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Influence of Light Intensity on Behavior and Performance of Broiler Chickens1
Influence of Light Intensity on Behavior and Performance of Broiler Chickens 1 R. C. NEWBERRY, J. R. HUNT, and E. E. GARDINER Agriculture Canada, Research Station, P. O. Box 1000, Agassiz, British Columbia, Canada, VOM 1A0 (Received for publication October 21, 1987)
1988 Poultry Science 67:1020-1025 INTRODUCTION
Proudfoot and Sefton (1978) suggested that rearing broiler chickens under low environmental light intensities results in good growth with low energy loss by reducing exercise. Deaton et al. (1976) reported that the feedrgain ratio of chickens increased as light intensity increased. They attributed this to higher activity in chickens kept under brighter lighting, resulting in excess energy use and greater wastage of feed in litter. However, they were comparing continuous low intensity light (12.9 lx) with bright light (204.5 lx) supplied on a 12 h light: 12 h dark lighting schedule. Therefore, their results could have been related to the duration of light, and changes from light to dark, rather than to the light intensity per se. Newberry et al. (1985) observed higher chicken activity in brighter (6 to 12 lx) vs. darker (.5 lx) areas within pens, but these birds were also being subjected to changes in light intensity over time. In a subsequent study using constant light intensity treatments ranging from .1 to 100 lx, Newberry et al. (1986) obtained a light intensity x age interaction for activity but expressed concern that the activity measurements may have been influenced by ob-
1
Agassiz Research Station Contribution Number 367.
1020
server presence. They found that light intensity had no effect on body weight, but that the feedigain ratio was higher under brighter light in one of two experiments. Other investigators (Barott and Pringle, 1951; Skoglund and Palmer, 1962) have observed that body weight was unaffected by light intensities ranging from 1 to 65 lx, but was reduced at intensities of 129 lx or higher. Contrary to the hypothesis that brighter lighting reduces performance due to increased activity, Weaver and Siegel (1968) reported that feeding activity was higher under 6.57 to 21.53 lx than .75 to 1.51 lx lighting, but that body weights and feed conversions were unaffected by light intensity. Weaver (1986) found that over the range of 9 to 31 lx, higher light intensity was correlated with increased body weight, improved feed conversion, and better carcass grades. The influence of light intensity on activity and performance remains ambiguous. Statements about the effect of lighting on activity have been based on qualitative data only (e.g., Cherry and Barwick, 1962; Deaton et al, 1976) or activity has been quantified using direct observation techniques, where the presence of the observer could have affected chicken behavior (e.g., Newberry et al., 1986). Weaver and Siegel (1968) observed birds through sliding
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
ABSTRACT The influence of two light intensity treatments, 180 and 6 lx, on behavior and performance of broiler chickens was examined in two experiments. The first experiment tested male chickens reared to 9 wk of age and the second experiment tested both sexes reared separately to 6 wk. Behavioral data were collected by scan sampling of behavior recorded on video tape. Standing, walking, and total activity were higher under the 180 lx than the 6-lx treatment (P<.01), whereas feeding and drinking were not significantly affected by light intensity. Body weight, feed and water consumption, and feed conversion were unaffected by light intensity. Incidence of leg disorders at 6 wk and the percentage of bruised carcasses at 64 days were significantly lower under the higher light intensity treatment in the first experiment, as was mortality to 3 and 6 wk in the second experiment. No significant light intensity x sex interactions were detected. Results did not support the hypothesis that brighter lighting reduces performance due to increased chicken activity. Use of brighter lighting had no adverse effects on performance and there was some evidence that it may have a beneficial effect on welfare by reducing bruising. (Key words: light intensity, behavior, performance, broilers)
LIGHT INTENSITY AND CHICKEN BEHAVIOR
panel openings but even this would not completely eliminate visual and auditory stimuli from the observer. In addition to these problems, effects of light intensity on chicken performance have been inconsistent within and between studies. The objectives of this study were to determine the influence of light intensity on chicken behavior over 24-h periods in the absence of an observer and to examine the effects of light intensity on the performance of male and female chickens. MATERIALS AND METHODS
