Changes of Plasma Growth Hormone, Insulin-Like Growth Factors-I, Thyroid Hormones, and Testosterone Concentrations in Embryos and Broiler Chickens Incubated under Monochromatic Green Light

Improved cell proliferation and testosterone secretion following exposure of TM3 Leydig cells to three-dimensional scaffold and light emitting diode

Green LED and three-dimensional (3D) scaffolds have recently received extensive attentions due to their impact on cell proliferation and differentiation. Melatonin, a circadian rhythm-regulating hormone, is involved in some physiological phenomena including testosterone biosynthesis. Lower testosterone biosynthesis results in some disorders such as puberty retarding, andropause, and muscle weakness. Therefore, our aim was to investigate the proliferation of Leydig cells and their testosterone-related Gene expression and secretion under the influence of 3D scaffold, green light and melatonin. The experimental groups of TM3 cells embedded in the 3D scaffold, were exposed to green light, melatonin, both and all three factors. Expression of cell cycle genes including PCNA, CYCLIND1, CDC2 and CDKN1B, and testosterone related genes; GATA4 and RORα were also examined. 3D scaffold enhanced Leydig cells proliferation, and testosterone-related genes expression. While melatonin decreased cell proliferation and testosterone-related genes expression. Green light did not significantly change the results but slightly decreased cell proliferation and testosterone synthesis. The combination of green light with melatonin significantly reduced the proliferation rate of TM3 cells and the expression of steroidogenic genes, while the combination of green light with scaffold improved the results. In general, the use of scaffolding enhances proliferation and testosterone-related genes expression of TM3 Leydig cells. Also, application of green light and scaffolding reduces the deleterious effects of melatonin on these cells.

The effect of selected in ovo green light photostimulation periods on post-hatch broiler growth and somatotropic axis activity

Targeted in ovo green light (GL) photostimulation during the last days of broiler egg incubation increases embryonic expression of the somatotropic axis, similar to in ovo green light photostimulation from embryonic day (ED) 0 to the end of incubation. The aim of this study was to examine the effect of selected in ovo GL photostimulation periods on post-hatch broiler growth. Four hundred twenty fertile broiler eggs were divided into 7 treatment groups: the first incubated in the dark (standard conditions) as a negative control; the second incubated under monochromatic GL from ED0-ED20 (positive control); the third group incubated under monochromatic GL light from ED15-ED20; the fourth, fifth and sixth groups were incubated under monochromatic GL on ED16, ED17, and ED18, respectively; and the seventh group was incubated under monochromatic GL from ED18-ED20. All illumination was provided intermittently using LED lamps. After hatch, all chicks were transferred to a controlled room under standard rearing conditions. The group incubated under green light from ED18 until hatch showed similar results to the positive control group in body weights, as well as breast muscle weights (as % of body weights), and an elevation in the somatotropic axis activity during the experiment. We suggest that broiler embryos can be exposed to in ovo GL photostimulation from ED18 until hatch (hatching period), and still exhibit the same performance as obtained by photostimulation from d 0 of incubation.

Effect of embryonic and post-hatch photo-stimulation with variable light sources on hatchability, endocrine parameters and growth performance in broiler chicken

The objective of this study was to investigate the effects of embryonic and post-hatch photo-stimulation with variable light sources with respect to hatchability parameters, hormonal profile and growth performance of commercial broiler chicken. Uniform sized Cobb broiler eggs (174) were procured from commercial hatchery and incubated in three different groups with arrangement of variable colour light source [Control group; Red light photo-stimulated (675 nm); Green light photo-stimulated group (575 nm) of light]. After hatching, as per earlier grouping, chicks hatched out from respective groups reared under continuous lighting in normal, red, green light up to six week of age in standard management condition in battery cages. The result of the present study indicated that photo-stimulation of incubated eggs with different lights sources had no significant effect on hatchability percentage and hatching time. Green light photo-stimulated group showed significantly higher body weight gain with better feed conversion ratio than red and control groups from 0 to 6 wk of age. Feed intake did not differ significantly within the groups. Green light photo-stimulation promotes growth performance traits via stimulating circulating level of gonadal axis and somatotrophic axis hormone. The results of the study provide evidence that green light photo-stimulation used in this study is beneficial in terms of improved growth performance without affecting hatchability in broiler chicken.

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

Providing a broiler chicken embryo with a lighting schedule during incubation may stimulate leg bone development. Bone development may be stimulated through melatonin, a hormone released in darkness that stimulates bone development, or increased activity in embryos exposed to a light-dark rhythm. Aim was to investigate lighting conditions during incubation and leg bone development in broiler embryos, and to reveal the involved mechanisms. Embryos were incubated under continuous cool white 500 lux LED light (24L), continuous darkness (24D), or 16h of light, followed by 8h of darkness (16L:8D) from the start of incubation until hatching. Embryonic bone development largely takes place through cartilage formation (of which collagen is an important component) and ossification. Expression of genes involved in cartilage formation (col1α2, col2α1, and col10α1) and ossification (spp1, sparc, bglap, and alpl) in the tibia on embryonic day (ED)13, ED17, and at hatching were measured through qPCR. Femur and tibia dimensions were determined at hatch. Plasma growth hormone and corticosterone and pineal melatonin concentrations were determined every 4h between ED18.75 and ED19.5. Embryonic heart rate was measured twice daily from ED12 till ED19 as a reflection of activity. No difference between lighting treatments on gene expression was found. 24D resulted in higher femur length and higher femur and tibia weight, width, and depth at hatch than 16L:8D. 24D furthermore resulted in higher femur length and width and tibia depth than 24L. Embryonic heart rate was higher for 24D and 16L:8D in both its light and dark period than for 24L, suggesting that 24L embryos may have been less active. Melatonin and growth hormone showed different release patterns between treatments, but the biological significance was hard to interpret. To conclude, 24D resulted in larger leg bones at hatch than light during incubation, but the underlying pathways were not clear from present data.

In-ovo green light photostimulation during different embryonic stages affect somatotropic axis

Previous studies demonstrated that in-ovo photostimulation with monochromatic green light increased the somatotropic axis expression in broilers embryos. The objective of the current study was to detect the critical period for in-ovo GL photostimulation, in order to find the optimal targeted photostimulation period during the incubation process. Three hundred thirty-six fertile broiler eggs were divided into 4 groups. The first group was incubated under dark conditions as a negative control. The second incubated under intermittent monochromatic green light using light-emitting diode (LED) lamps with an intensity of 0.1 W\m2 at shell level from d 0 of the incubation as a positive control. The third group incubated under intermittent monochromatic green light from d 10 of the incubation. The last group incubated under intermittent monochromatic green light from d 15 of the incubation. In-ovo green light photostimulation from embryonic d 0 (ED0) increased plasma growth hormone (GH), as well as hypothalamic growth hormone releasing hormone (GHRH) and liver growth hormone receptor (GHR) and insulin-like growth factor-1 (IGF-1) mRNA levels. In-ovo green light photostimulation from ED10 increased the GH plasma levels compared to the negative control group, without affecting somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1. In-ovo green light photostimulation from ED15 caused an increase in both the plasma GH levels and the somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1, compared to the negative control group. These results suggest that the critical period of somatotropic axis acceleration by GL photostimulation start at 15 d of incubation.