chapter four final version 300403 - bio.bris.ac.ukrunning ceiling fan heaters overnight. 4.3.2. Treatments Eight of the pens were assigned to have UV+ lighting and eight were assigned

four: effect of ultraviolet on quail

106

4. Effect of supplementary ultraviolet lighting on behaviour, morphology and corticosterone of

Japanese quail chicks

4.1. Summary

Most birds have visual sensitivity to ultraviolet (UV) wavelengths, and this sensitivity

appears to play a role in their colour vision. Several species have been found to use

UV cues in visually mediated behaviour, such as intraspecific signalling and foraging.

Artificial lighting is generally designed for human vision and is normally deficient in UV wavelengths. Hence there may be welfare implications for captive birds kept

under such lighting. I investigated whether the absence of UV wavelengths during

rearing adversely affects the welfare of Japanese quail, Coturnix coturnix japonica. I

also investigated the short-term effect of switching from UV containing to UV

deficient light, and vice versa. Stress was assessed by monitoring behaviour, body

mass, tarsus and feather length, fluctuating asymmetry and plasma corticosterone

levels. I did not detect any difference in any of these variables between birds reared

either with or without UV, and the levels of plasma corticosterone in birds of both

groups were so low as to be barely detectable. I conclude that rearing quail in an

absence of UV does not appear to have a significant impact on their welfare, as

measured using these indicators.

4.2. Introduction

Many species of bird are kept under artificial lighting, which typically emits mostly

medium to long wavelengths and has minimal ultraviolet (UV) emission (see review,

Lewis and Morris 1998). Birds utilise the human-visible spectrum and, in addition, all


107

diurnal species studied to date have been found to perceive the near UV (UVA, 315 -

400 nm; Bowmaker et al. 1997; Cuthill et al. 2000a,b; Hart 2001). Birds use UV cues

in a range of ecologically relevant tasks, such as mate choice and foraging (see

reviews: Bennett and Cuthill 1994; Cuthill et al. 2000a,b), and UV sensitivity forms

part of their colour vision system (Osorio et al. 1999b; Chapter 2, published as Smith

et al. 2002). Consequently, it has been suggested that housing birds under standard,

UV deficient artificial lighting may impair their welfare (Moinard and Sherwin 1999;

Sherwin and Devereux 1999; Maddocks et al. 2001b, 2002c). Poultry are known to

have a single cone type maximally sensitive to violet, that confers UV sensitivity

(Wortel et al. 1987; Hart et al. 1999; Prescott and Wathes 1999a) and which is

involved in the perception of colour (Osorio et al. 1999b; Chapter 2). Therefore, a lack

of UV in the illuminant is likely to affect normal colour vision.

Although much has been discovered about how birds use UV cues (reviewed by

Cuthill et al. 2000a,b; Church et al. in press), there has been relatively little research

into general environmental preferences or how the absence of UV may affect welfare

in poultry. Many features of poultry houses have variability in UV reflections that

could potentially provide useful visual information, such as the quality of feed and

various substrates (Prescott and Wathes 1999b). Parts of the plumage of certain breeds

also reflect UV (Prescott and Wathes 1999b; Sherwin and Devereux 1999), which

provides UV cues that may be used in mate choice decisions (Jones and Prescott 2000;

Jones et al. 2001) or to assess the status of other birds. Turkeys, Meleagris gallopavo,

were found to prefer artificial lighting with supplementary UV (Moinard and Sherwin

1999). Also, a lack of environmental enrichment, including UV cues, has been

associated with an increase in welfare-reducing behaviour such as feather pecking in

this species (Sherwin and Devereux 1999). Feather pecking is thought to be an

aberrant, redirected form of substrate pecking rather than an aggressive behaviour

(Huber-Eicher and Wechsler 1997) that may be induced by loss of UV cues on the

substrate. Lack of UV cues may also lead to increased aggression if such cues are used

for individual recognition or signal social status (Sherwin et al. 1999; Maddocks et al.

2001b).


108

As addition of supplementary UV light is likely to increase the perceived brightness of

the illumination as well as changing the spectral composition of the light, the apparent

welfare benefit of supplemental UV may result purely from a preference for brighter

lighting conditions (Greenwood et al. 2002; Chapter 3). This is noteworthy, as turkeys

have been shown to have a preference for higher light intensities (Sherwin 1998). It is

difficult to control precisely for perceived changes in brightness when manipulating

the spectral composition of a light source, as it is not known how avian visual systems

weight information from UV and other cones in the perception of brightness.

