SHV, and LW C pullets (3.6 vs. 1.8 and 2.3%, LW STAN, LW SHV, and LW C respectively). Similar to the rearing period, IRBT treatment and the various beak shapes had minimal effects on behavior during the laying period (Table 5). Hens in the SHV and STP treatments spent a greater percent of time preening than C hens (6.4 and 6.8 vs. 5.4%, respectively). During the laying period, LB hens were more active than LW at 23 wk of age but spent less time resting, preening, and performing low incidence behaviors (Table 5). At 39 wk, LW hens spent a greater percent of time performing nutritive, resting, and preening behaviors than LB.

Feather Cover and Comb Damage Experiment 2 At the start of the laying period (18 wk of age), there was no effect of the IRBT treatments or bird strain on feather cover, as feathering was excellent moving into the conventional cages (i.e., all hens had scores of 4 for all body areas). During the mid-laying period (42 wk of age), IRBT treatment, regardless of final beak shape, had an effect on the feather cover of the wings with C hens having poorer feather cover compared to treated hens (scores of 3.7 vs. 3.9,

respectively). Strain also had an effect on the feather cover of the wings at 42 wk of age with LB hens having poorer feather cover than LW (3.8 vs. 3.9, respectively). When LW hens were feather scored (60 wk of age), treated hens, regardless of beak shape, had better feather cover in all body areas scored as compared to C hens (Table 6). At 42 wk of age, interactions between IRBT treatment and strain were noted for the remaining body areas (neck, back, breast, and tail) (Table 7). In the neck region, C hens of both strains had poorest feather cover overall and within the SHV and STP treatments, LB hens had the poorest feather cover compared to LW hens. Interestingly, for the back, breast, and tail regions, LW C hens had the poorest feather cover scores compared to the other three treatments, but LB C hens did not. Comb damage was assessed to help quantify aggression during the laying period and data are shown in Table 6. At 42 wk of age, C hens had significantly higher scores, indicating more comb damage, than the SHV, STP, and STAN treatments (scores of 1.9 vs. 1.5, 1.2, and 1.3, respectively).

Mortality and Cause of Mortality Experiment 1 Beak treatment did not affect mortality levels over the 28 D period. The majority of the mortality during the 28 D period was unrelated to the IRBT treatments (yolk sac infection). There were differences in total mortality and mortality due to yolk sac infection between the 2 strains over the 28 D period. Total mortality was higher in LW pullets than LB (10.0 vs. 1.2%, respectively) as was yolk sac mortality (6.2 vs. 0.0%, respectively). Experiment 2 During the rearing period, the use of IRBT and the variations in beak shape that resulted from adjusting the IRBT treatment settings had no impact on mortality levels. There were also no differences in total mortality between the strains. There was no effect of the IRBT treatments on cause of mortality;

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Age (D)

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Table 5. Effect of infrared beak treatments and strain on the behavior (% of time) of Experiment 2 Lohmann LSL-Lite and Lohmann Brown pullets and hens over a 24-h period at 5, 9, 13, 17, 23, and 39 wk of age. Beak treatment Behavior

