Artificial polychromatic light affects growth and physiology in chicks

Effects of monochromatic light on hepatic glycogen and lipid synthesis in broilers

Animal growth is closely related to glycolipid metabolism, and the liver is the main organ for glycogen storage and fat synthesis in birds, but whether monochromatic light affects glycogen and lipid synthesis in the liver is unclear. Therefore, in this study, a total of 96 Arbor Acre (AA) broilers at posthatching d 0 (P0) were raised under 4 kinds of light-emitting diode (LED) lights, white light (WL), red light (RL), green light (GL), and blue light (BL), to posthatching d 21 (P21) and 35 (P35). The results showed that the liver, abdominal fat, and abdominal fat indices gradually increased with increasing age under monochromatic light treatments. The liver glycogen and triglyceride (TG) contents also showed an increasing trend. Furthermore, compared with those at P21, the mRNA levels of glycogen synthase (GS), glycogen synthase kinase-3β (GSK-3β), and protein kinase B (AKT1) in the liver were increased in the WL and RL groups at P35, and the mRNA levels of acetyl-CoA carboxylase (ACC) and apolipoprotein B (APOB) increased in all groups at P35. At the same time, the total antioxidant capacity (T-AOC) and liver superoxide dismutase (SOD) contents increased in all groups at P35 compared with those at P21. In addition, at P21, compared with WL, GL and BL promoted the serum glucose (GLU) and TG contents by increasing the mRNA levels of GS, GSK-3β, glucose-6-phosphatase (G6PC), ACC, and fatty acid synthase (FAS), but no effect on the proliferative ability and damage of hepatocytes. At P35, RL promoted the hepatic glycogen and TG contents by increasing GSK-3β, AKT1, ACC, and APOB mRNA levels, and the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were increased than in the WL group. These results suggest that the effects of light color on liver glycogen and lipid synthesis in broilers changed with age, and also provide a theoretical guidance for scientific use of color of light information to improve productive performance in broilers.

Features of development of visceral organs in embryos of egg cross chickens ‘Lohmann Brown’ under red and green monochromatic LED lighting

New data on the features of development of visceral organs in embryos of egg cross chickens Lohmann Brown under red and green monochromatic LED lighting were obtained. The effect of two continuous LED lighting modes has been studied: experimental modes - r ed and green light, control - d arkness. The absolute values of weight dimensions and specific growth rate (according to the Schmalhausen-Brody formula) of heart, muscular stomach, liver of chicken embryos were estimated using morphometric methods. The studies proved that red and green LED lighting has a stimulating effect on the embryonic development of visceral organs (heart, muscular stomach, liver) in Lohmann Brown egg cross compared to the control (darkness). Under red and green LED stimulation, chicken embryos prevailed in the heart mass from the 14th to the 20th day of embryogenesis. The muscular stomach and liver of chicken embryos developed more intensively under red illumination on the 18th and 20th days, and under green illumination - a similar effect on the muscular stomach was noted on the 19th and 20th days, on the liver - o n the 20th day. It has been established that in the early ontogenesis of Lohmann Brown chickens there were several critical stages (phases). They fall on different days of development and characterize the features of rhythmicity in growth processes of visceral organs in chicken embryogenesis under LED stimulation of red and green spectrum. Chicken embryos under red and green illumination had the highest growth rate of heart on the 17th and 20th day, respectively; muscular stomach under red illumination - o n the 17th and 20th days, liver - on the 16th and 17th day under red and green illumination. By the hatching period on the 20th day, there were no differences in the development of visceral organs of chicken embryos depending on red and green light spectrum. The hatching of Lohmann Brown chicken embryos exposed to red and green light occurred on the 20th day of incubation - a day earlier than under control conditions (darkness). The proposed biological causes underlying the effect of monochromatic light of different color spectrum on embryogenesis of chicken embryo and organs are discussed.

