N-Carbamylglutamate in ovo feeding improves carcass yield, muscle fiber development, and meat quality in broiler chickens

BACKGROUND

Insufficient endogenous nutrients in the broiler embryo can lead to muscle gluconeogenesis, which ultimately affects the post-hatching performance of chicks. This study investigated the effects of in ovo feeding (IOF) of N-carbamylglutamate (NCG) on the growth hormones, carcass yield, and meat quality in broilers. Fertile eggs from a 30-week-old Ross 308 breeder flock were divided into three treatment groups: NC (non-injection), SC (100 μL saline-injection), and NCG (2 mg NCG injection). Each group had six replicates, with 70 eggs per replicate during incubation. Injections were administered on the 17.5th day of embryonic development. After hatching, 270 chicks were selected for 42-day rearing for further sampling.

RESULTS

Chicks in the NCG group had significantly higher body weight (BW) and average daily gain (ADG) at the growing phase, increased growth and testosterone hormone in both feeding phases (21 and 42 days), and improved average daily gain (ADG) and food conversion ratio (FCR) in both grower and entire feeding phases (P < 0.05). Triiodothyronine (T3) and tetraiodothyronine (T4) levels, carcass yield, dressing, drum weight, breast muscle weight, drumstick weights, thighs, pectoralis major, and their part percentage of carcass were improved in the NCG group (P < 0.05), these effects were varied along feeding phases. Moreover, IOF of the NCG also improved pectoralis breast muscle color values at 24 h post mortem (P < 0.05).

CONCLUSION

These results suggest that NCG injection at the late embryonic age of broiler enhances growth performance and meat quality throughout the lifespan and this can probably be attributed to an increase in thyroid and testosterone hormones, indicating potential involvement in metabolic and nutrient partitioning pathway regulation. © 2024 Society of Chemical Industry.

Influence of Monochromatic Light during Incubation on the Production and Metabolism of Low-Temperature Broiler Chicks

The use of artificial lighting during the incubation phase is a tool that has been studied with the aim of increasing the production rates and hatchability. Using this, this study aims to investigate the effects of the luminous incidence of white and red monochromatic light on the production and metabolism of broiler chicks subjected to low temperatures. A total of 315 eggs of Ross 708 heavy breeders were used. The eggs were distributed randomly, with 35 eggs per tray, totaling 105 eggs per incubator. The treatments were the following: incubation without the use of light; the use of white monochromatic light; and the use of red monochromatic light. The lamps used were of the LED type. The samples were distributed in the factorial completely randomized experimental design with position effect on the tray. Candling, egg weighing, calculating the probability of survival and egg weight loss were performed. Temperatures were recorded using a thermographic camera. At birth, three chicks per tray were euthanized for evaluation: weight with and without yolk residue, gastrointestinal tract biometry, and blood and liver biochemistry. Analyses were performed using the R computational program. It was observed that there was a significant effect of the treatments on the levels of calcium, phosphorus, cholesterol, amylase, glucose, urea and glutamate pyruvate transaminase on the biochemical profile of the blood and on the thermographic temperatures of the eggs; the experiment was kept at low temperatures resulting in thermal stress, with an average temperature of 34.5 °C. Therefore, the use of red and white monochromatic light in the artificial incubation process for brown-colored eggs is not recommended, because in the post-hatching phase, it promoted the metabolism dysregulation on the blood biochemical profile to control the differentiation in the wavelength of traditional incubation.

Effects of prenatal dichromatic light exposure on hatching results and post-hatch performance of Japanese quail

Present study evaluated the effect of lighted incubation on pre- and post-hatch performance of Japanese quail. In a completely randomized design, 1200 eggs were evenly divided into 4 treatments groups having six replicates (each tray was considered as replicate), 50 eggs each. Different dichromatic lights (Green + Red; GR, Green + Blue; GB, and Blue + Red; BR) of 250 lux were provided during incubation for 12 h daily and effects of these lights very evaluated on hatching results and post-hatch growth. After hatch, 600 quail chicks were divided into 4 treatments, 6 replicates, and 25 birds each. Regarding hatching traits, better hatchability was found in the GR group compared to GB, BR, and dark group; while early embryonic mortality was lower in BR, GB, and dark group than GR; mid embryonic mortality was lower in dark group and late embryonic mortality was noted in the GR group than those of other treatment groups. In addition, moisture loss during incubation was minimum in BR and dark groups; however, chick spread was better in the GR group. In terms of growth performance, weight gain was better in the GR group; feed intake in dark, feed conversion ratio in BR, and livability were better in BR and GR group. In morphometrics, keel and shank length were higher in all the colored groups (GB, BR, and GR) whereas body length, wing spread, shank circumference, drumstick length, and circumference were higher in the GR group. Regarding serum chemistry, glucose, albumin, and globulin levels were higher in the GR group. It was concluded that under the experimental conditions, GR light at the prenatal stage to Japanese quail eggs positively influenced hatching performance and post-hatch growth.

