Key words:Behavior, Broilers, Fear Response, Monochromatic LED Light, Performance.The present study aimed to investigate the effect of rearing avian broiler under different monochromatic LED light color on their growth performance, physiological and fear responses. One hundred and thirty five unsexed day-old avian 48 chicks were randomly allocated into three light treatment (n=45 bird) each treatment 3 replicates (n=15 bird). The treatments were white, green, and blue light. The obtained results demonstrated that, broilers reared under blue and green light had higher body weight, weight gain, feed intake, carcass weight, carcass percent, hemoglobin, red blood cells, packed cell volume, total leucocytes count, lymphocytes, total protein, albumin, globulin and lower feed conversion ratio, bursa, liver, spleen relative weight, heterophils: lymphocytes ratio, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase compared with white light. Moreover, blue and green lights reared birds showed short tonic immobility duration and high levels of exploration in the open field test. In conclusion, rearing broilers under blue and green light for 23 h per day improve growth performance, physiological response, welfare, reduce stress and fear responses.

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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.

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Aims Heat stress (HS) is one of the most serious problems of poultry production. Copper (Cu) is an essential trace element that plays a crucial role in the organism defence against oxidative stress. Because of the low mineral availability of the commercial Cu salts, in a novel approach, copper oxide nanoparticles (CuO-NPs) were used to alleviate chronic heat stress-induced degenerative changes in two commercial broiler strains (Ross 308 and Cobb 500). Methods Birds of each broiler strain were divided into six groups, with three replicates each. The first group (N1) received 100% of the recommended Cu requirements as CuO and was housed under normal temperature (24 ± 2°C), the second and third groups (N2 and N3 respectively) received 100% and 50% of the recommended Cu requirements as CuO-NPs and were housed under normal temperature. The fourth, fifth and sixth groups (H1, H2 and H3 respectively) received the same level of Cu supplementation as did the first, second and third groups respectively, and they were housed under normal temperature until the age of 21 days, and then exposed to HS (33 ± 2°C/5 h per day for two successive weeks). Key results Dietary supplementation with CuO-NPs during HS altered the HS-induced responses of the birds, as confirmed by decreased liver malondehyde (MDA) concentration and enhanced superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx1) mRNA expression levels and enzyme activities (P < 0.001), with a distinct linear association between the gene expression level and enzyme activity. Copper oxide NPs also reduced HS-induced degenerative changes in the hepatic tissue. These nanoparticles modulated, although variably, liver HS protein 70 (HSP70), HS protein 90 (HSP90) and HS factor 3 (HSF3) mRNA transcript levels among Ross and Cobb chickens following HS (P < 0.001). Performance of both strains under HS was improved (as shown by a marked reduction in body temperature (P < 0.001) and a higher bodyweight (P < 0.01)) when CuO-NPs were supplemented in the diet, especially for the birds receiving 50% of the recommended Cu requirement, with different responses being noted in the two strains studied. Conclusion CuO-NPs could be used as a good alternative source of Cu in poultry nutrition during summer. Implications Dietary supplementation of CuO-NPs, especially at 50% of the birds’ recommended requirement, during heat stress could enhance bird performance, lower bird temperature and increase its resistance to negative consequences of elevated temperature.

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.