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Effect of the combination of white and red LED lighting during incubation on layer, broiler, and Pekin duck hatchability
Effect of the combination of white and red LED lighting during incubation on layer, broiler, and Pekin duck hatchability G. S. Archer,∗,1 D. Jeffrey,† and Z. Tucker† ∗
Department of Poultry Science, Texas A&M University; College Station, TX, 77845, USA; and † Maple Leaf Farms, Inc., Leesburg, Indiana 46538, USA and hatchling quality were measured. In Experiment 1, LED had fewer early dead embryos (P = 0.03), less overall embryo mortality (P = 0.05), fewer chicks with unhealed navels (P < 0.001), fewer chicks with defects (P < 0.001), and a higher percentage of fertile eggs that hatched (P = 0.05) than DARK. In Experiment 2, LED had fewer chicks with unhealed navels (P = 0.003), fewer chicks with defects (P = 0.001), and a higher percentage of fertile eggs that hatched (P = 0.04) than DARK. In Experiment 3, LED had fewer early dead embryos (P = 0.05), lower overall embryo mortality (P = 0.04), and a higher percentage of fertile eggs that hatched (P = 0.05), and had ducklings with lower bodyweights at hatch (P = 0.04) than DARK. These results indicate that providing both white and red light during incubation can improve chick quality across poultry varieties. This type of fixture could be used to improve commercial hatchery efficiency and chick quality.
ABSTRACT Previous research has shown that providing light during incubation can have positive effects on hatchability and chick quality; however, white light alone has been observed to improve these factors only in pigmented broiler eggs and non-pigmented white layer eggs. Monochromatic red light has been shown to improve hatchability in layer eggs. Therefore the objective of this study was to utilize one light fixture that emitted both white and monochromatic red light to determine if this one light source could improve hatchability in both types of chicken eggs and pigmented Pekin duck egg. To determine this, 3 experiments were conducted, the first using White Leghorn eggs (N = 6912), the second using commercial broiler eggs (N = 4608), and the third using commercial Pekin duck eggs (N = 3564) in which eggs were incubated with 12 h of light and 12 h of darkness (LED) or complete darkness (DARK); the light level was 250 lux. Hatchability, embryo mortality,
Key words: layer, broiler, duck, light, incubation 2017 Poultry Science 0:1–6 http://dx.doi.org/10.3382/ps/pex040
INTRODUCTION
Mohsen, 2002). A likely reason that this environmental factor is not used in commercial incubators it that previous lighting sources caused detrimental effects, as well as the secondary heating caused by incandescent light bulbs (Gold and Kalb, 1976) decreases hatchability. However, with the advent of LED technology this is no longer an issue. Light is an obviously important environmental stimulus during incubation as the avian embryo has evolved to respond to light stimulation. Avian embryos respond to light as early as 3 d of development (Erwin et al., 1971). Furthermore, light during incubation causes the development of central nervous system asymmetries (Rogers, 1982), alters opsin expression in photoreceptors (Rozenboim et al, 2013), enhances proliferation and differentiation of myoblast and myofiber synchronization (Halevy et al., 2006), and alters hormonal rhythms (Csernus et al, 2007). Light stimulation during incubation has been observed to increase growth (Rozenboim et al., 2004; Zhang et al., 2016), improve feed conversion (Zhang et al, 2011), reduce fear responses (Archer and Mench, 2014b; 2017), reduce stress susceptibility (Archer et al, 2009; Archer and Mench, 2013,
Environmental factors during incubation can affect the hatchability and quality of the chicks that hatch. It has been documented that temperature (Narin¸c et al., 2016), humidity (Bruzual et al., 2000), turning (Eliboil and Brake, 2006), carbon dioxide levels (Gildersleeve and Boeschen, 1983), and even sound (Stadelman, 1958) can all affect hatchability. Recent research has demonstrated that light exposure during incubation also can affect hatchability (Huth and Archer, 2015; Archer, 2015a,b, 2016b). This is not a new concept as others have observed increases in growth and hatchability (Walter and Voitle, 1972; Garwood et al., 1973; Shafey and Al-Mohsen, 2002; Shafey, 2004) and acceleration in hatch time (Garwood et al., 1973; Bohren and Siegel, 1975; Ghatpande et al., 1995; Fairchild and Christensen, 2000; Shafey and Al C 2017 Poultry Science Association Inc. Received November 9, 2016. Accepted January 18, 2017. 1 Corresponding author: [email protected]
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2014a,b; Archer, 2016), and alter behavior post hatch (Sui and Rose, 1997, Rogers et al., 2007; Riedstra and ¨ Groothuis, 2004). Ozkan et al. (2012) even concluded that light exposure during incubation resulted in chicks that were more prepared for novel situations post hatch. Birds are very sensitive to different wavelengths of light and different wavelengths of light affect their physiology. Hluch´ y et al. (2012) observed that different wavelengths of light could affect hatchability differentially. Furthermore, differences in hatch time have been attributed to the eggshell filtering of certain light wavelengths (Ghatpande et al., 1995). Adding to the ability of the eggshell to filter the light, it also absorbs about 99.8% that is emitted on it (Shafey et al., 2002, 2005). Huth and Archer (2015) observed that broiler eggs saw an increase in hatchability when exposed to white LED light while white layer eggs showed no improvement. Archer (2016) observed that both “warm” and “cool” LED light increased hatch and were filtered similarly into more of the red frequency range. Hluch´ y et al. (2012) found that red light produced a higher hatchability than blue, with white light having the highest overall hatchability in broilers. Archer (2016) observed that red light improved hatchability in white layer eggs but not broiler eggs; however, Archer (2017) observed that red light improved hatchability similarly to white light in broiler eggs. The intensity of light also may alter the effectiveness of different wavelengths though no research has been conducted on this to date. Most of the research in this area has been conducted in chickens with only a few studies looking at other species such as turkeys (Fairchild and Christensen, 2000; Rozenboim et al., 2003) and quail (Walter and Voitle, 1973). No research has been done to this point on duck eggs. As no research has been conducted investigating how combining white and red light during incubation will affect hatchability and chick quality, we conducted 3 experiments to investigate this. The objective of this study was to determine how the combination of red and white light affected white layer, broiler, and Pekin duck eggs in respect to hatchability, embryo mortality, and hatchling quality. It is hypothesized that all eggs incubated under these lighted conditions will result in greater hatchability and hatchling quality across all poultry types.
