The Effect of Full-Spectrum Fluorescent Lighting on Reproductive Traits of Caged Turkey Hens 1 ' 2

The Effect of Full-Spectrum Fluorescent Lighting on Reproductive Traits of Caged Turkey Hens 1 ' 2 T. D. SIOPES Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication September 6, 1983) ABSTRACT Large White turkey breeder hens were exposed to either incandescent or fullspectrum (FS) fluorescent lighting during two 20-week reproductive cycles in closed confinement. Data were recorded for body weights, feed intake, and reproductive traits. Body weights and feed intake were similar between treatments in both egg laying cycles. In addition, there were no significant differences in egg production, fertility, hatchability, or poult weight between the incandescent and light treatment in either the first or second year egg laying cycle. It was concluded that exposure of breeder turkey hens to light in closed confinement results in reproductive performance similar to that obtained with incandescent lighting. (Key words.- reproductive performance, turkeys, fluorescent light) INTRODUCTION The control of turkey production throughout the year with artificial lighting is widely practiced. Many different types of artificial lighting are available, including incandescent, fluorescent, and high intensity discharge (HID) lamps. Each of these light sources varies considerably in their efficiency and quality (color or wavelength) and quantity of their light output. Fluorescent and HID lamps are more efficient producers of light than incandescent light and therefore are more economical to operate. However, insufficient information is available as to the effects of these light sources on breeder turkey performance. Photostimulation of reproductive functions by the longer wavelengths of the visible portion of the electromagnetic spectrum has been amply demonstrated in birds (Woodard et al., 1968; Oishi and Lauber, 1973; Foss et al., 1972; Bissonette, 1932; Benoit and Ott, 1944). The photostimulation of egg production in turkeys occurs effectively with white or red but not blue light (Scott and Payne, 1937; Jones et al., 1982). 'Paper No. 8942 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC. 2 The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the product named nor criticism of similar ones not mentioned. 1984 Poultry Science 63:1122-1128 Within the visible light spectrum, incandescent light sources typically contain most of their energy in the longer wavelengths. The energy output of fluorescent lamps is highly variable with spectral outputs ranging from an even distribution over the visible spectrum to highly localized spectra, depending on the type of lamp utilized. Thus, reproductive responses of turkeys would be expected to vary according to the quality of the light output of any light source. and ultraviolet lamps in combination caused turkey hens to produce more eggs than obtained using incandescent lamps alone (Carson and Junnila, 1953). Payne and McDaniel (1958) found that white fluorescent light was ineffective in maintaining normal egg production in Bronze turkeys, but Cavalchini (1976) reported that the egg production of caged turkey hens was very similar in hens exposed to incandescent light or fluorescent light with a color output similar to incandescent bulbs. Siopes (1984) has reported that the reproductive performance of turkey hens exposed to incandescent light or coolwhite fluorescent light in closed confinement was similar in all aspects except that the hens in the fluorescent light had a reduced number of eggs after 20 weeks of production. Fluorescent light is available commercially that simulates the spectral output of sunlight. This full-spectrum fluorescent light has been reported to be more effective than cool-white fluorescent light in maintaining semen quantity 1122

