New Monochromatic Light Source for Laying Hens - Poultry Science

New Monochromatic Light Source for Laying Hens I. ROZENBOIM,*,1 E. ZILBERMAN,† and G. GVARYAHU† *The Hebrew University of Jerusalem, Faculty of Agriculture, Department of Animal Science, Rehovot, Israel, and †O.L.T. Ltd., Software Incubators Har Hotzvim Jerusalem, Israel ABSTRACT Artificial illumination is an important factor in the management of layers. In this study, a new monochromatic light system was developed for egg layers. Prelaying pullets (Lohmann) were marked and housed in nine light and temperature control rooms (15 battery cages, 3 hens per cage; n = 45), divided into three light treatments: 0.1 and 0.01 W/m2 light intensity using light emitting diode (LED) lamps and 0.1 W/m2 using mini-florescent bulbs (PL) (control). In each of the LED rooms, three wavelengths were tested: 560 (n = 9), 660 (n = 9), 880 (n = 6), and 660 intermitted lighting (15 min light 45 min dark, 660IN) (n = 9). Birds were exposed to 12 h light and 12 h of darkness using PL lamps. At 21 wk of age, the light period was increased to

12.75 h by using 5.5 h of LED lamps and 7.25 of PL light source for Groups 1 and 2, the third group received 12.75 h of PL light. Until 28 wk of age, light hours increased by 0.5 h/w using LED light for Groups 1 and 2 and PL source for the third group, reaching 16 h of light at 28 wk of age. Egg production and feed consumption were recorded daily; egg components were recorded weekly for 10 mo. A significant reduction in egg production was observed in all 880nm groups; no differences in egg production and quality were found in the other groups. Feed consumption was significantly lower by 7% in all 0.01 W/m2 groups. We suggest that an important reduction in rearing costs of laying hens may be obtained by using this system.

(Key words: light, light intensity, light spectrum, feed consumption) 1998 Poultry Science 77:1695–1698

INTRODUCTION In modern poultry houses, artificial illumination may be the only source of light provided to birds; thus, the duration, intensity, and quality of light become important environmental factors, as light influences both reproductive and productive systems in the domestic fowl. The role of light in biological activities associated with egg production is well known. Light quality can be defined by two criteria: 1) dose intensity, and 2) quality spectra (Andrews and Zimmerman 1990). In birds from subtropical and temperate latitudes, photostimulation increases egg production, whereas reduction in photoperiod delays or decreases production. In addition, light intensity plays an important role in rearing birds, mainly because birds need a certain light intensity to be photostimulated (North and Bell, 1990). The chicken eye, similarly to the human eye, is capable of seeing in a narrow part of the light spectrum (380 to 760 nm). Apart from the eyes, birds are equipped with active extra-retinal photoreceptors, located in

Received for publication October 24, 1997. Accepted for publication July 9, 1998. 1To whom correspondence should be addressed: ROZENBOI@ AGRI.HUJI.AC.IL

several parts of the brain, which are involved in transduction of photostimulation. Photostimulation, as affected by different wavelengths, has been discussed previously regarding chickens (Harrison et al., 1970), turkeys (Scott and Payne, 1937), sparrows (Ringoen, 1942), ducks (Benoit, 1964), and quail (Phogat et al., 1985). In general, red light stimulates egg production efficiently, whereas green or blue light has little or no effect. In commercial layers, during the first and second season, total egg production was significantly influenced by light color, with the greatest number of eggs produced in the group treated with red light. Furthermore, eggs laid under blue or green light were consistently larger then those laid under red light (Pyrzak et al., 1987). Because layers housed in lower deck cages in multi-deck houses are not exposed to the same intensity of light as those in upper cages, we considered the use of LED lamps installed at the top of each cage. The objective of this study was to investigate the possible use of LED light devices in commercial laying hens, and to integrate the effects of light intensity and spectra requirements in laying hens.

Abbreviation Key: IN = intermittent lighting; LED = light emitting diode; PL = mini-fluorescent bulbs.

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MATERIALS AND METHODS

Animals Seventeen-week-old White Leghorn hens (Lohmann) (n=405) were purchased from a commercial pullet grower farm. Upon arrival birds were housed in nine environmental and light-control rooms (n = 45, birds per room). In each room, birds were housed in a laying battery (15 cages, 3 birds per cage n = 45). Commercial laying feed (17% protein) was provided for ad libitum consumption according to the Lohmann Layers Guide Manual. Feed was provided manually in individual feeders previously designed for three hens.

