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Effects of Various Lighting Regimes on Diurnal Rhythms of EEG Components in the Chicken
918
J . GODET AND M . BELHANI
REFERENCES Cheney, B. A., K. Lothe, E. H. Morgan, S. K. Sood and C. A. Finch, 1967. Internal iron exchange in the rat. Am. J. Physiol. 212: 376-380. Clark, P., 1967. Uptake of iron by mature erythrocytes. Aust. J. Exp. Biol. Med. Sci. 45: 97-104. Godet, J., 1973. Synthese postnatale d'hemoglobine F chez le poulet. Comp. Rend. Acad. Sci. 276: 1201-1204. Godet, J., D. Schiirch, J. P. Blanchet and V. Nigon, 1970a. Evolution des caracteristiques erythrocytaires au cours du developpement post-embryonnaire du poulet. Exp. Cell Res. 60: 157-165.
Effects of Various Lighting Regimes on Diurnal Rhythms of EEG Components in the Chicken JIRO Y A N O , SHUNZO OSHIMA AND JIRO GOTOH
Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Nagoya,
Japan
(Received for publication July 17, 1973)
ABSTRACT Effects of different photoperiods on the appearance of EEG slow waves were examined in freely-moving chickens by a radio telemetry system. The experiments were performed under 14L10D, 18L6D, 21L3D and 24L. It was clear that the EEG components were strictly synchronized to light-dark cycles. Continuous illumination exerted a dampening effect on the appearance of the slow wave diurnal rhythms. Chickens exposed to light-dark cycles of 14L10D and 18L6D maintained a constant daily level of slow wave activity. These levels are regarded as a normal amount of slow wave activity in male chickens. The daily amount of slow wave activity under 21L3D and 24L is probably regulated in a way different from that under 14L10D and 18L6D. The illumination seems to exert a strong effect on the mechanism controlling the appearance of the EEG in chickens when compared to mammals. POULTRY SCIENCE 53: 918-923, 1974
T
HERE are a number of publications concerning the electroencephalograph (EEG) during sleep and wakefulness in birds (Ookawa and Gotoh, 1964; Ookawa and Kadono, 1968; Ookawa, 1972). The existence of 3 stages of sleep-wakefulness, i.e. wakefulness, slow sleep (SS)and paradoxical sleep (PS), has been established in chickens and Japanese quail as well as mammals. The PS appears periodically between the SS but its proportion to total sleep time does not exceed a few percent in chickens (Gotoh, 1968). This may suggest that the EEG of the chicken can be tentatively classified into two major patterns, fast wave and slow wave.
It is well known that sleep-wakefulness shows diurnal rhythms synchronized to daynight cycles. Investigations of diurnal rhythm of EEG components have been undertaken with cats under continuous illumination (Sterman et al, 1965; Chase and Sterman, 1967) and with rats (Colvin et al, 1968) and rabbits (Spie et al, 1970) under light-dark cycles. These reports showed diurnal fluctuations of EEG components. In birds, most investigations on the biological rhythm have been carried out from such viewpoints as migration, homing instinct and photoperiodism. Cain and Wilson(1971,1972) reported that the locomotor activities of the
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
Godet, J., D. Schiirch and V. Nigon, 1970b. Caracterisation et evolution des hemoglobines dans le cours du developpement postembryonnaire chez la poule. J. Embry. Exp. Morph. 23: 153-167. Konitzer, K., and K. Michalke, 1965. Der eisenstoffweschel der weissen Mous Ausscheichung und organ verterlung einen Fe59 tracer dosis. Acta Biol. Med. Germ. 14: 489-495. Ramsay, W. N. M., 1966. The incorporation of iron into hemoglobin in the domestic fowl. Quat. J. Exp. Physiol. 51: 221-228. Rusov, C , 1965. Recherches sur la ferrocinetique des volailles normales par Fe59. Med. Landbow. Opzechugs Genet. 30: 787-795.