FULL-SPECTRUM FLUORESCENT LIGHTING 1123 and quality in turkey toms (Snapir et ai, 1976). Similar studies have not been reported for turkey hens. The objective of this study was to evaluate the reproductive performance of turkey breeder hens exposed to full-spectrum (FS), fluorescent lighting in closed confinement. MATERIALS AND METHODS Large White turkey breeder hens that were hatched in September were reared on 16 hr of natural and artificial light per day (16L:8D) in floor pens within an open-sided house. These hens were then taken through two 20-week egg production cycles in closed confinement while being exposed to either incandescent light or lighting, which simulated the color output of natural sunlight. During each of these cycles 80 hens were maintained in the same room under the same conditions in individual wire cages, which were 46 cm x 61 cm X 56 cm, width X height X length. The use of laying cages permitted consistent and precise exposure to the light treatments throughout the study. The 40 hens in each light treatment were arranged in 4 blocks of 10 hens each. The test room was light-controlled and insulated, and although the room temperature was not controlled, the room was mechanically ventilated. The two light treatments _wgre separated within the room by a light-tight partition. ' Feed and fresh water were provided ad libitum throughout the entire study. The feed was a North Carolina State University breeder ration calculated to contain 16% protein, 3.05% calcium, and 2970 kcal ME/kg of feed. In each of the two breeding cycles the following observations were recorded: body weight, feed intake, time to first egg, rate of egg production, percent fertility, percent hatchability, and poult weight. All data were analyzed from means of replications by analyses of variance using the GLM procedure of the SAS 76 system (Barr et al, 1976). All percentage data were analyzed following arc sin transformation. First Year Cycle. The hens were moved into the cages at 25 weeks of age and exposed to 8 hr of incandescent light per day (8L:16D). At 33 weeks of age the hens were photostimulated with 16 hr of light per day (16L:8D) with half of the hens receiving incandescent light and half receiving light. The physical characteristics of the light environments were obtained with an ISCO model SR spectroradiometer (Instrumentation Specialties Co., Lincoln, NE) and are given in Table 1. The total illuminance was 76 lx in both light treatments of this study. The lamps had a peak energy output at 550 nm, and approximately 27% of the total energy in the visible spectrum occurred between 600 and 700 nm. The incandescent lamps used in this study had a peak output at 950 nm, and approximately 43% of the total energy in the visible spectra occurred between 600 and 700 nm. Body weights and feed intake were measured at 4-week intervals over the test period, but feed intake was obtained only during the last 2 weeks of each 4-week period. In addition to the time to first egg following photostimulation, the mean number of eggs per hen was determined for the first and second 10-week periods of the test. Hens were inseminated weekly for 3 consecutive weeks starting at 32 weeks of age and then biweekly for the remainder of the egg production period. Pooled semen from toms maintained in an adjacent, curtain-sided building on 15L:9D was diluted 1:1 with a commercial extender and.025 ml of semen was inseminated per hen. Percent fertility was determined by breaking eggs and visual examination for embryos in all eggs judged infertile by candling. Percent hatchability is the hatch of all fertile eggs. Both fertility and hatchability were determined at four 7-day egg collections ending after 6, 10, 14, and 16 weeks of egg production. Poults obtained from eggs collected during the 11th week of production were weighed in groups of 10 immediately upon removal from the incubator. Second Year Cycle. The second reproductive cycle was started at the same time of year as the first cycle (April). Twenty-four hens were selected from each of the light treatments of the first cycle and moved to floor pens and exposed to 8 hr of incandescent light per day (8L:16D) for 8 weeks prior to photostimulation. Thirty-two additional hens were also added to this prelaying treatment. These hens were sisters of the other hens and differed only in that they were maintained in floor pens, exposed to incandescent light, during. Following the 8-week prelaying treatment, the hens were equally distributed, according to previous history, into two groups of 40 hens each and placed back into the individual cages used during and photostimulated with

1124 SIOPES TABLE 1. Radiometric and photometric characteristics of incandescent and full-spectrum (FS) fluorescent light sources Light source Peak 950 550 Wavelength / ^ Range 400-1100 400-750 (400-1100 nm) 205.4 24.1 Irradi: ance - (MW/cr 16L:8D of either incandescent or light in the same manner and at the same intensity of light as in. All other conditions and data collection were repeated as in. RESULTS There were no statistically significant differences (P>.05) in body weight or feed intake between the two light treatments in either the first or second-year reproductive cycle (Tables 2 and 3). The mean body weights over the 20-week test period in Cycles 1 and 2 were nd 10.7 kg, respectively, for the incandescent light treatment and nd 10.5 kg, respectively, for the hens in light. The mean feed intake (g feed/kg body weight/day) associated with these body weights was 21.34 and 21.19 for the incandescent treatment in Cycles 1 and 2, respectively, and 20.48 and 21.44 for Cycles 1 and 2, respectively, in the hens receiving light. Treatment (400-750 nm) n ' 1 42.9 24.1 600-700 nm (MW/cm 2 ) (lx) 18.4 6.4 20.8 8.3 Total illuminance (lx) 76 76 The time to first egg following photostimulation was similar in both light treatments in Cycles 1 and 2 (Table 4). In addition, there were no significant differences (P>.05) in the number of eggs produced per hen at any of the measurement periods in either light treatment during or (Table 4). The mean number of eggs produced per hen over the 20-week test period of was 60.1 in the incandescent treatment and 55.5 in the FS fluorescent. In, 53.2 and 54.5 eggs per hen were produced in the incandescent and FS fluorescent light treatments, respectively. The fertility and hatchability of eggs produced during this study were not influenced differently by the light treatments after 6, 10, 14, or 16 weeks of egg production (Table 5). Mean fertility and hatchability of the four measurement periods of were 77.2 and 52.1%, respectively, for the incandescent light treatment as compared to 77.6 and 50.7%, respectively, for the treatment, whereas the percent fertility and hatchability TABLE 2. Effect of full-spectrum (FS) fluorescent lighting on the mean body weight of hens during two egg production cycles 4 10.1 a 10. l a.13 10.7a.14 8.12 10.8 a 10.4 a.11 12 Weeks of production 9.7 a 9.6 a.13 10.7 a.13 W)' 16 9.6* 9.1*.14 10.7 a 10.8 a.19 20 9.8 a.17 10.6 a.16 Mean.10 10.7 a.12 Within each column and cycle, means with similar letters are not significantly different (P>.05).