STP

7.3 9.5 69.8 3.4 0.3 7.3a,b < 0.1 2.2b,c

7.4 9.2 70.2 3.5 0.3 6.6b < 0.1 2.8a,b

4.9 11.6 65.1 4.3 0.2 6.3 < 0.1 7.5

STAN

Interaction

C

P value

LB

LW

P value

P value

SEM

7.4 9.3 69.8 3.6 0.3 6.5b < 0.1 3.1a

6.9 8.5 70.6 3.3 0.2 8.1a < 0.1 2.3c

0.89 0.66 0.81 0.99 0.35 0.05 0.71 0.01

6.9 10.5a 68.9b 3.6 0.3 7.3 < 0.1 2.5b

7.6 7.8b 71.3a 3.3 0.3 7.0 < 0.1 2.7a

0.61 < 0.01 < 0.01 0.52 0.28 0.17 0.25 < 0.01

0.81 0.40 0.69 0.21 0.07 0.60 0.66 < 0.01

0.23 0.51 0.44 0.22 0.02 0.31 0.00 0.17

5.5 11.0 65.0 5.2 0.3 6.5 < 0.1 6.4

5.5 11.0 62.5 4.9 0.3 6.0 < 0.1 9.5

4.3 10.4 66.7 4.6 0.2 7.1 < 0.1 6.6

0.55 0.48 0.65 0.38 0.27 0.62 0.78 0.31

5.0 11.7a 68.8 4.7 0.2 7.1 < 0.1 2.4b

5.1 10.3b 60.9 4.9 0.3 5.9 < 0.1 12.6a

0.83 0.01 0.19 0.20 0.47 0.06 0.27 < 0.01

0.73 0.61 0.85 0.37 0.22 0.32 0.42 0.73

0.20 0.35 1.21 0.17 0.03 0.30 0.02 1.45

4.1 13.4 60.9 6.2 0.0 6.6 < 0.1 8.8

4.4 13.5 58.8 7.4 0.1 6.5 < 0.1 9.1

4.5 13.3 58.8 7.0 0.0 6.3 < 0.1 10.0

3.7 13.5 61.0 6.1 0.1 7.1 < 0.1 8.5

0.52 0.52 0.67 0.09 0.12 0.47 0.63 0.39

4.0 14.3 66.5 6.5b 0.1 6.4 < 0.1 2.1b

4.4 12.5 53.2 6.8a 0.1 6.9 < 0.1 16.0a

0.23 0.90 0.12 < 0.01 0.97 0.20 0.40 < 0.01

0.59 0.30 0.13 0.10 0.80 0.31 0.94 0.50

0.14 0.36 1.84 0.23 0.01 0.21 0.01 1.87

3.5 14.6 57.6 6.4 0.2 6.4 < 0.1 11.1

4.0 15.1 58.2 6.5 0.2 6.2 < 0.1 9.9

3.9 14.7 58.7 6.4 0.2 6.5 < 0.1 9.7

3.3 15.7 59.0 5.9 0.1 5.9 < 0.1 10.1

0.15 0.97 0.30 0.88 0.59 0.46 0.37 0.13

3.3b 15.0a 66.4 6.0b 0.2a 6.2 0.0b 2.7b

4.0a 15.0b 50.3 6.6a 0.1b 6.2 < 0.1a 17.7a

< 0.01 < 0.01 0.14 < 0.01 < 0.01 0.64 0.01 < 0.01

0.12 0.64 0.14 0.67 0.70 0.11 0.10 0.14

0.16 0.27 2.10 0.20 0.03 0.20 0.01 1.97

14.5 26.8 43.5 6.4a 0.2 2.5 < 0.1 6.1

15.4 24.1 44.5 6.8a 0.1 2.2 0.1 6.7

16.0 24.0 44.3 6.2a,b 0.1 2.3 0.1 7.0

15.6 25.7 44.2 5.4b 0.1 2.2 0.2 6.5

0.43 0.35 0.11 0.02 0.57 0.91 0.44 0.77

14.7 28.8a 43.4b 5.0b 0.1 1.9 0.2 5.8b

16.0 21.4b 44.9a 7.4a 0.1 2.7 0.1 7.3a

0.53 < 0.01 < 0.01 < 0.01 0.82 0.06 0.10 0.01

0.45 0.99 0.41 0.17 0.57 0.11 0.55 0.40

0.43 1.10 0.28 0.40 0.02 0.23 0.03 0.33

15.8 28.1 43.5 4.9 0.1 1.5 < 0.1 6.0

15.0 25.1 45.6 5.3 0.1 1.7 0.1 7.1

15.5 25.0 44.7 5.4 0.2 1.8 0.1 7.2

15.0 25.6 45.6 6.7 0.1 1.5 0.1 5.4

0.40 0.21 0.83 0.34 0.36 0.87 0.71 0.45

14.1b 29.5 43.8b 5.2b 0.1 1.5 0.1 5.7

16.6a 22.5 45.9a 6.0a 0.1 1.7 < 0.1 7.1

0.04 0.12 < 0.01 < 0.01 0.99 0.56 0.11 0.09

0.92 0.56 0.87 0.45 0.35 0.91 0.31 0.56

0.49 1.12 0.46 0.35 0.04 0.14 0.01 0.47