DIURNAL RHYTHMS OF EEG
MATERIALS AND METHODS
bregma. The plastic holder of the FM transmitter (Narco Bio-systems Co., Texas) was fixed between the two electrodes with dental resin. Experiments were performed under four different lighting schedules: 14 hours illumination and 10 hours darkness (14L10D, Exp. 1), 18 hours illumination and 6 hours darkness (18L6D, Exp. 2), 21 hours illumination and 3 hours darkness (21L3D, Exp. 3) and continuous illumination (24L, Exp. 4). Illumination for each schedule was 06.00-20.00, 04.0022.00and 03.00-24.00, respectively. The light intensity was 50 lux at the floor level and 150 lux at the top of the cage. EEG signals from the transmitter were received by an FM receiver and fed into a multipurpose polygraphic recorder (Nihon Koden Co., Tokyo). The EEG was recorded for one minute at four minutes intervals continuously for several days in each chicken and were then analysed on the basis of its frequency. The EEG components with a frequency of less than 8 Hz. were counted as slow waves whereas those which appeared for a duration of less than one second were omitted. The slow wave components were summed up every hour and the time of slow wave appearance per hour (SW time) was calculated.
Experiments were carried out with 14 male White Leghorns at the age of 11 to 19 weeks. The birds were kept in cages in a sound-attenuated room throughout the experiments and room temperature was maintained conRESULTS stant at 22 ± 2° C. Food and water were available ad libitum. 1. Patterns of Diurnal Changes in SW Time. Birds were habituated to experimental Based on EEG data recorded for long terms lighting conditions for several days. Im- using the telemetry system, it was definite plantation of the electrodes was made with that the EEG components were strictly syna stereotaxic apparatus while under anesthe- chronized to light-dark cycles in chickens siaf rom the intravenous injection of pentobar- (Fig. 1). The SW time increased immediately bital sodium (30 mg. per kg. body weight). after the lights were turned off, and then Insect pins which were used for chronic decreased gradually during the dark period. electrodes were secured to the frontal bone During the light period it decreased to lower with dental resin. The recording electrode level. was placed 5 mm. lateral to the midline and In Exp. 2 and 3, it was observed that the 6 mm. anterior to the bregma, and the refer- SW time increased an hour before dark ence electrode was 10 mm. posterior to the period. In Exp. 1, however, SW time tended
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
laying hen increased during illumination and decreased during the dark period under 18 hours light and 6 hours darkness, but was distributed in a fairly even way over a 24 hour period when under continuous illumination. Miseris and Walcott (1970) demonstrated that in homing pigeons the activity rhythms were entrained with light-dark cycles but disappeared under constant light of a high intensity. These findings suggest that illumination is one of the most important factors influencing activity rhythms of birds. Oshima et al. (1974) reported that in broilers the EEG fast wave shows a rhythmicity when exposed to a fixed light-dark cycle. However, it has not been clarified how the diurnal patterns and the daily amount of certain EEG components of chickens will change under different illumination times. Therefore, the present study was undertaken to examine the effects of various photoperiods on the EEG slow wave components of chickens. This seems to be a necessary step for investigating the mechanism of sleep-wakefulness cycles of birds.
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J. YANO, S. OSHIMA AND J. GOTOH
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
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FIG. 1. Diurnal pattern of slow wave appearance under 14L10D (top), 18L6D (middle) and 21L3D (bottom) was based on the time of slow wave appearance per hour (SW time). Dots show the individual values of SW time calculated from each EEG recording for one hour. Horizontal bars show the period of darkness.
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DIURNAL RHYTHMS OF EEG
TABLE 1.—SW times obtained from EEG recordings for 24 hours, dark period and light period SW time (min./hour) Dark period Light period 24 hours 2.7 ± 0.40 26.1 ± 1.21 12.5 ± 0.69 4 (10)* (1-2, P < 0.01) (1-2, N.S.) (1-2, N.S.)** 5.0 ± 0.64 28.3 ± 1.54 10.8 ± 0.83 3 (7) 18L6D (2-3, P < 0.01) (2-3, N.S.) (2-3, P < 0.01) 2.0 ± 0.15 27.6 ± 0.94 5.2 ± 0.21 4 (8) 21L3D (1-3, N.S.) (1-3, N.S.) (1-3, P < 0.01) 5.5 ± 0.43 3 24L *Total number of recordings of 24 hour period. **Statistical significance in the difference between the groups indicated. P value was computed from t-test. Experiment
No. of birds
Light schedules 14L10D