Effect of photoperiod during incubation on embryonic temperature, hatch traits and performance of two commercial broiler strains

Provision of light during incubation has shown the potential to enhance hatching traits and affect posthatch productivity, physiology, and behavior. In this study, 2 repeated trials were conducted to investigate the effect of photoperiod and strain on the embryo temperature, hatching traits and posthatch growth performance of 2 commercial strains of broilers (Ross 308 and Cobb 500). In each trial, hatching eggs were randomly distributed into 6 incubators with 3 photoperiod treatments: blue LED light for 12 h d^-1 (12L:12D) or 18 h d^-1 (18L:6D) during entire incubation were compared with no illumination condition (DARK). Data were analyzed as a 3 × 2 factorial arrangement with the trial as the blocking factor. Embryos incubated under 12L:12D and 18L:6D had lower air cell temperature (P < 0.05) than the DARK embryos from d 13 of incubation onward except on the day of candling. The response of air cell temperature to periodic illumination differed between 2 strains. Cobb embryos had lower air cell temperature in 12L:12D than those incubated with 18L:6D from d 16 of incubation onward, whereas lower air cell temperature was found in Ross embryos when illuminated with 18L:6D photoperiod compared to those under 12L:12D. The 12L:12D treatment was associated with improved (P < 0.05) navel closure condition of hatchlings. There were no differences in hatchability, embryo mortality, body weight, or length at hatch among photoperiod groups or its combination with strain. No differences in production parameters were found between DARK and illuminated groups. However, 12L:12D had heavier (P < 0.05) body weight on d 14 of age and higher (P < 0.05) body weight gain than 18L:6D from d 7 to 14 of age. The results of this study indicate that providing blue LED light up to 18 h d^-1 has no detrimental effect on production of broilers, however, 12L:12D light regime improved chick quality at hatch compared to DARK and resulted in heavier birds by d 14 compared to 18L:6D.

Enhancing gosling growth and secretion of somatotrophic and thyrotrophic axis hormones through egg turning during incubation

1. Growth performance of Yangzhou geese hatched from eggs with turning angles of 50° or 70° was evaluated in association with serum hormones and somatotrophic gene mRNA expression.2. Egg turning at 70° significantly (P< 0.05) increased hatchability, gosling quality and hatching weight. Gosling post-hatch body weight, leg and breast muscle weight in the 70° turning group was significantly heavier until 50 d of age.3. Serum concentrations of GH were significantly higher until 30 d of age in the 70° turning group goslings, and those of IGF-I and T3 were higher from hatching to 50 d of age.4. The mRNA expression of GHRH, pituitary GH, liver and leg muscle IGF-I were all significantly higher at 1 and 30 d of age after hatch, but not at 70 d after hatch, in the 70° turning group.5. Egg turning at 70° during incubation improves embryo and gosling quality and growth performance through up-regulation of gene expression and secretion of somatotrophic axis hormones, GHRH, GH and IGF-I, as well as T3.

Monochromatic Green Light Stimulation during Incubation Alters Hepatic Glucose Metabolism That Improves Embryonic Development in Yangzhou Goose Eggs

The influence of monochromatic green light stimulation on hatching performance and embryo development has been studied in chickens, but not geese. The liver has crucial functions in the regulation of energy metabolism during embryogenesis, but its involvement in green light transduction is still unidentified. We aimed to determine the influence of monochromatic green light on Yangzhou goose hatching performance and embryo development. We also investigated the metabolomics and transcriptomic responses of the embryonic liver to green light to determine the underlying molecular mechanisms. Eggs were incubated under either 12 h of monochromatic green light/dark (12 L:12D) cycles or 24 h of darkness (0G:24D). Green light promoted embryonic development and hatching performance, also affected the expression of myogenic regulatory factors associated with muscle development. It also shortened hatching time and elevated plasma levels of growth hormone and insulin-like growth factor-1. Metabolomics and transcriptomic results revealed differentially expressed genes and metabolites with enhanced gluconeogenesis/glycolysis and increased plasma glucose and pyruvate levels under green light. Hence, the growth-promoting effect possibly through regulating energy metabolism in the liver and myogenic regulatory factors in muscle. Our findings provide important and novel insights into the mechanisms underlying the beneficial effects of green light on goose embryos.

The effect of monochromatic, combined, and mixed light-emitting diode light regimes on growth traits, fear responses, and slaughter-carcass characteristics in broiler chickens

This study aims to determine the effects of blue and green monochromatic, blue-green combination, and blue-green mixed led lighting systems on growth, fear, and carcass characteristics of broilers reared in an extensive indoor system. Experimental groups were formed as follows; 1-conventional (incandescent), 2-blue, 3-green, 4-blue-green combined (blue for the first 10 days, then green), 5-green-blue combined (green for the first 10 days, then blue), and 6-blue-green intermittent (alternating every 5 min) monochromatic lightings. It was detected that the average values of the body weight of chickens at 42 and 56 days of age in the green-blue group were higher than those of the other treatment groups (both P < 0.05). It was determined that the broilers in the green and green-blue groups had higher means of the β₀ parameter of Gompertz model. The tonic immobility, emergence test, home cage avoidance test, a looming human test, and box plus experimenter test were applied to determine the fear responses. It was determined that the worst results for fear responses of broilers were in the intermittent lighting group and green-blue combined group. As a result, it was determined that the application of green monochromatic lighting in the first 10 days of the fattening period and blue monochromatic lighting in the following period positively affected growth and slaughter-carcass characteristics. However, it was found that broilers reared under green-blue combined lighting had high fear levels.