MATERIALS AND METHODS Experiment 1 Layer Eggs: Animals and Husbandry There were 3 trials conducted in Experiment 1 using White Leghorn eggs (W-36, N = 6912) from hens that were minimally 50 wk of age. Eight GQF 1500 incubators and eight GQF 1550 hatchers (GQF Manufacturing, Savannah, GA) were used in each trial, and their front windows were blacked out with cardboard to prevent light intrusion into the machines. Eggs were set within 7 d of being laid. Four incubators were oper-
Figure 1. Comparison of spectrum readings through the shells of broiler, White Leghorn, and Pekin duck eggs to the unfiltered spectrum of the LEDs used in the incubators of Experiments 1, 2, and 3.
ated with the traditional dark method of incubation (0L:24D, DARK), while the other 4 were outfitted R with (Agrishift JLL short 8 watt LED, Once Inc, Plymouth, MN; LED) on each level, with 2 lights spaced evenly above the eggs. Lighting treatments were rotated among incubators between each trial to limit the effect of incubators on results. The lights were operated R LED master dimmer (Once Inc, Plyby a Agrishift mouth, MN), with a 12L:12D light schedule and the lights were dimmed to 40% to obtain an average of 250 lux at egg level as measured using a light meter (Extech 401027, Extech Instruments, Nashua, NH). Eggs and lights were scanned periodically throughout incubation with a thermal imaging camera (FLIR-T62101, Boston, MA) to ensure that eggshell temp was not affected by the LED lights (data not presented). Lights were very low profile so as not to disturb the airflow within the incubator. Spectrum of lights used is presented in Figure 1. Two egg trays were set on each rack with each tray holding 48 eggs, for a total of 6 trays over 3 levels equaling 288 eggs per incubator. The incubators were maintained at standard temperature and humidity levels of 99.5◦ F and 55%, respectively. Incubators were monitored twice daily to ensure proper functioning. The eggs were incubated for 18 d, at which time they were moved into the hatchers. Hatchers were not outfitted with lights, as previous research has shown this is not necessary (Archer, 2015a). All of the chicks were weighed and counted at hatch. The quality of the live chicks was assessed, and they were categorized and counted as either no defect, having an unhealed navel, having leg abnormalities, weak, dirty, having traits a hatchery would cull, or having any other abnormality. The remaining unhatched eggs were broken out and counted as pipped, broken, infertile, early dead, mid dead, and late dead.
Experiment 2 Broiler Eggs: Animals and Husbandry There were 2 trials conducted in Experiment 2 using broiler eggs (N = 4608) that were minimally 50 wk of
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Lighted incubation across poultry types Table 1. Data from Experiment 1 hatch. Embryo mortality (%), chick quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Mid dead
Late dead
Pipped
Dead chick
Total dead dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of Fertile
LED DARK SEM
3.60A 6.69B 0.72
0.03 0.03 0.02
7.49 12.66 1.97
5.91 13.23 2.14
0.00 0.00 0.00
17.02A 32.61B 4.02
21.13A 39.47B 2.70
0.25 0.83 0.22
0.66 2.46 0.70
0.88 3.35 0.99
77.05A 53.88B 3.53
42.19 42.85 0.02
82.98A 67.39B 4.02
A–B
Different letters within column indicate significant differences (P < 0.05).
Table 2. Data from Experiment 2 hatch. Embryo mortality (%), chick quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Mid dead
Late dead
Pipped
Dead chick
Total dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of fertile
LED DARK SEM
4.77A 8.19B 0.89
0.27 0.53 0.19
5.84 5.50 0.53
2.19 3.36 0.69
0.25 0.00 0.07
13.06 17.83 1.26
21.01A 38.79B 3.32
0.53 0.96 0.21
0.37 1.00 0.47
0.26 0.30 0.15
77.82A 58.88B 3.36
40.27 41.47 0.11
86.94A 81.98B 1.23
A–B
Different letters within column indicate significant differences (P < 0.05).
age. Unless otherwise noted, all trials followed the same procedures as in Experiment 1.
Experiment 3 Pekin Duck Eggs: Animals and Husbandry There were 2 trials conducted in Experiment 3 using Pekin duck eggs (N = 3564) that were minimally 50 wk of age. Unless otherwise noted, all trials followed the same procedures as in Experiment 1. Nine GQF 1500 incubators and nine GQF 1550 hatchers (GQF Manufacturing, Savannah, GA) were used in each trial, and their front windows were blacked out with cardboard to prevent light intrusion into the machines. Five incubators were operated with the traditional dark method of incubation (0L:24D, DARK), while the other 4 were R outfitted with (Agrishift JLL short 8 watt LED, Once Inc, Plymouth, MN; LED) on each level, with 2 lights spaced evenly above the eggs. Two egg trays were set on each rack with each tray holding 33 eggs, for a total of 6 trays over 3 levels equaling 198 eggs per incubator. The incubators were maintained at standard temperature and humidity levels of 99.5◦ F and 60%, respectively. The eggs were incubated for 25 d, at which time they were moved into the hatchers. All of the ducklings were weighed and counted at hatch. The quality of the live ducklings was assessed, and they were categorized and counted as either no defect, having an unhealed navel, having leg abnormalities, weak, dirty, having traits a hatchery would cull, or having any other abnormality. The remaining unhatched eggs were broken out and counted as pipped, broken, infertile, early dead, and late dead. All experiments were approved by the Texas A&M University IACUC committee (AUP# IACUC 20150254).
Statistical Methods One-way ANOVA was used to investigate treatment effects on hatchability, embryo mortality, and chick
quality. The least significant difference test was used to test all planned comparisons. All of the assumptions of ANOVA were tested (Shapiro-Wilk test for normality and Levene’s test for homogeneity of variance). No transformations were needed to meet assumptions. All analyses were performed using SAS 9.3 for Windows (SAS Institute Inc. Cary, NC, USA). Significant differences were determined at P < 0.05.
RESULTS In Experiment 1 (Table 1), there were no differences between LED and DARK treatments (P > 0.05) in the number of mid dead, late dead, pipped, dead chicks in trays, chicks with leg problems, dirty chicks, cull chicks, or chick weight at hatch. The LED treatment had fewer early dead embryos (P = 0.03), less overall embryo mortality (P = 0.05), fewer chicks with unhealed navels (P < 0.001), more no defect chicks (P < 0.001), and a higher percentage of fertile eggs that hatched (P = 0.05) than the DARK treatment. In Experiment 2 (Table 2), there were no differences between LED and DARK treatments (P > 0.05) in the number of mid dead, late dead, pipped, dead chicks in trays, chicks with leg problems, dirty chicks, cull chicks, or chick weight at hatch. The LED treatment had fewer early dead embryos (P = 0.05), fewer chicks with unhealed navels (P = 0.003), more no defect chicks (P = 0.001), and a higher percentage of fertile eggs that hatched (P = 0.04) than the DARK treatment. In Experiment 3 (Table 3), there were no differences between treatments (P > 0.05) in the number of late dead, pipped, dead ducklings in tray, or duckling quality. The LED treatment had fewer early dead embryos (P = 0.05), lower overall embryo mortality (P = 0.04), and a higher percentage of fertile eggs that hatched (P = 0.05), and had ducklings with lower bodyweights at hatch (P = 0.04) than the DARK treatment.