2. Change of Daily Amount of SW Time. Average SW times were obtained from 24 hour EEG recordings in each experiment (SW time/24 hours). The mean and standard error of SW time/24 hours in each group was shown in Table 1. Statistical analysis were made by calculating the standard error of the difference between the means of SW times and the resulting t values. In Exp. 4, the average of SW time was calculated throughout total recording time in each chicken. The SW time of Exp. 3 (5.2 min./hour) was significantly different from that of Exp. 1 (12.5 min./hour) and 2 (10.8 min./hour), but there was no difference between Exp. 1 and 2. This indicates that SW time/24 hours does not change in proportion to the length of the dark period. It is noted that SW time/24 hours shows a very small value in Exp. 3 and is similar to the average SW time in Exp. 4 (5.5 min./hour). To compare the changes of the SW time
among the three experiments, 24 values of the SW time were separated into two groups, namely SW time during light and dark periods (SW t i m e / L and SW time/D). As shown in Table 1, there are no differences among SW time/D of Exp. 1, 2 and 3 suggesting that the slow waves per hour are constant regardless of the length of dark periods. SW time/L of Exp. 2 was significantly different from those of Exp. 1 and 3. DISCUSSION It is not easy to record a long term EEG of chicken with leading cords because of the cutting of the lead wire or removal of electrodes by the chickens. EEG's with wire have been performed in sleeping chickens or young chicks. Radio telemetry system is useful for measuring physiological parameters of freely-moving animals. Diurnal changes of chicken EEG components show some difference from those of rats and rabbits. First, diurnal changes of the slow wave activity are more definitely synchronized with the light-dark cycles in chickens than in mammals. In rabbits the slow wave components appear constantly throughout the day, but more of the slow wave components are observed at night than during the day-light hours (Spie et al., 1970). Rats, which are nocturnal animals, show the reversed rhythmicity in EEG components
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
to decrease markedly two hours before the onset of darkness except for three observations. Data from individual chickens were essentially consistent in patterns of diurnal fluctuation in the EEG components and the behavior of SW time immediately before darkness. Continuous illumination exerted a dampening effect on the slow wave diurnal rhythms (Exp. 4).
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J. YANO, S. OSHIMA AND J. GOTOH
It is assumed that the daily amounts of slow wave activity which the chickens maintain under 14L10D and 18L6D show the normal value in male chickens. However, the daily amount of slow wave activity decreases strikingly in chickens under continuous illumination when compared to chickens under 14L10D or 18L6D. It seems apparent that in chickens the effects of light-dark cycles differ from those of continuous illumination with respect to the appearance of slow waves throughout the day. In the dark period, chickens exposed to 21L3D show the same amount of slow wave activity per hour as under other light regimes. The daily amount of slow wave activity, however, decreases
to a level similar to that under 24L, because of the absence of the compensatory increases during light period. These facts suggest that the chicken exposed to continuous illumination is regulated in a manner different from that when exposed to 14L10D and 18L6D. In this respect, 21L3D has an effect similar to continuous illumination. This regulation may not be influenced by the lights being turned off or on, but by the length of illumination and or darkness. REFERENCES Cain, J. R., and W. O. Wilson, 1971. Multichannel telemetry system for measuring body temperature: Circadian rhythm of body temperature, locomotor activity and oviposition in chickens. Poultry Sci. 50: 1437-1443. Cain, J. R., and W. O. Wilson, 1972. A test of the circadian rule of Ascoff with chicken hens. J. Interdiscip. Cycles Res. 3: 77-85. Chase, M. I., and M. B. Sterman, 1967. Maturation of patterns of sleep and wakefulness in the kitten. Brain Res. 5: 319-329. Colvin, G. B., D. I. Whitmoyer, R. D. Risk, D. O. Walter and C. H. Sawyer, 1968. Changes in sleepwakefulness in female rats during circadian and estrous cycles. Brain Res. 7: 173-181. Gotoh, G., 1968. Sleep and ovulations in the chicken. Nokino to Seishoku (Brain Functions and Reproductions), Vol. 2 (in Japanese). Ed. M. Kawakami, Kyoi Publishing Co., Tokyo, pp. 86-97. Miselis, R., and C. Walcott, 1970. Locomotor activity rhythms in homing pigeons (Columba livid). Anim. Behav. 18: 544-551. Ookawa, T., 1972. Avian wakefulness and sleep on the basis of recent electroencephalographic observations. Poultry Sci. 51: 1565-1574. Ookawa, T., and J. Gotoh, 1964. Electroencephalographic study of chickens: Periodic recurrence of low voltage and fast waves during behavioral sleep. Poultry Sci. 43: 1603-1604. Ookawa, T., and H. Kadono, 1968. Electroencephalogram of the Japanese quail (Cotumix conturnix Japonica) during non-anesthetized and anesthetized periods. Poultry Sci. 47: 320-325. Oshima, S., K. Shimada and T. Tonoue, 1974. Radio telemetric observations of the diurnal changes in respiratory rate, heart rate and intestinal motility of domestic fowl. Poultry Sci. 53: 503-508. Spie, H. G., D. I. Whitmoyer and C. H. Sawyer, 1970. Patterns of spontaneous and induced para-