The Role of Incubation Conditions on the Regulation of Muscle Development and Meat Quality in Poultry

Muscle is the most abundant edible tissue in table poultry, which serves as an important source of high protein for humans. Poultry myofiber originates in the early embryogenic stage, and the overall muscle fiber number is almost determined before hatching. Muscle development in the embryonic stage is critical to the posthatch muscle growth and final meat yield and quality. Incubation conditions including temperature, humidity, oxygen density, ventilation and lighting may substantially affect the number, shape and structure of the muscle fiber, which may produce long-lasting effect on the postnatal muscle growth and meat quality. Suboptimal incubation conditions can induce the onset of myopathies. Early exposure to suitable hatching conditions may modify the muscle histomorphology posthatch and the final muscle mass of the birds by regulating embryonic hormone levels and benefit the muscle cell activity. The elucidation of the muscle development at the embryonic stage would facilitate the modulation of poultry muscle quantity and meat quality. This review starts from the physical and biochemical characteristics of poultry myofiber formation, and brings together recent advances of incubation conditions on satellite cell migration, fiber development and transformation, and subsequent muscle myopathies and other meat quality defects. The underlying molecular and cellular mechanisms for the induced muscle growth and meat quality traits are also discussed. The future studies on the effects of external incubation conditions on the regulation of muscle cell proliferation and meat quality are suggested. This review may broaden our knowledge on the regulation of incubation conditions on poultry muscle development, and provide more informative decisions for hatchery in the selection of hatching parameter for pursuit of more large muscle size and superior meat quality.

Light regimen on health and growth of broilers: an update review

The importance of lighting regimen is increasing with the industrialization of poultry production, as lighting has been intimately associated with not only the establishment of rhythm and synchronous physiology of broiler chickens, but also the secretion of hormones associated with broiler maturation and growth. In recent years, increasing attention has been paid to the effects of lighting management on growth performance, immune status, and welfare of broilers. An appropriate lighting regimen, including proper source of lighting, intensity, duration, and wavelength (color) of light, is crucial to improve the growth performance and welfare of broilers. In this review, we updated the impacts of different light regimens on health and growth performance of broilers.

Improvement of goose embryonic and muscular developments by wider angle egg turning during incubation and the regulatory mechanisms

Egg turning during incubation plays important roles in achieving high hatching performance and gosling quality. The objective of this study was to improve embryonic and muscular developments so to achieve better gosling quality by wider egg turning angles during incubation, and to unravel the associated regulatory molecular mechanisms. In each of three consecutive incubations, 1,728 goose eggs were divided into 3 groups that were set in the same type of commercial incubators with turning angles adjusted differently to 50°, 60°, and 70°, respectively. On average of the 3 tests, incubation with wider 70° turning angle reduced the post-18-day embryo mortality, promoted embryonic growth and development, improved the hatchability and gosling quality. On embryonic day of 29, gene mRNA expression levels of the hypothalamic growth hormone-releasing hormone (GHRH), pituitary growth hormone (GH), and liver insulin-like growth factor 1 (IGF-1) were higher in the 70° turning group than in the 50° or 60° groups. Wider angle turning also increased mRNA expression levels of the muscle development regulatory genes such as MYF5, MyoD, Myogenin (MyoG), and MRF4. Changes in expression of the above genes, together with the upregulation of the Pax3 and Pax7 genes in leg muscles, well explained the enhancement of the muscular growth and development when eggs were incubated by wider turning angles. These results also extended our understanding of the impacts and mechanisms of egg turning during incubation on hatching performance and gosling quality.

Effects of light regime on the hatching performance, body development and serum biochemical indexes in Beijing You Chicken

The paper aimed to study the effects of light regime during the incubation on hatching performance, body development and serum biochemical indexes in Beijing You Chicken (BYC). A total of 1,408 BYC eggs were randomly allocated into 4 groups: 24 h dark as the control (Inc24D); 3 light regimes were 8 h light and 16 h dark group (Inc8L:16D); 12 h light and 12 h dark group (Inc12L:12D); 16 h light and 8 h dark group (Inc16L:8D), respectively. There were 352 eggs in each group, 4 replicates each group and 1 tray each replicate, 88 eggs each tray. Light-emitting diode (LED) strips, white light with temperature of 4,500 to 5,000 K, 150 to 200 lx were set up. The results showed that light regimes had no significant effects on hatching rate of eggs, hatching rate of fertile eggs and healthy rate of chicks (P > 0.05), but the hatching rate of eggs was the lowest in the Inc24D group (87.22%), and the highest in the Inc12L:12D group (93.64%); Lighted incubation significantly affected the incidence of leg problems of 1-day-old chicks (P < 0.05). The incidence rate of leg problems was the highest in the Inc24D group (4.21%), and was decreased in Inc12L:12D and Inc16L:8D groups (P < 0.05). Femur length in the Inc12L:12D group was greater than that in the Inc24D and Inc16L:8D groups (P = 0.011), but there were no differences between Inc8L:16D group and other three groups (P > 0.05). The relative brain weight of 1-day-old chicks was higher in Inc24D and Inc16L:8D groups than in Inc8L:16D group (P = 0.052), but had no difference with Inc12L:12D group. Light regimes during incubation had no effects on serum total protein, albumen, globulin, and urea nitrogen content of 1-day-old chicks (P > 0.05), while the globulin content in Inc12L:12D group was numerically greater than in other three groups (P = 0.063). Lysozyme content in Inc12L:12D group was higher than that in the Inc24D and Inc8L:16D groups (P < 0.05), but had no difference with that in Inc16L:8D group. Light regime had no effect on serum total antioxidant capability (T-AOC) (P > 0.05), but significantly affected the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) (P < 0.05). The GSH-Px and T-SOD activities in the Inc12L:12D group were higher than those in the Inc24D and Inc8L:16D groups. The MDA content of Inc24D was the highest (9.67 nmol/mL) compared to the others, which was very close to the significant level (P = 0.056). In conclusion, 12 h light and 12 h dark incubation has the potential to improve the hatching performance of BYC eggs, benefit for the long bone development, improve some serum immune and antioxidant indexes, and reduce the leg problems in 1-day-old chicks.

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.