However, in the absence of such knowledge, equalising the overall quantal flux to

attempt to equalise perceived brightness between the UV+ and UV- environments is a

logical control. Maddocks et al. (2001b) found that domestic chicks, Gallus gallus

domesticus, kept in UV deficient (UV-) conditions, had significantly higher basal

plasma corticosterone levels and showed a non-significant trend to be less exploratory

than their counterparts kept in UV containing (UV+) conditions when quantal flux was

similar across both conditions. Corticosterone is the major ‘stress’ hormone in birds,

which mediates short-term behavioural and physiological change to cope with adverse

environmental events (Wingfield 1994) and other environmental events that require

increased metabolic output (Reul et al. 2001). As prolonged high levels of

corticosterone are thought to be harmful (Wingfield 1994) and may reduce

performance in terms of commercial productivity (Beuving et al. 1989), this suggests

that provision of ‘full spectrum’ lighting may benefit poultry.

I report on an experiment similar to that which Maddocks et al. (2001b) carried out

using domestic chicks, in which Japanese quail, Coturnix coturnix japonica, were

reared under either UV+ or UV- conditions balanced for quantal flux. I assessed

welfare using a variety of indicator variables, namely behaviour, mass gain, size,

fluctuating asymmetry (FA) and plasma corticosterone. FA is the random deviation

from perfect bilateral symmetry in morphological traits, and is thought to increase

under conditions of developmental stress (Møller and Swaddle 1997). The degree of

FA in chickens has been shown to increase under certain lighting regimes, and is

positively correlated with tonic immobility and the difficulty the birds had in walking,

suggesting it is useful as a welfare indicator (Møller et al. 1999). Corticosterone can


109

be assessed by its basal level and rise in response to capture, handling and restraint

(see Wingfield 1994; Wingfield et al. 1995).

I predicted that even if UV does not have major welfare implications in the long term,

a change of lighting conditions might induce stress in the short term. I therefore also

investigated the short-term stress effects of switching the lighting from UV- to UV+,

and vice versa, by monitoring changes in behaviour and plasma corticosterone levels.

4.3. Materials and methods

4.3.1. Animals

Quail chicks were reared under either UV containing (UV+) or UV deficient (UV-)

light from the age of one day until they were three weeks old. The lighting treatment

in half of the pens within each treatment was switched when the birds were 19 days

old to assess the short-term response to a change in lighting conditions. The lighting in

the other half of the pens remained unchanged. The stress response to rearing under

each lighting condition prior to the light environment change on the evening of day 18

was assessed by measures of mass gain, tarsus and primary feather length, fluctuating

asymmetry (FA), behaviour and plasma corticosterone levels. The immediate short-

term response to a change in lighting after day 19 was assessed using behaviour and

corticosterone levels.

96 one day old quail chicks (obtained from Fayre Game, Liverpool) were randomly

allocated to sixteen pens (each 1.2 x 0.85 m and 2 m high, six chicks per pen). Each pen was light-proofed using hardboard and black cloth. The University of Bristol

veterinary officer advised that initially the young chicks should be maintained at

31±5°C and the temperature gradually reduced by about 1°C/day to 19±5°C. A heat

lamp (250 W, Pandorel radiant heat brooder, Bellsouth PTY Ltd, Australia) was


110

provided in each pen, the loss of heat from the lights at night was compensated for by

running ceiling fan heaters overnight.

4.3.2. Treatments

Eight of the pens were assigned to have UV+ lighting and eight were assigned UV-

lighting. The treatment received by each pen was counterbalanced for position within

the building. In each pen there was a standard fluorescent lamp (General Electric,

U.K.) and a 0.6 m, 18 W, UV blue/black lamp (Sylvania Lighting International

Lisarow, NSW, Australia), both of which were fitted to 240 V, 100 Hz ballasts (Ring

lighting, Leeds, U.K.). The lights were horizontally mounted on the wall at a height of

1.2 m above the floor. The light sources were identical in both treatments except that

UV blocking filters (Lee 226 UV blocking filter, Lee filters, Andover, U.K.; see Fig.

4.1. for transmission spectra) were placed over both of the lights in the UV- pens to

render the lighting conditions UV deficient. The design of the experiment was similar

to that of Maddocks et al. (2001b), except that for the visible-spectrum illumination

fluorescent lamps were used to illuminate the pens, whereas Maddocks et al. (2001b)

used halogen lamps (both studies used the same model of black-light and UV-filter).