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under the light-dark cycles. The slow wave components increase during illumination and decrease at darkness (Colvin et al, 1968). This rhythmicity, however, does not show as clear a pattern as in chickens. Because of the marked decrease in slow waves during the light period, the total SW time is lower in the chicken when compared to the mammals. This indicates that the appearance of the avian EEG is affected more by illumination. It was reported that EEG components show circadian rhythms in cat when under continuous illumination (Sterman etal., 1965; Chase and Sterman, 1967). This suggests that a time-measuring mechanism is involved in the appearance of the various EEG components in cats. The present study failed to ascertain a clear circadian rhythm of chicken EEG components when under continuous illumination. Changes in slow wave production immediately before the light turned off suggest the existence of some mechanism responsible for measuring time. Circadian activity rhythm tends to appear in homing pigeons when lowering the light intensity (Miselis and Walcott, 1970). It is possible that circadian rhythms would be detectable in chicken EEG components under continuous illumination with dim light.
DIURNAL RHYTHMS OF EEG doxical sleep in intact and hypophysectomized rabbits. Brain Res. 18: 155-164. Sterman, M. B., T. Knauss, D. Lehmann and C. D.
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Clemente, 1965. Circadian sleep and waking patterns in the laboratory cat. Electroenceph. Clin. Neurophysiol. 19: 509-517.
Mating Caged Egg-Type Breeder Females to Floor-Housed Males1 L . R. CHAMPION
(Received for publication July 18, 1973)
ABSTRACT A study was made to determine the fertility and hatchability of eggs from individually caged Single Comb White Leghorn breeder females rotated periodically and systematically to the floor to mate with a litter-floor-housed male (single male mating), with the primary thought that the use of cages for the females would reduce the high incidence of floor eggs observed in our floor, pedigree breeding pens. Fertility and hatchability data show that caged females placed on the litter floor with the male for approximately 2-1/2 hours (1:30 p.m. to 4:00 p.m.) once every six days can produce eggs that demonstrate fertility and hatchability levels which may generally be acceptable to a pedigree breeding operation. For all purposes, the incidence of floor eggs was negligible. Obviating human error in recording the hen number on the egg, accuracy of pedigree for eggs would appear to be assured. Foot disorders and leg weaknesses among the caged breeders" were not observed. The possibility that this procedure can be applied successfully to a wild bird pedigree breeding operation where artificial insemination is difficult is suggested. POULTOY SCIENCE 53: 923-926, 1974
INTRODUCTION ISTORICALLY, pedigree poultry breeding operations have principally involved single male, floor breeding pens. Under this system of management, the general procedure has been to remove the selectedj potential breeder pullets from their growing2 quarters just prior to sexual maturity and to3 place them in the breeding pen. Upon reaching sexual maturity, many of the pullets mustt be "taught" to lay in the nests provided, and despite a conscientious training effortt on the part of the caretaker, a commonJJ experience has been that certain pullets willU insist on laying their eggs on the floor. Thus, 1) the pedigree of the eggs laid by thesee insistent floor layers is lost, 2) the accuracy of measuring age at first egg becomes ques-
H
1. Journal Article No. 6467, Michigan AgriculturalJ Experiment Station.
tionable, 3) the true total egg record of the floor layer would not be available, and 4) the egg weight measurement of the particular bird is lost, among other important related parameters. Under a caged system of management, wherein a single male is placed in a multi-female cage, only one-half of the pedigree would be available. And, depending upon cage dimensions and population density, it may be difficult for the male to mate with the females. To our knowledge, there are no reports in the literature on the incidence of floor eggs in egg-type breeder birds. Recently, Hurnik et al. (1973) in a study which involved the effect of colored nests on the incidence of floor eggs fromRhode Island Reds (R.I.R.) and White Plymouth rocks (W.P.R.) found that the frequency of nest eggs favored the colored nests. Interestingly, their data showed that the percentage of floor eggs laid
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
Department of Poultry Science, Michigan State University, East Lansing, Michigan 48823
J . GODET AND M . BELHANI
REFERENCES Cheney, B. A., K. Lothe, E. H. Morgan, S. K. Sood and C. A. Finch, 1967. Internal iron exchange in the rat. Am. J. Physiol. 212: 376-380. Clark, P., 1967. Uptake of iron by mature erythrocytes. Aust. J. Exp. Biol. Med. Sci. 45: 97-104. Godet, J., 1973. Synthese postnatale d'hemoglobine F chez le poulet. Comp. Rend. Acad. Sci. 276: 1201-1204. Godet, J., D. Schiirch, J. P. Blanchet and V. Nigon, 1970a. Evolution des caracteristiques erythrocytaires au cours du developpement post-embryonnaire du poulet. Exp. Cell Res. 60: 157-165.