FULL-SPECTRUM FLUORESCENT LIGHTING 1125 Treatment Incendescent TABLE 3. Effect of full-spectrum (FS) fluorescent lighting on the mean feed intake of hens over two egg production cycles 4 22.15 a 21.33 3.65 23.00 a 23.55a.75 8 17.30 a 17.25a.52 22.00 a 21.63 3.46 12 Weeks of production (g feed/kg body 21.50 a 20.23a.36 20.40 a 21.98 a.60 16. 21.95a 21.85 a.69 19.38 a 21.28 a.51 20 23.78 a 21.73 a.68 21.18 a 18.75a 1.10 Within each column and cycle, means with similar letters are not significantly different (P>.05). for the incandescent and light treatment in were 82.0 and 59.8, respectively, and 84.4 and 66.9, respectively. Poult weights from eggs produced during the eleventh week of egg production were not different between the two light treatments in or (Table 6). The mean poult weight was 61.6 and 61.9 g for the incandescent light and light, respectively, in. In the poult weights were 68.1 in the incandescent light treatment and 68.0 in the light treatment. DISCUSSION It seems clear from the results of this study that when breeder turkey hens are maintained in closed-confinement and exposed to artificial light only, there is no beneficial effect on Mean 21.34a 20.48 a.50 21.19 a 21.44a.43 reproductive performance by providing light that simulates the color output of sunlight from light provided by incandescent light. Not all fluorescent light treatments are as effective as incandescent light in stimulating the reproductive performance of breeder turkeys. White fluorescent light (Payne and McDaniel, 1958) and cool-white fluorescent light (Siopes, 1984) resulted in late season decreases in egg production of turkey hens as compared to incandescent light treatments. However, other reproductive traits, including egg quality, fertility, and hatchability, were not adversely affected by cool-white fluorescent light. However, fluorescent light that simulated the color output of incandescent light resulted in a very similar rate of egg production to that obtained with incandescent light (Cavalchini, 1976). Fluorescent lights are available commercially TABLE 4. Effect of full-spectrum (FS) fluorescent lighting on the mean time to first egg following photostimulation and the mean number of eggs per hen during a first and second year egg production cycle Treatment Days to first egg 0-10 wk Number of eggs per hen 11-20 wk 0-20 wk 19.5 a 19.2 a.25 23.7a 25.7 a.42 39.4a 38.3 a 37.4a 33.9a 1.5 20.7 a 16.9 a 1.5 15.7a 20.6 a 1.8 60.1 a 55.5a 2.0 53.2 a 54.5a 2.6 Within each column and cycle, means with similar letters are not significantly different (P>.05).

1126 SIOPES TABLE 5. Effect of full-spectrum (FS) fluorescent lighting on fertility and hatchability during two 20-week egg production cycles Weeks of egg production Treatment 6 10 14 16 Mean Fertility 91.0 a 88.1 a 75.9 a 53.7 a 77.2 a 94.3 a 83.7 a 60.8 a 66.1 a 77.6 a 3.6 6.2 8.5 9.8 2.51 88.0 a 79.1 a 85.7 75.2 a 82.0 a 89.5 a 82.4 a 87.4 78.4 a 84.4 a 1.8 6.1 6.2 9.4 2.65 Hatchability 73.5 a 59.3 a 60.6 a 14.9 a 52.1 a 67.5 a 69.2 a 48.9 a 20.8 a 50.7 a 5.8 7.7 9.3 13.3 4.75 55.6 a 70.2 a 71.0 a 42.6 a 59.8 a 62.2 a 64.5 a 79.2 a 61.7 a 66.9 a 3.8 7.7 8.9 10.1 3.08 Within each column and cycle, means with similar letters are not significantly different (P>,05). that simulate the color output of sunlight, but there have been no previous reports of the response of turkey hens to these lights. In the present study, no significant differences occurred between the incandescent and light treatments for any of the performance parameters measured during the first and second year reproductive cycles. This included body weight, feed intake, time to first egg, rate of egg production, fertility, hatchability, and poult weights. It seems likely that the variations in reproductive performance in response to various fluorescent lights mentioned are wavelength (color) dependent. The longer wavelengths of the visible spectrum (red) can result in normal stimulation of the reproductive performance of turkeys, whereas the shorter wavelengths (blue) are ineffective (Scott and Payne, 1937; Jones et al., 1982). In a study of the effects of the color of light on the reproductive development of cockerels, Foss et al. (1972) reported that only near-red light (580 to 695 nm range) stimulated reproductive development equivalent to that obtained with white light. Blue (450 nm peak), green (545 nm peak), and far-red (685 to 1000 + range) were not stimulatory. Therefore, any light source that emits sufficient light in the longer wavelengths of the visible spectrum should be most effective in stimulating reproductive activity. As the photoreceptors mediating the photosexual responses are primarily located in the diencephalon (Benoit, 1964; Homma et al., 1977), and as Hartwig and van Veen (1979) have demonstrated in two species of birds that TABLE 6. Effect of full-spectrum (FS) fluorescent lighting on the mean poult weights from eggs produced during the 11th week of egg production Number Poult Treatment poults weight (g) 80 61.6 a 70 61.9 a 90 68. l a 80 68.0 a Within each cycle, means with similar letters are not significantly different (P>.05).