Figure 4.1. Transmission spectra of the flexible Lee 226 UV blocking filter that was

used to remove UV from the ambient light by covering the light sources.

0

0.2

0.4

0.6

0.8

1

300 350 400 450 500 550 600 650 700wavelength (nm)

trans

mis

sion


111

I aimed to vary spectral composition but not overall light intensity between light

treatments. Removing UV wavelengths in the UV- pens would also decrease the

overall light intensity. I used an Ocean Optics SD1000 spectroradiometer with a

cosine-corrected detector to quantify the average reduction in quantal flux over the

avian-visible spectrum (approximately 320 – 700 nm) that occurred when a UV

blocking filter was placed over the lights in a pen. Calculations showed that this

created an average decrease of 15% in quantal flux. I therefore partially covered the

lamps in the UV+ condition with strips of black cloth so that the overall avian visible

quantal flux was also reduced by around 15%. This ensured that the only significant difference between treatments was in spectral composition (see Fig. 4.2.).

Figure 4.2. Mean irradiance (quantal flux) in the UV+ and UV- pens. Standard errors

are plotted in one direction only (upwards for UV+ and downwards for UV-). It is

hard to discern the difference between the two treatments except between 300-400 nm,

where the UV+ pens have higher irradiance.

0

5

10

15

20

25

300 400 500 600 700Wavelength (nm)

Qua

ntal

flux

(µM

.m-2

.s-1..n

m-1

)

UV+UV-


112

The total quantal flux integrated over the avian visible spectrum (320-700 nm) did not

differ between treatments (repeated-measures ANOVA on log-transformed quantal

flux: F1,6=1.27, P=0.304). The variation in total irradiance within pens of the same

treatment was greater than the variation in total irradiance between pens within

treatments and both greatly exceeded the between-treatment variance (76%, 21% and

3% respectively, of the total variance as determined by fully nested ANOVA). The

chicks could therefore vary the light intensity they experienced by moving around the

pen, but were however always exposed to the appropriate spectral composition of

light. The quantal flux in the UV waveband (320-400 nm) was significantly higher in

the UV+ than UV- pens (repeated measures ANOVA on log (x+1) transformed

values: F1,6=829.7, P


113

4.3.3. Morphology

All of the quail were weighed on day 2 and again on day 16 prior to the light

environment change. The rate of weight gain in the two lighting conditions was

compared using paired t-tests on Minitab (Minitab 1998). On day 18 the left and right

tarsi of 40 birds, and the longest (fifth) primary on the left and right wings of 93 birds,

were measured to ascertain the degree of FA (see Svensson 1992 for measurement

techniques). Each tarsus and wing was measured five times. The degree of FA of birds

reared in UV+ and UV- was analysed using the methods advocated by Palmer and

Strobeck (2003). This involved testing for directional asymmetry, normality of the

signed asymmetry values and, using mixed-model ANOVA, testing whether FA

significantly exceeded measurement error. Only primary length passed all criteria for

FA and so the variance of signed wing asymmetries in each treatment was adjusted for

measurement error (‘FA index 10’ in Palmer and Strobeck 2003), and compared with

an F-test. In addition, the mean tarsus and wing lengths were calculated for each bird.

Tarsus and wing size for birds reared in UV+ and UV- were compared using two

sample t-tests (Minitab, 1998).

4.3.4. Behaviour

On days 3, 6, 9 and 14, one bird from each pen was observed for a 20 min period, with

a different bird being the focal animal on each of these days. Focal animals were

selected from within the pen randomly, with the constraint that no animal could be a

focal animal twice. In each observation session, two pens were observed

simultaneously by two different observers (myself and Verity J. Greenwood). Having

two observers enabled a bird in each UV+ pen to be observed simultaneously to a bird

in a UV- pen. I counterbalanced the order in which the pens were observed, and also

which observer was assigned to watch each treatment. Focal birds were also observed

on day 19 immediately after the lighting condition had been switched in half of the


114

pens on the previous night. We made observations from hides outside the pens and

recorded the frequencies of 15 measures of behaviour (see Table 4.1.).

Table 4.1. Description of all observed behaviours.