Means within a main effect with different superscripts are significantly different (P ≤ 0.05). SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite. Nutritive = time at feeder + time at drinker. Active = standing + walking. Rest = resting. Preen = preening. Comfort = dustbathing + feather ruffling + leg stretching + wing stretching. Exploratory = gentle pecking + object pecking. Aggression = aggressive pecking. Low incidence = perching + head shaking + head scratching + beak wiping + wing flapping + unknown.

a–c

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5 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence 9 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence 13 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence 17 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence 23 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence 39 wk of age Nutritive Active Rest Preen Comfort Exploratory Aggression Low incidence

SHV

Strain

9

INFRARED BEAK TREATMENT OF LAYER PULLETS

Table 6. Effect of infrared beak treatments and strain on the feather cover score (scale 1–4)1 and comb damage score (scale 0–4)2 of Experiment 2 Lohmann LSL-Lite and Lohmann Brown hens at 42 wk of age and Lohmann LSL-Lite hens at 60 wk of age. Beak treatment Age (wk)

Interaction

SHV

STP

STAN

C

P value

LB

LW

P value

P value

SEM

3.4a,b 3.1a

3.4b 3.0a

3.6a 3.0a

2.8c 2.6b

< 0.01 < 0.01

3.2b –

3.4a 2.9

< 0.01 –

0.02 –

0.03 0.03

3.9a 3.8a

3.9a 3.5a

3.9a 3.7a

3.5b 2.8b

< 0.01 < 0.01

3.8 –

3.8 3.4

0.57 –

< 0.01 –

0.02 0.05

3.6a 3.2a

3.6a 3.2a

3.7a 3.2a

3.1b 2.6b

< 0.01 < 0.01

3.5 –

3.5 3.0

0.28 –

< 0.01 –

0.03 0.05

3.9a 3.9a

3.9a 3.8a

3.9a 3.9a

3.7b 3.3b

< 0.01 < 0.01

3.8b –

3.9a 3.7

0.02 –

0.74 –

0.02 0.03

3.8a 2.9a

3.7a 3.1a

3.9a 3.1a

3.3b 2.1b

< 0.01 < 0.01

3.8a –

3.5b 2.8

< 0.01 –

< 0.01 –

0.03 0.05

1.5b 2.1

1.2b 1.9

1.3b 1.9

1.9a 2.2

< 0.01 0.13

1.4 –

1.5 2.0

0.68 –

0.41 –

0.05 0.06

Means within a main effect with different superscripts are significantly different (P ≤ 0.05). Score of 1 = no feather cover, 2 = greater than 50% of plumage missing, 3 = 50% or less of the plumage missing, and 4 = full, intact plumage (Davami et al., 1987; Sarica et al., 2008). 2 Score of 0 = no comb damage, 1 = single mark of pecking damage, 2 = 2 to 3 marks of pecking damage, 3 = greater than 3 marks of pecking damage, and 4 = extensive damage, presence of blood (Ali and Cheng, 1985). SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite. a–c 1

Table 7. Interaction between infrared beak treatments and strain on the feather scores of Experiment 2 Lohmann LSL-Lite and Lohmann Brown hens at 42 wk of age. Strain × beak treatment Body area Neck Back Breast Tail