temperatures (measured in central alley) for the 1st to 4th wk were 31, 29, 26, and 24 C, respectively, in both experiments. The mean room temperature after 4 wk, when brooders were switched off, was 20 C in Experiment 1 and 17 C in Experiment 2. Chicken activity should not be restricted at these temperatures by comparison with activity at higher temperatures (Deaton etal., 1976). Mortality checks were made at approximately 0745 h and 1520 h each day. The mean body weight of the chickens in each pen was determined at 21, 42, and, in Experiment 1, 63 days. Feed and water consumption and feed conversion were determined for each pen on a bird-day basis. The incidence of leg disorders was determined subjectively by counting the number of birds in each pen showing evidence of impaired walking ability (i.e, stiff, jerky, staggering, or unsteady gait, limping, inability to walk) when encouraged to walk. Behavioral data were collected in Experiment 1. Two video cameras were used to monitor the two pens of a block (one bright, one dim) over 1 24-h period each week, from the 2nd to the 9th wk. The behavior of the chickens in each pen was recorded on video tape using time-lapse video recorders. Recordings were made of the four blocks of pens over 4 consecutive days each week by moving the cameras to a different block each day according to a predetermined random schedule for each week. Video tapes were analysed by scan sampling (Altmann, 1974) the behavior in each pen at 30-min intervals throughout each 24-h recording. Chores were arranged so that caretakers were not present in pens at scan times. The percentage of birds feeding (standing at feeder), drinking (standing at drinker), walking, and standing (up on feet but not feeding, drinking, or walking) of those present in each pen was determined. The classification "active" referred to the total percentage of birds feeding, drinking, walking, and standing. All remaining birds were lying down and were considered inactive. Carcass grades were obtained for all birds in Experiment 1. Birds were processed at 64 days and graded by a plant inspector according to Canadian grade standards (Canada Agricultural Products Standards, 1986). Reasons for downgrading were recorded. Statistical Analysis. Behavior, mortality, leg disorder, and carcass grade data were transformed by arc sine prior to analysis. The effects on behavior of age (wk), block, light, time of
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Two experiments were conducted, each testing two light intensity treatments, bright (180 lx) vs. dim (6 lx). Light was provided by a clear incandescent light bulb hanging 1.2 m above the floor in the center of each 1.98 x 2.44-m light-proofed pen. Each bulb was fitted inside a 35-cm diam light shade, which directed the light downward. Bright pens were lit by a 100 W, 120-V bulb and dim pens by a 7.5 W, 115 to 125 V bulb. Light intensity, measured at floor level 20 cm out from the center of the pen in the absence of feeders and drinkers, was 180 lx in bright pens and 6 lx in dim pens. Light was provided 24 h/day at a constant level throughout each experiment. Peterson x Arbor Acre broiler chicks vaccinated against Marek's disease were obtained from a commercial hatchery. In Experiment 1, 35 randomly selected male 1-day-old chicks were placed in each of eight pens and reared to 9 wk of age. In Experiment 2, 65 chicks were placed in each of 16 pens (eight pens of each sex) and reared to 6 wk of age. Treatments were arranged among pens in a randomized complete block design with four blocks. Each pen contained one tube feeder (pan diameter 36.8 cm, 0 to 4 wk; 43.2-cm diam, 4 to 9 wk) and one drinker (with five nipples) in the first experiment and two feeders and two drinkers in the second experiment. Feeders and drinkers were raised as the birds grew so that birds had to stand up to feed and drink. Litter consisted of a 5-cm layer of wood shavings. All chickens were fed a 23% protein starter diet (0 to 3 wk) and 20% protein grower diet (3 to 6 wk). Birds in Experiment 1 were fed an 18% finisher diet from 6 to 9 wk. Heat was provided to each pen by a gas brooder with one quarter of the canopy over the pen. The temperature under the brooders was reduced gradually from 35 C at 1 day to 25 C at 4 wk. Mean room
1021
** .10
3.9 3.9 2.4 1.2 .9 .8 .5 .7
180 lx
.08
NS
**
(%)
Walking
Values given for each age X behavior X light intensity c o m b i n a t i o n are means of 192 observations.
.13
3.2
3.4
NS NS
3.7 4.0 3.9 3.5 2.7 2.9 2.6 2.7
6 1x
4.3 3.8 3.5 3.4 2.4 3.2 3.4 3.1
180 lx
Drinking
T o t a l percentage of chickens engaged in feeding, drinking, walking, a n d standing.
**P<.01.
*P<.05.
