Nutrition of the developing embryo and hatchling

Gene ontology defines pre-post- hatch energy dynamics in the complexus muscle of broiler chickens

BACKGROUND

Chicken embryos emerge from their shell by the piercing movement of the hatching muscle. Although considered a key player during hatching, with activity that imposes a substantial metabolic demand, data are still limited. The study provides a bioenergetic and transcriptomic analyses during the pre-post-hatching period.

METHODS

Weight and morphology alongside content determination of creatine and glycogen were analysed. Transcriptome identified differentially expressed genes and enriched biological processes associated with hatching muscle development, catabolism, and energy provision. Using gene set enrichment, we followed the dynamics of gene-sets involved in energy pathways of oxidative phosphorylation, protein catabolism, glycolysis/gluconeogenesis, and glycogen metabolism.

RESULTS

Results show several significant findings: (A) Creatine plays a crucial role in the energy metabolism of the hatching muscle, with its concentration remaining stable while glycogen concentration is depleted at hatch and placement. (B) The hatching muscle has the capacity for de-novo creatine synthesis, as indicated by the expression of related genes (AGAT, GAMT). (C) Transcriptome provided insights into genes related to energy pathways under conditions of pre-hatch oxygen and post-hatch glucose limitations (oxidative phosphorylation: NDUF, MT-ND, SDH, UQCR, COX, MT-CO, ATP5, MT-ATP; glycolysis/gluconeogenesis: FBP,G6PC, PFKM; glycogen metabolism: PPP1, PYGL, GYG1). (D) The post-hatch upregulation of protein catabolic processes genes (PSMA, RNF, UBE, FBX), which align with the muscle's weight dynamics, indicates a functional shift from movement during hatching to lifting the head during feeding.

CONCLUSIONS

There is a dynamic metabolic switch in the hatching muscle during embryo-to-hatchling transition. When glycogen concentration depletes, energy supply is maintained by creatine and its de-novo synthesis. Understanding the hatching muscle's energy dynamics is crucial, for reducing hatching failures in endangered avian species, and in domesticated chickens.

Carbon dots induce endoplasmic reticulum stress-mediated lipid dysregulation and embryonic developmental toxicity in zebrafish

Carbon dots (CDs) are widely utilized due to their exceptional physical and chemical properties. Nevertheless, there is a paucity of research examining the potential toxicity of carbon dots to human health, particularly with regard to developmental toxicity. The present study demonstrated that exposure to CDs resulted in increased mortality and malformations in zebrafish embryos. Further bioinformatics analyses indicated that CDs-induced lipid metabolism disorders may represent a significant pathway for developmental toxicity in zebrafish embryos. This can result in aberrant expression of genes involved in lipid metabolism, which ultimately leads to endoplasmic reticulum stress (ERS)-induced accumulation of excess lipids in the body. It can therefore be surmised that exposure to CDs in early life ultimately leads to developmental toxicity by inducing ERS-induced lipid metabolism disorders. The findings of this study suggest that there is a risk of long-term exposure to CDs from early life, and provide a theoretical basis and data support for the prevention of potential hazards of CDs.

The typical developmental trajectory and energy requirements of Shitou goose during the embryonic stage

Low hatchability has been a persistent challenge in the goose industry. Establishing standard atlases and comprehending embryonic development patterns are essential to improving the hatching rates of goose eggs. However, comprehensive descriptions of normal atlases, embryonic development, and energy requirements in geese are lacking. In this study, a total of 120 fertile eggs from well-known large Shitou goose were incubated using 12 nesting purebred female geese. During hatching, both the temperature of the eggshells and the weight of eggs were recorded, and daily photographs of the embryos were captured to monitor their development closely. After hatching, counted the number of pores per unit area of eggshells by choosing eggs from without sperm, dead embryos, and normally hatched. Furthermore, 150 Shitou goose eggs were hatched by automatic incubator, with adjustments made based on observed normal developmental stages that incubated by female geese. The eggs were carefully opened to meticulously document embryonic morphology and create a detailed development map. Measurements were taken of the eye diameter, length of the lower beak, tarsometatarsus bone, and embryo length. Subsequently, an analysis was conducted to assess the calcium, phosphorus, crude protein, and crude fat content to study the energy requirements for embryo development. characteristics on the 7th, 15th, 23rd and 28th days of Shitou goose hatching corresponded to the 5th, 10th, 17th and 19th days of chicken egg incubation, respectively. These days were distinguished individually by "visible embryo's eye", "closure", "sealing the door", and "flashing hair". Besides, the hatch rate of the incubator reached 86.67%, and the cumulative water loss rate increased with embryo age. Notably, normally developing embryos displayed a significantly higher number of pores on the eggshell surface compared to dead embryos (P < 0.05). Additionally, embryonic body length, eyeball diameter, and lower beak length exhibited continuous growth until day 19 of incubation, while tarsometatarsus length increased steadily from days 12 to 31. Liver size measurement began on the 10th day of incubation, while both leg and chest muscles showed continuous growth from the 12th day. For energy demand, the embryo primarily relied on protein sourced from the egg yolk within the first 10 days of development. Afterward, the egg yolk provided both protein and fat for embryonic growth. In summary, this study has generated a comprehensive developmental map for Shitou goose embryos, offering valuable insights into their growth and morphological changes throughout the incubation period. This map can serve as a reference for optimizing machine incubation techniques to enhance goose egg hatching rates and provide fresh perspectives on the development of geese.

Atorvastatin causes developmental and behavioral toxicity in yellowstripe goby (Mugilogobius chulae) embryos/larvae via disrupting lipid metabolism and autophagy processes

Atorvastatin (ATV) is one of the most commonly prescribed lipid-lowering drugs detected frequently in the environment due to its high use and low degradation rate. However, the toxic effects of residual ATV in the aquatic environment on non-target organisms and its toxic mechanisms are still largely unknown. In the present study, embryos of a native estuarine benthic fish, Mugilogobius chulae, were employed to investigate the developmental and behavioral toxic effects of ATV including environmentally relevant concentrations. The aim of this study was to provide a scientific basis for ecological risk assessment of ATV in the aquatic environment by investigating the changes of biological endpoints at multiple levels in M. chulae embryos/larvae. The results showed that ATV had significantly lethal and teratogenic effects on M. chulae embryos/larvae and caused abnormal changes in developmental parameters including hatch rate, body length, heart rate, and spontaneous movement. ATV exposure caused oxidative stress in M. chulae embryos/larvae subsequently inhibited autophagy and activated apoptosis, leading to abnormal developmental processes and behavioral changes in M. chulae embryos/larvae. The disruptions of lipid metabolism, autophagy, and apoptosis in M. chulae embryos/larvae caused by ATV exposure may pose a potential ecological risk at the population level.

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.

Proteomic Analysis of Egg Yolk Proteins During Embryonic Development in Wanxi White Goose

To investigate the alterations of yolk protein during embryonic development in Wanxi white goose, the egg yolk protein composition at days 0, 4, 7, 14, 18, and 25 of incubation (D0, D4, D7, D14, D18, and D25) was analyzed by two-dimensional gel electrophoresis combined with mass spectrometry. A total of 65 spots representing 11 proteins with significant abundance changes were detected. Apolipoprotein B-100, vitellogenin-1, vitellogenin-2-like, riboflavin-binding protein, and serotransferrin mainly participated in nutrient (lipid, riboflavin, and iron ion) transport, and vitellogenin-2-like showed a lower abundance after D14. Ovomucoid-like were involved in endopeptidase inhibitory activity and immunoglobulin binding and exhibited a higher expression after D18, suggesting a potential role in promoting the absorption of immunoglobulin and providing passive immune protection for goose embryos after D18. Furthermore, myosin-9 and actin (ACTB) were involved in the tight junction pathway, potentially contributing to barrier integrity. Serum albumin mainly participated in cytolysis and toxic substance binding. Therefore, the high expression of serum albumin, myosin-9, and ACTB throughout the incubation might protect the developing embryo. Apolipoprotein B-100, vitellogenin-1, vitellogenin-2-like, riboflavin-binding protein, and serotransferrin might play a crucial role in providing nutrition for embryonic development, and VTG-2-like was preferentially degraded/absorbed.