Behaviour Description

_____________________________________________________________________

Rest/sleep Legs folded under body with body resting on substrate

Walk/run Actively moving around the pen with body in contact with

ground

Leap Moving around pen out of contact with ground and flapping

wings

Stasis Mean duration of time spent in each quadrant of the pen, thus

negatively related to overall activity

Feed Frequency of pecks directed at food in the feeder

Drink Frequency of 1 sec intervals in which bird spends drinking

Peck Pecking directed at anything other than food, water or

conspecifics

Scratch Raking claws through substrate using vigorous leg movements

Preen Running beak through feathers

Dust bathing Flapping wings in substrate whilst sitting, partially burying

body in substrate

Stretching Either wing or leg extended away from body as far as possible

Chirping Audible vocalisation

Head shaking Shaking of head from side to side

Aggressive pecking Rapid pecks directed at other birds

Attacked Receipt of aggressive pecks, often causing bird to run away or

cower in submission


115

The data for chirping and dust bathing were omitted from subsequent analysis as these

behaviours were infrequent. The raw data were transformed (log x+1) to linearise the

relationship between variables and then reduced using Principal Component Analysis

(PCA; Chatfield and Collins, 1995) prior to further analysis. This reduced 13 original

variables into five orthogonal variables, the principal components (PCs), each of

which was derived from reduction of the pooled observational data for the whole

experiment. Each PC is a mathematical transformation of the raw data consisting of a

weighted linear sum of the original data (Chatfield and Collins 1995). The raw data

are transformed by multiplying by PC coefficients (weights), which can be either

positive or negative. The resulting PC scores for each extracted PC were then analysed

using repeated-measures ANOVA or GLM on Minitab (Minitab 1998). ‘Pen’ was the

unit of analysis as the birds within a group are not independent. Therefore, although

different birds were observed from each pen on different days, the data were treated as

repeated measures. The data from the periods before and after the light environment

change were analysed separately, with the additional factors ‘day’ (1 to 4) and

day*treatment in the pre-change analyses. The post-change data was analysed with

respect to the four conditions: UV+ changing to UV-, UV- changing to UV+, and

UV+ or UV- unchanged, using non-parametric statistics where residuals could not be

normalised.

4.3.5. Blood Sampling and Ethical Note

Whenever the effects of a potential stressor are investigated, there is inevitably a

moral concern that one may be applying a stressful and deleterious treatment.

However, in this case the stressor was UV deficient lighting, a treatment that is

applied to the vast majority of captive birds kept under artificial light. Blood sampling

was the only experience within this experiment that was not a normal event in bird

husbandry. I chose to use blood sampling because short-term changes in hormone

levels cannot be monitored by the non-invasive method of faecal sampling.


116

My blood sampling programme was designed to minimise the stress on any individual

bird, and blood samples were not taken from any bird more than once. Repeated blood

sampling may not have any deleterious effect on welfare. However, I also wished to

avoid confounding the effects of time and experience of handling on corticosterone

levels. On days 15 and 20 I took blood samples from two birds in each pen to obtain,

from the first, a measure of basal plasma corticosterone, and from the second, the level

of corticosterone 30 minutes post capture. I worked with a second experimenter,

Verity J. Greenwood, so that both of the birds could be caught and sampled

simultaneously in a design balanced for both treatment and sampler. We took a single

blood sample from the bird that had been the focal bird of the previous day’s

observation less than 1 min from the time of capture to obtain a basal level of

corticosterone. We then took a blood sample from the other bird at 30 min post

capture to gain a measurement of the rise in corticosterone in response to capture and

restraint. Birds that were blood sampled after 30 min were moved from their pen to a

procedure room and kept alone in cardboard boxes for 30 min. We sampled UV+ and

UV- pens alternately, ensuring that at any time-point we avoided sampling birds from

a pen adjacent to that which had just been disturbed. We did not notice any change in

behaviour of the birds in pens awaiting sampling.

We took a blood sample (0.1 ml) from each bird by puncture of the alar vein. We used

a 25 gauge needle to prick the vein and collected a drop of blood using a heparinized

capillary tube. The blood samples were centrifuged and the plasma stored in labelled

vials at -20 °C. Birds were inspected and returned to their pens after the procedure.

I monitored the birds regularly, and on day 14 removed two UV- pens from the

experiment as some birds in these pens were starting to consistently feather-peck the

other birds. I removed and separately housed these animals for the sake of the birds’

welfare. This reduced the number of UV- pens in the experiment from 8 to 6 at this

stage. Following the experiments, all the birds were inspected by the University of

Bristol veterinary officer, and re-homed.


117

4.3.6. Radioimmunoassay

Corticosterone concentrations in the blood samples were obtained by

radioimmunoassay using a similar procedure to that described by Wingfield et al. (1992). The principles of this technique are explained in the Appendix to this thesis.