LB SHV b,c

3.3 3.8a,b,c 3.4c 3.8a

LW SHV a

3.6 3.9a,b 3.8a,b 3.7a

LB STP c,d

3.2 3.9a,b,c 3.5a,b,c 3.8a

LW STP

LB STAN

a,b

3.6 3.9a,b,c 3.6a,b,c 3.6a

a,b,c

3.4 3.7b,c 3.5a,b,c 3.8a

LW STAN a

3.7 4.0a 3.8a 3.9a

LB C d,e

2.9 3.6c 3.4b,c 3.7a

LW C 2.8e 3.3d 2.9d 3.0b

Means within a row with different superscripts are significantly different (P ≤ 0.05). SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite.

a–e

however, LW pullets had higher mortality from yolk sac infections as compared to LB (2.2 vs. 0.0%, respectively) (Table 8). During the early to mid-laying period (18 to 42 wk of age), an interaction between IRBT treatment and strain was noted for total mortality. Mortality did not differ between the beak treatment groups within the LW strain (0.0, 2.8, 0.0, and 0.0%, SHV, STP, STAN, and C, respectively). Within the LB strain, C hens had significantly higher mortality compared to STP and STAN hens (22.2 vs. 0.0 vs. 1.4%, respectively). Comparison

between the strains shows that LB C hens had higher mortality than LW SHV, LW STAN, and LW C hens (22.2 vs. 0.0%, respectively). During this period, there was also an interaction between IRBT treatment and strain for mortality due to cannibalism, with LB C hens having significantly higher mortality as compared to LB STP and STAN hens (19.4 vs. 0.0%, respectively) and LW hens in all treatments (19.4 vs. 0.0%, respectively). During the late laying period (42 to 60 wk of age; LW hens only), there were no differences in total mortality between the IRBT treatments (Table 8).

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Neck 42 60 Back 42 60 Breast 42 60 Wings 42 60 Tail 42 60 Comb 42 60

Strain

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STRUTHERS ET AL.

Table 8. Effect of infrared beak treatments and strain on the total mortality and mortality by cause (as a % of birds placed) of Experiment 2 Lohmann LSL-Lite and Lohmann Brown pullets and hens. Beak treatment

Strain

Interaction

SHV

STP

STAN

C

P value

LB

LW

Total mortality 1 D to 18 wk 18 to 42 wk 42 to 60 wk

1.9 2.8 1.4

2.5 1.4 1.4

2.5 0.7 8.3

3.7 11.1 4.2

0.72 0.35 0.35

1.6 7.3a –

3.7 0.7b 3.8

Mortality due to yolk sac infection 1 D to 16 wk 0.6

0.6

2.5

0.6

0.51

0.0b

Mortality due to cannibalism 18 to 42 wk

0.0b

0.0b

9.7a

0.03

5.6a

1.4a,b

P value

P value

SEM

0.36 0.05 –

0.62 0.03 –

0.74 1.94 1.32

2.2a

0.02

0.51

0.51

0.0b

< 0.01

0.03

1.67

Means within a main effect with different superscripts are significantly different (P ≤ 0.05). SHV = large difference between top and bottom beak lengths. STP = intermediate difference between top and bottom beak lengths. STAN = small difference between top and bottom beak lengths. C = sham untreated control. LB = Lohmann Brown. LW = Lohmann LSL-Lite.

a,b

DISCUSSION IRBT Animal welfare is becomingly increasingly more important to consumers and because of this, long-standing management practices within the poultry industry, such as beak treatment, are coming under scrutiny. Some of the concerns that arise with the practice of beak treatment include the reduced ability of the bird to perform natural behaviors such as feeding, drinking, and preening as well as the possibility of acute and/or chronic pain following treatment (Kuenzel, 2007). Throughout the rearing period, particularly during the time that beak tissue was sloughing, the IRBT treatments used in the present study did not alter the force that pullets used to peck at food, suggesting an absence of pain because pullets were not hesitant to use their beaks or peck. This differs somewhat from previous literature (Jongman et al., 2008; Dennis and Cheng, 2010; Freire et al., 2011); however, these studies used HBT rather than IRBT, limiting the comparisons that can be made. Sloughing of the beak tissue did not appear to affect behavior during early life, particularly beak-related behaviors. This suggests that even though the shape of the beak was changing, pullets were not hesitant to use their beaks to peck at the feeder, drinker, or preen. This is further supported by the fact that there were no differences in feed intake during the rearing period (Struthers, 2018). Earlier studies observed decreased activity levels in HBT-treated birds (Duncan et al., 1989; Gentle et al., 1997) and IRBT-treated birds (Marchant-Forde et al., 2008) compared to untreated birds and attributed this decrease to acute pain. In the present study, when pullets were reared in cages, STAN pullets were more active (standing and walking) than C pullets during Experiment 1. This contrasts earlier studies further supporting that treated pullets were