Effects of Various Lighting Regimes on Diurnal Rhythms of EEG Components in the Chicken JIRO Y A N O , SHUNZO OSHIMA AND JIRO GOTOH
Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Nagoya,
Japan
(Received for publication July 17, 1973)
ABSTRACT Effects of different photoperiods on the appearance of EEG slow waves were examined in freely-moving chickens by a radio telemetry system. The experiments were performed under 14L10D, 18L6D, 21L3D and 24L. It was clear that the EEG components were strictly synchronized to light-dark cycles. Continuous illumination exerted a dampening effect on the appearance of the slow wave diurnal rhythms. Chickens exposed to light-dark cycles of 14L10D and 18L6D maintained a constant daily level of slow wave activity. These levels are regarded as a normal amount of slow wave activity in male chickens. The daily amount of slow wave activity under 21L3D and 24L is probably regulated in a way different from that under 14L10D and 18L6D. The illumination seems to exert a strong effect on the mechanism controlling the appearance of the EEG in chickens when compared to mammals. POULTRY SCIENCE 53: 918-923, 1974
T
HERE are a number of publications concerning the electroencephalograph (EEG) during sleep and wakefulness in birds (Ookawa and Gotoh, 1964; Ookawa and Kadono, 1968; Ookawa, 1972). The existence of 3 stages of sleep-wakefulness, i.e. wakefulness, slow sleep (SS)and paradoxical sleep (PS), has been established in chickens and Japanese quail as well as mammals. The PS appears periodically between the SS but its proportion to total sleep time does not exceed a few percent in chickens (Gotoh, 1968). This may suggest that the EEG of the chicken can be tentatively classified into two major patterns, fast wave and slow wave.
It is well known that sleep-wakefulness shows diurnal rhythms synchronized to daynight cycles. Investigations of diurnal rhythm of EEG components have been undertaken with cats under continuous illumination (Sterman et al, 1965; Chase and Sterman, 1967) and with rats (Colvin et al, 1968) and rabbits (Spie et al, 1970) under light-dark cycles. These reports showed diurnal fluctuations of EEG components. In birds, most investigations on the biological rhythm have been carried out from such viewpoints as migration, homing instinct and photoperiodism. Cain and Wilson(1971,1972) reported that the locomotor activities of the
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
Godet, J., D. Schiirch and V. Nigon, 1970b. Caracterisation et evolution des hemoglobines dans le cours du developpement postembryonnaire chez la poule. J. Embry. Exp. Morph. 23: 153-167. Konitzer, K., and K. Michalke, 1965. Der eisenstoffweschel der weissen Mous Ausscheichung und organ verterlung einen Fe59 tracer dosis. Acta Biol. Med. Germ. 14: 489-495. Ramsay, W. N. M., 1966. The incorporation of iron into hemoglobin in the domestic fowl. Quat. J. Exp. Physiol. 51: 221-228. Rusov, C , 1965. Recherches sur la ferrocinetique des volailles normales par Fe59. Med. Landbow. Opzechugs Genet. 30: 787-795.
DIURNAL RHYTHMS OF EEG
MATERIALS AND METHODS
bregma. The plastic holder of the FM transmitter (Narco Bio-systems Co., Texas) was fixed between the two electrodes with dental resin. Experiments were performed under four different lighting schedules: 14 hours illumination and 10 hours darkness (14L10D, Exp. 1), 18 hours illumination and 6 hours darkness (18L6D, Exp. 2), 21 hours illumination and 3 hours darkness (21L3D, Exp. 3) and continuous illumination (24L, Exp. 4). Illumination for each schedule was 06.00-20.00, 04.0022.00and 03.00-24.00, respectively. The light intensity was 50 lux at the floor level and 150 lux at the top of the cage. EEG signals from the transmitter were received by an FM receiver and fed into a multipurpose polygraphic recorder (Nihon Koden Co., Tokyo). The EEG was recorded for one minute at four minutes intervals continuously for several days in each chicken and were then analysed on the basis of its frequency. The EEG components with a frequency of less than 8 Hz. were counted as slow waves whereas those which appeared for a duration of less than one second were omitted. The slow wave components were summed up every hour and the time of slow wave appearance per hour (SW time) was calculated.