Chicken embryo as a model in epigenetic research

Epigenetics is defined as the study of changes in gene function that are mitotically or meiotically heritable and do not lead to a change in DNA sequence. Epigenetic modifications are important mechanisms that fine tune the expression of genes in response to extracellular signals and environmental changes. In vertebrates, crucial epigenetic reprogramming events occur during early embryogenesis and germ cell development. Chicken embryo, which develops external to the mother's body, can be easily manipulated in vivo and in vitro, and hence, it is an excellent model for performing epigenetic studies. Environmental factors such as temperature can affect the development of an embryo into the phenotype of an adult. A better understanding of the environmental impact on embryo development can be achieved by analyzing the direct effects of epigenetic modifications as well as their molecular background and their intergenerational and transgenerational inheritance. In this overview, the current possibility of epigenetic changes during chicken embryonic development and their effects on long-term postembryonic development are discussed.

Providing colored photoperiodic light stimulation during incubation: 1. Effects on embryo development and hatching performance in broiler hatching eggs

Providing lighting schedule during incubation has been shown to improve chick quality and reduce stress posthatch. This study was conducted to evaluate the effects of providing light of different colors during incubation on embryo development, air cell temperature, the spread of hatch, and hatching performance. Four batches of eggs (n = 2,176, 1,664, 1,696 and 1,600) from Ross 308 broiler breeders were used in the experiment. In each trial, eggs were randomly distributed into 4 lighting treatments. The incubation lighting treatments included: incubated under dark as control, illuminated with white, red or blue lights for 12 h daily. There were no incubation lighting treatment differences in embryo development, the spread of hatch, hatchability, embryo mortality, hatch weight, chick length, navel closure quality, yolk-free body weight, or relative spleen weight. However, embryos incubated under red light had lower average air cell temperature than those in dark, white or blue light treatments. This finding may suggest higher melatonin secretion during the scotophase when illuminated with red light. Male chicks incubated under dark had a higher bursa of Fabricius weight than males illuminated with blue light. In conclusion, these results suggest that the red, white and blue light stimulation during incubation had no negative effects on hatchability, embryo mortality, spread of hatch or day-old chick quality, but may have potential impacts on immunity and energy metabolism in broiler embryos.

Providing colored photoperiodic light stimulation during incubation: 2. Effects on early posthatch growth, immune response, and production performance in broiler chickens

Previous findings have reported that providing light during incubation can affect hatchability and chick quality. This study was conducted to investigate the effects of providing light during incubation on posthatch broiler production parameters, thermoregulation and immune response. Lights with different wavelengths were used over the course of four separate hatches. Ross 308 broiler hatching eggs were randomly distributed into 4 lighting treatments for each hatch. The incubation lighting treatments included: dark as control, white, red, or blue lights for 12 h d^-1 (200 lux at egg level). Broilers hatched from each incubator with the same gender were placed into one of 8 sets of pens (3 pens/set) and raised under 18 h d^-1 photoperiod. Six birds per pen were immunized intraocularly with AviPro ND-IB Polybanco vaccine on d 10 and 21 posthatch. Chicks hatched under white and blue lights had heavier (P < 0.05) body weight and higher (P < 0.05) feed consumption than the control group during the first 6 h postplacement. No differences in vent temperature were found among treatments at 24 h posthatch (P > 0.05). Chicks hatched with light stimulation however had more stable (P < 0.05) cloaca temperature at 36 h posthatch. No differences in average body weight gain, feed consumption or feed conversion ratio were found among lighting treatments between d 7 and d 35. On d 14 of age, birds hatched from red light had higher (P < 0.05) total IgG concentration than those hatched under dark, blue or white light. These results indicated that in ovo light stimulation with different wavelengths did not affect growth parameters of broilers at market age. Providing photoperiodic blue and white light during incubation improved the production parameters of broilers during the first week posthatch.

Effect of exposure to different light colors on embryonic development and neurophysiological traits in the chick embryo

Background and Aim:

Many environmental factors exist that influence embryonic development which is missing in the poultry industry, such as light in incubation facilities or hatcheries. Light plays an important role in the growth and development of chick embryos, whereas dark environments can lead to hatching failure or embryo distortion. Therefore, this study aimed to demonstrate the importance of light and its various colors on the growth and development of broiler chick embryos.

Materials and Methods:

Four treatments were used to study the impact of various light colors on the growth of embryos and their neurophysiological traits: Dark without light (D), red light (RL), blue light (BL), and green light (GL), with three replicates per treatment (25 eggs/replicate) for a total of 300 fertile Ross 308 eggs. Each treatment was assigned to one incubator (75 eggs/incubator), whereas all other conditions were kept the same.

Results:

The results showed a significant increase (p<0.01) in embryonic development for embryo weight, chick body weight, hatchability, and embryo index for RL, BL, and especially GL. RL, BL, and especially GL significantly increased (p<0.01) neurophysiological traits of the neurons, brain weight, and brain index.

Conclusion:

The use of light during the embryonic period affects the development of the embryo and its neurophysiological traits.