Plasma samples (20 µl aliquots) were extracted in diethyl ether after adding 2000 cpm of tritiated corticosterone ([1,2,6,7-3H]-corticosterone label, Amersham, U.K.) so that

the recovery efficiency of the extraction could be estimated. These evaporated extracts

were reconstituted in 550 µl of assay diluent, 100 µl aliquots of which were

subsequently added to 750 µl scintillant (UltimaGold, Packard, Groningen, The

Netherlands). These were counted in a scintillation counter to calculate percent

recovery. Duplicate 200 µl aliquots of each extract (each containing 7.3 µl of extracted

plasma) were assayed using an anticorticosterone antiserum code B21-42 (Endocrine

Sciences, Tarzana, California, U.S.A.) and [1,2,6,7-3H]-corticosterone label

(Amersham, U.K.). Corticosterone concentrations were corrected for recovery

efficiency (percentage recoveries varied between 70 and 87%) and expressed in ng/ml.

The assay was run with a bound:free ratio of 0.64, 50% binding was 1.03 ng/ml and

the detection limit (for 7.3 µl aliquots of extracted plasma) was 0.95 ng/ml. Plasma

corticosterone levels from before and after the light environment change on day 18

were analysed separately using non-parametric statistics.

4.4. Results

4.4.1. Morphology

There was no significant effect of rearing in UV+ or UV- on mass gain (defined as

mass at 16 minus mass at day 2, t95=0.96, P=0.337), size as measured by tarsus length

(t37=1.80, P=0.081) or the length of the fifth primary (t89 =1.64, P=0.104, see Table

4.2. for means). The non-significant trend for tarsi was for the mean length to be

2.65% greater under UV+ conditions. Following the approach of Palmer and Strobeck


118

(2003), I investigated whether the degree of fluctuating asymmetry (FA) in tarsus and

wing lengths differed between treatments, using mixed model ANOVA on Minitab

(Minitab 1998). I first investigated whether the degree of measurement error exceeded

the degree of FA in each trait, by treating individual bird as a random effect and ‘side’

(left or right side of measured trait) as a fixed effect in the analysis. A significant

bird*side interaction would show that there was variance in the data beyond that due

to measurement error, which would indicate the presence of genuine FA. I found that

for my tarsus measurements, the bird*side interaction was not significant

(F39,320=1.30, P=0.115), which showed that if genuine FA was present, it was

obscured by measurement error. However, there was a significant bird*side interaction

for the wing length data (F92,744=2.41, P


119

Table 4.2. There was no effect of rearing with UV on mass gain (mass at day 16

minus mass at day 2), or the length of the wing and the tarsus. Values shown are X ±

SE.

_____________________________________________________

Trait UV+ reared UV- reared

_____________________________________________________

Mass gain (g) 73.06±1.23 71.43±1.13

Length of tarsus (mm) 31.34±0.31 30.53±0.34

Length of 5th primary (mm) 97.37±0.44 96.28±0.50

_____________________________________________________

Table 4.3. Coefficients relating the first five principal components to the (log-

transformed) original behavioural variables.

Behaviour PC1 PC2 PC3 PC4 PC5

_____________________________________________________________________

Rest/sleep -0.297 0.236 -0.278 -0.222 -0.222

Walk/run 0.456 0.285 -0.113 0.134 -0.076

Leap 0.111 0.112 0.555 -0.044 -0.159

Stasis -0.494 -0.074 -0.123 0.211 0.012

Feed 0.147 -0.108 0.398 0.382 -0.225

Drink 0.279 -0.107 0.177 -0.351 0.456

Peck 0.384 0.028 -0.307 -0.174 0.119

Scratch 0.290 -0.296 -0.119 0.236 0.261

Preen 0.243 -0.155 -0.122 -0.432 -0.488

Stretching 0.045 -0.495 -0.283 -0.012 -0.000

Head shaking -0.140 -0.311 0.433 -0.319 0.382

Aggressive pecking 0.189 0.105 -0.038 0.459 0.417

Attacked 0.014 0.597 0.070 -0.179 0.143

Numbers in bold show the three highest values for each PC, which correspond to the behaviours that

influence that PC most strongly.


120

Figure 4.3. PC1 and PC4 are summary descriptors of various behaviours (derived

from PCA; see Table 4.3.). (a) There was a non-significant trend for mean PC1 scores

to be higher in UV- than UV+, and PC1 scores increased over subsequent observation

sessions. (b) Mean PC4 scores decreased over subsequent observation sessions, but

did not differ between treatments. Vertical bars show SEs.