Stress and immunity in poultry: light management and nanotechnology as effective immune enhancers to fight stress

The poultry industry plays a significant role in boosting the economy of several countries, particularly developing countries, and acts as a good, cheap, and affordable source of animal protein. A stress-free environment is the main target in poultry production. There are several stressors, such as cold stress, heat stress, high stocking density, and diseases that can affect birds and cause several deleterious changes. Stress reduces feed intake and growth, as well as impairs immune response and function, resulting in high disease susceptibility. These effects are correlated with higher corticosteroid levels that modulate several immune pathways such as cytokine-cytokine receptor interaction and Toll-like receptor signaling along with induction of excessive production of reactive oxygen species (ROS) and thus oxidative stress. Several approaches have been considered to boost bird immunity to overcome stress-associated effects. Of these, dietary supplementation of certain nutrients and management modifications, such as light management, are commonly considered. Dietary supplementations improve bird immunity by improving the development of lymphoid tissues and triggering beneficial immune modulators and responses. Since nano-minerals have higher bioavailability compared to inorganic or organic forms, they are highly recommended to be included in the bird's diet during stress. Additionally, light management is considered a cheap and safe approach to control stress. Changing light from continuous to intermittent and using monochromatic light instead of the normal light improve bird performance and health. Such changes in light management are associated with a reduction of ROS production and increased antioxidant production. In this review, we discuss the impact of stress on the immune system of birds and the transcriptome of oxidative stress and immune-related genes, in addition, how nano-minerals supplementations and light system modulate or mitigate stress-associated effects.

Metabolism of Melatonin Synthesis-Related Indoles in the Turkey Pineal Organ and Its Modification by Monochromatic Light

The metabolism of pineal indoles is closely related to alterations in the light and dark phases of a daily cycle. Recent research showed important interspecies differences in the pineal biochemistry, and a strong impact of monochromatic light on many physiological processes in birds. Therefore, the aims of study were to characterize the metabolism of melatonin-synthesis indoles in the pineal organ of the domestic turkey, and to determine the changes occurring in this metabolism under the influence of different wavelengths and intensities of light. For this purpose, 3-week-old turkeys were kept under 16 lx white light, or under blue, green, and red light with intensities of 16, 32, and 64 lx during the photophase, and after 7 d were sacrificed at 4 h intervals. The activities of melatonin-synthesizing enzymes and the contents of indoles were measured in the same pineal organ. The results revealed that the activities of tryptophan hydroxylase and arylalkylamine N-acetyltransferase, and the levels of all tryptophan derivatives had significant daily changes in birds kept under each light condition used. The profile of pineal indole metabolism in 4-week-old turkeys was characterized by high-amplitude rhythms in the activity of arylalkylamine N-acetyltransferase and the contents of N-acetylserotonin and melatonin, equal relative amounts of serotonin and 5-hydroxyindoleacetic acid, and higher content of melatonin than N-acetylserotonin. The monochromatic light significantly modified the pineal indole metabolism, and its effects were dependent on the color and intensity of light. Pronounced changes occurred in the level of serotonin synthesis and the daily rhythm course of melatonin synthesis.

The effect of supplementary ultraviolet wavelengths on the performance of broiler chickens