Effects of Monochromatic Lighting During Incubation and Vaccination on the Splenic Transcriptome Profiles of Chicken

Lighting is a crucial environmental variable in poultry operations, but illumination during incubation is relatively understudied. The ability to stimulate development or immune performance using in ovo lighting is a promising approach for improving poultry health and welfare. This study investigated how monochromatic green light during incubation and vaccination method and timing affected chicken splenic gene expression patterns. We performed this study with 1,728 Hy-Line white layer eggs incubated under two light treatments during incubation: continuous dark and continuous green monochromatic light, over the entire incubation period. Half the eggs in each light treatment received in ovo vaccination, applied on embryonic day 18 (ED18). The remaining half were vaccinated by spraying on hatch day. After hatching, the light treatments followed the industry-standard lighting regimens. The study had six treatment groups with light-dark pairs for non-vaccinated, in ovo vaccinated, and post-hatch vaccinated. We assessed splenic gene expression at ED18 and at 7 days post-hatch (PH) in all the treatments. We isolated and sequenced 24 mRNA libraries on the Illumina platform, followed by bioinformatics and differential gene expression analyses. RNAseq analysis showed between 62 and 6,755 differentially expressed genes (DEGs) between comparisons, with the most prominent differences observed between ED and PH samples, followed by comparisons between vaccination methods. In contrast, light vs. dark treatments at ED showed limited effects on transcriptomic profiles. However, we observed a synergistic effect of lighting during incubation on post-hatch vaccination responses, with differentially expressed genes (DEGs) unique to the light treatment showing stimulation of cell proliferation with significance for immune activity (inferred from gene ontology terms). Gene ontology and pathway analysis indicated biological processes like cellular component organization or biogenesis, rhythmic process, developmental process, response to stimulus, and immune system processes were explained by the DEGs. While lighting is an important source of circadian stimulation, other controlled studies are required to clarify whether in ovo circadian entrainment plays a role in modulating immune responses.

Reproductive aspects of Japanese quails (Coturnix coturnix japonica) hatched from eggs incubated under different light colors

The objective of this study was to evaluate the effect of exposure to different colors of light during egg incubation on the reproductive parameters of male and female Japanese quails. A total of 1776 eggs were incubated under four lighting conditions for 24 h a day during the entire incubation period: white LEDs, green LEDs, red LEDs and darkness (control). The experimental design was a randomized block (incubation time) with four treatments of six replicates of two cages each. After hatching, the birds were housed in brood cages with 18 birds each to 35 days of age, when they were sexed and transferred to production cages for evaluation of reproductive parameters. After the onset of laying, the number of eggs in each cage was recorded daily, and the values were used to obtain the age of the females at first egg and at 80% laying. At 35 and 60 days of age, several birds from each cage were euthanized for anatomical and histological evaluation of the gonads. Two females from each cage were weighed every three days until 60 days of age to determine the growth curve. After 60 days, eggs from each cage were collected and assessed for external and internal quality. At 70, 74 and 78 days of age, semen collection was performed and seminal quality was evaluated. Then, the males were transferred to cages containing 9 females for the fertility test. Hatchability was higher (P < 0.05) in eggs incubated in the dark and under the red LED. The age of maximum growth was higher (P < 0.05) in birds from eggs incubated in the dark and under the white LED. There was no difference (P > 0.05) in the anatomical and histological characteristics of the testicles between the groups incubated under different light colors, except for the diameter of the seminiferous tubules, which was greater (P = 0.05) in the dark and in the white LED groups. There was no effect (P > 0.05) of light color during incubation on the productive index or egg quality of adult birds. There was also no effect (P > 0.05) on sperm quality, except for sperm motility, the values of which were higher (P < 0.05) in birds from eggs incubated in different colors of light. However, this difference was not sufficient to significantly (P > 0.05) influence bird fertility. It is concluded that under the studied conditions, the incubation of quail eggs under white, red, and green LED lamps does not influence the reproductive characteristics of the quails.

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.

Monochromatic green light stimulation during incubation shortened the hatching time via pineal function in White Leghorn eggs

Background

Effect of monochromatic green light illumination on embryo development has been reported in chickens. The avian pineal gland is an important photo-endocrine organ formed by a mediodorsal protrusion during embryonic development. However, the involvement of pineal gland in the light transduction process remains to be elucidated. In the present study, we investigated the influence of monochromatic green light on hatching time and explored the possible mechanism via pineal function.

Results

A total of 600 eggs of White Leghorn (Shaver strain) were incubated under photoperiods of either 12 h of light and 12 h of darkness using monochromatic green light (12L:12D group) or 24 h of darkness (0L:24D group) for 18 d. Compared to 0L:24D group, the green light stimulation shortened the hatching time without extending the hatch window or impairing hatchability. The liver of embryos incubated in the 12L:12D light condition was heavier than those of the 0L:24D group on d 21 post incubation which may be linked to the observed increase in the serum concentration of insulin-like growth factor 1 (IGF-1); primary secretion of the liver. Histological structure analysis of pineal gland demonstrated that the light stimulation increased follicle area, wall thickness and lumen area on d 10 and d 12 post incubation. Rhythmic function analysis demonstrated that three clock related genes (brain and muscle ARNT-like-1, BMAL1; circadian locomotor output cycles kaput, CLOCK; and cryptochrome-1, CRY1) and a melatonin rate-limiting enzyme related gene (arylalkylamine N-acetyltransferase, AANAT) were rhythmically expressed in the pineal gland of the 12L:12D group, but not in the 0L:24D group. Simultaneously, the light stimulation also increased the concentration of melatonin (MT), which was linked to hepatocyte proliferation and IGF-1 secretion in previous studies.

Conclusions

The 12L:12D monochromatic green light stimulation during incubation shortened hatching time without impairing hatching performance. Pineal gland’s early histological development and maturation of its rhythmic function were accelerated by the light stimulation. It may be the key organ in the photo-endocrine axis that regulates embryo development, and the potential mechanism could be through enhanced secretion of MT in the 12L:12D group which promotes the secretion of IGF-1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-020-00539-x.

