Effect of wave length of light on growth and reproduction in Japanese quail (Coturnix coturnix japonica)

Continuous exposure to red light induces photorefractoriness in broiler breeder pullets

The management of body weight (BW) in broiler breeder pullets is critical to offset the negative correlation between their growth potential and reproductive success. Therefore, a precision feeding system was developed to allocate feed individually based on real-time BW in more frequent, smaller portions. However, this system requires access beyond the 8 h daylength of the rearing period. Since green and red spectra have been shown to stimulate growth and sexual maturation, respectively, this study aimed to evaluate the impact of continuous supplemental illumination of feeders with monochromatic wavelengths on sexual maturation. Furthermore, the best combination of supplemental and daytime lighting for optimizing the pullet-to-hen transition period was investigated. This study contained a 2 × 4 × 2 factorial arrangement, with 2 daytime lights (dtRED and dtGREEN; n = 2 rooms), 4 supplemental lights (sBLUE, sGREEN, sRED, and sCON; n = 12 pens), and 2 supplemental intensities (High and Low). At 3 wk of age (woa), 480 female Ross 708 chicks were randomly distributed across treatments (n = 10/pen). All birds were feed restricted per management guidelines and maintained under 8 h of dtRED or dtGREEN. Birds were photostimulated at 20 woa with 14L:10D. All birds were weighed weekly, with age at first egg (AFE) and production rate calculated weekly per pen. Birds under sRED were heavier than all other treatments from 27 woa to the end of the study (P < 0.001; 30 woa), resulting in hens that were over 400-g heavier. This resulted from a delayed AFE and lower production rate under sRED, with higher intensity further hindering reproductive performance (P < 0.001). Interestingly, despite the inhibitory effect of continuous red lighting (sRED) on reproduction, dtRED resulted in a 3.15% higher rate of lay than dtGREEN. Therefore, this study suggests that while red light remains superior at stimulating reproduction, continuous red supplemental lighting results in photorefractoriness. Thus, we recommend green light in PF systems.

Targeted differential photostimulation alters reproductive activities of domestic birds

Modern poultry production systems use environmentally controlled houses providing only artificial illumination. The role of light in reproduction of poultry depends on light quality (photoperiod, intensity/brightness, and spectrum), which enables us to provide custom-made illumination, targeted for the elevation of reproductive activities. Artificial targeted illumination significantly affects poultry reproduction. This phenomenon is based on the mechanism of light absorption in birds, which consists of two main components: the eye (retinal photoreceptors) and brain extraretinal photoreceptors. Several experiments on turkey hens and broiler breeder males and females have shown that photostimulation of brain extraretinal photoreceptors, while maintaining retinal photoreceptors under non-photostimulatory conditions, elevates reproductive activity by increasing egg production of hens and semen quality of roosters. In addition, we found acceleration in all gonadal axis parameters, leading to the acceleration in the production rate. Furthermore, we studied the role of retinal activation in gonadal axis suppuration and identified the role of serotonin in this phenomenon. As for today, several broiler breeder farms use targeted illumination based on our studies with excellent results.

Improving Gander Reproductive Efficacy in the Context of Globally Sustainable Goose Production

The goose is a popular poultry species, and in the past two decades the goose industry has become highly profitable across the globe. Ganders low reproductive performance remains a barrier to achieving high fertility and hatchability in subsequent flocks. To address the global demand for cheaper animal protein, various methodologies for improving avian (re)production should be explored. A large amount of literature is available on reproduction traits and techniques for commercial chicken breeder flocks, while research on improved reproduction in ganders has been carried out to a lesser extent. The present review aims to provide a comprehensive literature overview focusing on recent advancements/techniques used in improving gander reproductive efficacy in the context of ensuring a globally sustainable goose industry.