2
1
SEM
*
NS
6.3
6.6
X
Significance Age Light intensity Light intensity X
10.4 11.4 7.8 5.2 4.4 4.5 4.0 3.0
6 1x
11.2 11.1 7.7 5.3 4.0 5.8 3.9 3.7
180 lx
2 3 4 5 6 7 8 9
(wk)
Age
Feeding
1.6
3.3 3.2 2.1 1.3 .9 .5 .6 .7
6 lx
TABLE 1. Effect of light intensity and age on behavior of male chickens1
from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015 6.4
7.2 11.9 8.0 5.4 4.6 4.7 4.1 5.2
180 lx
Standing
5.6
7.4 8.8 6.8 4.3 4.3 4.2 3.6 5.3
6 1x
18.2
26.6 30.7 21.7 15.3 11.9 14.5 12.0 12.8
180 lx
.33
NS
**
Active 2
16.7
24.7 27.4 20.5 14.3 12.3 12.0 10.7 11.7
61x
H
rn
%
Z
o
LIGHT INTENSITY AND CHICKEN BEHAVIOR
day (at 30-min intervals), and their interactions were examined by analysis of variance using a split-plot design, with age as the main plot and interactions with block as error terms. Changes in behavior with time of day were further examined by regression analysis. Analysis of variance was used to examine the effects on performance parameters at each age of light and block in Experiment 1, and block, light, sex, and light x sex in Experiment 2. RESULTS AND DISCUSSION
periodicities of 1.5 to 4 h and about 30 min in activity levels of isolated chicks maintained under constant light and temperature. Short periodicities in group behavior were not apparent in the present study, probably due to variation in periodicities between individuals and within individuals at different ages (Broom, 1980). Weaver and Siegel (1968) observed that feeding behavior was highest at 0800 h and attributed this to the arrival of the caretaker at 0730 h each day. In the present study, peak morning and afternoon activity levels were also observed approximately 30 min following caretaker visits. Light intensity had few significant effects on performance parameters (Table 2). Body weight, feed consumption (data not shown), water consumption, and feed conversion were unaffected by light intensity or block at 3, 6, or 9 wk in Experiment 1, or at 3 and 6 wk in Experiment 2 (3-wk data not shown). Feed and water consumption results were consistent with the absence of a light intensity effect on feeding and drinking behavior. It would appear that the increased activity of chickens in bright pens did not increase birds' energy requirements sufficiently to affect feed conversion. Contrary to the findings of Deaton et al. (1976), chickens were not observed to waste feed in the litter. The absence of an adverse effect of bright lighting on growth contrasts with earlier findings (Barott and Pringle, 1951; Cherry and Barwick, 1962; Skoglund and Palmer, 1962), although not with more recent results (Deaton et al., 1981;
1ST
T23
TIME OF DAY
FIGURE 1. Effect of time of day on the percentage of chickens standing (dotted line) and active (solid line). Standing and activity declined significantly (P<.05) with increasing time.
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Feeding, drinking, walking, standing, and activity (Table 1) all declined significantly with increasing age, which is in agreement with previous findings for activity (Newberry et al., 1985, 1986) and feeding behavior (Weaver and Siegel, 1968). Behavior was also affected by light intensity. Chickens stood and walked significantly more in bright pens than dim pens and were therefore more active, confirming previous impressions (Cherry and Barwick, 1962; Deaton et al., 1976; Newberry et al., 1985). Feeding and drinking behavior were not influenced by light level. However, drinking behavior differed significantly between blocks (P<.05). Standing behavior was significantly affected by the interaction between light intensity and age, with birds standing more under bright than dim light from 3 to 8 wk but not at 2 and 9 wk. Also, there was a significant light intensity x age interaction for feeding, with birds spending more time feeding in bright than dim light at 2, 5, 7, and 9 wk and less time in the remaining weeks. By comparison with the low light treatment of 6 lx in this experiment, Weaver and Siegel (1968) used a low light treatment of less than 2 lx, which may explain their finding that feeding behavior was consistently lower under low lighting conditions. Time of day influenced standing and total activity (P<.05) (Figure 1) but not feeding, drinking, or walking behavior. Interactions of light intensity, age, and block with time of day were not significant. The proportion of chickens standing and active declined significantly between morning and evening, indicating the presence of a diurnal rhythm of behavior among groups of chickens kept under constant lighting conditions. This diurnal rhythm could have been triggered by diurnal changes in temperature, sounds from people passing by the barn during working hours, and the regular arrival of caretakers for mortality checks. Broom (1980) demonstrated a 24-h periodicity, and also shorter
1023
1801x 61x
Light
Male Female
Sex
SEM
180 lx 6 1x
Light
SEM
Level
Factor
1.67b 1.76a .01
.07
.09
1.72 a 1.70 a
.01
5.98a 4.96b
07
1.61 1.61a
2.30a 1.92b
.04
02a
a
6 wk
5.56a 5.38a
24
.24
3.46 3.42a
12a
9 wk (L/bird)
a
6 wk (kg/kg) a
02
98a
99
9 wk
Cumulative feed:gain ratio
and sex on performance
2.09a 2.12a
3.62 a 3 68
(kg)
9 wk
2.09 2.12a
a
6 wk
Cumulative water consumption
of light intensity
1.3
17.9a 9.4b
14.6a 12.7a
1.0
4 . 35 12.1a
Lb
6 wk
5
35.0" 42.1a
9 wk
Incidence of leg disorders
parameters
6 wk
9 wk
Cumulative mortality
9 wk
Bruised carcasses
a b ' Within c o l u m n , e x p e r i m e n t , a n d factor, m e a n s bearing different superscripts are significantly different ( P < . 0 5 ) . In E x p e r i m e n t 2, there were no significant light X sex interactions.