Analysis of the first 5 PCs showed that rearing condition with respect to UV had no

significant effect on PC2, PC3, PC4 or PC5 before the light environment change (main

effect of treatment: PC2: F1,14=0.07, P=0.790; PC3: F1,14=0.84, P=0.375; PC4:

F1,14=0.88, P=0.363; PC5: F1,14=0.40, P=0.538). However, the first PC showed a non-

significant trend to be higher in UV- conditions during this period (F1,14=3.89,

-2

-1

0

1

2

3

3 6 9 14Day

PC1

scor

e

UV-UV+

Fig.

4.3a

Fig.

4.3b

-1.5-1

-0.50

0.51

1.5

3 6 9 14

Day

PC4

scor

e

UV-UV+


121

P=0.069, see Fig. 4.3a). PC1 is positively associated with walking, running and

pecking at the ground, and negatively associated with staying in the same area of the

pen (see Table 4.3.). Birds in UV- therefore tended to move more often between

different areas of the pen, and tended to walk and run more, and to peck at the ground

more frequently than birds in UV+ (see Fig. 4.3a). I must be very cautious in

considering this trend, because if I set the experiment-wise significance level at 0.05, I

should only accept any of these five tests as significant if P < 0.010. There was no

significant short-term effect on behaviour resulting from a change in light environment

(GLM on the change between days 14 and 19, i.e. before and after the lighting

changed: PC1: F3,10=2.06, P=0.169; PC2: F3,10=0.56, P=0.651; PC3: F3,10=0.59,

P=0.636; PC4: F3,10=0.63, P =0.612; PC5: F3,10=0.03, P=0.993).

As it has been suggested that lack of UV may promote feather-pecking due to loss of

ultraviolet cues in the plumage (Sherwin and Devereux 1999; Maddocks et al. 2001b)

I also separately analysed the number of pecks made by birds in each treatment

towards other birds, as well as the number of pecks they received from others. These

behaviours were quite rare (means of 1.87 and 3.19 occurrences/hour, respectively),

and occurred at similar rates in both treatments, both before and after the light

environment change occurred on day 18 (repeated measures ANOVA on log (1+x)

transformed values; pre-light change: pecks given, F3,14=0.87, P=0.367; pecks

received, F3,14=0.00, P=0.993; post light change: pecks given, Kruskal-Wallis test:

H3=1.29, P =0.731; pecks received, H3=3.77, P =0.287). However, it is notable that I

had to remove two of the eight UV- pens from the experiment on day 18 for welfare

reasons, as some birds in them had started to feather-peck each other. The removal of

these two pens from the experiment will have affected the results post-light

environment change but, even if I include these pens with a fictitious maximal level of

pecking, treatment differences are far from significant (P>0.337 for pecks given and

received). This phenomenon was not completely exclusive to UV- pens, as feather

pecking was starting to occur by day 21 in a UV+ pen as well, at which point the

experiment had ended.


122

Although there was no significant effect of treatment, behaviour did change

significantly with observation day prior to the light environment change. There was a

significant change in PC1 and PC4 over time (PC1: F3,42=5.30, P=0.003; PC2:

F3,42=1.21, P=0.318; PC3: F3,42=0.75, P=0.527; PC4: F3,42=5.11, P=0.004; PC5:

F3,42=1.26, P=0.300), with PC1 scores increasing and PC4 scores decreasing over time

(see Figs 4.3a and 4.3b, respectively). PC1 is mostly positively associated with

walking or running, pecking the ground, and moving between different areas of the

pen (see Table 4.3.). Amount of time spent performing these activities increased over

time. PC4 is mostly positively associated with drinking and pecking other birds, but

negatively correlated with preening (see Table 4.3.). Amount of time spent drinking

and pecking others decreased, whilst preening increased over subsequent observation

sessions. None of the time*treatment interactions were significant (PC1: F3,42=0.66,

P=0.581; PC2: F3,42=0.63, P=0.597; PC3: F3,42=0.80, P=0.503; PC4: F3,42=0.69, P

=0.563; PC5: F3,42=2.57, P=0.067), the marginal effect for PC5 showing no obvious

pattern across time.

4.4.3. Plasma Corticosterone

Data for blood samples taken before and after the light environment change were

analysed. Birds that had basal corticosterone levels that were so low that they were

beneath the assay detection limit were assigned the minimum detectable corticosterone

level (0.95 ng/ml) to enable further analysis. Many birds, particularly those sampled

immediately, had corticosterone levels below the assay detection limit and therefore

had to be assigned identical values (see Table 4.4.).


