Effects of lighting schedule during incubation of broiler chicken embryos on leg bone development at hatch and related physiological characteristics

Effects of incubation lighting with green or white light on brown layers: Hatching performance, feather pecking and hypothalamic expressions of genes related with photoreception, serotonin and stress systems

The aim of this study was to evaluate the effect of 16L:8D photoperiod with green (GREEN) or white (WHITE) lights during incubation on hatching performance, blood melatonin, corticosterone, and serotonin levels, hypothalamic expressions of genes related to photoreception, serotonin, and stress systems in layers in relation with feather pecking behavior. Dark incubation (DARK) was the control. Eggs (n = 1,176) from Brown Nick breeders in 2 batches (n = 588/batch) were incubated in the experiment. A total of 396 female chicks and 261 hens were used at rearing and laying periods until 40 wk. Incubation lighting did not affect hatchability, day-old chick weight, and length, but resulted in a more synchronized hatch as compared with the DARK. The effect of incubation lighting on blood hormones was not significant except for reduced serotonin in the GREEN group at the end of the experiment. There was no effect of incubation lighting on gentle, severe, and aggressive pecking of birds during the early rearing period. From 16 wk, GREEN hens showed increased gentle pecking with increasing age. WHITE hens had the highest gentle pecking frequency at 16 wk while they performed less gentle but higher severe and aggressive pecks at 24 and 32 wk. At hatching, the hypothalamic expression of CRH, 5-HTR1A, and 5-HTR1B was higher for the WHITE group compared with both GREEN and DARK, however, 5-HTT expression was higher in GREEN than WHITE which was similar to DARK. Except for the highest VA opsin expression obtained for WHITE hens at 40 wk of age, there was no change in hypothalamic expression levels of rhodopsin, VA opsin, red, and green opsins at any age. Although blood hormone levels were not consistent, results provide preliminary evidence that incubation lighting modulates the pecking tendencies of laying hens, probably through the observed changes in hypothalamic expression of genes related to the serotonin system and stress. Significant correlations among the hypothalamic gene expression levels supplied further evidence for the associations among photoreception, serotonin, and stress systems.

Effect of blue and red monochromatic light during incubation on the early post-embryonic development of immune responses in broiler chicken

1. The light regime during incubation can influence embryonic and post-embryonic life and its effects can be mediated by rhythmic melatonin production in the embryonic pineal gland.2. This study explored whether the incubation of chick embryos under red or blue monochromatic light, which induces maximum and minimum melatonin production, respectively, can influence the development and reactivity of the immune system in chicks.3. In hatchlings, basal expression of immune genes (AvBD-1, PSEN-1, and IL-6) was evaluated in the duodenum using real-time PCR. The expression of these genes was measured weekly for three weeks after hatching, 3 h after intraperitoneal lipopolysaccharide (LPS) injection. At these times, the heterophile/lymphocyte ratio (He/Ly) was evaluated on blood smears, plasma immunoglobulin Y (IgY) concentrations by ELISA and IL-6 gene expression in the spleen by real-time PCR were determined.4. During development, the He/Ly ratio and plasma IgY concentration were not significantly influenced by the light quality during incubation. Red light increased gene expression of AvBD-1 in hatchlings and IL-6 in two-week-old chickens compared to birds incubated under blue light. The expression of IL-6 after LPS stimulation increased in an age-dependent manner, both in the duodenum and the spleen, reflecting the maturation of the immune system.5. The results suggested that red light may increase the local immune response in the gut immediately after hatching, but this effect was not apparent during later development.

Melatonin, Its Beneficial Effects on Embryogenesis from Mitigating Oxidative Stress to Regulating Gene Expression

Embryogenesis is a complex multi-stage process regulated by various signaling molecules including pineal and extrapineal melatonin (MT). Extrapineal MT is found in the placenta and ovaries, where it carries out local hormonal regulation. MT is necessary for normal development of oocytes, fertilization and subsequent development of human, animal and avian embryos. This review discusses the role of MT as a regulator of preimplantation development of the embryo and its implantation into endometrial tissue, followed by histo-, morpho- and organogenesis. MT possesses pronounced antioxidant properties and helps to protect the embryo from oxidative stress by regulating the expression of the NFE2L2, SOD1, and GPX1 genes. MT activates the expression of the ErbB1, ErbB4, GJA1, POU5F1, and Nanog genes which are necessary for embryo implantation and blastocyst growth. MT induces the expression of vascular endothelial growth factor (VEGF) and its type 1 receptor (VEGF-R1) in the ovaries, activating angiogenesis. Given the increased difficulties in successful fertilization and embryogenesis with age, it is of note that MT slows down ovarian aging by increasing the transcription of sirtuins. MT administration to patients suffering from infertility demonstrates an increase in the effectiveness of in vitro fertilization. Thus, MT may be viewed as a key factor in embryogenesis regulation, including having utility in the management of infertility.

Melatonin: Effects on Cartilage Homeostasis and Therapeutic Prospects in Cartilage-related Diseases

Cartilage is a relatively simple connective tissue that plays a variety of roles in the human body, including joint support and protection, load bearing of the intervertebral discs, joint lubrication, formation of the external structure of the ears and nose and support of the trachea. The maintenance of cartilage homeostasis is therefore crucial. Cartilage-related diseases are difficult to diagnose and treat because their molecular and pathological mechanisms are not fully understood. Melatonin, which has a wide range of physiological effects, is an endocrine hormone mainly secreted by the pineal gland. Its biological effects include its antioxidant, antiaging, analgesic, and hypnotic effects and its ability to stabilize the circadian rhythm. In recent years, research on cartilage homeostasis and melatonin has been increasing, and melatonin has gradually been used in the treatment of cartilage-related diseases. Therefore, this article will briefly review the role of melatonin in cartilage homeostasis, including its anti-inflammatory effects and effects in protecting cartilage from damage by other factors and promoting chondrocyte growth and the expression of cartilage-related genes. Based on the above, the current status and future developmental direction of melatonin in the treatment of cartilage-related diseases are also discussed, demonstrating the broad prospects of melatonin in maintaining cartilage homeostasis and treating cartilage injury-related diseases.