Light Systems The Light Emitting Diode lighting device,2 which utilized lamps consisting of a single p-n junction, is a simple semiconductor device. Light is emitted when the junction is forward biased so that minority carrier injection and electron-hole recombination occur. Many types of LED lamps are currently available commercially. The major benefits of these lamps are: good efficiency (each lamp consumes 70 mW/h), long operating life (100,000 h of operation), moisture resistance, and availability in different peak wavelengths (Craford, 1985). Birds were divided into three treatment groups (n=135). The first three groups (housed in three separate rooms) were provided with LED devices3 installed at the top of each cage, with an intensity of 0.1 W/m2 at bird-head level. Watts per square meter units were used because extraretinal photoreceptors located in bird’s head detect energy level penetrating through the skull). The second three groups (housed in three separate rooms) were provided with a LED lighting device installed at the top of each cage with an intensity of 0.01 W/m2 at bird-head level. The third group was (housed in three separate rooms) provided with mini-fluorescent light bulbs (9 W),4 0.1 W/ m2 at bird-head level, and served as controls.

TABLE 1. Light schedule of layers illuminated with light emitted diode (LED) or mini-florescent light bulbs Age (wk) 17 to 20 21 22 23 24 25 26 27 28 to 58

White light

LED light

Total light

(h) 7.00 7.25 6.25 5.25 4.25 3.25 3.25 3.25 3.25

5.0 5.5 7.0 8.5 10.0 11.5 12.0 12.5 13.0

12.00 12.00 13.25 13.75 14.25 14.45 15.25 15.45 16.25

was illuminated with 880 nm (peak wavelength of 880 nm half-band width between 840 to 920 nm) LED lamps (n = 9 in three replicates). Upon arrival, at 17 wk of age, birds were provided with 10 h of white light (mini-florescent light bulb 9 W warm white color 41 0.1 W/m2 at birds head level). This whitelight illumination was provided as recommended by Lohmann manual guide, and by the Israeli Ministry of Agriculture Extension Service, for the control-treated group (n = 45, in three replicates). The light schedule is presented in detail in Table 1, and was applied from 17 wk of age until termination of the experiment at 58 wk of age. Egg production and feed consumption were recorded daily; egg weight, shell weight and thickness, and yolk and albumen weights were recorded once a week. All

Light Treatments Each of the LED treatment groups was divided into four subgroups: The first subgroup was provided with 560 nm (peak wavelength of 560 nm, half-band width between 552 to 565 nm) LED lamps (n = 12 in three replicates); the second subgroup was provided with 660 nm (peak wavelength of 660 nm, half-band width between 650 to 670nm) LED lamps (n = 12 in three replicates); the third subgroup was provided with 660 nm LED lamps that operated in an intermittent schedule of 15 min light and 45 min dark (n = 12 in three replicates); and the fourth group

2OLT Ltd., Jerusalem, Israel. 3Li-Cor, Inc. Lincoln, NE 68504. 4OSRAM, GmbH Munich, 8000 Germany.

FIGURE 1. Egg production of laying hens reared under light intensity of 0.1 W/m2 (Figure 1a) and 0.01 W/m2 (Figure 1b) at different light spectra.

NEW MONOCHROMATIC LIGHT SOURCE FOR LAYING HENS

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FIGURE 2. Summarized results of 10 mo of egg production (mean ± SE) by laying hens reared under 0.1 or 0.01 W/m2 light intensity and under different light spectra. Values marked with no common letters are significantly different (P < 0.5).

FIGURE 3. Summarized results of 10 mo of feed consumption per hen per day (mean ± SE) by laying hens reared under 0.1 or 0.01 W/m2 light intensity and under different light spectra. Values marked with no common letters are significantly different (P < 0.05).

measurements were conducted until 58 wk of age, when the experiment was terminated.

Actual feed consumption per egg laid is presented in Figure 4. A significant reduction in this parameter was found in all birds reared under 0.01 W/m2 light intensity reaching lower levels in 660 nm birds. Birds reared under 0.1 W/m2 were not different than the control group. There were no differences in egg size, shell weight and thickness, and yolk and albumen weights.

Data Analysis All data were analyzed by one way analysis of variance, according to the design of eight experimental groups (two LED groups by four wave length) and one control. Differences between groups were tested using Duncan’s multiple range test. All statistical analyses were by the SAS General Linear Models (GLM) procedure (SAS Institute, 1987).