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ARCHER ET AL. Table 3. Data from Experiment 3 hatch. Embryo mortality (%), duckling quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Late dead
Pipped
Dead ducklings
Total dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of fertile
LED DARK SEM
8.35A 12.67B 1.10
8.63 10.57 1.16
2.80 5.47 0.74
0.20 0.00 0.05
19.98A 28.71B 2.17
9.38 14.43 2.26
0.56 1.79 0.44
0.19 0.34 0.09
0.43 1.99 0.60
89.28 81.15 2.52
52.86A 59.03B 1.49
79.54A 71.18B 2.11
A–B
Different letters within column indicate significant differences (P < 0.05).
DISCUSSION In these 3 experiments we sought to evaluate the embryo mortality, hatchability, and chick/duckling quality of White Leghorn eggs, broiler eggs, and Pekin duck eggs that were exposed to a combination of white and red LED light during incubation. Our hypothesis that the combined spectrum of light would improve hatchability and chick quality across poultry varieties was mostly proven true. We in fact observed an improvement in hatchability of fertile eggs as a result of the experimental light exposure in White Leghorn eggs, broiler eggs, and Pekin duck eggs. Chick quality was statistically improved in both chicken types; however, it was only numerically increased in the duck eggs. The percentage of embryos that died during the early period of incubation was decreased in the all varieties of eggs by the light exposure during incubation. This improvement in early dead mortality is not consistent with previous research (Huth and Archer, 2015; Archer, 2015a,b, 2016, 2017). The improvement in early dead mortality may be a result of this new combination of white and red light used in this current study, as previous studies used only white light alone or monochromatic light wavelengths alone. This again illustrates the complexity of the interaction of light and avian physiology. The lack of improvement in all other embryo mortality is consistent with previous research, as the improved hatchability seems to be a cumulative effect more than a specific improvement in embryo viability at different time points. The increased hatchability utilizing this combined white and red light LED appears to support the idea that red light is important for the development of avian embryos. As observed by Huth and Archer (2015) white light alone improves hatchability only when the eggs are pigmented like broiler eggs and not when they are nonpigmented like White Leghorn eggs. Others have observed no improvement in hatchability (Shafey, 2004) or even reduced hatchability (Bowling et al., 1981) when White Leghorn eggs are exposed to white light during incubation; furthermore, others also have observed improvement in hatchability in broiler eggs when they are exposed to white light during incubation (Walter and Voitle, 1972; Garwood et al., 1973; Shafey and AlMohsen, 2002). Red light has been documented to improve hatchability as well (Hluch´ y et al., 2012; Archer, 2015b, 2017), even in White Leghorn eggs (Archer, 2015b, 2017). Huth and Archer (2015b) concluded that
because the brown eggshells were filtering the white light to a reddish hue, the White Leghorn eggs saw no improvement. Non-pigmented eggs let the full spectrum of visible light through the shell. As demonstrated by this study and previous ones (Hluch´ y et al., 2012; Archer, 2015b, 2017), red light appears to be the key wavelength for improving hatchability, as all eggs had improved hatchability with the addition of red to the white light. Previously, only pigmented eggs showed improvement in hatch without the addition of white light (Huth and Archer, 2015). The mechanism for this improvement is still unknown and merits future research to ascertain what it is. Whatever the mechanism may be, simply by combining white and red light into one fixture an improvement in hatchability was observed across all eggs in this study. Chick quality at hatch also was improved by the light exposure during incubation in both chicken varieties, but duckling quality was not statistically improved by the light treatment. An increased chick quality as a result of white light exposure during incubation has been previously observed (Huth and Archer, 2015; Archer 2016). Red light exposure also has been shown to improve chick quality (Archer, 2015b, 2017). Specifically, the improvement in percentage of chicks with fully healed navels has been attributed with the accelerated growth caused by light exposure resulting in improved maturation of the navel over dark trials (Erwin, et al., 1971). Ducks eggs exposed to light did not have a statistical difference in duckling quality. It should be noted though that duckling quality percentage overall was much higher than chick quality in the other 2 experiments. In light of that fact, elucidating statistical differences might not be possible unless many more replications are utilized, as evidenced by the very slight trend (P = 0.10) observed here. It is also possible that duckling quality is not controlled in the same manner by light as it is in chickens. Overall, the combined white and red light used in this study demonstrated a real potential benefit to the incubation process. It increases chick quality in both layer and broiler chickens, as well as increases overall hatchability in both chickens and ducks. Other research (Archer and Mench, 2013, 2014a,b; Rozenboim et al., 2004; Zhang et al., 2016) has demonstrated further improvements of light exposure post hatch making this environmental factor during incubation a really important management tool that currently is not being utilized. By using both white and red light in
Lighted incubation across poultry types
one fixture, incubators could be designed or retrofitted with one light source for multiple poultry varieties. Additional research on a larger scale would emphasize the benefits, but utilizing light during incubation appears to be a very promising management tool.
ACKNOWLEDGMENTS We would like to thank Once, Inc., for its donation of the lighting fixtures used in this research. We also would like to thank Hy-line North America, Tyson Foods, Inc., and Maple Leaf Farms for their donation of eggs used in this research.
REFERENCES Archer, G. S. 2015a. Timing of light exposure during incubation to improve hatchability, chick quality and post-hatch wellbeing in broiler chickens: 21 or 18 days. Int. J. Poult. Sci. 14:293–299. Archer, G. S. 2015b. Effect of exposing layer and broiler eggs to red or white light during incubation. Int. J. Poult. Sci. 14:491–496. Archer, G. S. 2016. Spectrum of white light during incubation: Warm vs cool white LED lighting. Int. J. Poult. Sci. 15: 343–348. Archer, G. S., H. L. Shivaprasad, and J. A. Mench. 2009. Effect of providing light during incubation on the health, productivity, and behavior of broiler chickens. Poult. Sci. 88:29–37. Archer, G. S., and J. A. Mench. 2013. The effects of light stimulation during incubation on indicators of stress susceptibility in broilers. Poult. Sci. 92:3103–3108. Archer, G. S., and J. A. Mench, 2014a. Timing of light exposure during incubation to improve hatchability, chick quality and posthatch well-being in broiler chickens: 21 or 18 days. International J. Poult. Sci. 14:293–299. Archer, G. S., and J. A. Mench. 2014b. Natural incubation patterns and the effects of exposing eggs to light at various times during incubation on post-hatch fear and stress responses in broiler (meat) chickens. Appl. Anim. Behav. Sci. 152:44–51. Archer, G. S. 2017. Exposing broiler eggs to green red, and white light during incubation. Animal. In press. Archer, G. S., and J. A. Mench. 2017. Exposing avian embryos to light affects post-hatch anti-predator fear responses. Applied Animal Behavior Science. 186:80–84. Bohren, B., and P. Siegel. 1975. Light effects during incubation on lines of White Leghorns selected for fast and slow hatching. Poult. Sci. 54:1372–1374. Bowling, J. A., B. Howarth, and D. L. Fletcher. 1981. The effects of lighted incubation on eggs with pigmented and nonpigmented yolk. Poult. Sci. 60:2328–2332. Bruzual, J. J., S. D. Peak, J. Brake, and E. D. Peebles. 2000. Effects of relative humidity during incubation on hatchability and body weight of broiler chicks from young breeder flocks. Poult. Sci. 79:827–830. Csernus, V. J., A. D. Nagy, and N. Faluhelyi. 2007. Development of the rhythmic melatonin secretion in the embryonic chicken pineal gland. Gen. Comp. Endocrinol. 152:148–153. Elibol, O., and J. Brake. 2006. Effect of egg turning angle and frequency during incubation on hatchability and incidence of unhatched broiler embryos with head in the small end of the egg. Poult. Sci. 85:1433–1437. Erwin, W. T., M. A. Boone, and B. D. Barnett. 1971. Response of the Developing Embryo to Light. Poult. Sci. 50:1883–1884. Fairchild, B., and V. Christensen. 2000. Photostimulation of turkey eggs accelerates hatching times without affecting hatchability, liver or heart growth, or glycogen content. Poult. Sci. 79:1627– 1631. Garwood, V. A., E. J. Thornton, and P. C. Lowe. 1973. The effect of continuous illumination of incubating chicken eggs on embryonic development. Poult. Sci. 52:337–340.