Experiment no.
B o d y weight
T A B L E 2. Effect
from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Z
> r
m
TO 50
% rn
LIGHT INTENSITY AND CHICKEN BEHAVIOR
consumption, water consumption, feed:gain ratio, and the incidence of leg disorders (Table 2). Of greater interest was the finding that the two sexes responded similarly to light intensity for all parameters measured. Results confirmed previous indications that chicken activity is increased under higher light intensities. Results did not support the hypothesis that brighter lighting reduces performance due to increased chicken activity. ACKNOWLEDGMENTS
The technical assistance of K. Ingram, T. Yule, and the barn crew is gratefully acknowledged. REFERENCES Altmann, J., 1974. Observational study of behaviour: sampling methods. Behaviour 49:227-267. Barott, H. G., and E. M Pringle, 1951. Effect of environment on growth and feed and water consumption of chickens. IV. The effect of light on early growth. J. Nutr. 45:265-274. Broom, D. M., 1980. Activity rhythms and position preferences of domestic chicks which can see a moving object. Anim. Behav. 28:201-211. Canada Agricultural Products Standards, 1986. Processed Poultry Regulations. Can. Minist. Supply Serv., Ottawa, Ont., Canada. Cherry, P., and M. W. Barwick, 1962. The effect of light on broiler growth. I. Light intensity and colour. Br. Poult. Sci. 3:31-39. Deaton, J. W., F. N. Reece, L. F. Kubena, and J. D. May, 1976. Effect of varying light intensity on broiler performance. Poultry Sci. 55:515-519. Deaton, J. W., F. N. Reece, J. L. McNaughton, and B. D. Lott, 1981. Effect of light intensity and low-level intermittent lighting on broiler performance during a high density, limited-area brooding period. Poultry Sci. 60:2385-2387. Newberry, R. C , J. R. Hunt, and E. E. Gardiner, 1985. Effect of alternating lights and strain on behavior and leg disorders of roaster chickens. Poultry Sci. 64:1863-1868. Newberry, R. C , J. R. Hunt, and E. E. Gardiner, 1986. Light intensity effects on performance, activity, leg disorders, and sudden death syndrome of roaster chickens. Poultry Sci. 65:2232-2238. Proudfoot, F. G., and A. E. Sefton, 1978. Feed texture and light treatment effects on the performance of chicken broilers. Poultry Sci. 57:408-416. Skoglund, W. C , and D, H. Palmer, 1962. Light intensity studies with broilers. Poultry Sci. 41:1839-1842. Weaver, W. D., 1986. Influence of light intensity in commercial facilities on broiler performance. Poultry Sci. 65:142. (Abstr.) Weaver, W. D., and P. B. Siegel, 1968. Photoperiodism as a factor in feeding rhythms of broiler chickens. Poultry Sci. 47:1148-1154.
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Newberry et al., 1986). It may be that light intensity has less effect on current strains of broilers than on strains grown in the past. The proportion of birds with leg disorders (Table 2) was significantly lower under bright than dim lighting at 6 wk, but not at 3 or 9 wk in Experiment 1. The block effect was also significant (P<.05) at 6 wk, but not at 3 or 9 wk. Therefore, it is not clear whether the reduced incidence of leg disorders was related to the higher activity that occurred under bright lighting in this experiment. Light intensity had no significant influence on the incidence of leg disorders in Experiment 2, which is in agreement with previous results (Newberry et al., 1986). In view of the high proportion of male chickens that exhibited walking disabilities (35% or more at 9 wk of age), continued efforts are needed to identify behavioral and environmental factors contributing to the development of leg disorders. Mortality (Table 2) was not significantly affected by light intensity in the first experiment but was lower in bright than dim light at both 3 (data not given) and 6 wk in Experiment 2 (P<.05). The cause of this discrepancy is not apparent. Mortality was higher in dim than bright pens in all weeks of Experiment 2. Block effects were nonsignificant and there was no evidence that increased mortality under the 6-lx treatment resulted from depressed feed and water intake during the brooding period. Deaton et al. (1981) reported higher mortality in chicks brooded under 5 lx than 75 lx, but mortality rates under their 5, 38, and 151-lx treatments did not differ significantly. Although carcass grades (Experiment 1) were not significantly affected by light intensity (42% Grade A in bright light and 33% Grade A in dim light, SEM ± 3.3) chickens kept under bright light showed half as much bruising as those kept under dim light (P<.05; Table 2). It is possible that birds reared under dim light struggled more when exposed to bright lighting conditions during shipping, resulting in more bruising. Alternatively, perhaps they bruised more easily because they were more "tender" as a result of lower activity. Light intensity and block had no significant influence on carcass downgrading due to breast blisters, leg deformities, and other causes (data not shown). Not surprisingly, sex of chicken (Experiment 2) had a significant effect on body weight, feed
1025
1988 Poultry Science 67:1020-1025 INTRODUCTION
Proudfoot and Sefton (1978) suggested that rearing broiler chickens under low environmental light intensities results in good growth with low energy loss by reducing exercise. Deaton et al. (1976) reported that the feedrgain ratio of chickens increased as light intensity increased. They attributed this to higher activity in chickens kept under brighter lighting, resulting in excess energy use and greater wastage of feed in litter. However, they were comparing continuous low intensity light (12.9 lx) with bright light (204.5 lx) supplied on a 12 h light: 12 h dark lighting schedule. Therefore, their results could have been related to the duration of light, and changes from light to dark, rather than to the light intensity per se. Newberry et al. (1985) observed higher chicken activity in brighter (6 to 12 lx) vs. darker (.5 lx) areas within pens, but these birds were also being subjected to changes in light intensity over time. In a subsequent study using constant light intensity treatments ranging from .1 to 100 lx, Newberry et al. (1986) obtained a light intensity x age interaction for activity but expressed concern that the activity measurements may have been influenced by ob-
1
Agassiz Research Station Contribution Number 367.