Targeted differential illumination improves reproductive traits of broiler breeder males

Artificial targeted illumination has a pivotal role in reproductive processes of poultry. The light-absorption mechanism in birds consists of 2 main components: the eye (retinal photoreceptors) and extraretinal photoreceptors located in the brain. Previous studies conducted on hens have shown that photostimulation of brain extraretinal photoreceptors elevates reproductive activity, whereas retinal photostimulation suppresses it. We tested the effect of targeted differential photostimulation (TDP) on reproductive activities of broiler breeder males. Fifty broiler breeder roosters (Ross), 21 wk of age, were divided into 5 environmentally controlled light-treatment rooms (n = 10) equipped with individual cages. Rooms 1 and 2 had 2 parallel lighting systems consisting of red light (630 nm) and green light (514 nm), and rooms 3 and 4 had parallel red and blue (456 nm) lighting systems. Room 5, illuminated with white light, served as the control. Birds of all groups were kept under short day (6L:18D) for 2 wk with both lighting systems in each treatment room turned on. At 23 wk of age, birds were photostimulated by gradually increasing one of the lighting systems to 14 h of light in each room, while the other lighting system was left on short day (6L:18D). Weekly semen samples were collected until 65 wk of age and analyzed for volume, motility, concentration and vitality. Monthly blood samples were drawn for plasma hormone assays. At 65 wk of age, roosters were euthanized and hypothalamus, pituitary gland, retina and testes samples were taken for mRNA expression analysis. TDP using long-day red light and short-day green light significantly increased reproductive performance, manifested by higher semen volume, motility and concentration, and testis weight; furthermore, this group had higher plasma testosterone levels, higher GnRH mRNA expression in the hypothalamus, lower levels of aromatase in the testes, and lower mRNA expression of hypothalamic serotonin transporter, and of pituitary prolactin and its receptors in the testes. This is the first study showing a positive effect of TDP on reproduction of broiler breeder roosters.

Transcriptome Analysis of Long Noncoding RNAs and mRNAs in Granulosa Cells of Jinghai Yellow Chickens Illuminated With Red Light

Jinghai Yellow chickens are a new indigenous breed with a dual purpose in China, but their egg laying performance is limited. Compared with white light (WL), exposure to red light (RL) can improve the egg laying performance of hens. Herein, to elucidate the molecular mechanism by which RL affects the egg laying performance, RNA sequencing was used to analyze long noncoding RNAs (lncRNAs) and mRNAs from granulosa cells of small yellow follicles from Jinghai Yellow chickens in RL and WL groups. A total of 12,466 lncRNAs were identified among the assembled transcripts, of which 168 lncRNAs were significantly different between the RL and WL groups (101 downregulated and 67 upregulated). Additionally, 1182 differentially expressed mRNAs were identified (958 downregulated and 224 upregulated). Integrated network analysis demonstrated that numerous differential mRNAs were involved in follicular development through steroid hormone synthesis, oocyte meiosis, and the PI3K-Akt signaling pathway. The impact of lncRNAs on cis and trans target mRNAs indicates that some lncRNAs play important roles in follicular development of small yellow follicles. The results provide a starting point for studies aimed at understanding the molecular mechanisms by which monochromatic light affects follicular development and egg production in hens.

The mediation of pigeon egg production by regulating the steroid hormone biosynthesis of pigeon ovarian granulosa cells