In ovo green light photostimulation during the late incubation stage affects somatotropic axis activity

Targeted green light photostimulation during the last stage of broiler incubation increases expression of the somatotropic axis. The purpose of this study was to further shorten the in ovo green light photostimulation and determine the critical age for photostimulation in broilers embryos, as a future strategy for broiler incubation. Fertile broilers eggs (n = 420) were divided into 5 treatment groups. The first group was incubated under standard conditions (in the dark) as the negative control group. The second was incubated under intermittent monochromatic green light using light-emitting diode lamps with an intensity of 0.1 W/m² at shell level from embryonic day (ED) 0 of incubation until hatch, as a positive control. The third, fourth, and fifth groups were incubated under intermittent monochromatic green light from ED 15, 16, and 18 of incubation, respectively, until hatch. All treatment groups showed elevated somatotropic axis expression compared with the negative control, with the group incubated under monochromatic green light from ED 18 until hatch showing results closest to the positive control. This suggests that broiler embryos can be exposed to in ovo green light photostimulation from a late stage of incubation (when transferring the eggs to the hatchery) and exhibit essentially the same outcome as obtained by photostimulation during the entire incubation period.

Effects of different light durations during incubation on hatching, subsequent growth, welfare, and meat quality traits among three broiler strains

Present study was aimed to evaluate the hatching traits and subsequent performance of broilers strains under the intermittent and continuous light regime during incubation. In total, 2250 eggs from Hubbard classic, Cobb-500, and Ross-308 strains (750 eggs from each of same age breeders) were incubated under three different light durations. First treatment was the incubation totally under darkness where no light was able to penetrate in the assigned section of machine. In the second treatment, eggs were incubated at 12 h of lightness and 12 h of darkness. In the third treatment, the eggs received lightning of 24 h. Data were collected for hatching traits and hatch window, growth performance, welfare aspects, and meat quality. A two-way factorial analysis was performed using SAS software applying Duncan's multiple range test. The results showed that hatching traits were improved when Hubbard breeder eggs were provided with light period of 12 h. However, gait score was non-significantly different among the treatment. The meat quality was better in Hubbard broilers obtained after 12 h of intermittent light during incubation. Blood biochemistry was also improved in Hubbard broilers of 12 h of light duration. It was concluded that 12 h of light period during incubation is beneficial for getting better hatchability and subsequent performance of Hubbard broilers.

Effects of monochromatic green light stimulation during embryogenesis on hatching and posthatch performance of four strains of layer breeder

Providing green light during incubation has been shown to accelerate the embryo development and shorten the hatching time in broilers. Few studies have concentrated on the exact effects on layer breeders in the aspects of hatching and posthatch performance. In this study, 4 strains of layer breeder eggs, namely White Leghorn, Rhode Island Red, Columbia Rock, and Barred Rock were used to assess the effects of monochromatic green light during embryogenesis on hatching performance, chick quality, and pubertal growth. Each strain of 600 eggs was incubated under photoperiods of either 12 h of light and 12 h of darkness (12L:12D, light group) or 0 h of light and 24 h of darkness (0L:24D, dark group) for 18 D, with 2 replicates for each treatment. The results showed hatch time, time reaching 90% hatch, and average hatch time were significantly shorter among the 4 strains in the light group (P < 0.01). In addition, hatch window and peak hatching period were not extended by the green light stimulation (P > 0.05). There was no significant difference in hatchability of fertile eggs, chick weight/egg weight, or chick quality among the 4-strain eggs between the light group and dark group (P > 0.05). There was no difference (P > 0.05) in posthatch BW between different light treatments of the 3 strains (White Leghorn, Columbia Rock, and Barred Rock), whereas the BW of Rhode Island Red was higher in light group than that of the dark group at 8 to 12 wk of age (P < 0.05) and the difference disappeared from week 14. The results demonstrate that 12L:12D monochromatic green light stimulation during embryogenesis shortens the hatching time with no negative effects on hatching and posthatch performance. These effects were consistent among the 4 layer strains.

Effects of bamboo leaf extract on growth performance, meat quality, and meat oxidative stability in broiler chickens

This study was conducted to investigate the effects of dietary bamboo leaf extract (BLE) on growth performance, meat quality, oxidative stability, and nuclear factor erythroid 2-related factor 2 (Nrf2) related gene expression of breast meat in broilers. A total of 576 one-day-old male Arbor Acres broilers were divided into 6 groups. The control group (CTR) was fed basal diet, while BLE1, BLE2, BLE3, BLE4, and BLE5 were fed basal diet supplemented with 1.0, 2.0, 3.0, 4.0, and 5.0 g BLE per kg feed, respectively. Compared with the CTR group, BLE2 and BLE5 increased average daily feed intake from 1 to 21 D and 22 to 42 D (P < 0.05), BLE1 and BLE2 improved average daily gain (ADG) and feed to gain ratio from 22 to 42 D (P < 0.05). Throughout the trial period, the highest body weight and favorable ADG and feed to gain ratio were observed in the BLE2 group. The drip loss at 24 h and pH at 45 min postmortem of breast meat were linearly improved by BLE supplementation (P < 0.05). Shear force was significantly lower in BLE2 and BLE3 than that in CTR group. Increasing supplementation of BLE linearly improved free radical scavenging capacity and decreased malondialdehyde content of breast meat during 12 D of storage (P < 0.05). Total antioxidant capacity and glutathione peroxidase activity were linearly increased by BLE supplementation (P < 0.05). Compared with the CTR group, the mRNA expression of Nrf2 and glutathione peroxidase in BLE3, BLE4, and BLE5 groups was significantly promoted, and glutathione S-transferase gene expression was increased in BLE2, BLE4, and BLE5 (P < 0.05). The highest (P < 0.05) heme oxygennase-1 gene expression was observed in BLE5. In conclusion, broiler supplemented with BLE improved growth performance and meat quality, BLE supplementation might activate Nrf2 pathway to alleviate lipid oxidation and increase antioxidant capacity of breast meat. The dosage of 2.0 to 3.0 g/kg BLE in broiler diet was recommanded.