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Ghatpande, A., S. Ghatpande, and M. Z. Khan. 1995. Effect of different intensities of fluorescent light on the early development of chick embryos in ovo. Cell. Mol. Biol. Res. 41:613–621. Gildersleeve, R. P., and D. P. Boeschen. 1983. The effects of incubator carbon dioxide level on turkey hatchability. Poult. Sci. 62:779–784. Gold, P. S., and J. Kalb. 1976. Secondary heating of chicken eggs exposed to light during incubation. Poult. Sci. 55:34–39. Halevy, O., Y. Piestun, I. Rozenboim, and Z. YablonkaReuveni. 2006. In ovo exposure to monochromatic green light promotes skeletal muscle cell proliferation and affects myofiber growth in posthatch chicks. Amer. J. of Physiol. – Regul., Integrat. and Comp. Physiol. 290:R1062– R1070. Hluch´ y, S., R. Toman, M. Cabaj, and M. Adamkoviˇcov´a. 2012. The effect of white and monochromatic lights on chicken hatching. Scientific Papers Anim. Sci. and Biotechnol. 45.2: 408–410. Huth, J. C., and G. S. Archer. 2015. Effects of LED lighting during incubation on layer and broiler hatchability, chick quality, stress susceptibility and post-hatch growth. Poult. Sci. 94:3052–3058. Narin¸c, D., S. Erdo˘ gan, E. Tahtabi¸cen, and T. Aksoy. 2016. Effects of thermal manipulations during embryogenesis of broiler chickens on developmental stability, hatchability and chick quality. Animal. 8:1328–1335. ¨ Ozkan, S., S. Yalcin, E. Babacanoglu, H. Kozanoglu, F. Karadas, and S. Uysal. 2012. Photoperiodic lighting (16 hours of light:8 hours of dark) programs during incubation: 1. Effects on growth and circadian physiological traits of embryos and early stress response of broiler chickens. Poult. Sci. 91:2912–2921. Riedstra, B., and T. Groothuis. 2004. Prenatal light exposure affects early feather-pecking behaviour in the domestic chick. Anim. Behav. 67:1037–1042. Rogers, L. J. 1982. Light experience and asymmetry of brainfunction in chickens. Nature 297:223–225. Rogers, L. J., R. J. Andrew, and A. N. Johnston. 2007. Light experience and the development of behavioural lateralization in chicks III. Learning to distinguish pebbles from grains. Behav. Brain. Res. 177:61–69. Rozenboim, I., R. Huisinga, O. Halevy, and M. E. El Halawani. 2003. Effect of embryonic photostimulation on the posthatch growth of turkey poults. Poult. Sci. 82:1181–1187. Rozenboim, I., I. Biran, Y. Chaiseha, S. Yahav, A. Rosenstrauch, D. Sklan, and O. Halevy. 2004. The effect of a green and blue monochromatic light combination on broiler growth and development. Poult. Sci. 83:842–845. Rozenboim, I., M. E. El Halawani, Y. Kashash, Y. Piestun, and O. Halevy. 2013. The effect of monochromatic photostimulation on growth and development of broiler birds. Gen. Comp. Endocrinol. 190:214–219. Shafey, T. 2004. Effect of lighted incubation on embryonic growth and hatchability performance of two strains of layer breeder eggs. Br. Poult. Sci. 45:223–229. Shafey, T., and T. Al-Mohsen. 2002. Embryonic growth, hatching time and hatchability performance of meat breeder eggs incubated under continuous green light. Asian-Austral. J. Anim. Sci. 15:1702–1707. Shafey, T. M., T. H. Al-mohsen, A. A. Al-Sobayel, M. J. Al-Hassan, and M. M. Ghnnam. 2002. Effects of eggshell pigmentation and egg size on the spectral properties and characteristics of eggshell of meat and layer breeder eggs. Asian-Austral. J. Anim. Sci. 15:297–302. Shafey, T., H. Al-Batshan, M. Ghannam, and M. Al-Ayed. 2005. Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs. Br. Poult. Sci. 46:190–198. Stadelman, W. J. 1958. The effect of sounds of varying intensity on hatchability of chicken egg. Poult. Sci. 37:166–169. Sui, N., and S. P. Rose. 1997. Effects of dark rearing and light exposure on memory for a passive avoidance task in day-old chicks. Neurobiol. of learning and memory. 68:230–238.
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Walter, J. H., and R. A. Voitle. 1972. Effects of photoperiod during incubation on embryonic and post-embryonic development of broilers. Poult. Sci. 51:1122–1126. Walter, J. H., and R. A. Voitle. 1973. Effects of photoperiod during incubation on embryonic and post-embryonic development of quail and chickens 1. Br. Poult. Sci. 14:533–540. Zhang, L., H. J. Zhang, X. Qiao, H. Y. Yue, S. G. Wu, J. H. Yao, and G. H. Qi. 2011. Effect of monochromatic light stimuli
during embryogenesis on muscular growth, chemical composition, and meat quality of breast muscle in male broilers. Poult. Sci. 91:1026–1031. Zhang, L., X. D. Zhu, X. F. Wang, J. L. Li1, F. Gao, and G. H. Zhou. 2016. Green light-emitting diodes light stimuli during incubation enhances posthatch growth without disrupting normal eye development of broiler embryos and hatchlings. Asian-Austral. J. Anim. Sci. in press doi: http://dx.doi.org/10.5713/ajas.15.0976.