Qualities of the light environment, such as the spectral composition of light, have been shown to impact growth and performance of broiler chickens. UVA light is visible to broiler chickens, whereas UVB wavelengths promote endogenous vitamin D synthesis, which could support their rapid development. The aim of the current study was to investigate the impacts of supplementary UVA and UVB wavelengths on performance indicators of broiler chickens. Day-old Ross 308 chicks (n = 638), reared to a target stocking density of 33 kg/m², were randomly assigned to 1 of 3 lighting treatments: A) White light emitting diode (LED) and supplementary UVA LED lighting (18-h photoperiod); B) White LED with supplementary UVA and UVB fluorescent lighting providing 30 μW/cm² UVB at bird level (lights on for 8 h of the total photoperiod to avoid overexposure of UVB); and C) White LED control group, representative of farm conditions (18-h photoperiod). Mortality was recorded, and broiler chickens were individually weighed at 8, 15, 22, 27, and 34 D of age. Generalized linear models and nonlinear mixed effects models (Gompertz curve) were fitted to determine the effects of UV wavelengths on broiler mortality and growth performance. UV did not impact breast or leg weight of broiler chickens but was associated with differences in mortality, growth, and end weight. Broiler chickens provided with UVA for the full 18-h photoperiod had slower initial growth than control broilers and a reduction in mortality. Results from male broilers reared with supplementary UVA + UVB for 8 h indicated they could reach finishing weights sooner than controls, which supports the potential for UVA + B to improve the growth performance of males. Results suggest that the provision of supplementary UVA + UVB wavelengths may improve the performance of male broiler chickens. The reduction in mortality in the UVA only treatment may warrant further investigation. The inclusion of UV wavelengths within poultry lighting regimes represents a promising area of further study.

Exposure to artificial light at night during the larval stage has delayed effects on juvenile corticosterone concentration in American toads, Anaxyrus americanus

Artificial Light At Night (ALAN) is an environmental stressor that can disrupt individual physiology and ecological interactions. Hormones such as corticosterone are often responsible for mediating an organism's response to environmental stressors. We investigated whether ALAN was associated with a corticosterone response and whether it exacerbated the effects of another common stressor, predation. We tested for consumptive, non-consumptive, and physiological effects of ALAN and predator presence (dragonfly larvae) on a widespread amphibian, the American toad (Anaxyrus americanus). We found predators had consumptive (decreased survival) and non-consumptive (decreased growth) effects on larval toads. ALAN did not affect larval toads nor did it interact with the predator treatment to increase larval toad predation. Despite the consumptive and non-consumptive effects of predators, neither predators nor ALAN affected corticosterone concentration in the larval and metamorph life-stages. In contrast to studies in other organisms, we did not find any evidence that suggested ALAN alters predator-prey interactions between dragonfly larvae and toads. However, there was an inverse relationship between corticosterone and survival that was exacerbated by exposure to ALAN when predators were absent. Additionally, larval-stage exposure to ALAN increased corticosterone concentration in juvenile toads. Our results suggest the physiological effects of ALAN may not be demonstrated until later life-stages.

The Clock Keeps Ticking: Circadian Rhythms of Free-Ranging Polar Bears

Life in the Arctic presents organisms with multiple challenges, including extreme photic conditions, cold temperatures, and annual loss and daily movement of sea ice. Polar bears ( Ursus maritimus) evolved under these unique conditions, where they rely on ice to hunt their main prey, seals. However, very little is known about the dynamics of their daily and seasonal activity patterns. For many organisms, activity is synchronized (entrained) to the earth’s day/night cycle, in part via an endogenous (circadian) timekeeping mechanism. The present study used collar-mounted accelerometer and global positioning system data from 122 female polar bears in the Chukchi and Southern Beaufort Seas collected over an 8-year period to characterize activity patterns over the calendar year and to determine if circadian rhythms are expressed under the constant conditions found in the Arctic. We reveal that the majority of polar bears (80%) exhibited rhythmic activity for the duration of their recordings. Collectively within the rhythmic bear cohort, circadian rhythms were detected during periods of constant daylight (June-August; 24.40 ± 1.39 h, mean ± SD) and constant darkness (23.89 ± 1.72 h). Exclusive of denning periods (November-April), the time of peak activity remained relatively stable (acrophases: ~1200-1400 h) for most of the year, suggesting either entrainment or masking. However, activity patterns shifted during the spring feeding and seal pupping season, as evidenced by an acrophase inversion to ~2400 h in April, followed by highly variable timing of activity across bears in May. Intriguingly, despite the dynamic environmental photoperiodic conditions, unpredictable daily timing of prey availability, and high between-animal variability, the average duration of activity (alpha) remained stable (11.2 ± 2.9 h) for most of the year. Together, these results reveal a high degree of behavioral plasticity in polar bears while also retaining circadian rhythmicity. Whether this degree of plasticity will benefit polar bears faced with a loss of sea ice remains to be determined.