Impact of lighting color and duration on productive performance and Newcastle disease vaccination efficiency in broiler chickens

Background and Aim

Manipulating lighting colors and regimens is considered an effective mean for improving broiler productivity. The influence of red, blue, and white light-emitting diode (LED) was investigated using three different regimens of lighting and darkness; continuous 23 h light (L):1 h dark (D), continuous 18 h L:6 h D, and intermittent 16 h L:8 h D hours on the performance, carcass weight (CW), feed and water intake (WI), serum glucose (GLUCO), triglycerides (TG), and cholesterol (TC), intestinal bacterial load, growth and metabolic hormones, and efficiency of Newcastle disease (ND) vaccine.

Materials and Methods

A total of 252 1-day-old Ross broilers on deep litter were divided into nine groups. The 1^st, 4^th, and 7^th groups were exposed to continuous 23L:1D, the 2^nd, 5^th, and 8^th groups were exposed to continuous 18L:6D, and the 3^rd, 6^th, and 9^th groups were exposed to intermittent 16L:8D (4L:2D, 4 times) lighting regimen using red, blue, and white LED lights, respectively. A total of 1350 samples (225 sera, 225 swabs, and 900 organ samples) were collected.

Results

Blue LED group revealed a highly significant increase (p<0.01) in live body weight, body weight gain, performance index, CW, spleen, heart, and liver weights, and anti-ND antibody titer, as well as a highly significant decline (p<0.01) of feed intake, WI, GLUCO, TG, TC, growth hormone, insulin, tri-iodothyronine (T3), tetra-iodothyronine (T4), total bacterial count (TBC), and total Enterobacteriaceae count compared to red and white LED lights in all tested lighting regimens. Continuous 23L:1D and 18L:6D regimens were significantly (p<0.01) superior to intermittent 16L:8D in their influence on the performance, CW, biochemistry, hormonal profile, and bacterial load.

Conclusion

The blue LED light associated with continuous 18L:6D or 23L:1D h regimen is highly recommended in broiler houses for their enhancing the productive performance, growth, and immunity.

Mel1c Mediated Monochromatic Light-Stimulated IGF-I Synthesis through the Intracellular Gαq/PKC/ERK Signaling Pathway

Previous studies have demonstrated that monochromatic light affects plasma melatonin (MEL) levels, which in turn regulates hepatic insulin-like growth factor I (IGF-I) secretion via the Mel1c receptor. However, the intracellular signaling pathway initiated by Mel1c remains unclear. In this study, newly hatched broilers, including intact, sham operation, and pinealectomy groups, were exposed to either white (WL), red (RL), green (GL), or blue (BL) light for 14 days. Experiments in vivo showed that GL significantly promoted plasma MEL formation, which was accompanied by an increase in the MEL receptor, Mel1c, as well as phosphorylated extracellular regulated protein kinases (p-ERK1/2), and IGF-I expression in the liver, compared to the other light-treated groups. In contrast, this GL stimulation was attenuated by pinealectomy. Exogenous MEL elevated the hepatocellular IGF-I level, which is consistent with increases in cyclic adenosine monophosphate (cAMP), G_αq, phosphorylated protein kinase C (p-PKC), and p-ERK1/2 expression. However, the Mel1c selective antagonist prazosin suppressed the MEL-induced expression of IGF-I, G_αq, p-PKC, and p-ERK1/2, while the cAMP concentration was barely affected. In addition, pretreatment with Ym254890 (a G_αq inhibitor), Go9863 (a PKC inhibitor), and PD98059 (an ERK1/2 inhibitor) markedly attenuated MEL-stimulated IGF-I expression and p-ERK1/2 activity. These results indicate that Mel1c mediates monochromatic GL-stimulated IGF-I synthesis through intracellular G_αq/PKC/ERK signaling.

Various LED Wavelengths Affected Myofiber Development and Satellite Cell Proliferation of Chick Embryos via the IGF-1 Signaling Pathway

An effect of monochromatic light illumination on muscle mass has been discovered in chickens; however, its effect on the development of embryonic muscle remains unclear. Our previous studies demonstrated that monochromatic green light promoted satellite cell proliferation and muscle growth in posthatching broilers. In this study, we investigated the effects and mechanisms of monochromatic light exposure on muscle development in late embryogenesis. Seven hundred and fifty fertile broiler eggs were randomly assigned to blue (B-group), green (G-group), red (R-group), white (W-group) lights or darkness (D-group) throughout the incubation period. The muscle weight and fiber size were highest in the G-group compared to the other groups during embryonic days (E) 17 to E20. The proliferation of satellite cells isolated from the G-group was highest, and in vivo green light remarkably increased the number of proliferating cell nuclear antigen (PCNA)-positive cells in skeletal muscle. Meanwhile, plasma IGF-1 was higher (15.5-16.2%) in the G-group than that in D- and R-groups, and the satellite cells isolated from the G-group had a more sensitive response to IGF-1. These findings demonstrate green monochromatic photobiomodulation promoted the muscle growth and satellite cell proliferation was related to the IGF-1 signaling pathway in late embryogenesis.