Department of Poultry Science, Texas A&M University; College Station, TX, 77845, USA; and † Maple Leaf Farms, Inc., Leesburg, Indiana 46538, USA and hatchling quality were measured. In Experiment 1, LED had fewer early dead embryos (P = 0.03), less overall embryo mortality (P = 0.05), fewer chicks with unhealed navels (P < 0.001), fewer chicks with defects (P < 0.001), and a higher percentage of fertile eggs that hatched (P = 0.05) than DARK. In Experiment 2, LED had fewer chicks with unhealed navels (P = 0.003), fewer chicks with defects (P = 0.001), and a higher percentage of fertile eggs that hatched (P = 0.04) than DARK. In Experiment 3, LED had fewer early dead embryos (P = 0.05), lower overall embryo mortality (P = 0.04), and a higher percentage of fertile eggs that hatched (P = 0.05), and had ducklings with lower bodyweights at hatch (P = 0.04) than DARK. These results indicate that providing both white and red light during incubation can improve chick quality across poultry varieties. This type of fixture could be used to improve commercial hatchery efficiency and chick quality.
ABSTRACT Previous research has shown that providing light during incubation can have positive effects on hatchability and chick quality; however, white light alone has been observed to improve these factors only in pigmented broiler eggs and non-pigmented white layer eggs. Monochromatic red light has been shown to improve hatchability in layer eggs. Therefore the objective of this study was to utilize one light fixture that emitted both white and monochromatic red light to determine if this one light source could improve hatchability in both types of chicken eggs and pigmented Pekin duck egg. To determine this, 3 experiments were conducted, the first using White Leghorn eggs (N = 6912), the second using commercial broiler eggs (N = 4608), and the third using commercial Pekin duck eggs (N = 3564) in which eggs were incubated with 12 h of light and 12 h of darkness (LED) or complete darkness (DARK); the light level was 250 lux. Hatchability, embryo mortality,
Key words: layer, broiler, duck, light, incubation 2017 Poultry Science 0:1–6 http://dx.doi.org/10.3382/ps/pex040
INTRODUCTION
Mohsen, 2002). A likely reason that this environmental factor is not used in commercial incubators it that previous lighting sources caused detrimental effects, as well as the secondary heating caused by incandescent light bulbs (Gold and Kalb, 1976) decreases hatchability. However, with the advent of LED technology this is no longer an issue. Light is an obviously important environmental stimulus during incubation as the avian embryo has evolved to respond to light stimulation. Avian embryos respond to light as early as 3 d of development (Erwin et al., 1971). Furthermore, light during incubation causes the development of central nervous system asymmetries (Rogers, 1982), alters opsin expression in photoreceptors (Rozenboim et al, 2013), enhances proliferation and differentiation of myoblast and myofiber synchronization (Halevy et al., 2006), and alters hormonal rhythms (Csernus et al, 2007). Light stimulation during incubation has been observed to increase growth (Rozenboim et al., 2004; Zhang et al., 2016), improve feed conversion (Zhang et al, 2011), reduce fear responses (Archer and Mench, 2014b; 2017), reduce stress susceptibility (Archer et al, 2009; Archer and Mench, 2013,
Environmental factors during incubation can affect the hatchability and quality of the chicks that hatch. It has been documented that temperature (Narin¸c et al., 2016), humidity (Bruzual et al., 2000), turning (Eliboil and Brake, 2006), carbon dioxide levels (Gildersleeve and Boeschen, 1983), and even sound (Stadelman, 1958) can all affect hatchability. Recent research has demonstrated that light exposure during incubation also can affect hatchability (Huth and Archer, 2015; Archer, 2015a,b, 2016b). This is not a new concept as others have observed increases in growth and hatchability (Walter and Voitle, 1972; Garwood et al., 1973; Shafey and Al-Mohsen, 2002; Shafey, 2004) and acceleration in hatch time (Garwood et al., 1973; Bohren and Siegel, 1975; Ghatpande et al., 1995; Fairchild and Christensen, 2000; Shafey and Al C 2017 Poultry Science Association Inc. Received November 9, 2016. Accepted January 18, 2017. 1 Corresponding author: [email protected]
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2014a,b; Archer, 2016), and alter behavior post hatch (Sui and Rose, 1997, Rogers et al., 2007; Riedstra and ¨ Groothuis, 2004). Ozkan et al. (2012) even concluded that light exposure during incubation resulted in chicks that were more prepared for novel situations post hatch. Birds are very sensitive to different wavelengths of light and different wavelengths of light affect their physiology. Hluch´ y et al. (2012) observed that different wavelengths of light could affect hatchability differentially. Furthermore, differences in hatch time have been attributed to the eggshell filtering of certain light wavelengths (Ghatpande et al., 1995). Adding to the ability of the eggshell to filter the light, it also absorbs about 99.8% that is emitted on it (Shafey et al., 2002, 2005). Huth and Archer (2015) observed that broiler eggs saw an increase in hatchability when exposed to white LED light while white layer eggs showed no improvement. Archer (2016) observed that both “warm” and “cool” LED light increased hatch and were filtered similarly into more of the red frequency range. Hluch´ y et al. (2012) found that red light produced a higher hatchability than blue, with white light having the highest overall hatchability in broilers. Archer (2016) observed that red light improved hatchability in white layer eggs but not broiler eggs; however, Archer (2017) observed that red light improved hatchability similarly to white light in broiler eggs. The intensity of light also may alter the effectiveness of different wavelengths though no research has been conducted on this to date. Most of the research in this area has been conducted in chickens with only a few studies looking at other species such as turkeys (Fairchild and Christensen, 2000; Rozenboim et al., 2003) and quail (Walter and Voitle, 1973). No research has been done to this point on duck eggs. As no research has been conducted investigating how combining white and red light during incubation will affect hatchability and chick quality, we conducted 3 experiments to investigate this. The objective of this study was to determine how the combination of red and white light affected white layer, broiler, and Pekin duck eggs in respect to hatchability, embryo mortality, and hatchling quality. It is hypothesized that all eggs incubated under these lighted conditions will result in greater hatchability and hatchling quality across all poultry types.