The aim of this study was to determine the molecular mechanism of miR-205b targeting 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1) on the apoptosis and proliferation of granulosa cells (GC) of pigeons. Our previous studies suggested that HSD11B1 was the target gene of miR-205b and played a key role in steroid hormone biosynthesis and GC development. The adenovirus-miR-205b recombinant virus and adenovirus-cli-miR-205b-sh recombinant virus were generated, verified, and their characteristics determined. The recombinant viruses were used to infect the GC of pigeons, with real time quantitative PCR used to examine the expressions of HSD11B1 and related genes. The HSD11B1 antibody was obtained and verified, and Western blotting was used to detect the protein level of HSD11B1. The Cell Counting Kit-8 assay kit was used to detect cell viability, and the Annexin V-FITC/PI kit was used for the apoptosis assays. The expression of HSD11B1 was significantly lower in the overexpression (OE) than in OE negative control (OE-NC) treatments and significantly higher in short hairpin (SH) than in SH negative control (SH-NC) treatments. The expression levels of cytochrome P4503A5 was significantly higher in SH and lower in OE treatments, and the rhythms of cytochrome P450 aromatase mRNA levels were similar. The mRNA level of cytochrome P450scc in OE was lower than in OE-NC treatments and higher in SH than in SH-NC treatments. The protein expressions of HSD11B1 were decreased in the GC of OE, whereas increased in the SH group. The Cell Counting Kit-8 assay revealed that overexpression of miR-205b significantly suppressed proliferation of the GC of pigeons, whereas interference of miR-205b significantly induced the proliferation of the GC. The overexpression and the interference of miR-205b did not have a significant effect on cell cycle. The overexpression of miR-205b significantly increased the number of apoptotic cells, whereas the interference of miR-205b decreased the number of apoptotic cells. These findings indicated that miR-205b mediated pigeon egg production by regulating the steroid hormone biosynthesis of the pigeon ovarian GC by targeting HSD11B1, which may be useful in increasing pigeon egg production.

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Higher light wavelengths have been shown to stimulate extra-retinal photoreceptors more efficiently than lower wavelengths to promote reproduction in poultry. We developed a light emitting diode (LED) bulb that emits 60% of its light in the red spectrum (LED-R), and evaluated the effects of different light sources on growth and reproduction in commercial layer hens. Three rooms equipped with either 100W incandescent, 15W compact fluorescent (CFL), or 10W LED-R bulbs were populated with 96 Lohmann LSL-Lite layers housed in individual cages from 14 to 69 weeks of age (woa). Pullets were initially maintained on a 10-h photoperiod, then photostimulated at 18 woa. Surprisingly, regardless of the light source, plasma levels of estradiol peaked at 16 woa, 2 weeks before photostimulation, and egg-laying was initiated at 19 woa. As a direct correlation between age at first egg and body weight was identified, metabolic cues most likely served as a primary trigger to initiate sexual maturation prior to photostimulation. Overall egg production and cumulative egg numbers were similar among treatments. Interestingly, a second increase in estradiol was observed at 52 woa under all treatments, suggesting an additional ovarian stimulation, possibly associated with an additional follicular recruitment at that age. Overall, changes in estradiol concentrations were more pronounced in hens maintained under LED-R light than in hens exposed to incandescent and CFL, especially for the second increase, suggesting that a higher amount of red light leads to stronger ovarian activity. Maintaining hens under LED-R bulbs also resulted in lower feed consumption, which combined with the lower energy consumption of LED-bulbs (LED-R: 306 kW; incandescent: 2,514 kW; CFL: 422 kW) could reduce the production cost.

Effect of fluorescent vs. poultry-specific light-emitting diode lights on production performance and egg quality of W-36 laying hens

More energy-efficient, durable, affordable, and dimmable light-emitting diode (LED) lights are finding applications in poultry production. However, data are lacking on controlled comparative studies concerning the impact of such lights during the pullet rearing and subsequent laying phase. This study evaluated two types of poultry-specific LED light (PS-LED) vs. fluorescent light (FL) with regards to their effects on hen laying performance. A total of 432 Hy-Line W-36 laying hens were tested in two batches using four environmental chambers (nine cages per chamber and 6 birds per cage) from 17 to 41 weeks of age (WOA). Dim-to-red PS-LED and warm-white FL were used in the laying phase. The hens had been reared under a dim-to-blue PS-LED or a warm-white FL from 1 to 16 WOA. The measured performance variables included 1) timing of sexual maturity, 2) egg production performance, 3) egg quality, and 4) egg yolk cholesterol. Results showed that the two types of light used during the laying phase had comparable performance responses for all response parameters (P > 0.05) with a few exceptions. Specifically, eggs laid from hens in the PS-LED treatment had lower shell thickness (P = 0.01) and strength (P = 0.03) than those in the FL treatment at 41 WOA. The two types of light used during the rearing phase did not influence the 17 to 41 WOA laying performance, except that hens reared under the PS-LED laid eggs with lower shell thickness (P = 0.02) at 32 WOA as compared to hens reared under the FL. This study demonstrates that the emerging poultry-specific LED lights yield comparable production performance and egg quality of W-36 laying hens to the traditional fluorescent lights.