1020
server presence. They found that light intensity had no effect on body weight, but that the feedigain ratio was higher under brighter light in one of two experiments. Other investigators (Barott and Pringle, 1951; Skoglund and Palmer, 1962) have observed that body weight was unaffected by light intensities ranging from 1 to 65 lx, but was reduced at intensities of 129 lx or higher. Contrary to the hypothesis that brighter lighting reduces performance due to increased activity, Weaver and Siegel (1968) reported that feeding activity was higher under 6.57 to 21.53 lx than .75 to 1.51 lx lighting, but that body weights and feed conversions were unaffected by light intensity. Weaver (1986) found that over the range of 9 to 31 lx, higher light intensity was correlated with increased body weight, improved feed conversion, and better carcass grades. The influence of light intensity on activity and performance remains ambiguous. Statements about the effect of lighting on activity have been based on qualitative data only (e.g., Cherry and Barwick, 1962; Deaton et al, 1976) or activity has been quantified using direct observation techniques, where the presence of the observer could have affected chicken behavior (e.g., Newberry et al., 1986). Weaver and Siegel (1968) observed birds through sliding
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
ABSTRACT The influence of two light intensity treatments, 180 and 6 lx, on behavior and performance of broiler chickens was examined in two experiments. The first experiment tested male chickens reared to 9 wk of age and the second experiment tested both sexes reared separately to 6 wk. Behavioral data were collected by scan sampling of behavior recorded on video tape. Standing, walking, and total activity were higher under the 180 lx than the 6-lx treatment (P<.01), whereas feeding and drinking were not significantly affected by light intensity. Body weight, feed and water consumption, and feed conversion were unaffected by light intensity. Incidence of leg disorders at 6 wk and the percentage of bruised carcasses at 64 days were significantly lower under the higher light intensity treatment in the first experiment, as was mortality to 3 and 6 wk in the second experiment. No significant light intensity x sex interactions were detected. Results did not support the hypothesis that brighter lighting reduces performance due to increased chicken activity. Use of brighter lighting had no adverse effects on performance and there was some evidence that it may have a beneficial effect on welfare by reducing bruising. (Key words: light intensity, behavior, performance, broilers)
LIGHT INTENSITY AND CHICKEN BEHAVIOR
panel openings but even this would not completely eliminate visual and auditory stimuli from the observer. In addition to these problems, effects of light intensity on chicken performance have been inconsistent within and between studies. The objectives of this study were to determine the influence of light intensity on chicken behavior over 24-h periods in the absence of an observer and to examine the effects of light intensity on the performance of male and female chickens. MATERIALS AND METHODS
temperatures (measured in central alley) for the 1st to 4th wk were 31, 29, 26, and 24 C, respectively, in both experiments. The mean room temperature after 4 wk, when brooders were switched off, was 20 C in Experiment 1 and 17 C in Experiment 2. Chicken activity should not be restricted at these temperatures by comparison with activity at higher temperatures (Deaton etal., 1976). Mortality checks were made at approximately 0745 h and 1520 h each day. The mean body weight of the chickens in each pen was determined at 21, 42, and, in Experiment 1, 63 days. Feed and water consumption and feed conversion were determined for each pen on a bird-day basis. The incidence of leg disorders was determined subjectively by counting the number of birds in each