MATERIALS AND METHODS Experiment 1 Layer Eggs: Animals and Husbandry There were 3 trials conducted in Experiment 1 using White Leghorn eggs (W-36, N = 6912) from hens that were minimally 50 wk of age. Eight GQF 1500 incubators and eight GQF 1550 hatchers (GQF Manufacturing, Savannah, GA) were used in each trial, and their front windows were blacked out with cardboard to prevent light intrusion into the machines. Eggs were set within 7 d of being laid. Four incubators were oper-
Figure 1. Comparison of spectrum readings through the shells of broiler, White Leghorn, and Pekin duck eggs to the unfiltered spectrum of the LEDs used in the incubators of Experiments 1, 2, and 3.
ated with the traditional dark method of incubation (0L:24D, DARK), while the other 4 were outfitted R with (Agrishift JLL short 8 watt LED, Once Inc, Plymouth, MN; LED) on each level, with 2 lights spaced evenly above the eggs. Lighting treatments were rotated among incubators between each trial to limit the effect of incubators on results. The lights were operated R LED master dimmer (Once Inc, Plyby a Agrishift mouth, MN), with a 12L:12D light schedule and the lights were dimmed to 40% to obtain an average of 250 lux at egg level as measured using a light meter (Extech 401027, Extech Instruments, Nashua, NH). Eggs and lights were scanned periodically throughout incubation with a thermal imaging camera (FLIR-T62101, Boston, MA) to ensure that eggshell temp was not affected by the LED lights (data not presented). Lights were very low profile so as not to disturb the airflow within the incubator. Spectrum of lights used is presented in Figure 1. Two egg trays were set on each rack with each tray holding 48 eggs, for a total of 6 trays over 3 levels equaling 288 eggs per incubator. The incubators were maintained at standard temperature and humidity levels of 99.5◦ F and 55%, respectively. Incubators were monitored twice daily to ensure proper functioning. The eggs were incubated for 18 d, at which time they were moved into the hatchers. Hatchers were not outfitted with lights, as previous research has shown this is not necessary (Archer, 2015a). All of the chicks were weighed and counted at hatch. The quality of the live chicks was assessed, and they were categorized and counted as either no defect, having an unhealed navel, having leg abnormalities, weak, dirty, having traits a hatchery would cull, or having any other abnormality. The remaining unhatched eggs were broken out and counted as pipped, broken, infertile, early dead, mid dead, and late dead.
Experiment 2 Broiler Eggs: Animals and Husbandry There were 2 trials conducted in Experiment 2 using broiler eggs (N = 4608) that were minimally 50 wk of
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Lighted incubation across poultry types Table 1. Data from Experiment 1 hatch. Embryo mortality (%), chick quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Mid dead
Late dead
Pipped
Dead chick
Total dead dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of Fertile
LED DARK SEM
3.60A 6.69B 0.72
0.03 0.03 0.02
7.49 12.66 1.97
5.91 13.23 2.14
0.00 0.00 0.00
17.02A 32.61B 4.02
21.13A 39.47B 2.70
0.25 0.83 0.22
0.66 2.46 0.70
0.88 3.35 0.99
77.05A 53.88B 3.53
42.19 42.85 0.02
82.98A 67.39B 4.02
A–B
Different letters within column indicate significant differences (P < 0.05).
Table 2. Data from Experiment 2 hatch. Embryo mortality (%), chick quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Mid dead
Late dead
Pipped
Dead chick
Total dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of fertile
LED DARK SEM
4.77A 8.19B 0.89
0.27 0.53 0.19
5.84 5.50 0.53
2.19 3.36 0.69
0.25 0.00 0.07
13.06 17.83 1.26
21.01A 38.79B 3.32
0.53 0.96 0.21
0.37 1.00 0.47
0.26 0.30 0.15
77.82A 58.88B 3.36
40.27 41.47 0.11
86.94A 81.98B 1.23
A–B
Different letters within column indicate significant differences (P < 0.05).
age. Unless otherwise noted, all trials followed the same procedures as in Experiment 1.
Experiment 3 Pekin Duck Eggs: Animals and Husbandry There were 2 trials conducted in Experiment 3 using Pekin duck eggs (N = 3564) that were minimally 50 wk of age. Unless otherwise noted, all trials followed the same procedures as in Experiment 1. Nine GQF 1500 incubators and nine GQF 1550 hatchers (GQF Manufacturing, Savannah, GA) were used in each trial, and their front windows were blacked out with cardboard to prevent light intrusion into the machines. Five incubators were operated with the traditional dark method of incubation (0L:24D, DARK), while the other 4 were R outfitted with (Agrishift JLL short 8 watt LED, Once Inc, Plymouth, MN; LED) on each level, with 2 lights spaced evenly above the eggs. Two egg trays were set on each rack with each tray holding 33 eggs, for a total of 6 trays over 3 levels equaling 198 eggs per incubator. The incubators were maintained at standard temperature and humidity levels of 99.5◦ F and 60%, respectively. The eggs were incubated for 25 d, at which time they were moved into the hatchers. All of the ducklings were weighed and counted at hatch. The quality of the live ducklings was assessed, and they were categorized and counted as either no defect, having an unhealed navel, having leg abnormalities, weak, dirty, having traits a hatchery would cull, or having any other abnormality. The remaining unhatched eggs were broken out and counted as pipped, broken, infertile, early dead, and late dead. All experiments were approved by the Texas A&M University IACUC committee (AUP# IACUC 20150254).
Statistical Methods One-way ANOVA was used to investigate treatment effects on hatchability, embryo mortality, and chick
quality. The least significant difference test was used to test all planned comparisons. All of the assumptions of ANOVA were tested (Shapiro-Wilk test for normality and Levene’s test for homogeneity of variance). No transformations were needed to meet assumptions. All analyses were performed using SAS 9.3 for Windows (SAS Institute Inc. Cary, NC, USA). Significant differences were determined at P < 0.05.
RESULTS In Experiment 1 (Table 1), there were no differences between LED and DARK treatments (P > 0.05) in the number of mid dead, late dead, pipped, dead chicks in trays, chicks with leg problems, dirty chicks, cull chicks, or chick weight at hatch. The LED treatment had fewer early dead embryos (P = 0.03), less overall embryo mortality (P = 0.05), fewer chicks with unhealed navels (P < 0.001), more no defect chicks (P < 0.001), and a higher percentage of fertile eggs that hatched (P = 0.05) than the DARK treatment. In Experiment 2 (Table 2), there were no differences between LED and DARK treatments (P > 0.05) in the number of mid dead, late dead, pipped, dead chicks in trays, chicks with leg problems, dirty chicks, cull chicks, or chick weight at hatch. The LED treatment had fewer early dead embryos (P = 0.05), fewer chicks with unhealed navels (P = 0.003), more no defect chicks (P = 0.001), and a higher percentage of fertile eggs that hatched (P = 0.04) than the DARK treatment. In Experiment 3 (Table 3), there were no differences between treatments (P > 0.05) in the number of late dead, pipped, dead ducklings in tray, or duckling quality. The LED treatment had fewer early dead embryos (P = 0.05), lower overall embryo mortality (P = 0.04), and a higher percentage of fertile eggs that hatched (P = 0.05), and had ducklings with lower bodyweights at hatch (P = 0.04) than the DARK treatment.