Effects of different monochromatic LED light colours on fear reactions and physiological responses in Mulard ducks

Although the effects of monochromatic light on behaviour and performance of birds have been extensively studied, it is not known how rearing Mulard ducks in different monochromatic lights affects their fear reactions, physiological responses to stress and welfare. A total of 108 newly hatched Mulard ducks, representing three replicates, were housed in either blue light (BL), green light (GL), red light (RL) or white light (WL) for 12 weeks. Ducks were exposed to a light/dark schedule of 23 L/1 D, and food and water were provided ad libitum. At the beginning of the 13th week of the rearing period, behavioural measurements of fear were assessed by using a tonic immobility test, open field test and fear of man test. Physiological responses of the birds to stress such as heterophil : lymphocyte ratio, total leukocyte count and plasma concentrations of corticosterone were also assessed. Results demonstrated that birds exposed to both RL and WL displayed higher levels of behavioural indicators of fear including tonic immobility durations (P < 0.01), latency to first immobilisation (P < 0.001) and avoidance of man index (P < 0.001), and higher levels of physiological indicators of stress such as heterophil : lymphocyte ratios (P < 0.001) and plasmas concentrations of corticosterone (P < 0.001), and lower total leukocytic counts (P < 0.01) compared with birds exposed to either BL or GL. Rearing Mulard ducks in BL or GL appeared to reduce their fear reactions and physiological responses to stress and to enhance their ability to cope with the environment and may therefore improve their welfare.

Analysis of Pigeon (Columba) Ovary Transcriptomes to Identify Genes Involved in Blue Light Regulation

Monochromatic light is widely applied to promote poultry reproductive performance, yet little is currently known regarding the mechanism by which light wavelengths affect pigeon reproduction. Recently, high-throughput sequencing technologies have been used to provide genomic information for solving this problem. In this study, we employed Illumina Hiseq 2000 to identify differentially expressed genes in ovary tissue from pigeons under blue and white light conditions and de novo transcriptome assembly to construct a comprehensive sequence database containing information on the mechanisms of follicle development. A total of 157,774 unigenes (mean length: 790 bp) were obtained by the Trinity program, and 35.83% of these unigenes were matched to genes in a non-redundant protein database. Gene description, gene ontology, and the clustering of orthologous group terms were performed to annotate the transcriptome assembly. Differentially expressed genes between blue and white light conditions included those related to oocyte maturation, hormone biosynthesis, and circadian rhythm. Furthermore, 17,574 SSRs and 533,887 potential SNPs were identified in this transcriptome assembly. This work is the first transcriptome analysis of the Columba ovary using Illumina technology, and the resulting transcriptome and differentially expressed gene data can facilitate further investigations into the molecular mechanism of the effect of blue light on follicle development and reproduction in pigeons and other bird species.