pen showing evidence of impaired walking ability (i.e, stiff, jerky, staggering, or unsteady gait, limping, inability to walk) when encouraged to walk. Behavioral data were collected in Experiment 1. Two video cameras were used to monitor the two pens of a block (one bright, one dim) over 1 24-h period each week, from the 2nd to the 9th wk. The behavior of the chickens in each pen was recorded on video tape using time-lapse video recorders. Recordings were made of the four blocks of pens over 4 consecutive days each week by moving the cameras to a different block each day according to a predetermined random schedule for each week. Video tapes were analysed by scan sampling (Altmann, 1974) the behavior in each pen at 30-min intervals throughout each 24-h recording. Chores were arranged so that caretakers were not present in pens at scan times. The percentage of birds feeding (standing at feeder), drinking (standing at drinker), walking, and standing (up on feet but not feeding, drinking, or walking) of those present in each pen was determined. The classification "active" referred to the total percentage of birds feeding, drinking, walking, and standing. All remaining birds were lying down and were considered inactive. Carcass grades were obtained for all birds in Experiment 1. Birds were processed at 64 days and graded by a plant inspector according to Canadian grade standards (Canada Agricultural Products Standards, 1986). Reasons for downgrading were recorded. Statistical Analysis. Behavior, mortality, leg disorder, and carcass grade data were transformed by arc sine prior to analysis. The effects on behavior of age (wk), block, light, time of
Downloaded from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Two experiments were conducted, each testing two light intensity treatments, bright (180 lx) vs. dim (6 lx). Light was provided by a clear incandescent light bulb hanging 1.2 m above the floor in the center of each 1.98 x 2.44-m light-proofed pen. Each bulb was fitted inside a 35-cm diam light shade, which directed the light downward. Bright pens were lit by a 100 W, 120-V bulb and dim pens by a 7.5 W, 115 to 125 V bulb. Light intensity, measured at floor level 20 cm out from the center of the pen in the absence of feeders and drinkers, was 180 lx in bright pens and 6 lx in dim pens. Light was provided 24 h/day at a constant level throughout each experiment. Peterson x Arbor Acre broiler chicks vaccinated against Marek's disease were obtained from a commercial hatchery. In Experiment 1, 35 randomly selected male 1-day-old chicks were placed in each of eight pens and reared to 9 wk of age. In Experiment 2, 65 chicks were placed in each of 16 pens (eight pens of each sex) and reared to 6 wk of age. Treatments were arranged among pens in a randomized complete block design with four blocks. Each pen contained one tube feeder (pan diameter 36.8 cm, 0 to 4 wk; 43.2-cm diam, 4 to 9 wk) and one drinker (with five nipples) in the first experiment and two feeders and two drinkers in the second experiment. Feeders and drinkers were raised as the birds grew so that birds had to stand up to feed and drink. Litter consisted of a 5-cm layer of wood shavings. All chickens were fed a 23% protein starter diet (0 to 3 wk) and 20% protein grower diet (3 to 6 wk). Birds in Experiment 1 were fed an 18% finisher diet from 6 to 9 wk. Heat was provided to each pen by a gas brooder with one quarter of the canopy over the pen. The temperature under the brooders was reduced gradually from 35 C at 1 day to 25 C at 4 wk. Mean room
1021
** .10
3.9 3.9 2.4 1.2 .9 .8 .5 .7
180 lx
.08
NS
**
(%)
Walking
Values given for each age X behavior X light intensity c o m b i n a t i o n are means of 192 observations.
.13
3.2
3.4
NS NS
3.7 4.0 3.9 3.5 2.7 2.9 2.6 2.7
6 1x
4.3 3.8 3.5 3.4 2.4 3.2 3.4 3.1
180 lx
Drinking
T o t a l percentage of chickens engaged in feeding, drinking, walking, a n d standing.
**P<.01.
*P<.05.