Metabolomics analysis of the yolk of Zhijin white goose during the embryogenesis based on LC-MS/MS

The egg yolk of the goose is rich in lipids, proteins and minerals, which is the main source of nutrition during the goose embryogenesis. Actually, the magnitude and variety of nutrients in yolk are dynamically changed to satisfy the nutritional requirements of different growth and development periods. The yolk sac membrane (YSM) plays a role in metabolizing and absorbing nutrients from the yolk, which are then consumed by the embryo or extra-fetal tissues. Therefore, identification of metabolites in egg yolk can help to reveal nutrient requirement in goose embryo. In this research, to explore the metabolite changes in egg yolk at embryonic day (E) 7, E12, E18, E23, and E28, we performed the assay using ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). The findings showed that E7 and E12, E23 and E28 were grouped together, while E18 was significantly separated from other groups, indicating the changes of egg yolk development and metabolism. In total, 1472 metabolites were identified in the egg yolk of Zhijin white goose, and 636 differential metabolites (DMs) were screened, among which 264 were upregulated and 372 were downregulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the DMs were enriched in the biosynthesis and metabolism of amino acids, digestion and absorption of protein, citrate cycle (TCA cycle), aminoacyl-tRNA biosynthesis, phosphotransferase system (PTS), mineral absorption, cholesterol metabolism and pyrimidine metabolism. Our study may provide new ideas for improving prehatch embryonic health and nutrition.

Effects of monensin sodium and live attenuated oocyst vaccine as coccidiosis management programs on productive performance, bone quality and mineral utilisation in broiler chickens

1. The following study was conducted to evaluate the influence of coccidiosis vaccine-induced metabolic stress on the utilisation of minerals in broilers. The starter, grower and finisher phase diets, including macro- and micro minerals at the recommended levels for the breed standards, were fed to chickens between 1 and 39 d of age.2. A total of 486, one-d-old male broilers were randomly distributed into three coccidiosis management programs (CMP) with six replications each. The CMP comprised: monensin sodium (MON), coccidiosis vaccine (VAC), not treated with MON or VAC (CNT).3. No significant differences between CMP were observed for body weight and weight gain among treatments. When compared to the CNT, the VAC program increased feed intake (P < 0.05) between d 1 to 13 and 14 to 26, while FCR worsened in the latter (P < 0.05) and the former (P = 0.05) periods.4. For birds in the MON and VAC programs, tibia bone length at d 13 and bone diameter at d 39 were both enhanced (P < 0.05). Meat yield characteristics were comparable among the CMP.5. Faeces of VAC birds had a lower (P < 0.05) dry matter and ash content than those in CNT program. CMP had no effect on serum or bone mineral concentrations at any point in time. For minerals, Mg, Na, and K faecal excretion was reduced (P < 0.01) as a result of the VAC program at d 13 with a trend at d 26.6. Compared to the CNT, the VAC program decreased the percentage ratio of drip loss (P = 0.08), water holding capacity (P < 0.01) and cooking loss (P < 0.01) in breast meat.7. Overall, the results showed that current broiler industry practices are capable of meeting the mineral needs of broilers vaccinated against coccidiosis.

In ovo feeding of vitamins in broilers: A comprehensive meta-analysis of hatchability and growth performance

In ovo feeding has been introduced as a cost-effective method to improve hatchability and broiler performance. Specifically, several studies have focused on the impact of vitamins. However, due to variations in experimental conditions across all trials, drawing general conclusions appears challenging. Therefore, we conducted a meta-analysis of 17 published papers, including a maximum of 134 sample size to evaluate the potential effects of in ovo feeding of vitamins in broilers. Studies were retrieved by consulting scientific repositories such as Pubmed, Scopus, Scielo, Web of Science, and Google Scholar. A binary logistic model was used to determine the parameters influencing hatchability. To assess variations in hatchling weight and growth parameters based on the vitamin category, a mixed model analysis of variance was performed, considering the study as a random effect and the vitamin category as a fixed effect. Finally, a linear mixed model was used to develop equations that explain the evolution of growth parameters based on vitamin concentration, volume, and day of injection. The results revealed that for better hatchability, it is preferable to consider heavier eggs (p = 0.007), lower volumes (p = 0.039), and late injection (p = 0.022). Vitamin E was associated with higher hatchling weight (p = 0.037), while vitamin C exhibited the lowest overall feed conversion ratio (p = 0.042). Interactions were observed between the day of injection and vitamin concentration or volume of injection for all studied growth parameters. In summary, the findings of this study suggest that hatchability during in ovo feeding is influenced by technique-related parameters, whereas growth parameters can be modulated by the category of vitamin injected. Consequently, this study lays the groundwork for future investigations assessing the effects of in ovo feeding in broilers, as it highlights the relationship between the methodology and potential outcomes.

In-ovo feeding with creatine monohydrate: implications for chicken energy reserves and breast muscle development during the pre-post hatching period

The most dynamic period throughout the lifespan of broiler chickens is the pre-post-hatching period, entailing profound effects on their energy status, survival rate, body weight, and muscle growth. Given the significance of this pivotal period, we evaluated the effect of in-ovo feeding (IOF) with creatine monohydrate on late-term embryos' and hatchlings' energy reserves and post-hatch breast muscle development. The results demonstrate that IOF with creatine elevates the levels of high-energy-value molecules (creatine and glycogen) in the liver, breast muscle and yolk sac tissues 48 h post IOF, on embryonic day 19 (p < 0.03). Despite this evidence, using a novel automated image analysis tool on day 14 post-hatch, we found a significantly higher number of myofibers with lower diameter and area in the IOF creatine group compared to the control and IOF NaCl groups (p < 0.004). Gene expression analysis, at hatch, revealed that IOF creatine group had significantly higher expression levels of myogenin (MYOG) and insulin-like growth factor 1 (IGF1), related to differentiation of myogenic cells (p < 0.01), and lower expression of myogenic differentiation protein 1 (MyoD), related to their proliferation (p < 0.04). These results imply a possible effect of IOF with creatine on breast muscle development through differential expression of genes involved in myogenic proliferation and differentiation. The findings provide valuable insights into the potential of pre-hatch enrichment with creatine in modulating post-hatch muscle growth and development.

Factors influencing the development of gastrointestinal tract and nutrient transporters' function during the embryonic life of chickens-A review

Intestinal morphology and regulation of nutrient transportation genes during the embryonic and early life of chicks influence their body weight and feed conversion ratio through the growing period. The intestine development can be monitored by measuring villus morphology and enzymatic activity and determining the expression of nutrient transporters genes. With the increasing importance of gut development and health in broiler production, considerable research has been directed towards factors affecting intestine development. Thus, this article reviews (1) intestinal development during embryogenesis, and (2) maternal factors, in ovo administration, and incubation conditions that influence intestinal development during embryogenesis. Conclusively, (1) chicks from heavier eggs may have a better-developed intestine than chicks from younger ones, (2) in ovo supplementation with amino acids, minerals, vitamins or a combination of several probiotics and prebiotics stimulates intestine development and increases the expression of intestine mucosal-related genes and (3) the long storage period, improper incubation temperature and imbalanced ventilation can negatively influence intestinal morphology and nutrient transporters gene expression. Finally, understanding the intestine development during embryonic life will enable us to enhance the productivity of broilers.