Experiments were carried out with 14 male White Leghorns at the age of 11 to 19 weeks. The birds were kept in cages in a sound-attenuated room throughout the experiments and room temperature was maintained conRESULTS stant at 22 ± 2° C. Food and water were available ad libitum. 1. Patterns of Diurnal Changes in SW Time. Birds were habituated to experimental Based on EEG data recorded for long terms lighting conditions for several days. Im- using the telemetry system, it was definite plantation of the electrodes was made with that the EEG components were strictly syna stereotaxic apparatus while under anesthe- chronized to light-dark cycles in chickens siaf rom the intravenous injection of pentobar- (Fig. 1). The SW time increased immediately bital sodium (30 mg. per kg. body weight). after the lights were turned off, and then Insect pins which were used for chronic decreased gradually during the dark period. electrodes were secured to the frontal bone During the light period it decreased to lower with dental resin. The recording electrode level. was placed 5 mm. lateral to the midline and In Exp. 2 and 3, it was observed that the 6 mm. anterior to the bregma, and the refer- SW time increased an hour before dark ence electrode was 10 mm. posterior to the period. In Exp. 1, however, SW time tended
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
laying hen increased during illumination and decreased during the dark period under 18 hours light and 6 hours darkness, but was distributed in a fairly even way over a 24 hour period when under continuous illumination. Miseris and Walcott (1970) demonstrated that in homing pigeons the activity rhythms were entrained with light-dark cycles but disappeared under constant light of a high intensity. These findings suggest that illumination is one of the most important factors influencing activity rhythms of birds. Oshima et al. (1974) reported that in broilers the EEG fast wave shows a rhythmicity when exposed to a fixed light-dark cycle. However, it has not been clarified how the diurnal patterns and the daily amount of certain EEG components of chickens will change under different illumination times. Therefore, the present study was undertaken to examine the effects of various photoperiods on the EEG slow wave components of chickens. This seems to be a necessary step for investigating the mechanism of sleep-wakefulness cycles of birds.
919
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J. YANO, S. OSHIMA AND J. GOTOH
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
T
I
M
E
FIG. 1. Diurnal pattern of slow wave appearance under 14L10D (top), 18L6D (middle) and 21L3D (bottom) was based on the time of slow wave appearance per hour (SW time). Dots show the individual values of SW time calculated from each EEG recording for one hour. Horizontal bars show the period of darkness.
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DIURNAL RHYTHMS OF EEG
TABLE 1.—SW times obtained from EEG recordings for 24 hours, dark period and light period SW time (min./hour) Dark period Light period 24 hours 2.7 ± 0.40 26.1 ± 1.21 12.5 ± 0.69 4 (10)* (1-2, P < 0.01) (1-2, N.S.) (1-2, N.S.)** 5.0 ± 0.64 28.3 ± 1.54 10.8 ± 0.83 3 (7) 18L6D (2-3, P < 0.01) (2-3, N.S.) (2-3, P < 0.01) 2.0 ± 0.15 27.6 ± 0.94 5.2 ± 0.21 4 (8) 21L3D (1-3, N.S.) (1-3, N.S.) (1-3, P < 0.01) 5.5 ± 0.43 3 24L *Total number of recordings of 24 hour period. **Statistical significance in the difference between the groups indicated. P value was computed from t-test. Experiment
No. of birds
Light schedules 14L10D
2. Change of Daily Amount of SW Time. Average SW times were obtained from 24 hour EEG recordings in each experiment (SW time/24 hours). The mean and standard error of SW time/24 hours in each group was shown in Table 1. Statistical analysis were made by calculating the standard error of the difference between the means of SW times and the resulting t values. In Exp. 4, the average of SW time was calculated throughout total recording time in each chicken. The SW time of Exp. 3 (5.2 min./hour) was significantly different from that of Exp. 1 (12.5 min./hour) and 2 (10.8 min./hour), but there was no difference between Exp. 1 and 2. This indicates that SW time/24 hours does not change in proportion to the length of the dark period. It is noted that SW time/24 hours shows a very small value in Exp. 3 and is similar to the average SW time in Exp. 4 (5.5 min./hour). To compare the changes of the SW time