2
1
SEM
*
NS
6.3
6.6
X
Significance Age Light intensity Light intensity X
10.4 11.4 7.8 5.2 4.4 4.5 4.0 3.0
6 1x
11.2 11.1 7.7 5.3 4.0 5.8 3.9 3.7
180 lx
2 3 4 5 6 7 8 9
(wk)
Age
Feeding
1.6
3.3 3.2 2.1 1.3 .9 .5 .6 .7
6 lx
TABLE 1. Effect of light intensity and age on behavior of male chickens1
from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015 6.4
7.2 11.9 8.0 5.4 4.6 4.7 4.1 5.2
180 lx
Standing
5.6
7.4 8.8 6.8 4.3 4.3 4.2 3.6 5.3
6 1x
18.2
26.6 30.7 21.7 15.3 11.9 14.5 12.0 12.8
180 lx
.33
NS
**
Active 2
16.7
24.7 27.4 20.5 14.3 12.3 12.0 10.7 11.7
61x
H
rn
%
Z
o
LIGHT INTENSITY AND CHICKEN BEHAVIOR
day (at 30-min intervals), and their interactions were examined by analysis of variance using a split-plot design, with age as the main plot and interactions with block as error terms. Changes in behavior with time of day were further examined by regression analysis. Analysis of variance was used to examine the effects on performance parameters at each age of light and block in Experiment 1, and block, light, sex, and light x sex in Experiment 2. RESULTS AND DISCUSSION
periodicities of 1.5 to 4 h and about 30 min in activity levels of isolated chicks maintained under constant light and temperature. Short periodicities in group behavior were not apparent in the present study, probably due to variation in periodicities between individuals and within individuals at different ages (Broom, 1980). Weaver and Siegel (1968) observed that feeding behavior was highest at 0800 h and attributed this to the arrival of the caretaker at 0730 h each day. In the present study, peak morning and afternoon activity levels were also observed approximately 30 min following caretaker visits. Light intensity had few significant effects on performance parameters (Table 2). Body weight, feed consumption (data not shown), water consumption, and feed conversion were unaffected by light intensity or block at 3, 6, or 9 wk in Experiment 1, or at 3 and 6 wk in Experiment 2 (3-wk data not shown). Feed and water consumption results were consistent with the absence of a light intensity effect on feeding and drinking behavior. It would appear that the increased activity of chickens in bright pens did not increase birds' energy requirements sufficiently to affect feed conversion. Contrary to the findings of Deaton et al. (1976), chickens were not observed to waste feed in the litter. The absence of an adverse effect of bright lighting on growth contrasts with earlier findings (Barott and Pringle, 1951; Cherry and Barwick, 1962; Skoglund and Palmer, 1962), although not with more recent results (Deaton et al., 1981;
1ST
T23
TIME OF DAY
FIGURE 1. Effect of time of day on the percentage of chickens standing (dotted line) and active (solid line). Standing and activity declined significantly (P<.05) with increasing time.
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Feeding, drinking, walking, standing, and activity (Table 1) all declined significantly with increasing age, which is in agreement with previous findings for activity (Newberry et al., 1985, 1986) and feeding behavior (Weaver and Siegel, 1968). Behavior was also affected by light intensity. Chickens stood and walked significantly more in bright pens than dim pens and were therefore more active, confirming previous impressions (Cherry and Barwick, 1962; Deaton et al., 1976; Newberry et al., 1985). Feeding and drinking behavior were not influenced by light level. However, drinking behavior differed significantly between blocks (P<.05). Standing behavior was significantly affected by the interaction between light intensity and age, with birds standing more under bright than dim light from 3 to 8 wk but not at 2 and 9 wk. Also, there was a significant light intensity x age interaction for feeding, with birds spending more time feeding in bright than dim light at 2, 5, 7, and 9 wk and less time in the remaining weeks. By comparison with the low light treatment of 6 lx in this experiment, Weaver and Siegel (1968) used a low light treatment of less than 2 lx, which may explain their finding that feeding behavior was consistently lower under low lighting conditions. Time of day influenced standing and total activity (P<.05) (Figure 1) but not feeding, drinking, or walking behavior. Interactions of light intensity, age, and block with time of day were not significant. The proportion of chickens standing and active declined significantly between morning and evening, indicating the presence of a diurnal rhythm of behavior among groups of chickens kept under constant lighting conditions. This diurnal rhythm could have been triggered by diurnal changes in temperature, sounds from people passing by the barn during working hours, and the regular arrival of caretakers for mortality checks. Broom (1980) demonstrated a 24-h periodicity, and also shorter
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1801x 61x
Light
Male Female
Sex
SEM
180 lx 6 1x
Light
SEM
Level
Factor
1.67b 1.76a .01
.07
.09
1.72 a 1.70 a
.01
5.98a 4.96b
07
1.61 1.61a
2.30a 1.92b
.04
02a
a
6 wk
5.56a 5.38a
24
.24
3.46 3.42a
12a
9 wk (L/bird)
a
6 wk (kg/kg) a
02
98a
99
9 wk
Cumulative feed:gain ratio
and sex on performance
2.09a 2.12a
3.62 a 3 68
(kg)
9 wk
2.09 2.12a
a
6 wk
Cumulative water consumption
of light intensity
1.3
17.9a 9.4b
14.6a 12.7a
1.0
4 . 35 12.1a
Lb
6 wk
5
35.0" 42.1a
9 wk
Incidence of leg disorders
parameters
6 wk
9 wk
Cumulative mortality
9 wk
Bruised carcasses
a b ' Within c o l u m n , e x p e r i m e n t , a n d factor, m e a n s bearing different superscripts are significantly different ( P < . 0 5 ) . In E x p e r i m e n t 2, there were no significant light X sex interactions.
Experiment no.