Uterine Fluid Extracellular Vesicles Proteome Is Altered During the Estrous Cycle

Uterine environment is tightly and finely regulated via various signaling pathways mediated through endocrine, exocrine, autocrine, juxtacrine, and paracrine mechanisms. In utero signaling processes are paramount for normal and abnormal physiology which involves cell to cell, cells to gametes, cells to embryo, and even interkingdom communications due to presence of uterine microbiota. Extracellular vesicles (EVs) in the uterine fluid (UF) and their cargo components are known to be mediators of in utero signaling and communications. Interestingly, the changes in UF-EV proteome during the bovine estrous cycle and the effects of these differentially enriched proteins on embryo development are yet to be fully discovered. In this study, shotgun quantitative proteomics-based mass spectrometry was employed to compare UF-EV proteomes at day 0, 7, and 16 of the estrous cycle to understand the estrous cycle-dependent dynamics. Furthermore, different phase UF-EVs were supplemented in embryo cultures to evaluate their impact on embryo development. One hundred fifty-nine UF-EV proteins were differentially enriched at different time points indicating the UF-EV proteome is cycle-dependent. Overall, many identified pathways are important for normal uterine functions, early embryo development, and its nutritional needs, such as antioxidant activity, cell morphology and cycle, cellular homeostasis, cell adhesion, and carbohydrate metabolic process. Furthermore, the luteal phase UF-EVs supplementation increased in vitro blastocyst rates from 25.0 ± 5.9% to 41.0 ± 4.0% (p ≤ 0.05). Our findings highlight the importance of bovine UF-EV in uterine communications throughout the estrous cycle. Interestingly, comparison of hormone-synchronized EV proteomes to natural cycle UF-EVs indicated shift of signaling. Finally, UF-EVs can be used to improve embryo production in vitro.

Perfluorohexanesulfonic acid (PFHxS) induces oxidative stress and causes developmental toxicities in zebrafish embryos

Perfluorohexanesulfonic acid (PFHxS) is a short-chain perfluoroalkyl substance widely used to replace the banned perfluorooctanesulfonic acid (PFOS) in different industrial and household products. It has currently been identified in the environment and human bodies; nonetheless, the possible toxicities are not well-known. Zebrafish have been used as a toxicant screening model due to their fast and transparent developmental processes. In this study, zebrafish embryos were exposed to PFHxS for five days, and various experiments were performed to monitor the developmental and cellular processes. Liquid chromatography-mass spectrometry (LC/MS) analysis confirmed that PFHxS was absorbed and accumulated in the zebrafish embryos. We reported that 2.5 µM or higher PFHxS exposure induced phenotypic abnormalities, marked by developmental delay in the mid-hind brain boundary and yolk sac edema. Additionally, larvae exposed to PFHxS displayed facial malformation due to the reduction of neural crest cell expression. RNA sequencing analysis further identified 4643 differentiated expressed transcripts in 5 µM PFHxS-exposed 5-days post fertilization (5-dpf) larvae. Bioinformatics analysis revealed that glucose metabolism, lipid metabolism, as well as oxidative stress were enriched in the PFHxS-exposed larvae. To validate these findings, a series of biological experiments were conducted. PFHxS exposure led to a nearly 4-fold increase in reactive oxygen species, possibly due to hyperglycemia and impaired glutathione balance. The Oil Red O' staining and qPCR analysis strengthens the notions that lipid metabolism was disrupted, leading to lipid accumulation, lipid peroxidation, and malondialdehyde formation. All these alterations ultimately affected cell cycle events, resulting in S and G2/M cell cycle arrest. In conclusion, our study demonstrated that PFHxS could accumulate and induce various developmental toxicities in aquatic life, and such data might assist the government to accelerate the regulatory policy on PFHxS usage.

Notch mediates the glycolytic switch via PI3K/Akt signaling to support embryonic development

BACKGROUND

Energy metabolism disorder or insufficient energy supply during incubation will affect the development and survival of avian embryos. Especially, β-oxidation could not provide the continuous necessary energy for avian embryonic development due to the increasing energy demand under hypoxic conditions during the mid-late embryonic stages. The role and mechanism of hypoxic glycolysis replacing β-oxidation as the main source of energy supply for avian embryonic development in the mid-late stages is unclear.

RESULTS

Here, we found that in ovo injection with glycolysis inhibitor or γ-secretase inhibitor both decreased the hepatic glycolysis level and impaired goose embryonic development. Intriguingly, the blockade of Notch signaling is also accompanied by the inhibition of PI3K/Akt signaling in the embryonic primary hepatocytes and embryonic liver. Notably, the decreased glycolysis and impaired embryonic growth induced by the blockade of Notch signaling were restored by activation of PI3K/Akt signaling.

CONCLUSIONS

Notch signaling regulates a key glycolytic switch in a PI3K/Akt-dependent manner to supply energy for avian embryonic growth. Our study is the first to demonstrate the role of Notch signaling-induced glycolytic switching in embryonic development, and presents new insight into the energy supply patterns in embryogenesis under hypoxic conditions. In addition, it may also provide a natural hypoxia model for developmental biology studies such as immunology, genetics, virology, cancer, etc.

6-Benzylaminopurine causes lipid dyshomeostasis via disruption of glycerophospholipid metabolism in zebrafish

6-Benzylaminopurine (6-BA) is ubiquitous in agricultural production and is accessible to humans through diets. The modulation of lipid metabolism by 6-BA has been previously demonstrated in plants and oleaginous microorganisms. Therefore, whether it alters lipid homeostasis in other living organisms requires further investigation. In this study, doses ≥10 mg 6-BA/L caused malformation of the yolk sac, steatosis, and other hepatopathies in zebrafish larvae. Exposure to 25 mg 6-BA/L resulted in increased levels of triglyceride and total cholesterol. Results of transcriptomic analysis indicated that 6-BA alters genes associated with fatty acid and glycerophospholipid metabolism. Among them, the expression levels of hmgcra, elovl7b, and apobb.2 were downregulated, whereas those of lpcat3, bco1l, cyp7al, fabp1b.1, elp6, pde6ha, apoa4b.2_2, sgk1, dgkaa, and mogat2 were upregulated. Correspondingly, a study of the metabolome identified lysophosphatidylcholine (LPC) as the major differentially expressed metabolite in response to 6-BA treatment. Therefore, abnormal accumulation of LPCs and dyshomeostasis of glycerophospholipid metabolism were identified as potential mechanisms causing the toxicity of 6-BA, which should be assessed to understand the risks of 6-BA and the products contaminated by it. ENVIRONMENTAL IMPLICATION: 6-Benzylaminopurine (6-BA), an important residue in "toxic bean sprouts," is ubiquitous in agricultural production and is common in typical diets. Its regulation of lipid metabolism has been demonstrated in plants and oleaginous microorganisms. Whether it alters lipid homeostasis in other organisms and the underlying mechanisms remain largely unknown. The worldwide use of 6-BA and the potential exposure of humans have aroused public attention owing to its hazardous effects; thus, its hazardous effects, particularly those on lipid homeostasis, deserve careful clarification.