likely not experiencing pain post-IRBT in the present study. Moving birds to a laying environment that is different from their rearing environment (for example, from floor-pens to cages) may affect behavior and this should be considered in the context of the present study. Craig et al. (1988) found that floor-reared pullets had lower activity for the first few days after transfer to conventional cages compared to pullets that had been reared in cages, likely due to floor-reared pullets being more fearful of the novel cage environment. In the present study, it appears that rearing environment had little effect on the behavior of hens once they entered the laying environment; however, a limitation to this is that behavior was not recorded immediately following placement in the laying barn. Exploratory behavior is thought to be expressed when birds are not in pain and their basic needs have been met (Duncan, 1998). In the present study, when pullets were reared in floor pens, C pullets spent more time exploring their environment than pullets with STP or STAN beak shapes. This is similar to Gentle and McKeegan (2007) who found that a greater proportion of untreated control birds pecked at the environment compared to birds that were beak treated using either HBT or IRBT. However, the authors found no behavioral evidence that birds were experiencing pain or stress and concluded that the change in behavior likely arose by chance (Gentle and McKeegan, 2007). In the present study, when taken in conjunction with the pecking force data from Experiment 1, it is unlikely that the Experiment 2 pullets were performing less exploratory pecking because they were in pain after IRBT. One possible reason for the differences in exploratory pecking between the STP, STAN, and C treatments could be due to reduced sensory feedback in the treated beaks, which would make exploratory pecking less rewarding and pullets may have been less motivated to perform the behavior (Freire et al., 2008; Jongman et al., 2008).

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Age

INFRARED BEAK TREATMENT OF LAYER PULLETS

cannibalism-related mortality, regardless of the treatment settings used or the final beak shape. In conclusion, the beak shapes created by using different IRBT treatment settings and the subsequent sloughing of the beak tissue had minor effects on the behavior of layer pullets and hens while simultaneously improving welfare in comparison to birds that had natural, untreated beaks. The results of these 2 experiments demonstrate that LW and LB layer pullets and hens were able to cope with the change in beak shape that occurred due to IRBT. Despite previous research classifying SHV and STP beaks as “abnormalities” and suggesting that any detectable difference between the top and bottom beak lengths may be a welfare concern (Kajlich et al., 2016), the results of the present study do not reflect this. Very few differences were noted between the 3 beak shapes created by IRBT suggesting that even if some variation in beak shape occurs, welfare is not necessarily negatively impacted. However, large variations in beak shape post-IRBT can be minimized by following the standard operating procedures for the PSP and implementing a quality control program at the hatchery.