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ARCHER ET AL. Table 3. Data from Experiment 3 hatch. Embryo mortality (%), duckling quality (%), weight (g), and hatch of fertile (%). Treatment
Early dead
Late dead
Pipped
Dead ducklings
Total dead
Un-healed navel
Leg or weak
Dirty feather
Cull
No defect
Weight
Hatch of fertile
LED DARK SEM
8.35A 12.67B 1.10
8.63 10.57 1.16
2.80 5.47 0.74
0.20 0.00 0.05
19.98A 28.71B 2.17
9.38 14.43 2.26
0.56 1.79 0.44
0.19 0.34 0.09
0.43 1.99 0.60
89.28 81.15 2.52
52.86A 59.03B 1.49
79.54A 71.18B 2.11
A–B
Different letters within column indicate significant differences (P < 0.05).
DISCUSSION In these 3 experiments we sought to evaluate the embryo mortality, hatchability, and chick/duckling quality of White Leghorn eggs, broiler eggs, and Pekin duck eggs that were exposed to a combination of white and red LED light during incubation. Our hypothesis that the combined spectrum of light would improve hatchability and chick quality across poultry varieties was mostly proven true. We in fact observed an improvement in hatchability of fertile eggs as a result of the experimental light exposure in White Leghorn eggs, broiler eggs, and Pekin duck eggs. Chick quality was statistically improved in both chicken types; however, it was only numerically increased in the duck eggs. The percentage of embryos that died during the early period of incubation was decreased in the all varieties of eggs by the light exposure during incubation. This improvement in early dead mortality is not consistent with previous research (Huth and Archer, 2015; Archer, 2015a,b, 2016, 2017). The improvement in early dead mortality may be a result of this new combination of white and red light used in this current study, as previous studies used only white light alone or monochromatic light wavelengths alone. This again illustrates the complexity of the interaction of light and avian physiology. The lack of improvement in all other embryo mortality is consistent with previous research, as the improved hatchability seems to be a cumulative effect more than a specific improvement in embryo viability at different time points. The increased hatchability utilizing this combined white and red light LED appears to support the idea that red light is important for the development of avian embryos. As observed by Huth and Archer (2015) white light alone improves hatchability only when the eggs are pigmented like broiler eggs and not when they are nonpigmented like White Leghorn eggs. Others have observed no improvement in hatchability (Shafey, 2004) or even reduced hatchability (Bowling et al., 1981) when White Leghorn eggs are exposed to white light during incubation; furthermore, others also have observed improvement in hatchability in broiler eggs when they are exposed to white light during incubation (Walter and Voitle, 1972; Garwood et al., 1973; Shafey and AlMohsen, 2002). Red light has been documented to improve hatchability as well (Hluch´ y et al., 2012; Archer, 2015b, 2017), even in White Leghorn eggs (Archer, 2015b, 2017). Huth and Archer (2015b) concluded that
because the brown eggshells were filtering the white light to a reddish hue, the White Leghorn eggs saw no improvement. Non-pigmented eggs let the full spectrum of visible light through the shell. As demonstrated by this study and previous ones (Hluch´ y et al., 2012; Archer, 2015b, 2017), red light appears to be the key wavelength for improving hatchability, as all eggs had improved hatchability with the addition of red to the white light. Previously, only pigmented eggs showed improvement in hatch without the addition of white light (Huth and Archer, 2015). The mechanism for this improvement is still unknown and merits future research to ascertain what it is. Whatever the mechanism may be, simply by combining white and red light into one fixture an improvement in hatchability was observed across all eggs in this study. Chick quality at hatch also was improved by the light exposure during incubation in both chicken varieties, but duckling quality was not statistically improved by the light treatment. An increased chick quality as a result of white light exposure during incubation has been previously observed (Huth and Archer, 2015; Archer 2016). Red light exposure also has been shown to improve chick quality (Archer, 2015b, 2017). Specifically, the improvement in percentage of chicks with fully healed navels has been attributed with the accelerated growth caused by light exposure resulting in improved maturation of the navel over dark trials (Erwin, et al., 1971). Ducks eggs exposed to light did not have a statistical difference in duckling quality. It should be noted though that duckling quality percentage overall was much higher than chick quality in the other 2 experiments. In light of that fact, elucidating statistical differences might not be possible unless many more replications are utilized, as evidenced by the very slight trend (P = 0.10) observed here. It is also possible that duckling quality is not controlled in the same manner by light as it is in chickens. Overall, the combined white and red light used in this study demonstrated a real potential benefit to the incubation process. It increases chick quality in both layer and broiler chickens, as well as increases overall hatchability in both chickens and ducks. Other research (Archer and Mench, 2013, 2014a,b; Rozenboim et al., 2004; Zhang et al., 2016) has demonstrated further improvements of light exposure post hatch making this environmental factor during incubation a really important management tool that currently is not being utilized. By using both white and red light in
Lighted incubation across poultry types
one fixture, incubators could be designed or retrofitted with one light source for multiple poultry varieties. Additional research on a larger scale would emphasize the benefits, but utilizing light during incubation appears to be a very promising management tool.
ACKNOWLEDGMENTS We would like to thank Once, Inc., for its donation of the lighting fixtures used in this research. We also would like to thank Hy-line North America, Tyson Foods, Inc., and Maple Leaf Farms for their donation of eggs used in this research.
REFERENCES Archer, G. S. 2015a. Timing of light exposure during incubation to improve hatchability, chick quality and post-hatch wellbeing in broiler chickens: 21 or 18 days. Int. J. Poult. Sci. 14:293–299. Archer, G. S. 2015b. Effect of exposing layer and broiler eggs to red or white light during incubation. Int. J. Poult. Sci. 14:491–496. Archer, G. S. 2016. Spectrum of white light during incubation: Warm vs cool white LED lighting. Int. J. Poult. Sci. 15: 343–348. Archer, G. S., H. L. Shivaprasad, and J. A. Mench. 2009. Effect of providing light during incubation on the health, productivity, and behavior of broiler chickens. Poult. Sci. 88:29–37. Archer, G. S., and J. A. Mench. 2013. The effects of light stimulation during incubation on indicators of stress susceptibility in broilers. Poult. Sci. 92:3103–3108. Archer, G. S., and J. A. Mench, 2014a. Timing of light exposure during incubation to improve hatchability, chick quality and posthatch well-being in broiler chickens: 21 or 18 days. International J. Poult. Sci. 14:293–299. Archer, G. S., and J. A. Mench. 2014b. Natural incubation patterns and the effects of exposing eggs to light at various times during incubation on post-hatch fear and stress responses in broiler (meat) chickens. Appl. Anim. Behav. Sci. 152:44–51. Archer, G. S. 2017. Exposing broiler eggs to green red, and white light during incubation. Animal. In press. Archer, G. S., and J. A. Mench. 2017. Exposing avian embryos to light affects post-hatch anti-predator fear responses. Applied Animal Behavior Science. 186:80–84. Bohren, B., and P. Siegel. 1975. Light effects during incubation on lines of White Leghorns selected for fast and slow hatching. Poult. Sci. 54:1372–1374. Bowling, J. A., B. Howarth, and D. L. Fletcher. 1981. The effects of lighted incubation on eggs with pigmented and nonpigmented yolk. Poult. Sci. 60:2328–2332. Bruzual, J. J., S. D. Peak, J. Brake, and E. D. Peebles. 2000. Effects of relative humidity during incubation on hatchability and body weight of broiler chicks from young breeder flocks. Poult. Sci. 79:827–830. Csernus, V. J., A. D. Nagy, and N. Faluhelyi. 2007. Development of the rhythmic melatonin secretion in the embryonic chicken pineal gland. Gen. Comp. Endocrinol. 152:148–153. Elibol, O., and J. Brake. 2006. Effect of egg turning angle and frequency during incubation on hatchability and incidence of unhatched broiler embryos with head in the small end of the egg. Poult. Sci. 85:1433–1437. Erwin, W. T., M. A. Boone, and B. D. Barnett. 1971. Response of the Developing Embryo to Light. Poult. Sci. 50:1883–1884. Fairchild, B., and V. Christensen. 2000. Photostimulation of turkey eggs accelerates hatching times without affecting hatchability, liver or heart growth, or glycogen content. Poult. Sci. 79:1627– 1631. Garwood, V. A., E. J. Thornton, and P. C. Lowe. 1973. The effect of continuous illumination of incubating chicken eggs on embryonic development. Poult. Sci. 52:337–340.