Allantoic fluid metabolome reveals specific metabolic signatures in chicken lines different for their muscle glycogen content

Nutrient availability in eggs can affect early metabolic orientation in birds. In chickens divergently selected on the Pectoralis major ultimate pH, a proxy for muscle glycogen stores, characterization of the yolk and amniotic fluid revealed a different nutritional environment. The present study aimed to assess indicators of embryo metabolism in pHu lines (pHu+ and pHu-) using allantoic fluids (compartment storing nitrogenous waste products and metabolites), collected at days 10, 14 and 17 of embryogenesis and characterized by 1H-NMR spectroscopy. Analysis of metabolic profiles revealed a significant stage effect, with an enrichment in metabolites at the end of incubation, and an increase in interindividual variability during development. OPLS-DA analysis discriminated the two lines. The allantoic fluid of pHu- was richer in carbohydrates, intermediates of purine metabolism and derivatives of tryptophan-histidine metabolism, while formate, branched-chain amino acids, Krebs cycle intermediates and metabolites from different catabolic pathways were more abundant in pHu+. In conclusion, the characterization of the main nutrient sources for embryos and now allantoic fluids provided an overview of the in ovo nutritional environment of pHu lines. Moreover, this study revealed the establishment, as early as day 10 of embryo development, of specific metabolic signatures in the allantoic fluid of pHu+ and pHu- lines.

Slow and Fast-Growing Chickens Use Different Antioxidant Pathways to Maintain Their Redox Balance during Postnatal Growth

The evolution of parameters known to be relevant indicators of energy status, oxidative stress, and antioxidant defense in chickens was followed. These parameters were measured weekly from 1 to 42 days in plasma and/or muscles and liver of two strains differing in growth rate. At 1-day old, in plasma, slow-growing (SG) chicks were characterized by a high total antioxidant status (TAS), probably related to higher superoxide dismutase (SOD) activity and uric acid levels compared to fast-growing (FG) chicks whereas the lipid peroxidation levels were higher in the liver and muscles of SG day-old chicks. Irrespective of the genotype, the plasma glutathione reductase (GR) and peroxidase (GPx) activities and levels of hydroperoxides and α- and γ-tocopherols decreased rapidly post-hatch. In the muscles, lipid peroxidation also decreased rapidly after hatching as well as catalase, GR, and GPx activities, while the SOD activity increased. In the liver, the TAS was relatively stable the first week after hatching while the value of thio-barbituric acid reactive substances (TBARS) and GR activity increased and GPx and catalase activities decreased. Our study revealed the strain specificities regarding the antioxidant systems used to maintain their redox balance over the life course. Nevertheless, the age had a much higher impact than strain on the antioxidant ability of the chickens.

Physiological effects of in ovo delivery of bioactive substances in broiler chickens

The poultry industry has improved genetics, nutrition, and management practices, resulting in fast-growing chickens; however, disturbances during embryonic development may affect the entire production cycle and cause irreversible losses to broiler chicken producers. The most crucial time in the chicks' development appears to be the perinatal period, which encompasses the last few days of pre-hatch and the first few days of post-hatch. During this critical period, intestinal development occurs rapidly, and the chicks undergo a metabolic and physiological shift from the utilization of egg nutrients to exogenous feed. However, the nutrient reserve of the egg yolk may not be enough to sustain the late stage of embryonic development and provide energy for the hatching process. In addition, modern hatchery practices cause a delay in access to feed immediately post-hatch, and this can potentially affect the intestinal microbiome, health, development, and growth of the chickens. Development of the in ovo technology allowing for the delivery of bioactive substances into chicken embryos during their development represents a way to accommodate the perinatal period, late embryo development, and post-hatch growth. Many bioactive substances have been delivered through the in ovo technology, including carbohydrates, amino acids, hormones, prebiotics, probiotics and synbiotics, antibodies, immunostimulants, minerals, and microorganisms with a variety of physiological effects. In this review, we focused on the physiological effects of the in ovo delivery of these substances, including their effects on embryo development, gastrointestinal tract function and health, nutrient digestion, immune system development and function, bone development, overall growth performance, muscle development and meat quality, gastrointestinal tract microbiota development, heat stress response, pathogens exclusion, and birds metabolism, as well as transcriptome and proteome. We believe that this method is widely underestimated and underused by the poultry industry.

Effect of in ovo creatine monohydrate on hatchability, post-hatch performance, breast muscle yield and fiber size in chicks from young breeder flocks

Younger broiler breeder flocks produce smaller eggs containing smaller yolks, with potentially lower energy reserves for the developing chick. Creatine is a naturally occurring energy source and is abundant in metabolically active tissues; providing this to chicks in ovo should provide additional energy to improve hatchability and post-hatch growth. Thus, post-hatch performance of male and female chicks hatched from younger breeder flocks supplemented with creatine monohydrate (CrM) in ovo was investigated. Four hundred eggs from Ross 308 breeder hens aged 27 to 29 wk were collected and at d 14 assigned to a treatment group and received 1) no injection, 2) 0.75% saline injection, or 3) 8.16 mg creatine monohydrate in 0.75% saline. At hatch 72 birds (24/treatment) were euthanized and BW, breast muscle, heart and liver weight were obtained, and breast muscle tissue was placed in 10% buffered formalin. Birds were then placed in raised metal pens (24 pens; 10-11 birds/pen; 8 replicates/treatment) and grown to d 42 with BW and pen feed intake measured once a week. At d 42, ninty-six birds were euthanized (2 male and 2 female/pen) and the process occurred as at hatch. Body composition was obtained for 48 birds (2/pen; 1 male,1 female) with a dual energy X-ray absorptiometry (DXA) scanner. Breast muscle tissue was processed for histological analysis and breast muscle fiber parameters were analyzed by ImageJ. While not statistically significant, the CrM treatment group saw an improved hatch rate (CrM: 93.5%, Saline: 88.6%, Control: 88.8%) and reduced early post hatch mortality. Chicks given in ovo CrM had significantly increased creatine concentrations in both liver and heart tissue at hatch compared to those in the saline and control groups. BW, BW gain, and final body composition parameters were not statistically different between treatments and in ovo CrM did not affect breast muscle fiber number or area. The creatine injection likely improved the energy status of the growing embryo resulting in the improved hatch rate but leaving little reserves for post-hatch growth.

Effects of the Number of Crested Cushions in Runzhou White-Crested Ducks on Serum Biochemical Parameters

We investigated the effects of crest cushions in Runzhou white-crested (RWC) ducks. A total of 322 duck eggs were collected for incubation; 286 eggs were fertilized, and 235 RCW ducks were hatched. All the RWC ducks were weighed after 100 days and counted, and the volume of the crest cushion was measured. The number of crest cushions was positively correlated with the body weight, volume of the crest cushion, and distance from the mouth (p < 0.05). The serum Ca, Mg, Fe, Cu, Zn, and Se contents in the multiple-crest-cushion group were significantly higher (p < 0.05), as were the levels of triglycerides, immunoglobulin A, immunoglobulin G, immunoglobulin M, and immunoglobulin D (p < 0.01). The opposite results were seen for glycosylated low-density lipoprotein (p < 0.01). Propionic acid and acetic acid contents differed significantly between the two groups (p < 0.05), as did butyric acid content (p < 0.01), being higher in the multiple-crest-cushion group. Thus, an increase in the number of crest cushions coincided with a change in various serum biochemical indicators. The number of crest cushions might be involved in regulating various mechanisms of RWC ducks and might have an immunoregulatory effect.