FULL-SPECTRUM FLUORESCENT LIGHTING 1127 only wavelengths of light greater than 600 nm penetrate to the diencephalon, it seems pertinent to quantify light energy in the 600 to 700 nm range to evaluate the effects of different light intensities and light sources with different color outputs. For the light treatments of the present study this information is given in Table 1. A large portion of the light energy from incandescent lamps occurs in the longer wavelengths of the visible spectrum and a strong photostimulatory effect on reproductive activity occurs. In the 600 to 700 nm range this amounts to about 43% of the total light energy in the visible spectrum (Table 1). Fluorescent light sources such as cool-white fluorescent lamps have a major portion of their light energy away from the red portion of the color spectrum, but about 22% of the light energy of the visible spectrum occurs within the 600 to 700 nm range (Siopes, 1984). According to manufacturers specifications, the energy output of full-spectrum fluorescent lighting is increased in most wavelengths of the visible spectrum so that the color output simulates sunlight. Of particular importance is the increased amount of light in the longer wavelengths of the visible spectrum, which is typically deficient in many commercial fluorescent lamps. In our study the energy content of the light in the 600 to 700 nm range was approximately 27% of the total energy emitted in the visible spectrum. Even though this is considerably less than the 43% energy distribution over the same wavelengths in incandescent light, it is apparently sufficient to result in a reproductive performance similar to that obtained with incandescent light. In addition, it seems likely that adverse responses in reproductive performance as a result of exposure to light sources deficient in the output of light at the far end of the visible spectrum, such as observed with cool-white fluorescent light (Siopes, 1984), are overcome by light as a result of additional light output (22 vs. 27% in cool-white fluorescent and light, respectively) in the longer wavelengths (red) of the visible spectrum. However, beneficial effects from light output at other wavelengths, alone or in combination, from FS fluorescent light cannot be ruled out. In the present study the total illuminance was 76 lx in both treatments, but in the 600 to 700 nm range the illuminance was 20.8 lx in the incandescent light and 8.3 lx in the FS fluorescent light. The irradiance in the visual spectrum (400 to 750 nm), the wavelength range of 600 to 700 nm, and the total irradiance were quite different between the two light treatments (Table 1). Because both light treatments resulted in very similar reproductive responses by the hens it is clear that this did not require equalized levels of light energy. This is in agreement with several studies reported for turkeys that show that once a photostimulatory level of light intensity is achieved, there is little benefit to reproductive performance of additional light intensity (Asmundson et ah, 1946; Thomason et al, 1972; McCartney, 1971; Siopes, 1984). Oishi and Lauber (1973) and Siopes and Wilson (1980) reported that light intensity was not the key variable in the gonadal response of quail to light. They suggested that wavelength per se is the most important aspect of light for control of the photosexual response. Under the conditions of the present study, the light treatment contained a wavelength distribution sufficient to result in a reproductive performance very similar to that observed with incandescent light. Presumably, this was due primarily, if not entirely, to sufficient light output from the longer wavelengths (600 to 700 nm) of the visible spectrum. ACKNOWLEDGMENTS The author wishes to acknowledge the technical assistance of Mike Mann and the statistical assistance of Pam Jenkins. REFERENCES Asmundson, V. S., F. W. Lorenz, and B. D. Moses, 1946. Influence of light intensity on ovulation in turkeys. Poultry Sci. 25:346-354. Barr, A. J., J. H. Goodnight, J. P. Sail, and J. T. Helwig, 1976. A User's Guide to SAS 76. SAS Inst., Inc., Raleigh, NC. Benoit, J., 1964. The role of the eye and of the hypothalamus in the photostimulation of gonads in the duck. Ann. New York Acad. Sci. 117: 205-216. Benoit, J., and L. Ott, 1944. External and internal factors in sexual activity. Effect of irradiation and different wavelengths on the mechanism of photostimulation of the hypophysis and on testicular growth in the immature duck. Yale J. Biol. Med. 17:27-46. Bissonette, T. H., 1932. Studies on the sexual cycle in birds. VI. Effects of white, green and red lights of equal luminous intensity on the testis activity of the European starling (Sturnus vulgaris). Physiol. Zool. 5:92-123.

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