among the three experiments, 24 values of the SW time were separated into two groups, namely SW time during light and dark periods (SW t i m e / L and SW time/D). As shown in Table 1, there are no differences among SW time/D of Exp. 1, 2 and 3 suggesting that the slow waves per hour are constant regardless of the length of dark periods. SW time/L of Exp. 2 was significantly different from those of Exp. 1 and 3. DISCUSSION It is not easy to record a long term EEG of chicken with leading cords because of the cutting of the lead wire or removal of electrodes by the chickens. EEG's with wire have been performed in sleeping chickens or young chicks. Radio telemetry system is useful for measuring physiological parameters of freely-moving animals. Diurnal changes of chicken EEG components show some difference from those of rats and rabbits. First, diurnal changes of the slow wave activity are more definitely synchronized with the light-dark cycles in chickens than in mammals. In rabbits the slow wave components appear constantly throughout the day, but more of the slow wave components are observed at night than during the day-light hours (Spie et al., 1970). Rats, which are nocturnal animals, show the reversed rhythmicity in EEG components
Downloaded from http://ps.oxfordjournals.org/ at University of Cambridge on June 18, 2015
to decrease markedly two hours before the onset of darkness except for three observations. Data from individual chickens were essentially consistent in patterns of diurnal fluctuation in the EEG components and the behavior of SW time immediately before darkness. Continuous illumination exerted a dampening effect on the slow wave diurnal rhythms (Exp. 4).
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J. YANO, S. OSHIMA AND J. GOTOH
It is assumed that the daily amounts of slow wave activity which the chickens maintain under 14L10D and 18L6D show the normal value in male chickens. However, the daily amount of slow wave activity decreases strikingly in chickens under continuous illumination when compared to chickens under 14L10D or 18L6D. It seems apparent that in chickens the effects of light-dark cycles differ from those of continuous illumination with respect to the appearance of slow waves throughout the day. In the dark period, chickens exposed to 21L3D show the same amount of slow wave activity per hour as under other light regimes. The daily amount of slow wave activity, however, decreases
to a level similar to that under 24L, because of the absence of the compensatory increases during light period. These facts suggest that the chicken exposed to continuous illumination is regulated in a manner different from that when exposed to 14L10D and 18L6D. In this respect, 21L3D has an effect similar to continuous illumination. This regulation may not be influenced by the lights being turned off or on, but by the length of illumination and or darkness. REFERENCES Cain, J. R., and W. O. Wilson, 1971. Multichannel telemetry system for measuring body temperature: Circadian rhythm of body temperature, locomotor activity and oviposition in chickens. Poultry Sci. 50: 1437-1443. Cain, J. R., and W. O. Wilson, 1972. A test of the circadian rule of Ascoff with chicken hens. J. Interdiscip. Cycles Res. 3: 77-85. Chase, M. I., and M. B. Sterman, 1967. Maturation of patterns of sleep and wakefulness in the kitten. Brain Res. 5: 319-329. Colvin, G. B., D. I. Whitmoyer, R. D. Risk, D. O. Walter and C. H. Sawyer, 1968. Changes in sleepwakefulness in female rats during circadian and estrous cycles. Brain Res. 7: 173-181. Gotoh, G., 1968. Sleep and ovulations in the chicken. Nokino to Seishoku (Brain Functions and Reproductions), Vol. 2 (in Japanese). Ed. M. Kawakami, Kyoi Publishing Co., Tokyo, pp. 86-97. Miselis, R., and C. Walcott, 1970. Locomotor activity rhythms in homing pigeons (Columba livid). Anim. Behav. 18: 544-551. Ookawa, T., 1972. Avian wakefulness and sleep on the basis of recent electroencephalographic observations. Poultry Sci. 51: 1565-1574. Ookawa, T., and J. Gotoh, 1964. Electroencephalographic study of chickens: Periodic recurrence of low voltage and fast waves during behavioral sleep. Poultry Sci. 43: 1603-1604. Ookawa, T., and H. Kadono, 1968. Electroencephalogram of the Japanese quail (Cotumix conturnix Japonica) during non-anesthetized and anesthetized periods. Poultry Sci. 47: 320-325. Oshima, S., K. Shimada and T. Tonoue, 1974. Radio telemetric observations of the diurnal changes in respiratory rate, heart rate and intestinal motility of domestic fowl. Poultry Sci. 53: 503-508. Spie, H. G., D. I. Whitmoyer and C. H. Sawyer, 1970. Patterns of spontaneous and induced para-