Supply and demand of creatine and glycogen in broiler chicken embryos

Optimal embryonic development and growth of meat-type chickens (broilers) rely on incubation conditions (oxygen, heat, and humidity), on nutrients and on energy resources within the egg. Throughout incubation and according to the embryo's energy balance, the main energy storage molecules (creatine and glycogen) are continuously utilized and synthesized, mainly in the embryonic liver, breast muscle, and the extraembryonic yolk sac (YS) tissue. During the last phase of incubation, as the embryo nears hatching, dynamic changes in energy metabolism occur. These changes may affect embryonic survival, hatchlings' uniformity, quality and post hatch performance of broilers, hence, being of great importance to poultry production. Here, we followed the dynamics of creatine and glycogen from embryonic day (E) 11 until hatch and up to chick placement at the farm. We showed that creatine is stored mainly in the breast muscle while glycogen is stored mainly in the YS tissue. Analysis of creatine synthesis genes revealed their expression in the liver, kidney, YS tissue and in the breast muscle, suggesting a full synthesis capacity in these tissues. Expression analysis of genes involved in gluconeogenesis, glycogenesis, and glycogenolysis, revealed that glycogen metabolism is most active in the liver. Nevertheless, due to the relatively large size of the breast muscle and YS tissue, their contribution to glycogen metabolism in embryos is valuable. Towards hatch, post E19, creatine levels in all tissues increased while glycogen levels dramatically decreased and reached low levels at hatch and at chick placement. This proves the utmost importance of creatine in energy supply to late-term embryos and hatchlings.

Profiling intestinal stem and proliferative cells in the small intestine of broiler chickens via in situ hybridization during the peri-hatch period

Mature small intestines have crypts populated by stem cells which produce replacement cells to maintain the absorptive villus surface area. The embryonic crypt is rudimentary and cells along the villi are capable of proliferation. By 7 d post-hatch the crypts are developed and are the primary sites of proliferation. Research characterizing the proliferative expansion of the small intestine during the peri-hatch period is lacking. The objective of this study was to profile the changes of genes that are markers of stem cells and proliferation: Olfactomedin 4 (Olfm4), Leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5), and marker of proliferation Ki67 from embryonic day 17 to 7 d post-hatch using quantitative PCR and in situ hybridization (ISH). The expression of the stem cell marker genes differed. Olfm4 mRNA increased while Lgr5 mRNA decreased post-hatch. Ki67 mRNA decreased post-hatch in the duodenum and was generally the greatest in the ileum. The ISH was consistent with the quantitative PCR results. Olfm4 mRNA was only seen in the crypts and increased with morphological development of the crypts. In contrast Lgr5 mRNA was expressed in the crypt and the villi in the embryonic periods but became restricted to the intestinal crypt during the post-hatch period. Ki67 mRNA was expressed throughout the intestine pre-hatch, but then expression became restricted to the crypt and the center of the villi. The ontogeny of Olfm4, Lgr5, and Ki67 expressing cells show that proliferation in the peri-hatch intestine changes from along the entire villi to being restricted within the crypts.

Effect of adding and in ovo injecting hatching eggs produced with omega-3 on some hatching traits and body weight of Japanese quail

This study was conducted at a private hatchery in Thi-Qar Governorate to determine the effect of adding omega-3 fatty acid to quail's diet with the outcome of ovo injecting the resulting hatching eggs with omega-3 on some hatching traits and body weight of Japanese quail. A total of 540 eggs were used. The experiment treatments were as follows: T1: Negative control (without adding oil); T2: Positive control (adding 0.01% sunflower oil); T3: Feed the parent with 0.01% omega-3 oil; T4: Feed the parent with 0.01% omega-3 oil, and the resulting eggs were in ovo injected with 0.01 ml omega-3; T5: Feed the parent by 0.01% omega-3 oil, and the resultant eggs were in ovo injected with 0.01 ml sunflower; T6: Feed the parent by 0.01% sunflower oil, and the resulting eggs were in ovo injected with 0.01 ml sunflower; T7: Feed the parent by 0.01% sunflower oil, and the resultant eggs were in ovo injected with 0.01 ml omega-3; T8: Feed the parent by free diet, and the resulting eggs were in ovo injected with 0.01 ml omega-3; T9: Feed the parent by free diet, and the resultant eggs were in ovo injected with 0.01 ml sunflower. The results showed a significant improvement in T4 (the treatment whose parents were fed omega-3 and in ovo injected with omega-3 oil) compared to the control treatment on hatching rate and fertility rate of whole eggs, with a significant decrease in the percentage of embryonic mortality and pipped eggs for the hatched chicks. Feeding Japanese quail mothers with omega-3 hatching egg injections led to a substantial increase in the average weekly body weight. Keywords: in ovo injecting, hatching eggs, with omega-3, hatching traits, body weight, Japanese quail.

Phenology of the transcriptome coincides with the physiology of double-crested cormorant embryonic development

The rigorous timing of the dynamic transcriptome within the embryo has to be well orchestrated for normal development. Identifying the phenology of the transcriptome along with the physiology of embryonic development in birds may suggest periods of increased sensitivity to contaminant exposure depending on the contaminant's mechanism of action. Double-crested cormorants (Nannopterum auritum, formerly Phalacrocorax auritus) are commonly used in ecotoxicological studies, but relatively little is known about their functional transcriptome profile in early development. In this study, we tracked the phenology of the transcriptome during N. auritum embryogenesis. Fresh eggs were collected from a reference site and artificially incubated from collection until four days prior to hatching. Embryos were periodically sampled throughout incubation for a total of seven time points. A custom microarray was designed for cormorants (over 14,000 probes) and used for transcriptome analysis in whole body (days 5, 8) and liver tissue (days 12, 14, 16, 20, 24). Three main developmental periods (early, mid, and late incubation) were identified with differentially expressed genes, gene sets, and pathways within and between each developmental transition. Overall, the timing of differentially expressed genes and enriched pathways corresponded to previously documented changes in morphology, neurology, or physiology during avian embryonic development. Targeted investigation of a subset of genes involved in endogenous and xenobiotic metabolism (e.g., cytochrome P450 cyp1a, cyp1b1, superoxide dismutase 1 sod1) were expressed in a pattern similar to reported endogenous compound levels. These data can provide insights on normal embryonic development in an ecologically relevant species without any environmental contaminant exposure.

Developmental changes in lipid and fatty acid metabolism and the inhibition by in ovo feeding oleic acid in Muscovy duck embryogenesis

Hepatic lipid and fatty acid (FA) metabolism are critical for regulating energetic homeostasis during embryogenesis. At present, it remains unclear how an exogenous FA intervention affects embryonic development in an avian embryo model. In Exp. 1, 30 fertilized eggs were sampled on embryonic days (E) 16, 19, 22, 25, 28, 31 and the day of hatch (DOH) to determine the critical period of lipid metabolism. In Exp. 2, a total of 120 fertilized eggs were divided into two groups (60 eggs/group) for in ovo feeding (IOF) procedures on E25. Eggs were injected into the yolk sac with PBS as the control group and with oleic acid (OA) as the IOF-OA treatment group. Samples were collected on E28 and E31. In Exp. 1, hepatic triacylglycerol (TG) and cholesterol (CHO) contents increased while serum TG content decreased from E16 to DOH (P < 0.05). Both serum and liver displayed an increase in unsaturated FA and a decrease in saturated FA (P < 0.05). There was a quadratic increase in the target gene and protein expression related to hepatic FA de novo synthesis and oxidation (P < 0.05), whose inflection period was between E22 and E28. In Exp. 2, compared with the control embryos, IOF-OA embryos had an increased yolk sac TG content on E28 and E31, and a decreased serum TG and CHO content on E28 (P < 0.05). The IOF-OA embryos had less OA in the yolk sac and liver on E28, and less unsaturated FA in the serum and liver on E31 than did the control embryos (P < 0.05). Hepatic gene mRNA expression related to FA uptake, synthesis, and oxidation on E28 was lower in IOF-OA than in control embryos (P < 0.05), not on E31 (P > 0.05). Maximal metabolic changes in lipid and FA metabolism occurred on E22-E28 in Muscovy duck embryogenesis, along with the altered target gene and protein expression related to lipogenesis and lipolysis. IOF-OA intervention on E25 could inhibit the target gene expression related to FA uptake, synthesis, and oxidation, which may influence the normal FA metabolism on E28 during embryogenesis.