Human-Friendly Light-Emitting Diode Source Stimulates Broiler Growth

Previous study and our laboratory have reported that short-wavelength (blue and green) light and combination stimulate broiler growth. However, short-wavelength stimuli could have negative effects on poultry husbandry workers. The present study was conducted to evaluate the effects of human-friendly yellow LED light, which is acceptable to humans and close to green light, on broiler growth. We also aimed to investigate the potential quantitative relationship between the wavelengths of light used for artificial illumination and growth parameters in broilers. After hatching, 360 female chicks ("Meihuang" were evenly divided into six lighting treatment groups: white LED strips (400-700 nm, WL); red LED strips (620 nm, RL); yellow LED strips (580 nm, YL); green LED strips (514 nm, GL); blue LED strips (455 nm, BL); and fluorescent strips (400-700 nm, FL). From 30 to 72 days of age, broilers reared under YL and GL were heavier than broilers treated with FL (P < 0.05). Broilers reared under YL obtained the similar growth parameters with the broilers reared under GL and BL (P > 0.05). Moreover, YL significantly improved feeding efficiency when compared with GL and BL at 45 and 60 days of age (P < 0.05). In addition, we found an age-dependent effect of light spectra on broiler growth and a quantitative relationship between LED light spectra (455 to 620 nm) and the live body weights of broilers. The wavelength of light (455 to 620 nm) was found to be negatively related (R2 = 0.876) to live body weight at an early stage of development, whereas the wavelength of light (455 to 620 nm) was found to be positively correlated with live body weight (R2 = 0.925) in older chickens. Our results demonstrated that human-friendly yellow LED light (YL), which is friendly to the human, can be applied to the broilers production.

The effect of monochromatic photostimulation on growth and development of broiler birds

The only light source for chickens in environmentally controlled houses is an artificial one. Thus, source, spectra, intensity and regimen of light supplementation became major factors in modern meat type bird management. Light spectra affect growth in meat type birds both in ovo and post hatch. Broilers photostimulated in ovo with green light gained significantly more weight than birds incubated under dark conditions. Furthermore, we defined the cellular and molecular events associated with the effect of in ovo green photostimulation on muscle growth. We found that in ovo photostimulation have a stimulatory effect on the proliferation and differentiation of satellite cells and a promoting effect on the uniformity of the muscle fibers in the early post-hatch period. How does in ovo photostimulation affect intracellular events, such as proliferation and differentiation of muscle cells, leading to post-hatch muscle growth? It is possible that the monochromatic green light penetrates the eggshell and has a direct effect on the embryo's muscle. We were unable to detect any proliferative effect of monochromatic green light on cultured myoblasts derived from standard (un-illuminated) E17 embryos and 3-day-old chicks. A more likely explanation is that green light indirectly affects myoblast proliferation by activating the endocrine system; the latter receives photic cues from the retinal or extra-retinal photoreceptors. We gathered some evidence to support these findings; we have shown a higher expression of growth hormone (GH) receptor mRNA in satellite cells derived from green light illuminated chicks. In addition, plasma GH levels and IGF-I levels in muscle tissue, were higher in the green group relative to the dark one in early post-hatch. Another possible explanation for this phenomenon could be that growth factor secretion is activated in response to green light photostimulation. Both retinal and extra-retinal photoreceptors are active during embryogenesis and can be first detected at E14. Combinations of in ovo and post-hatch green light photostimulation to broilers and turkeys did not cause synergetic effect on growth. In a recent study, we found that in ovo green light photostimulation suppresses the green and red opsin receptors gene expression in the last three days before hatching, while red light enhances their expression. Furthermore, we found that the down-regulation of the green and red opsins in response to incubation under monochromatic green lighting lasted up to 9days post hatch, suggesting a possible epigenetic effect.

Japanese quail's genetic background modulates effects of chronic stress on emotional reactivity but not spatial learning

Chronic stress is known to enhance mammals' emotional reactivity and alters several of their cognitive functions, especially spatial learning. Few studies have investigated such effects in birds. We investigated the impact of a two-week stress on Japanese quail's emotional reactivity and spatial learning. Quail is an avian model widely used in laboratory studies and for extrapolation of data to other poultry species. As sensitivity to chronic stress can be modulated by intrinsic factors, we tested juvenile female Japanese quail from three lines, two of them divergently selected on tonic immobility duration, an indicator of general fearfulness. The different emotional reactivity levels of quail belonging to these lines can be revealed by a large variety of tests. Half of the birds were submitted to repeated unpredictable aversive events for two weeks, whereas the other half were left undisturbed. After this procedure, two tests (open field and emergence tests) evaluated the emotional reactivity of treated and control quails. They were then trained in a T-maze for seven days and their spatial learning was tested. The chronic stress protocol had an impact on resting, preening and foraging in the home cage. As predicted, the emotional reactivity of treated quails, especially those selected for long tonic immobility duration, was higher. Our spatial learning data showed that the treatment enhanced acquisition but not memorization. However, intrinsic fearfulness did not seem to interact with the treatment in this test. According to an inverted U-shaped relationship between stress and cognition, chronic stress can improve the adaptability of birds to a stressful environment. We discussed the mechanisms possibly implied in the increase of emotional reactivity and spatial abilities.