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under the light-dark cycles. The slow wave components increase during illumination and decrease at darkness (Colvin et al, 1968). This rhythmicity, however, does not show as clear a pattern as in chickens. Because of the marked decrease in slow waves during the light period, the total SW time is lower in the chicken when compared to the mammals. This indicates that the appearance of the avian EEG is affected more by illumination. It was reported that EEG components show circadian rhythms in cat when under continuous illumination (Sterman etal., 1965; Chase and Sterman, 1967). This suggests that a time-measuring mechanism is involved in the appearance of the various EEG components in cats. The present study failed to ascertain a clear circadian rhythm of chicken EEG components when under continuous illumination. Changes in slow wave production immediately before the light turned off suggest the existence of some mechanism responsible for measuring time. Circadian activity rhythm tends to appear in homing pigeons when lowering the light intensity (Miselis and Walcott, 1970). It is possible that circadian rhythms would be detectable in chicken EEG components under continuous illumination with dim light.
DIURNAL RHYTHMS OF EEG doxical sleep in intact and hypophysectomized rabbits. Brain Res. 18: 155-164. Sterman, M. B., T. Knauss, D. Lehmann and C. D.
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Clemente, 1965. Circadian sleep and waking patterns in the laboratory cat. Electroenceph. Clin. Neurophysiol. 19: 509-517.
Mating Caged Egg-Type Breeder Females to Floor-Housed Males1 L . R. CHAMPION
(Received for publication July 18, 1973)
ABSTRACT A study was made to determine the fertility and hatchability of eggs from individually caged Single Comb White Leghorn breeder females rotated periodically and systematically to the floor to mate with a litter-floor-housed male (single male mating), with the primary thought that the use of cages for the females would reduce the high incidence of floor eggs observed in our floor, pedigree breeding pens. Fertility and hatchability data show that caged females placed on the litter floor with the male for approximately 2-1/2 hours (1:30 p.m. to 4:00 p.m.) once every six days can produce eggs that demonstrate fertility and hatchability levels which may generally be acceptable to a pedigree breeding operation. For all purposes, the incidence of floor eggs was negligible. Obviating human error in recording the hen number on the egg, accuracy of pedigree for eggs would appear to be assured. Foot disorders and leg weaknesses among the caged breeders" were not observed. The possibility that this procedure can be applied successfully to a wild bird pedigree breeding operation where artificial insemination is difficult is suggested. POULTOY SCIENCE 53: 923-926, 1974
INTRODUCTION ISTORICALLY, pedigree poultry breeding operations have principally involved single male, floor breeding pens. Under this system of management, the general procedure has been to remove the selectedj potential breeder pullets from their growing2 quarters just prior to sexual maturity and to3 place them in the breeding pen. Upon reaching sexual maturity, many of the pullets mustt be "taught" to lay in the nests provided, and despite a conscientious training effortt on the part of the caretaker, a commonJJ experience has been that certain pullets willU insist on laying their eggs on the floor. Thus, 1) the pedigree of the eggs laid by thesee insistent floor layers is lost, 2) the accuracy of measuring age at first egg becomes ques-
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1. Journal Article No. 6467, Michigan AgriculturalJ Experiment Station.
tionable, 3) the true total egg record of the floor layer would not be available, and 4) the egg weight measurement of the particular bird is lost, among other important related parameters. Under a caged system of management, wherein a single male is placed in a multi-female cage, only one-half of the pedigree would be available. And, depending upon cage dimensions and population density, it may be difficult for the male to mate with the females. To our knowledge, there are no reports in the literature on the incidence of floor eggs in egg-type breeder birds. Recently, Hurnik et al. (1973) in a study which involved the effect of colored nests on the incidence of floor eggs fromRhode Island Reds (R.I.R.) and White Plymouth rocks (W.P.R.) found that the frequency of nest eggs favored the colored nests. Interestingly, their data showed that the percentage of floor eggs laid
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Department of Poultry Science, Michigan State University, East Lansing, Michigan 48823