Unveiling and application of the chicken egg proteome: An overview on a two-decade achievement

Egg proteins are not only the most complete and ideal form of protein for human or embryo nutrition but also play the vital role in the food industry. Egg proteins are subjected to many potential changes under various conditions, which may further alter the nutritional value, physicochemical-properties, and bioactivities of proteins. Recent advances in our understanding of the proteome of raw egg matrix from different species and dynamic changes occurring during storage and incubation are developing rapidly. This review provides a comprehensive overview of the main characteristics of chicken egg proteome, covering all its components and applications under various conditions, such as markers detection, egg quality evaluation, genetic and biological unknown identification, and embryonic nutritional supplementation, which not only contributes to our in-depth understanding of each constituent functionality of proteome, but also provides information to increase the value to egg industry.

The effects of hen's age and egg storage duration on selected growth parameters of turkey embryos

The aim of this study was to determine the effects of hen's age (A) and egg storage duration (T) on selected growth parameters of turkey embryos. At 32, 38, 46, and 51 wk of hen's age, 1,512 eggs laid on one or 2 consecutive days were collected randomly and marked. At each sampling date, the eggs were randomly divided into 4 groups and were stored for various periods of time, that is, 7, 10, 13, and 17 d. All eggs were stored at a temperature of 15°C and relative air humidity of 76%. On d 9, 15, 21, and 24 of incubation, 5 eggs containing live embryos were randomly selected from each group for analysis of the following parameters: relative body weight (RBW) of embryos, relative weight of the yolk sac (RWY), relative weight of unused albumen (RWA). The effects of hen's age and egg storage duration on the RBW of embryos were observed on d 15, 21, and 24 of incubation (P < 0.05). The effects of hen's age and egg storage duration on RWY were noted on all analyzed days of incubation (P < 0.05). Embryos in eggs laid by younger hens (aged 32 and 38 wk) and stored for a shorter period were characterized by a faster rate of albumen utilization than embryos in eggs laid by older hens (aged 46 and 51 wk). The largest amount of unused albumen was found in eggs laid by hens in wk 51 of the laying season (P < 0.05), and stored for 17 d (P < 0.05). In conclusion, numerous interactions (AxT) between selected growth parameters of turkey embryos indicate that the quality of hatching eggs changes with hen's age, affecting their suitability for long-term storage under standard conditions. Therefore, eggs laid by younger breeders should not be stored for longer periods due to undesirable changes in RWY and RWA.

Determination of the Optimal In-Feed Amino Acid Ratio for Japanese Quail Breeders Based on Utilization Efficiency

Simple Summary

Breeder reproductive responses are optimized if nutritional, environmental, and health requirements are adequately met. Thus, the ideal concentration of amino acids in the diet must be obtained to prevent excess or deficiency to the animal. This may occur due to the inefficiency in the production or excessive excretion of nitrogen. Therefore, it is necessary to determine the optimal relationship for this nutrient category. These results contribute to ensuring optimal ratios of essential amino acids in the diets of Japanese quail breeders based on amino acid efficiency.

Abstract

The description of the genetic potential is the first step to estimating amino acid requirements and the ideal amino acid relation (IAAR). The aim of this study was to estimate the parameters that describe the daily maximum theoretical nitrogen retention (NR_maxT, mg/BWkg^0.67), daily nitrogen maintenance requirement (NMR, mg/BWkg^0.67), protein quality (b), dietary efficiency of the limiting amino acid (bc⁻¹) and determine the lysine requirement and the IAAR for Japanese quail breeders. Two nitrogen balance assays were performed, one assay using 49 quails distributed in seven treatments (protein levels between 70.1 and 350.3 g/kg) and seven replicates and other assay to determine the IAAR by the use of bc⁻¹, 12 treatments and 10 replicate, with a control diet (CD) and 11 treatments that had limited essential amino acids by providing only 60% of the CD. The values obtained for NR_maxT, NMR, b and bc⁻¹ were 3386.61, 0.000486 and 0.000101, respectively. The daily intake of Lys was 291 mg/bird day. Lys was set at 100% for determining the IAAR: 87, 67, 21, 117, 96, 66, 142, 39, and 133 for Met + Cys, Thr, Trp, Arg, Val, Ile, Leu, His, and Phr + Tyr, respectively, for Japanese quail breeders.

Microbial composition of egg component and its association with hatchability of laying hens

The internal quality of eggs is critical for human consumption and embryonic development. However, microorganisms inside eggs have not been thoroughly investigated for their roles in determining the egg's internal quality. Here, a total of 21 hens were selected from more than 1,000 chickens based on their hatching results and were divided into high- and low-hatchability groups. Then, we collected 72 eggs from these 21 hens to obtain egg whites and yolks, including 54 fresh eggs and 18 eggs after 12 days of incubation. We characterized the microbial composition of egg yolks and whites, the microbial change along incubation, and differences in microbial abundance between the high- and low-hatchability groups. The results indicated that egg whites are not sterile. Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were the dominant phyla in egg yolk and white. There was a large difference in the microbial composition between egg whites and yolks, and this difference increased after 12 days of incubation. Egg whites have lower microbial diversity than egg yolks owing to the presence of antibacterial substances such as lysozyme in the egg white. After a 12-day incubation, the microbial diversity decreased in egg whites but increased slightly in egg yolks. Meanwhile, the microbes in egg white can migrate to egg yolk during incubation. Additionally, Genus Muribaculaceae was identified as a biomarker in egg yolks incubated for 12 days and was more often detected in healthy groups. On the contrary, more genus Rothia were found in the fresh egg yolk of the low hatchability groups and was considered to have low virulence. These findings shed light on the composition and differences in microbiota between egg yolks and whites and may open new avenues for studying embryonic development in chickens.

Development of breast muscle parameters, glycogen reserves, and myogenic gene expression in goslings during pre- and post-hatching periods

This study aimed to better understand the development patterns of breast muscle and glycogen reserves in goslings during pre- and post-hatching periods. The timepoints for sampling were embryonic days 23 and 27 of hatching and days 1, 4, and 7 post hatching. We found that the body weight of goslings increased with age. The small intestine developed with age and remained reasonably constant on day 4 post hatching. The breast muscle development decreased with age and stayed relatively stable on day 1 post hatching. The diameter of myofiber increased prior to hatching and then decreased while hatching. The development patterns of breast muscle glycogen reserves were similar to the diameter of myofiber. In contrast, the contents of liver glycogen began to decrease before hatching and then increased rapidly after hatching. Moreover, the expression of Myf-5 increased with age. The expression of MSTN was maintained at high levels prior to hatching, dropped immediately after hatching, and then gradually increased with age. Additionally, we also observed that the glycogen content in the breast muscle was positively correlated with the diameter of the myofiber. The liver glycogen content was positively correlated to the relative weight of the breast muscle, the diameter of the myofiber, and the breast muscle glycogen content. The development pattern of the myofiber was synchronized with the change in the MSTN/Myf-5 ratio. This study provided a profile to understand the development patterns of breast muscle, glycogen reserves, and myogenic gene expression in goslings, which was beneficial to understanding the characteristics of energy reserves during the early life of goslings.