123

Table 4.4. Corticosterone concentrations (median (LQ, UQ) ng/ml) before the light

environment change for birds sampled at 1 and 30 minutes post capture.

Time UV+ UV-

Basal 0.95 (0.95, 0.95) 0.95 (0.95,0.95)

30 min 0.96 (0.95, 2.34) 1.01 (0.95, 2.34)

The minimum concentration detectable by the assay was 0.95 ng/ml.

At day 15, before the light environment change, in qualitative terms if not in

magnitude, quail chicks showed a typical corticosterone response to the capture-

handling-restraint procedure. Birds being sampled immediately post capture had a

lower level of corticosterone than those sampled 30 min post capture (Wilcoxon

matched-pairs signed-ranks test; T=45.0, Ntest=9, P=0.009), although the rise was not

great. There was clearly no measurable treatment effect on basal corticosterone levels,

as all basal corticosterone levels were below the assay detection limit, with the

exception of one bird reared in UV-. There was no effect of lighting condition on

corticosterone levels taken 30 min post capture (Mann Whitney U test: W=69.0, N=8,

8, P=0.956).

At day 20, after the light environment change, corticosterone levels were even lower

than at day 15. All birds had basal corticosterone below the detectable limit and only

four had supra-limit levels after capture and restraint (two from pens switched from

UV+ to UV-, one from a pen switched from UV- to UV+ and one from an unchanged

UV+ pen). This precluded statistical analysis, but no trends were apparent.


124

4.5. Discussion

Rearing quail chicks with or without ultraviolet (UV) wavelengths had no significant

effect on any of my chosen morphological, behavioural or physiological indicators of

stress. Quail reared in UV- conditions achieved similar body mass and size (as

measured by wing and tarsus lengths) to their counterparts reared in UV+. Although

Møller et al. (1999) found that certain lighting regimes are associated with increased

levels of fluctuating asymmetry (FA) in bilateral traits in chickens, I found no effect of

rearing without UV on FA in quail. Behaviour was not affected by treatment, although

behaviour varied significantly with day of observation. Chicks became increasingly

active and spent more time pecking at the ground and preening over subsequent

observation sessions, and correspondingly spent less time pecking at other birds, and

drinking (see Figure 4.3a,b in conjunction with Table 4.3.). These changes may be an

effect of age, or increased familiarity with the rearing environment, including perhaps

the presence of humans.

As plasma concentrations of corticosterone are known to increase in wild birds in

response to stress (Wingfield et al. 1995), I predicted that elevated levels would occur

in UV- conditions if such conditions are deleterious. However, although birds showed

the typical pattern of hormonal response to capture stress (higher levels 30 min post-

capture as compared to basal levels), corticosterone levels did not differ significantly

between treatments. Indeed, basal levels were at the lower detection limit for all

except one bird, across both treatments. Neither was there any measurable significant

difference in behaviour or corticosterone levels in response to a change in lighting

conditions from UV+ to UV-, or vice versa. However, the hormonal response to

capture and restraint (corticosterone concentration at 30 min post-capture) showed a

non-significant trend to decline over the experiment. This decline mirrors the pattern

of results found by Maddocks et al. (2001b), and again this may be due to age-related

change or to experience of humans (Jones and Waddington 1992). It was not due to

familiarity with blood-sampling, as different birds were sampled at each time point.


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Any treatment differences in corticosterone concentration may have been obscured by

the fact that many of the samples had corticosterone levels so low as to be

undetectable by my assay. These were instead assigned the lowest level of

corticosterone that the assay could detect, which reduced the power of my statistical

analysis. Whilst it might be argued that treatment differences might have been

detected by using a more sensitive radioimmunoassay procedure, I followed the same

procedure as that used by Maddocks et al. (2001b), who obtained measurable

corticosterone levels from chickens. It appears that these quail simply had much lower

corticosterone levels than chickens (ca. 10% lower) when housed and treated under

similar conditions. Consequently, even though not all samples could be assigned

precise levels of corticosterone, it is clear that rearing in, or switching to, UV-

conditions does not cause even minor rises in the levels of plasma corticosterone in

quail.