Influence of red light on reproductive performance, eggshell ultrastructure, and eye morphology in Thai-native hens

In total, 120 Thai-native pullets (Gallus domesticus) aged 18 wk were housed in floor pens, located in a conventional open-sided shed under natural daylight (12L:12D) and randomly divided into 3 groups; Groups 1 (DF) and 2 (DR) were reared under natural daylight and supplemented with fluorescent or red light, respectively, whereas group 3 (R) was maintained in light-controlled pens and exposed only to red light. The red light was produced by light-emitting diodes. All treatments were provided with 16 h of light per day (16L:8D) during a 26-wk egg-laying period, and there were 4 replicate pens of 10 hens for each treatment. Photostimulation of these light sources was initiated at 18 wk of age and subsequent effects on reproductive performance were observed during the experimental period. Morphological characteristics of the eyes and eggshell microstructure were examined at the end of the study. Feed and water were provided ad libitum. There were no significant differences in BW, feed intake, egg weight, egg quality, or mortality rate due to the treatment. Pullets in the R and DR treatment groups commenced egg production significantly earlier than those in the DF treatment group. In early-season egg production (0-8 wk), cumulative egg number was significantly (P < 0.05) higher for the R treatment (25.9 eggs/hen) than for the DR (20.9) and DF (19.5) treatment groups. No significant differences in total egg production per hen occurred among the treatment groups. At 2 wk following photostimulation, hens in the R treatment group had significantly (P < 0.05) higher serum estradiol concentrations compared with hens in the other treatment groups. Neither eggshell structure nor eye morphology was affected by the treatments. It was concluded that the spectrum of red light did not affect live performance, egg production, egg quality, eggshell microstructure, or eye morphology of Thai-native hens, except for in accelerating sexual development. The light-emitting diode lighting system would be beneficial for energy savings and the reduction of rearing costs.

Effect of embryonic photostimulation on the posthatch growth of turkey poults

Artificial illumination, including light quality, is important in modern meat-type poultry management. In the present study, the effect of in ovo monochromatic green light photostimulation on posthatch growth of turkey poults was investigated. In experiment 1, 182 turkey eggs were divided into two light treatment groups (n = 91). The first group was intermittently photostimulated (3 min on and 3 min off) with green light provided by five light-emitting diodes (LED) per egg at 0.1 W/m2 at the upper eggshell surface. The second group was incubated in the dark and served as the control. Posthatch BW were recorded at 0, 2, 6, 13, 20, 28, 35, and 59 d of age. A heavier BW, occurring at 28 d of age and persisting until the end of the experiment (59 d of age), was observed in the in ovo green light stimulated females as compared to their corresponding controls. In experiment 2, 273 turkey eggs were divided into three light treatment groups (n = 91). The first group was intermittently photostimulated (15 min on and 15 min off) with green light provided by seven LED per egg at 0.14 W/m2. The second group was photostimulated with white light provided by one mini-incandescent lamp per egg at light intensity and schedule similar to the first group. Eggs of the third group were incubated in the dark and served as controls. Posthatch BW were recorded at 0, 7, 14, 28, 42, 56, and 79 d of age. No differences were found among the BW of males incubated under different light conditions. As in experiment 1, female turkeys with stimulated green light in ovo had greater BW compared to their corresponding control and white light groups from 28 d of age until termination of the experiment at 79 d of age. Breast muscle weight was greater in female turkeys incubated under green light when compared to white and dark incubation treatment groups. We suggest that in ovo green light photostimulation enhances the posthatch BW of female turkey poults.