Multiple Effects of Egg Weight, in Ovo Carbohydrates, and Sex of Birds on Posthatch Performance in Broilers

Chickens raised for their meat (Gallus gallus domesticus) tend to have a critical phase of life right after hatching due to the management of modern production systems. Early nutrition strategies such as in ovo intervention can be an alternative means to support growth and gut health by compensating for the energy deficit after pipping out of the egg. In the current study, 1200 Ross 308 eggs were used to examine the effects of a complex carbohydrate solution of disaccharides and glucose applied in ovo on hatchability, the hatching time of different-sized eggs, and the development, performance, and carcass characteristics of broilers of both sexes. The eggs were divided into three treatment groups: intact (NT), in ovo saline (ioS), and in ovo carbohydrate mixture (ioCH). The incubation protocol was performed according to the recommendations of Aviagen (2019), and the in ovo process was carried out on day 17 by manually injecting 0.5 mL of the solutions into the amniotic fluid. After hatching, the birds were kept in floor pens until day 35 and fed ad libitum in a three-phase feeding program. Body weight, average daily weight gain, feed intake and conversion, and carcass characteristics were measured during the trial. In ovo carbohydrates reduced hatchability by 15%, while growth performance and the weight of thigh and breast muscle were enhanced significantly (p < 0.05) compared with ioS as a possible outcome of carbohydrate-to-muscle satellite cell proliferation and protein accumulation. However, further study is needed to refine the in ovo carbohydrate supplementation method to minimize the mortality of embryos during hatching.

Evaluation of in ovo feeding of low or high mixtures of cysteine and lysine on performance, intestinal morphology and physiological responses of thermal-challenged broiler embryos

The objective of this study was to evaluate the effect of in ovo feeding cysteine, lysine or their combinations on the perinatal and post-hatch physiological responses of broiler embryos exposed to heat stress during incubation. A total of two thousand fertile eggs of broiler breeders (Ross 308) flock (at 38 weeks of age) were used for this study. In the first 10 days, the eggs were incubated using the conventional protocol of relative humidity and temperature of 55% and 37.8°C respectively. From day ten onward, the temperature was increased to 39.6°C for 6 h per day. On day 17.5, 1,500 eggs with the evidence of living embryos were randomly selected and assigned to 6 treatments having five replicates of 50 eggs each. The treatments were: un-injected eggs (UI), eggs injected with only 0.5 ml distilled water (DW), 3.5 mg/egg cysteine (CY), 2mg/egg lysine (LY), 3.4 mg cysteine+2 mg lysine (CLH) and 1.7 mg cysteine+1 mg lysine (CLL). On day 21, the hatchability, anatomical characteristics, chick quality and the antioxidant status of the chicks were evaluated. During the post-hatch phase, data were collected on the haematology, biochemical parameters, growth performance and intestinal morphology of the birds. The results revealed that the hatchability of CY chicks was higher (p &lt; 0.05) than in the other treatments, while the lowest values were recorded in CLH. The hatching muscle of the chicks of CLL was similar to those of CY but higher (p &lt; 0.05) than the others. The MDA of DW and UI chickens was similar and higher than birds in the other treatment groups. The serum SOD of CLL birds was comparable to that of CY but higher than the values recorded in the other treatments. The final weights of CLL chickens were similar to those of LY but significantly higher (p &lt; 0.05) than those of the other treatments. The duodenal villus heights of the birds of CLL were higher than those of the other treatment groups, whereas the villus height of the birds of CLH was higher than those of UI, DW and CY. Overall, in ovo feeding of cysteine alone improved the hatchability of thermally-challenged broiler embryos. In contrast, a low-dose mixture of cysteine plus lysine improved the post-hatch growth performance.

Research Note: Developmental changes of glucose metabolism are associated with insulin signaling in goose embryo

This study aimed to investigate whether the developmental changes in glucose metabolism were associated with insulin signaling in the middle and later stages of goose embryos. Serum and liver were sampled on embryonic day 19, 22, 25, 28, and day of hatchment, with 30 eggs at each sampling time point, and 6 replicates of 5 embryos. The embryonic growth traits, serum glucose, hormone levels, and the hepatic mRNA expressions of target genes related to glucose metabolism and insulin signaling were measured at each time point. Relative body weight, relative liver weight, and relative body length decreased linearly and quadratically from embryonic day 19 to day of hatchment, while relative yolk weight decreased linearly from embryonic day 19 to day of hatchment. Serum glucose, insulin, and free triiodothyronine levels increased linearly with increasing incubation time, while no differences were observed in serum glucagon and free thyroxine levels. The hepatic mRNA expression related to glucose catabolism (hexokinase, phosphofructokinase, and pyruvate kinase) and insulin signaling (insulin receptor, insulin receptor substrate protein, Src homology collagen protein, extracellular signal-regulated kinase, and ribosomal protein S6 kinase, 70 ku) increased quadratically from embryonic day 19 to day of hatchment. The expression of citrate synthase and isocitrate dehydrogenase mRNA decreased linearly and quadratically respectively from embryonic day 19 to day of hatchment. Serum glucose levels were positively related to serum insulin (r = 1.00) and free triiodothyronine (r = 0.90) levels, as well as the hepatic mRNA expression of insulin receptor (r = 1.00), insulin receptor substrate protein (r = 0.64), extracellular signal-regulated kinase (r = 0.81), and ribosomal protein S6 kinase, 70 ku (r = 0.81) related to insulin signaling. In conclusion, glucose catabolism was enhanced and had positive correlations with the insulin signaling in the middle and later stages of geese embryogenesis.

Impact of growth curve and dietary energy-to-protein ratio of broiler breeders on offspring quality and performance

The impact of growth curve (GC) and dietary energy-to-protein ratio of broiler breeder hens on chick quality and broiler performance was investigated. Pullets (n = 1,536) were randomly allotted to 24 pens and assigned to 1 of 8 treatments from hatch onwards, according to a 2 × 4 factorial arrangement with 2 GC (standard growth curve = SGC or elevated growth curve = EGC, +15%) and 4 diets, differing in energy-to-protein ratio (96%, 100%, 104%, and 108% AME_n diet). At 28 and 36 wk of age, 60 hatching eggs per maternal pen were selected for incubation and 768-day-old broilers were assigned to 32 pens according to maternal treatment.

Broilers from EGC breeders were 1.9 g heavier at hatch (P < 0.001) and 36 g heavier at slaughter (P = 0.001) than broilers from SGC breeders due to a 1.0 g/d higher growth rate (P = 0.003) and 1.5 g/d higher feed intake (P = 0.006) from hatch to 32 d of age. An increase in breeder dietary energy-to-protein ratio resulted in a linear decrease in embryonic mortality in the first 3 d of incubation (β = -0.2% per % AME_n; P = 0.05). At hatch, broiler BW decreased with an increasing breeder dietary energy-to-protein ratio (β = -0.1 g per % AME_n; P = 0.001), whereas at slaughter broiler BW increased with an increasing breeder dietary energy-to-protein ratio (β = 3.2 g per % AME_n; P = 0.02). This was due to a linear increase in growth rate (β = 0.1 g/d per % AME_n; P = 0.004) and feed intake (β = 0.1 g/d per % AME_n; P = 0.02). Additionally, an increase in breeder dietary energy-to-protein ratio resulted in a linear decrease in body weight corrected feed conversion ratio (β = -0.002 per % AME_n; P = 0.002). Overall, it can be concluded that a higher GC of breeders and an increase in breeder dietary energy-to-protein ratio enhances offspring performance.