Artificial light at night decreases metamorphic duration and juvenile growth in a widespread amphibian

Artificial light at night (ALAN) affects over 20% of the earth's surface and is estimated to increase 6% per year. Most studies of ALAN have focused on a single mechanism or life stage. We tested for indirect and direct ALAN effects that occurred by altering American toads' (Anaxyrus americanus) ecological interactions or by altering toad development and growth, respectively. We conducted an experiment over two life stages using outdoor mesocosms and indoor terraria. In the first phase, the presence of ALAN reduced metamorphic duration and periphyton biomass. The effects of ALAN appeared to be mediated through direct effects on toad development, and we found no evidence for indirect effects of ALAN acting through altered ecological interactions or colonization. In the second phase, post-metamorphic toad growth was reduced by 15% in the ALAN treatment. Juvenile-stage ALAN also affected toad activity: in natural light, toads retreated into leaf litter at night whereas ALAN toads did not change behaviour. Carry-over effects of ALAN were also present; juvenile toads that had been exposed to larval ALAN exhibited marginally increased activity. In this time frame and system, our experiments suggested ALAN's effects act primarily through direct effects, rather than indirect effects, and can persist across life stages.

The effect of 580 nm-based-LED mixed light on growth, adipose deposition, skeletal development, and body temperature of chickens

Though previous study indicated that the 580 nm-yellow-LED-light showed an stimulating effect on growth of chickens, the low luminous efficiency of the yellow LED light cannot reflect the advantage of energy saving. In present study, the cool white LED chips and yellow LED chips have been combined to fabricate the white × yellow mixed LED light, with an enhanced luminous efficiency. A total 300 newly hatched chickens were reared under various mixed LED light. The results indicated that the white × yellow mixed LED light had "double-edged sword" effects on bird's body weight, bone development, adipose deposition, and body temperature, depending on variations in ratios of yellow component. Low yellow ratio of mixed LED light (Low group) inhibited body weight, whereas medium and high yellow ratio of mixed LED light (Medium and High groups) promoted body weight, compared with white LED light (White group). A progressive change in yellow component gave rise to consistent changes in body weight over the entire experiment. Moreover, a positive relationship was observed between yellow component and feed conversion ratio. High group-treated birds had greater relative abdominal adipose weight than Medium group-treated birds (P = 0.048), whereas Medium group-treated birds had greater relative abdominal adipose weight than Low group-treated birds (P = 0.044). We found that mixed light improved body weight by enhancing skeletal development (R² = 0.5023, P = 0.0001) and adipose deposition (R² = 0.6012, P = 0.0001). Birds in the Medium, High and Yellow groups attained significantly higher surface temperatures compared with the White group (P = 0.010). The results suggest that the application of the mixed light with high level of yellow component can be used successfully to improve growth and productive performance in broilers.

Artificial light and biological responses of broiler chickens: dose-response

Light intensity is an important aspect for broiler production. However, previous results do not provide a solid scientific basis for quantifying the response of broilers to light intensity. This study performed a meta-analysis to model the response of broilers to 0.1-200 lux of light intensity. Meta-analysis was used to integrate smaller studies and increase the statistical power over that of any single study and explore new hypotheses. The results indicated that light intensity <5 lux caused welfare concern (P < 0.05) and light intensity <1 lux induced productivity loss of broiler (P < 0.05), whereas greater level of light intensity >10 lux led to increased mortality (P < 0.01) and decreased uniformity (P < 0.05). Meta-regression showed that 30-200 lux light intensity was negatively related to BW (P = 0.047) and feed intake change (P = 0.054), whereas a quadratic relationship was observed between feed conversion ratio change and 50-180 lux light intensity (R2 = 0.95). In addition, the majority of carcass characteristics (abdominal fat weight and wing weight) and metabolic indicators (K+, Ca2+, and T3) were affected by light intensity >5 lux. To conclude, this meta-analysis based on published data quantitatively identified that 5 lux of light intensity during grow-out period should be the minimum level to maintain a well productivity and welfare of broiler chickens.