Strain The main objective of this research was to determine the effects of variation in beak shape and sloughing of the beak tissue; however, 2 egg-layer strains were used to help determine how different genotypes react to IRBT. Although there are a limited number of studies that have examined the effects of beak treatment on different egg-layer strains concurrently, it has been hypothesized that brown-feathered strains may exhibit more pain-related behaviors and neuroma formation following HBT (Marchant-Forde et al., 2008). It is not yet fully understood if brown-feathered strains are more negatively affected by IRBT as well. In the present study, regardless of if pullets were beak treated or not, both strains spent the majority of the 8 h rearing photoperiod (during which behavior was recorded) being active. Increased activity levels have been associated with improved well-being in both broilers (Bizeray et al., 2002) and layers (Pohle and Cheng, 2009). Throughout the rearing period of Experiment 2, LW pullets spent a greater percent of time perching (classified as a low incidence behavior). Commercial perches were not provided; however, the drinker system served as a makeshift perch. The differences in time spent perching may be due in part to the differences in BW between the strains. LB pullets were heavier than LW pullets throughout the rearing period (Struthers, 2018), which may have limited their ability to perch. Perching can serve as a means to escape aggressive birds (Newberry et al., 2001). At 17 wk in the present study, LW pullets were more aggressive than LB and this may have contributed to the increased perching observed in LW pullets at this age. Although the

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Preening has been found to decrease following HBT (Duncan et al., 1989; Gentle et al., 1997) suggesting pain or sensitivity in the beak following beak treatment. When day-old chicks were treated using either HBT or IRBT, Marchant-Forde et al. (2008) found that preening increased in treated birds (particularly in HBT birds) relative to control birds and suggested that the change in beak shape reduced the ability of the bird to preen. It is possible that this is the reason for the increased time spent preening observed in SHV and STP hens in the present study, however, this can be challenged because there were no consistent effects of the IRBT treatments on preening throughout the rearing and laying periods. Another possible explanation could be a less aggressive or stressful environment in comparison to the hens with intact beaks, who had higher cannibalism-related mortality. In Experiment 2, hens with intact beaks consistently had poorer feather cover than hens with IRBT-treated beaks. These results are similar to previous studies that have been conducted on commercial farms (Damme and Urselmans, 2013; Riber and Hinrichsen, 2017). Comparison of hens with the 3 IRBT-created beak shapes showed no differences in feather cover indicating that regardless of the amount of tissue treated and/or sloughed, hens with blunted beaks were less able to grasp and damage the plumage of conspecifics. To the author’s knowledge, comb damage has never been evaluated in relation to beak treatment. From the results of Experiment 2, it is evident that the removal of the sharp hook of the beak that occurs with IRBT is effective at limiting the damage that can be inflicted upon the combs of other birds. Overall, the feather cover and comb damage data from Experiment 2 suggests that leaving hens with intact beaks can have detrimental consequences for plumage and comb condition thereby negatively affecting bird welfare. One of the major welfare concerns of birds with untreated beaks is an increased risk of mortality from cannibalism. Not only does cannibalism represent an animal welfare concern, it can also have economic consequences for producers. Data from the early to midlaying period of Experiment 2 demonstrated that leaving birds with intact beaks, particularly LB birds in this case, results in significantly higher total mortality and mortality due to cannibalism as compared to birds with treated beaks. This is consistent with previous studies done using commercial layer flocks (Weeks et al., 2016; Riber and Hinrichsen, 2017). One of the most important findings of the present study was the interaction between IRBT treatment and strain on mortality due to cannibalism from 18 to 42 wk of age. The data support that there may be a genetic component to the behavior and that the LB strain may be more prone to cannibalism than the LW strain, which is consistent with the findings of previous studies (Abrahamsson and Tauson, 1995). This interaction also highlights how effective IRBT is at reducing

11

12

STRUTHERS ET AL.

ACKNOWLEDGMENTS The authors would like to acknowledge the Natural Sciences and Engineering Research Council of Canada, the Saskatchewan Egg Producers, and the Canadian Poultry Research Council for their financial support; Clark’s Poultry Inc. (Brandon, MB) for allowing the use of their facilities; and the University of Saskatchewan Poultry Centre staff and students for their technical assistance.