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Ghatpande, A., S. Ghatpande, and M. Z. Khan. 1995. Effect of different intensities of fluorescent light on the early development of chick embryos in ovo. Cell. Mol. Biol. Res. 41:613–621. Gildersleeve, R. P., and D. P. Boeschen. 1983. The effects of incubator carbon dioxide level on turkey hatchability. Poult. Sci. 62:779–784. Gold, P. S., and J. Kalb. 1976. Secondary heating of chicken eggs exposed to light during incubation. Poult. Sci. 55:34–39. Halevy, O., Y. Piestun, I. Rozenboim, and Z. YablonkaReuveni. 2006. In ovo exposure to monochromatic green light promotes skeletal muscle cell proliferation and affects myofiber growth in posthatch chicks. Amer. J. of Physiol. – Regul., Integrat. and Comp. Physiol. 290:R1062– R1070. Hluch´ y, S., R. Toman, M. Cabaj, and M. Adamkoviˇcov´a. 2012. The effect of white and monochromatic lights on chicken hatching. Scientific Papers Anim. Sci. and Biotechnol. 45.2: 408–410. Huth, J. C., and G. S. Archer. 2015. Effects of LED lighting during incubation on layer and broiler hatchability, chick quality, stress susceptibility and post-hatch growth. Poult. Sci. 94:3052–3058. Narin¸c, D., S. Erdo˘ gan, E. Tahtabi¸cen, and T. Aksoy. 2016. Effects of thermal manipulations during embryogenesis of broiler chickens on developmental stability, hatchability and chick quality. Animal. 8:1328–1335. ¨ Ozkan, S., S. Yalcin, E. Babacanoglu, H. Kozanoglu, F. Karadas, and S. Uysal. 2012. Photoperiodic lighting (16 hours of light:8 hours of dark) programs during incubation: 1. Effects on growth and circadian physiological traits of embryos and early stress response of broiler chickens. Poult. Sci. 91:2912–2921. Riedstra, B., and T. Groothuis. 2004. Prenatal light exposure affects early feather-pecking behaviour in the domestic chick. Anim. Behav. 67:1037–1042. Rogers, L. J. 1982. Light experience and asymmetry of brainfunction in chickens. Nature 297:223–225. Rogers, L. J., R. J. Andrew, and A. N. Johnston. 2007. Light experience and the development of behavioural lateralization in chicks III. Learning to distinguish pebbles from grains. Behav. Brain. Res. 177:61–69. Rozenboim, I., R. Huisinga, O. Halevy, and M. E. El Halawani. 2003. Effect of embryonic photostimulation on the posthatch growth of turkey poults. Poult. Sci. 82:1181–1187. Rozenboim, I., I. Biran, Y. Chaiseha, S. Yahav, A. Rosenstrauch, D. Sklan, and O. Halevy. 2004. The effect of a green and blue monochromatic light combination on broiler growth and development. Poult. Sci. 83:842–845. Rozenboim, I., M. E. El Halawani, Y. Kashash, Y. Piestun, and O. Halevy. 2013. The effect of monochromatic photostimulation on growth and development of broiler birds. Gen. Comp. Endocrinol. 190:214–219. Shafey, T. 2004. Effect of lighted incubation on embryonic growth and hatchability performance of two strains of layer breeder eggs. Br. Poult. Sci. 45:223–229. Shafey, T., and T. Al-Mohsen. 2002. Embryonic growth, hatching time and hatchability performance of meat breeder eggs incubated under continuous green light. Asian-Austral. J. Anim. Sci. 15:1702–1707. Shafey, T. M., T. H. Al-mohsen, A. A. Al-Sobayel, M. J. Al-Hassan, and M. M. Ghnnam. 2002. Effects of eggshell pigmentation and egg size on the spectral properties and characteristics of eggshell of meat and layer breeder eggs. Asian-Austral. J. Anim. Sci. 15:297–302. Shafey, T., H. Al-Batshan, M. Ghannam, and M. Al-Ayed. 2005. Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs. Br. Poult. Sci. 46:190–198. Stadelman, W. J. 1958. The effect of sounds of varying intensity on hatchability of chicken egg. Poult. Sci. 37:166–169. Sui, N., and S. P. Rose. 1997. Effects of dark rearing and light exposure on memory for a passive avoidance task in day-old chicks. Neurobiol. of learning and memory. 68:230–238.
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Walter, J. H., and R. A. Voitle. 1972. Effects of photoperiod during incubation on embryonic and post-embryonic development of broilers. Poult. Sci. 51:1122–1126. Walter, J. H., and R. A. Voitle. 1973. Effects of photoperiod during incubation on embryonic and post-embryonic development of quail and chickens 1. Br. Poult. Sci. 14:533–540. Zhang, L., H. J. Zhang, X. Qiao, H. Y. Yue, S. G. Wu, J. H. Yao, and G. H. Qi. 2011. Effect of monochromatic light stimuli
during embryogenesis on muscular growth, chemical composition, and meat quality of breast muscle in male broilers. Poult. Sci. 91:1026–1031. Zhang, L., X. D. Zhu, X. F. Wang, J. L. Li1, F. Gao, and G. H. Zhou. 2016. Green light-emitting diodes light stimuli during incubation enhances posthatch growth without disrupting normal eye development of broiler embryos and hatchlings. Asian-Austral. J. Anim. Sci. in press doi: http://dx.doi.org/10.5713/ajas.15.0976.