In ovo exposure to monochromatic lights affect posthatch muscle growth and satellite cell proliferation of chicks: role of IGF-1

To study the role of IGF-1 on stimulation with monochromatic light during incubation altering posthatch muscle growth, chicken embryos were exposed to blue light, green light, red light, white light or darkness throughout embryonic period and then were raised in white light conditions upon hatching. Comparing with the other treatment groups, the chicks in green light group had heavier hatching weights, higher muscle indexes and larger muscle fibers. Both in vivo and in vitro studies showed that the number and proliferative activity of satellite cells in green light group were the highest. Plasma IGF-1 level and skeletal muscle IGF-1R mRNA level were higher in green light group. Moreover, exogenous IGF-1 increased the proliferative activity of satellite cell in a dose-dependent fashion. These results suggest that stimulation with monochromatic green light during incubation promoted posthatch muscle growth and satellite cell proliferation of chicks through IGF-1 signaling.

Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells.

Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0–21 d), the values of the eggshell pigment (ΔE, L^∗, a^∗, b^∗) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380–780 nm.

Result. Three measured indicators of eggshell color, ΔE, L^∗ and a^∗, did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation.

Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity.

Green Light-emitting Diodes Light Stimuli during Incubation Enhances Posthatch Growth without Disrupting Normal Eye Development of Broiler Embryos and Hatchlings

Monochromatic green light-emitting diodes (LED) light stimuli influences the posthatch growth performance of chicks. This study was undertaken with the following objectives: i) to examine whether the green LED light stimuli induces an overheating effect by determining weight loss rate of fertile eggs during incubation period; ii) to look for the development of eyes and other primary organs at different ages of embryos and newly hatched chicks. Arbor Acres fertile broiler eggs (n = 480) were randomly assigned to 3 incubation groups and exposed to continuous white light, green light, or a dark environment (control) from the first day to 19 d of incubation. The light sourced from LED lamps with the intensity of 30 lx at eggshell level. The results showed that either green or white light stimuli during incubation did not significantly affect the weight loss rate of fertile eggs, hatching time, hatchability, chick embryo, or body weight (BW), the weight percentage of heart, liver, and eyes, as well as obvious systematic abnormalities in eye weight, side-to-side, back-to-front, or corneal diameter from 15 d of embryogenesis to 6 d of posthatch (p>0.05). Compared with the dark condition, green light stimuli during incubation tended to increase feed intake (p = 0.080), improved the BW gain of chicks during 0 to 6 day posthatch (p<0.05), and increased the percentage of pectoral muscle to the BW on 3- and 6-day-old chicks. In addition, embryos or chicks in green light had lower weight percentage of yolk retention on 19 d of embryogenesis and 1 d of posthatch in comparison to those in dark or white group (p<0.05). These results suggest that providing 30 lx green LED light stimuli during incubation has no detrimental effect on the development of eyes, heart and liver of embryos and hatchlings, but does have potential benefits in terms of enhancement of the chick growth during the early posthatch stages. In addition, the fertile broiler eggs stimulated with 30 lx green LED light during incubation does not cause an overheating effect.

Secretion pathway of liver IGF-1 via JAK2/STAT3 in chick embryo under the monochromatic light

This study reveals mechanism of monochromatic light on the IGF-1 secretion of chick embryo liver. The chick embryos were incubated and exposed to continuous red, green, blue light or a dark environment. Compared to other light-treated groups, green light increased IGF-1 and melatonin concentrations both in plasma and liver, and Mel1a, Mel1b and Mel1c receptors expressions in liver but decreased p-JAK2, p-STAT3 and ROS in liver. IGF-1 had a positive correlation with melatonin, but a negative relevance with p-JAK2 and p-STAT3. In vitro, the IGF-1 level in the hepatocyte supernatant was enhanced by melatonin with lower p-JAK2/p-STAT3 and ROS levels, which was suppressed by Mel1c antagonist but not Mel1a/Mel1b or Mel1b antagonists. AG490 (JAK/STAT inhibitor) promoted role of melatonin-Mel1c modulated IGF-1 secretion. These results suggest the antioxidant effect of melatonin mediated the green light-enhanced IGF-1 secretion of chick embryo liver through Mel1c receptor to inhibit the JAK2/STAT3 pathway.

Evidence in duck for supporting alteration of incubation temperature may have influence on methylation of genomic DNA

Incubation temperature has an immediate and long-term influence on the embryonic development in birds. DNA methylation as an important environment-induced mechanism could serve as a potential link between embryos’ phenotypic variability and temperature variation, which reprogrammed by DNA (cytosine-5)-methyltransferases (DNMTS) and Methyl-CpG binding domain proteins (MBPS) 3&5 (MBD3&5). Five genes in DNMTS and MBPS gene families were selected as target genes, given their important role in epigenetic modification. In this study, we aimed to test whether raising incubation temperature from 37.8°C to 38.8°C between embryonic days (ED) 1–10, ED10–20 and ED20–27 have effect on DNA methylation and whether DNMTS, MBPS play roles in thermal epigenetic regulation of early development in duck. Real-time quantitative PCR analysis showed that increased incubation temperature by 1°C has remarkably dynamic effect on gene expression levels of DNMTS and MBPS. Slight changes in incubation temperature significantly increased mRNA levels of target genes in breast muscle tissue during ED1–10, especially for DNMT1, DNMT3A and MBD5. In addition, higher temperature significantly increased enzyme activities of DNMT1 in leg muscle during ED10–20, liver tissue during ED1–10, ED20–27 and DNMT3A in leg muscle and breast muscle tissue during ED10–20. These results suggest that incubation temperature has an extended effect on gene expression levels and enzyme activities of DNMTS and MBPS, which provides evidence that incubation temperature may influence DNA methylation in duck during early developmental stages. Our data indicated that DNMTS and MBPS may involved in thermal epigenetice regulation of embryos during the early development in duck. The potential links between embryonic temperature and epigenetic modification need further investigation