REFERENCES Abrahamsson, P., and R. Tauson. 1995. Aviary systems and conventional cages for laying hens. Acta. Agric. Scand. 45:191– 203. Ali, A., and K. M. Cheng. 1985. Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+ /rc) controls. Poult. Sci. 64:789–794. Bizeray, D., I. Estevez, C. Leterrier, and J. M. Faure. 2002. Effects of increasing environmental complexity on the physical activity of broiler chickens. App. Anim. Behav. Sci. 20:27–41. Canadian Council on Animal Care. 2009. CCAC Guidelines on: The Care and Use of Farm Animals in Research, Teaching and Testing. Canadian Council on Animal Care, Ottawa, ON, Canada. Carruthers, C., T. Gabrush, K. Schwean-Lardner, T. D. Knezacek, H. L. Classen, and C. Bennett. 2012. On-farm survey of beak characteristics in White Leghorns as a result of hot blade trimming or infrared beak treatment. J. Appl. Poult. Res. 21:645– 650. Craig, J. V., N. A. Okpokho, and G. A. Milliken. 1988. Floor- and cage-rearing effects on pullets’ initial adaptation to multiple-hen cages. App. Anim. Behav. Sci. 20:319–333. Damme, K., and S. Urselmans. 2013. Infrared beak treatment – a temporary solution? Lohmann Info. 48:36–44. Davami, A., M. J. Wineland, W. T. Jones, R. L. Ilardi, and R. A. Peterson. 1987. Effects of population size, floor space, and feeder space upon productive performance, external appearance, and plasma corticosterone concentration of laying hens. Poultry Science 66(2):251–257. Dennis, R. L., A. G. Fahey, and H.-W. Cheng. 2009. Infrared beak treatment method compared with conventional hot-blade trimming in laying hens. Poult. Sci. 88:38–43.

Dennis, R. L., and H.-W. Cheng. 2010. Effects of beak trimming on pecking force. Int. J. Poult. Sci. 9:863–866. Duncan, I. J. H. 1998. Behavior and behavioral needs. Poult. Sci. 77:1766–1772. Duncan, I. J. H., G. S. Slee, E. Seawright, and J. Breward. 1989. Behavioural consequences of partial beak amputation (beak trimming) in poultry. Brit. Poult. Sci. 30:479–488. Freire, R., M. A. Eastwood, and M. Joyce. 2011. Minor beak trimming in chickens leads to loss of mechanoreception and magnetoreception1. J. Anim. Sci. 89:1201–1206. Freire, R., P. C. Glatz, and G. Hinch. 2008. Self-administration of an analgesic does not alleviate pain in beak trimmed chickens. Asian Australas. J. Anim. Sci 21:443–448. Gentle, M. J., and D. E. F. McKeegan. 2007. Evaluation of the effects of infrared beak trimming in broiler breeder chicks. Vet. Record 160:145–148. Gentle, M. J., and L. N. Hunter. 1991. Physiological and behavioural responses associated with feather removal in Gallus gallus var domesticus. Res Vet. Sci. 50:95–101. Gentle, M. J., B. O. Hughes, A. Fox, and D. Waddington. 1997. Behavioural and anatomical consequences of 2 beak trimming methods in 1- and 10-d old domestic chicks. Brit. Poult. Sci. 38:453– 463. Glatz, P. C. 2000. Beak trimming methods - Review. Asian Australas. J. Anim. Sci 13:1619–1637. Glatz, P. C. 2005. What is beak-trimming and why are birds trimmed? Pages 1–17 in Poultry Welfare Issues: Beak Trimming. P. C. Glatz, ed. Nottingham University Press, Nottingham, UK. Hughes, C., J. Griffin, and K. Schwean-Lardner. 2017. Effect of beak shape of IRBT hens on welfare and productivity. Poult. Sci. 96(ESuppl. 1):266. (Abstr.) Hurnik, J. F., A. B. Webster, and P. B. Siegel. 1995. Dictionary of Farm Animal Behaviour. Iowa State Univ. Press, Ames, IA. Jongman, E. C., P. C. Glatz, and J. L Barnett. 2008. Changes in behaviour of laying hens following beak trimming at hatch and re-trimming at 14 weeks. Asian Australas. J. Anim. Sci 21: 291– 298. Kajlich, A. S., H. L. Shivaprasad, D. W. Trampel, A. E. Hill, R. L. Parsons, S. T. Millman, and J. A. Mench. 2016. Incidence, severity, and welfare implications of lesions observed postmortem in laying hens from commercial noncage farms in California and Iowa. Avian Dis. 60:8–15. Kuenzel, W. J. 2007. Neurobiological basis of sensory perception: welfare implications of beak trimming. Poult. Sci. 86:1273–1282. Lambton, S. L., T. G. Knowles, C. Yorke, and C. J. Nicol. 2010. The risk factors affecting the development of gentle and severe feather pecking in loose housed laying hens. Appl. Anim. Behav. Sci. 123:32–42. Marchant-Forde, R. M., A. G. Fahey, and H.-W. Cheng. 2008. Comparative effects of infrared and one-third hot-blade trimming on beak topography, behavior, and growth. Poult. Sci. 87:1474–1483. National Farm Animal Care Council (NFACC). 2016. Codes of practice for the care and handling of pullets and laying hens. Accessed May 2018. http://www.nfacc.ca/codes-of-practice/ poultry-layers. Newberry, R. C., I. Estevez, and L. J. Keeling. 2001. Group size and perching behaviour in young domestic fowl. Appl. Anim. Behav. Sci. 73:117–129. Pohle, K., and H.-W. Cheng. 2009. Furnished cage system and hen well-being: comparative effects of furnished cages and battery cages on behavioral exhibitions in White Leghorn chickens. Poult. Sci. 88:1559–1564. Prescott, N. B., and R. H. C. Bonser. 2004. Beak trimming reduces feeding efficiency of hens. J. Appl. Poult. Res. 13:468–471. Riber, A. B., and L. K. Hinrichsen. 2017. Welfare consequences of omitting beak trimming in barn layers. Front. Vet. Sci. 4:222. Sarica, M., S. Boga, and U. S. Yamak. 2008. The effects of space allowance on egg yield, egg quality and plumage condition of laying hens in battery cages. Czech J. Anim. Sci. 53:345–353. Savory, C. J. 1995. Feather pecking and cannibalism. Worlds Poult. Sci. J. 51:215–219. Struthers, S. 2018. The impact of infrared beak treatment on the production, behaviour, and welfare of layer pullets and hens. MSc thesis. Univ. Saskatchewan, Saskatoon.