Maddocks et al. (2001b) reared chickens under UV+ and UV- conditions in an

experiment of similar design, and found a non-significant trend (P=0.054) for more

exploratory behaviour and environmental pecking in UV+ conditions. In contrast, I

found that there was a non-significant trend (P=0.069) for quail chicks to peck, walk,

run and alter their location within the pen less in UV+ conditions (see Fig 4.3a in

conjunction with Table 4.3.). However, the trend towards my UV- environment being

more attractive for pecking is at odds with Maddocks et al.’s (2001b) suggestion that

UV- environments may make birds more wary of pecking the environment because of

a loss of visual cues. There are three potential explanations for these apparently

conflicting results. First, it is possible that the apparently different effects of UV on

behaviour observed here and in Maddocks et al. (2001b) are not biologically

significant. After all, although the trends are opposite, they were not significant in

either study. However, a second possibility is that different species may have differing

levels of need for UV cues. Chickens are known to have UV reflecting plumage

(Prescott and Wathes 1999b; Sherwin and Devereux 1999), to prefer to preen under

daylight (Nuboer 1993) and to use UV in mate choice (Jones and Prescott 2000; Jones

et al. 2001), and hence may find UV+ conditions beneficial. No comparable

information exists for quail. However, as quail can discriminate UV cues from the rest


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of the spectrum and use UV cues when foraging (Chapter 2, published as Smith et al.

2002), it seems likely that quail would utilise UV sensitivity in a similar manner to

chickens. Third, the type of light sources I used differed from that of Maddocks et al.

(2001b). I manipulated the spectral distribution of fluorescent lamps plus black-lights,

whereas Maddocks et al. (2001b) manipulated the spectral distribution of incandescent

halogen lamps plus black-lights. Poultry are known to prefer fluorescent to

incandescent light sources (Widowski et al. 1992), perhaps because the spectral

distribution of fluorescent lamps more closely resembles daylight than that of

incandescent lamps (Lewis and Morris 1998). My light sources would have been

richer in short wavelengths of the ‘blue’ waveband than those of Maddocks et al.

(compare Fig. 4.2 with Fig. 1 of Maddocks et al. 2001b), and consequently my

supplemental UV light may have had a less dramatic effect on the availability of

visual cues in the shorter wavelengths, especially as the violet-sensitive cone of

poultry would be stimulated by these short blue wavelengths. This may also explain

why Maddocks et al. (2001b) found basal corticosterone levels elevated in conjunction

with UV- conditions in chickens, whilst I found no such effect in quail.

Although I found no measurable short-term response in behaviour or corticosterone in

response to a change from UV+ to UV- conditions, or vice versa, interpretation of

these results is problematic. Two of the eight UV- pens were removed from the

experiment before the light environment change occurred, as the birds within them had

started to feather-peck each other. This reduced the sample size in the UV- treatment,

and also excluded the two pens within that treatment in which welfare was presumably

poorest. There is evidence that turkey poults receive less feather pecking in

environments enriched by various materials and supplementary UV lighting (Sherwin

et al. 1999). Hence, it is plausible that the development of feather pecking in these

pens was promoted by the absence of UV. However, as feather pecking had also

developed in a UV+ pen by the end of the experiment, and as the sample size of pens

was low (eight per treatment), it is difficult to tell whether or not the feather pecking in

the two UV- pens was triggered by a lack of UV cues.


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In general my results are not consistent with previous work suggesting that UV+

conditions are beneficial for poultry (Moinard and Sherwin 1999; Sherwin et al. 1999;

Lewis et al. 2000; Maddocks et al. 2001b). I found that behaviour changed and the

corticosterone response to capture and restraint decreased as the birds grew older. The

lack of rise of corticosterone in response to handling by the time the quail had reached

three weeks old indicates that procedures such as blood sampling may not be stressful

for this species.

Although I found no measurable effect of UV on the morphology, behaviour or

plasma corticosterone of quail, it should be noted that the welfare benefits of

providing supplemental UV light might vary with species and context. Species, such

as Galliformes, with violet-sensitive cones, which are stimulated by short blue

wavelengths as well as UV, may be less vulnerable to any deleterious effect of UV-

conditions than species, such as passerines and parrots, whose UV sensitivity is

conferred by cones that are maximally sensitive to UV (see Hart 2001, for details on

species differences). Also, supplemental UV light may be of greater importance in

conjunction with incandescent lamps which have long-wavelength dominated

emission spectra, than with fluorescent lamps which are richer in short wavelengths.

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chapter four final version 300403 - bio.bris.ac.ukrunning ceiling fan heaters overnight. 4.3.2. Treatments Eight of the pens were assigned to have UV+ lighting and eight were assigned