B o d y weight
T A B L E 2. Effect
from http://ps.oxfordjournals.org/ at University of Rhode Island on February 6, 2015
Z
> r
m
TO 50
% rn
LIGHT INTENSITY AND CHICKEN BEHAVIOR
consumption, water consumption, feed:gain ratio, and the incidence of leg disorders (Table 2). Of greater interest was the finding that the two sexes responded similarly to light intensity for all parameters measured. Results confirmed previous indications that chicken activity is increased under higher light intensities. Results did not support the hypothesis that brighter lighting reduces performance due to increased chicken activity. ACKNOWLEDGMENTS
The technical assistance of K. Ingram, T. Yule, and the barn crew is gratefully acknowledged. REFERENCES Altmann, J., 1974. Observational study of behaviour: sampling methods. Behaviour 49:227-267. Barott, H. G., and E. M Pringle, 1951. Effect of environment on growth and feed and water consumption of chickens. IV. The effect of light on early growth. J. Nutr. 45:265-274. Broom, D. M., 1980. Activity rhythms and position preferences of domestic chicks which can see a moving object. Anim. Behav. 28:201-211. Canada Agricultural Products Standards, 1986. Processed Poultry Regulations. Can. Minist. Supply Serv., Ottawa, Ont., Canada. Cherry, P., and M. W. Barwick, 1962. The effect of light on broiler growth. I. Light intensity and colour. Br. Poult. Sci. 3:31-39. Deaton, J. W., F. N. Reece, L. F. Kubena, and J. D. May, 1976. Effect of varying light intensity on broiler performance. Poultry Sci. 55:515-519. Deaton, J. W., F. N. Reece, J. L. McNaughton, and B. D. Lott, 1981. Effect of light intensity and low-level intermittent lighting on broiler performance during a high density, limited-area brooding period. Poultry Sci. 60:2385-2387. Newberry, R. C , J. R. Hunt, and E. E. Gardiner, 1985. Effect of alternating lights and strain on behavior and leg disorders of roaster chickens. Poultry Sci. 64:1863-1868. Newberry, R. C , J. R. Hunt, and E. E. Gardiner, 1986. Light intensity effects on performance, activity, leg disorders, and sudden death syndrome of roaster chickens. Poultry Sci. 65:2232-2238. Proudfoot, F. G., and A. E. Sefton, 1978. Feed texture and light treatment effects on the performance of chicken broilers. Poultry Sci. 57:408-416. Skoglund, W. C , and D, H. Palmer, 1962. Light intensity studies with broilers. Poultry Sci. 41:1839-1842. Weaver, W. D., 1986. Influence of light intensity in commercial facilities on broiler performance. Poultry Sci. 65:142. (Abstr.) Weaver, W. D., and P. B. Siegel, 1968. Photoperiodism as a factor in feeding rhythms of broiler chickens. Poultry Sci. 47:1148-1154.
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Newberry et al., 1986). It may be that light intensity has less effect on current strains of broilers than on strains grown in the past. The proportion of birds with leg disorders (Table 2) was significantly lower under bright than dim lighting at 6 wk, but not at 3 or 9 wk in Experiment 1. The block effect was also significant (P<.05) at 6 wk, but not at 3 or 9 wk. Therefore, it is not clear whether the reduced incidence of leg disorders was related to the higher activity that occurred under bright lighting in this experiment. Light intensity had no significant influence on the incidence of leg disorders in Experiment 2, which is in agreement with previous results (Newberry et al., 1986). In view of the high proportion of male chickens that exhibited walking disabilities (35% or more at 9 wk of age), continued efforts are needed to identify behavioral and environmental factors contributing to the development of leg disorders. Mortality (Table 2) was not significantly affected by light intensity in the first experiment but was lower in bright than dim light at both 3 (data not given) and 6 wk in Experiment 2 (P<.05). The cause of this discrepancy is not apparent. Mortality was higher in dim than bright pens in all weeks of Experiment 2. Block effects were nonsignificant and there was no evidence that increased mortality under the 6-lx treatment resulted from depressed feed and water intake during the brooding period. Deaton et al. (1981) reported higher mortality in chicks brooded under 5 lx than 75 lx, but mortality rates under their 5, 38, and 151-lx treatments did not differ significantly. Although carcass grades (Experiment 1) were not significantly affected by light intensity (42% Grade A in bright light and 33% Grade A in dim light, SEM ± 3.3) chickens kept under bright light showed half as much bruising as those kept under dim light (P<.05; Table 2). It is possible that birds reared under dim light struggled more when exposed to bright lighting conditions during shipping, resulting in more bruising. Alternatively, perhaps they bruised more easily because they were more "tender" as a result of lower activity. Light intensity and block had no significant influence on carcass downgrading due to breast blisters, leg deformities, and other causes (data not shown). Not surprisingly, sex of chicken (Experiment 2) had a significant effect on body weight, feed
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