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same number of birds per strain were placed into the conventional cages and stocking density was equal between the strains during the laying period, differences in body size may have had an impact on some of the results that were observed. For example, during early laying period, LB hens stood and walked more compared to LW hens, who spent more time resting. This suggests that the LB hens may have had less space to lay down when resting. Feather cover differed between the 2 strains and this could be attributed to the fact that feather loss may be easier to quantify on white-feathered birds (Damme and Urselmans, 2013). In the present study, LW hens had better feather cover during the laying period, which is in agreement with Damme and Urselmans (2013); however, they did not score individual body areas. Overall, despite the concern within the poultry industry that brown-feathered strains may have more difficultly following IRBT than white-feathered strains, the results of this study do not reflect this concern within the limits of the 2 genotypes that were used.

INFRARED BEAK TREATMENT OF LAYER PULLETS Struthers, S., H. L. Classen, S. Gomis, and K. SchweanLardner. The effect of beak tissue sloughing and posttreatment beak shape on the productivity of infrared beaktreated layer pullets and hens. Poult. Sci. Accessed April 2019. https://doi.org/10.3382/ps/pez230.

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Weeks, C. A., S. L. Lambton, and A. G. Williams. 2016. Implications for welfare, productivity and sustainability of the variation in reported levels of mortality for laying hen flocks kept in different housing systems: a meta-analysis of ten studies. PLoS ONE 11:e0146394. Downloaded from https://academic.oup.com/ps/advance-article-abstract/doi/10.3382/ps/pez274/5487640 by Nottingham Trent University user on 27 August 2019