Modulatory Effect of Monochromatic Blue Light on Heat Stress Response in Commercial Broilers

In a novel approach, monochromatic blue light was used to investigate its modulatory effect on heat stress biomarkers in two commercial broiler strains (Ross 308 and Cobb 500). At 21 days old, birds were divided into four groups including one group housed in white light, a second group exposed to blue light, a 3rd group exposed to white light + heat stress, and a 4th group exposed to blue light + heat stress. Heat treatment at 33°C lasted for five h for four successive days. Exposure to blue light during heat stress reduced MDA concentration and enhanced SOD and CAT enzyme activities as well as modulated their gene expression. Blue light also reduced the degenerative changes that occurred in the liver tissue as a result of heat stress. It regulated, though variably, liver HSP70, HSP90, HSF1, and HSF3 gene expression among Ross and Cobb chickens. Moreover, the Cobb strain showed better performance than Ross manifested by a significant reduction of rectal temperature in the case of H + B. Furthermore, a significant linear relationship was found between the lowered rectal temperature and the expression of all HSP genes. Generally, the performance of both strains by most assessed parameters under heat stress is improved when using blue light.

A new method to manipulate broiler chicken growth and metabolism: Response to mixed LED light system

Present study introduced a new method to manipulate broiler chicken growth and metabolism by mixing the growth-advantage LED. We found that the green/blue LED mixed light system (G-B and G × B) have the similar stimulatory effect on chick body weight with single green light and single blue light (G and B), compared with normal artificial light (P = 0.028). Moreover, the percentage of carcass was significantly greater in the mixed light (G × B) when compared with the single light (P = 0.003). Synchronized with body weight, the mixed light (G-B and G × B) had a significant improved influence on the feed conversion of birds compared with normal light (P = 0.002). A significant improvement in feed conversion were found in mixed light (G × B) compared with single LED light (P = 0.037). G group resulted in a greater high-density lipoprotein cholesterol level than B group (P = 0.002), whereas B group resulted in a greater low-density lipoprotein cholesterol level than G group (P = 0.017). The mixed light significantly increased the birds’ glucose level in comparison with the single light (P = 0.003). This study might establish an effective strategy for maximizing growth of chickens by mixed LED technology.

The relationship of spectral sensitivity with growth and reproductive response in avian breeders (Gallus gallus)

A previous study demonstrated that birds that are exposed to light at night develop advanced reproductive systems. However, spectrum might also affect the photoperiodic response of birds. The present study was aimed to investigate the effects of spectral composition on the growth and reproductive physiology of female breeders, using pure light-emitting diode spectra. A total of 1,000 newly hatched female avian breeders (Gallus gallus) were equally allocated to white-, red-, yellow-, green- and blue-light treated groups. We found that blue-light treated birds had a greater and faster weight gain than did red- and yellow-light treated birds (P = 0.02 and 0.05). The red light expedited the sexual maturation of the chicks, whose age at sexual maturity was 7 and 14 days earlier than that of the green- and blue-light treated birds, respectively. The accumulative egg production of the red-light treated birds was 9 and 8 eggs more than that of the blue- and green-light treated birds. The peak lay rate of the red-light treated groups was significantly greater than the blue-light treated birds (P = 0.028). In conclusion, exposure to short-wavelength light appears to promote growth of female breeder birds, whereas exposure to long-wavelength light appears to accelerate reproductive performance.

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.