RESULTS Weekly egg production (presented as hen housed percentage), is presented in Figure 1a for birds illumniated with 0.1 W/m2, and Figure 1b for birds illuminated with 0.01 W/m2. A significant decrease in egg production was observed in the group treated with 880 nm reared under 0.1 W and 0.01 W/m2, compared to all other light treatment groups reared under corresponding light intensities. No significant differences were found between any of the other groups and the control group. Figure 2 presents a summary of egg production measured over 38 wk of production. A significant reduction in egg production per hen per 10 mo of production was observed in the groups illuminated under 880 nm in both 0.1 and 0.01 W/m2 (213 ± 3.5 and 213 ± 7.9, respectively), as compared to control (227 ± 0.8). A slight increase, although not significant, was observed in the group reared under 0.01 W/m2 (230 ± 4.2) as compared to all other treated groups. The control group (average 115 ± 0.9 g per hen per d) was significantly higher in feed consumption compared to all other 0.01 W/m2 light treated groups (108 ± 0.8 g per hen per d at 560 nm, 107 ± 1.4 g/d per hen at 660 nm, 106 ± 2 g/d per hen at 66 0in) and the lowest feed consumption was observed in the 880 nm groups 103 ± 2.3 g per hen per d). No significant difference was found in feed consumption between birds reared under 0.1 W/ m2 and the control group.

DISCUSSION In the present study we demonstrate for the first time that caged laying hens can be reared under individual lighting devices based on LED lamps installed at the top of the cage. We suggest that by using optimal light spectra, light intensity can be decreased sharply, resulting in a significant decrease in the feed intake of the birds. This method of lighting laying hens can be highly beneficial for producers as savings in rearing costs were observed. Furthermore, we suggest that the reduction in feed intake and energy costs will increase net profit by 20-30% depending on feed cost. Table 2 summarizes the

FIGURE 4. Summarized results of 10 mo of feed consumption per egg (grams per egg per hen) (mean ± SE) of laying hens reared under 0.1 or 0.01 W/m2 light intensity and under different light spectra. Values marked with no common letters are significantly different (P < 0.05).

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TABLE 2. Cost effectiveness of LED lighting system (660 nm, 0.01 W/m2) compared to conventional lighting device (13 W mini-florescent light bulbs) in a 15,000 caged layers (3 hens per cage) housed in a double deck stair step Lighting system Conventional LED Lighting Device Savings, %

Energy

Feed intake

(W/house) 1,3001 1,0802

(kg/d) 1,7253 1,6054

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that egg weight may be changed due to different light rearing conditions. Pyrzak et al. (1987) suffested that egg weight was affected by light treatment. We suggest that lighting caged laying hens by 660 nm LED lighting devices at head level can reduce light intensity to the minimum required for egg laying with a clear reduction in feed intake. This device may become a future lighting system for caged layers facilities, especially for multiple floor cages.

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lamps per house 13 W/lamp. 20.216 W/cage × 5,000 cages. 3115 g feed/d × 15,000 hens. 4107 g feed/d × 15,000 hens.

cost effectiveness of the LED lighting system compared to a conventional lighting device. The calculation, for 15,000 layers housed in 5,000 cages (3 hens per cage) in a double-deck stair-step configuration, demonstrates a significant reduction in rearing (–7% in feed and –17% in lighting energy costs. Rearing birds under 0.01W/m2 significantly reduced feed intake, regardless of light spectra. Boshouwers and Nicaise (1987) examined the effect of light intensity on energy expenditure of laying hens; a decrease in light intensity from 120 to 1 lx was found to reduce the total energy expenditure by 18%. This phenomenon was due to a reduction in activity-related energy expenditure in birds reared under low light intensity. Furthermore, low light intensity was found to reduce heat production and core body temperature, probably due to a reduction in physical activity (Li et al., 1992). On the contrary, Charles (1984) suggested that light intensity does not play an important role in feed intake of laying hens. In the present experiment, the absolute reduction in feed intake in all groups reared under 0.01W/m2 light intensity, feed efficiency was significant, and was lowest in the 660 nm light spectra group. Although in the present study egg production by birds reared under the red light source was not significantly different from control, the increase was in agreement with prior reports that the photosexual responses of birds are wavelength-dependent. Quail kept under red illumination produced more eggs compared to birds reared under green or blue light (Woodward et al., 1969). Similarly, turkeys reared under day-light spectra produced more eggs if white or red light were used as the supplement rather than blue light (Scott and Payne, 1937). Although egg weight was not effected by light color or intensity in our experiment, other research suggests

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