The effect of monochromatic light on broiler growth and development

Artificial illumination, including light quality, is crucial in modem broiler management. In the present study, a new, highly efficient, monochromatic light system has been developed for broilers. One hundred and eighty male broiler chicks (Anak) were divided into four light treatment groups (n = 45) in three replicates each. All birds were housed in a single room previously divided by wooden bars into 12 sealed cells of 1 m2. Feed and water were provided for ad libitum consumption. Light intensity was 0.1 W/m2 at the height of birds' heads and was scheduled for 23 h of light and 1 h of dark during the entire experimental period. Light treatments were: control white (mini-incandescent light bulbs), blue (480 nm), green (560 nm), and red (660 nm). Body weight was recorded periodically, feed consumption was measured daily, and feed efficiency was calculated. Blood samples were taken at 1, 9, and 32 d of age and plasma testosterone was determined. Two necropsies were conducted, at 23 and 35 d of age, and selected glands and organs were weighed. In the group reared under green light, a significant enhancement in weight gain was observed as early as 3 d of age; this gain was maintained during the entire experimental period. Broilers reared under blue light had a later onset of growth enhancement and were significantly heavier than those reared under white and red light at 20 d of age. Plasma testosterone levels were significantly higher in birds reared under blue light. Breast muscle weights were significantly higher in the birds reared under green light at 23 and 35 d of age. These results suggest that green and blue light stimulate growth.

New monochromatic light source for laying hens

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-fluorescent 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.

The effects of color and intensity of light on behavior and leg disorders in broiler chickens

Two experiments were conducted to investigate whether manipulating the wavelength and intensity of light could be used to increase activity and reduce locomotion disorders in meat chickens. The first experiment examined the effects of wavelength and intensity of light on bird activity. Male (n = 60) and female (n = 48) chicks were reared from Day 1 to 35 in red or blue light at three intensities. Walking, standing, drinking, aggression, and wing stretching increased with intensity in red but not blue light. In the second experiment, the effects of stimulating bird activity with bright red light in the early or late part of the rearing period on locomotion and leg disorders were examined. Male (n = 24) and female (n = 24) chicks were reared from Day 7 in either dim blue light to Day 55 (Treatment All Blue), or bright red light to Day 22, followed by dim blue light to Day 55 (Treatment Early Red), or dim blue light to Day 22, bright red light to Day 38, and dim blue light to Day 55 (Treatment Late Red). Bright red light considerably increased walking, feeding and stretching, particularly when applied early in the growth period. There were residual effects on activity after the birds had returned to dim blue light. Red light increased growth when provided at the beginning of the rearing period, but decreased it when provided later. Bone strength was reduced in treatment Late Red, which appeared to be related to the lower body weights of birds in this treatment. Bone length, weight, and torsion were not affected by treatment, but the tibia plateau angle was reduced by Early Red light in female birds. In Treatment All Blue, there was a high incidence of gait abnormalities, which was reduced by Early and Late Red light. It is concluded that rearing meat chickens in bright red light increases activity, which reduces locomotion disorders in the late rearing period. It is preferable to provide the stimulatory light early in the rearing period.

The effects of color of lighting on the behavior and production of meat chickens

Male and female meat chickens were reared for 28 d in blue, green, red, or white light at 30 lx and the effects on tissue growth and bird behavior recorded. Birds reared in red or white light were more active, as expressed by greater walking activity in the white light treatment and by greater floor-pecking, wing-stretching, and aggression in the red light treatment. In these two treatments, gut contents and skin and bone weights were reduced. After 28 d, the preference of the birds for blue, red, or green lights was determined, as well as residual effects of rearing color on bird growth. In the first few hours of the test, the birds chose to remain in their rearing color, except that the birds reared in red light quickly showed a preference for blue light. After 1 wk, birds in all treatments showed a preference for blue light, except that the birds reared in blue light showed some preference for a novel color, green. It was concluded that blue or green light is preferable to red or white light for broilers because it keeps the birds calmer and is chosen by the birds themselves.