Hepatic glycerolipid metabolism is critical to the egg laying rate of Guangxi Ma chickens

Yolk formation in liver is an important process for egg production in hens. The correlations between egg laying rate decline and liver function changes in Guangxi Ma chickens remain unclear. In this study, a total of 21,750 genes and 76,288 transcripts were identified in the RNA expression profiles isolated from liver tissues of 5 groups of Guangxi Ma chickens divided according to the age and egg laying rate. Numerous differential genes (DEGs) were identified after pairwise comparison among samples, and time series analysis categorization (age-related factors) revealed that down-regulated DEGs with aging were predominantly involved in lipid transportation and metabolic processes in the low egg laying rate groups. Notably, functional enrichment analysis confirmed that DGAT2, LIPG, PNPLA2, LPL, CEL, LIPC, DGKD, AGPAT2, AGPAT1 and AGPAT3 were highlighted as hub genes in glycerolipid metabolism pathway, which may be an essential non-age related factors of egg laying rate by regulating the synthesis of triacylglycerol (TAG) in liver. Finally, we categorized DEGs in Guangxi Ma chickens with different egg laying rate caused by age-related factors and found that DEGs with different expression patterns performing different biological functions. The analysis of DEGs with lower egg laying rate caused by non-age related factors and showed that the transportation of TAG was suppressed. Furthermore, critical genes and pathways involved in the synthesis of TAG in livers were identified, which dynamically regulated the formation of yolk precursors. Our results expanded the knowledge of the molecular mechanisms of the yolk precursor synthesis in chicken livers. The results will be helpful to explore the factors that affect egg laying rate from the perspective of yolk synthesis and provide a theoretical basis for improving the egg production of Guangxi Ma chickens.

Proteomic Analysis of Chicken Chorioallantoic Membrane (CAM) during Embryonic Development Provides Functional Insight

In oviparous animals, the egg contains all resources required for embryonic development. The chorioallantoic membrane (CAM) is a placenta-like structure produced by the embryo for acid-base balance, respiration, and calcium solubilization from the eggshell for bone mineralization. The CAM is a valuable in vivo model in cancer research for development of drug delivery systems and has been used to study tissue grafts, tumor metastasis, toxicology, angiogenesis, and assessment of bacterial invasion. However, the protein constituents involved in different CAM functions are poorly understood. Therefore, we have characterized the CAM proteome at two stages of development (ED12 and ED19) and assessed the contribution of the embryonic blood serum (EBS) proteome to identify CAM-unique proteins. LC/MS/MS-based proteomics allowed the identification of 1470, 1445, and 791 proteins in CAM (ED12), CAM (ED19), and EBS, respectively. In total, 1796 unique proteins were identified. Of these, 175 (ED12), 177 (ED19), and 105 (EBS) were specific to these stages/compartments. This study attributed specific CAM protein constituents to functions such as calcium ion transport, gas exchange, vasculature development, and chemical protection against invading pathogens. Defining the complex nature of the CAM proteome provides a crucial basis to expand its biomedical applications for pharmaceutical and cancer research.

Chicken Incubation Conditions: Role in Embryo Development, Physiology and Adaptation to the Post-Hatch Environment

The chicken hatching egg is a self-contained life-supporting system for the developing embryo. However, the post-hatch performance of birds depends on several factors, including the breeder management and age, egg storage conditions and duration before incubation, and the incubation conditions. Studies have determined the effect of incubation factors on chick post-hatch growth potential. Therefore, chick physical quality at hatch is receiving increasing attention. Indeed, although incubation temperature, humidity, turning and ventilation are widely investigated, the effects of several variables such as exposure of the embryo to high or low levels, time of exposure, the amplitude of variations and stage exposures on embryo development and post-hatch performance remain poorly understood. This review paper focuses on chick quality and post-hatch performance as affected by incubation conditions. Also, chick physical quality parameters are discussed in the context of the parameters for determining chick quality and the factors that may affect it. These include incubation factors such as relative humidity, temperature, turning requirements, ventilation, in ovo feeding and delay in feed access. All these factors affect chick embryo physiology and development trajectory and consequently the quality of the hatched chicks and post-hatch performance. The potential application of adapted incubation conditions for improvement of post-hatch performance up to slaughter age is also discussed. It is concluded that incubation conditions affect embryo parameters and consequently post-hatch growth differentially according to exposure time and stage of exposure. Therefore, classical physical conditions are required to improve hatchability, chick quality and post-hatch growth.

Remodeling of Hepatocyte Mitochondrial Metabolism and De Novo Lipogenesis During the Embryonic-to-Neonatal Transition in Chickens

Embryonic-to-neonatal development in chicken is characterized by high rates of lipid oxidation in the late-term embryonic liver and high rates of de novo lipogenesis in the neonatal liver. This rapid remodeling of hepatic mitochondrial and cytoplasmic networks occurs without symptoms of hepatocellular stress. Our objective was to characterize the metabolic phenotype of the embryonic and neonatal liver and explore whether these metabolic signatures are preserved in primary cultured hepatocytes. Plasma and liver metabolites were profiled using mass spectrometry based metabolomics on embryonic day 18 (ed18) and neonatal day 3 (nd3). Hepatocytes from ed18 and nd3 were isolated and cultured, and treated with insulin, glucagon, growth hormone and corticosterone to define hormonal responsiveness and determine their impacts on mitochondrial metabolism and lipogenesis. Metabolic profiling illustrated the clear transition from the embryonic liver relying on lipid oxidation to the neonatal liver upregulating de novo lipogenesis. This metabolic phenotype was conserved in the isolated hepatocytes from the embryos and the neonates. Cultured hepatocytes from the neonatal liver also maintained a robust response to insulin and glucagon, as evidenced by their contradictory effects on lipid oxidation and lipogenesis. In summary, primary hepatocytes from the embryonic and neonatal chicken could be a valuable tool to investigate mechanisms regulating hepatic mitochondrial metabolism and de novo lipogenesis.

Nutrient sources differ in the fertilised eggs of two divergent broiler lines selected for meat ultimate pH

The pHu+ and pHu− lines, which were selected based on the ultimate pH (pHu) of the breast muscle, represent a unique model to study the genetic and physiological controls of muscle energy store in relation with meat quality in chicken. Indeed, pHu+ and pHu− chicks show differences in protein and energy metabolism soon after hatching, associated with a different ability to use energy sources in the muscle. The present study aimed to assess the extent to which the nutritional environment of the embryo might contribute to the metabolic differences observed between the two lines at hatching. Just before incubation (E0), the egg yolk of pHu+ exhibited a higher lipid percentage compared to the pHu− line (32.9% vs. 27.7%). Although ¹H-NMR spectroscopy showed clear changes in egg yolk composition between E0 and E10, there was no line effect. In contrast, ¹H-NMR analysis performed on amniotic fluid at embryonic day 10 (E10) clearly discriminated the two lines. The amniotic fluid of pHu+ was richer in leucine, isoleucine, 2-oxoisocaproate, citrate and glucose, while choline and inosine were more abundant in the pHu− line. Our results highlight quantitative and qualitative differences in metabolites and nutrients potentially available to developing embryos, which could contribute to metabolic and developmental differences observed after hatching between the pHu+ and pHu− lines.

Nutritional stimulation by in-ovo feeding modulates cellular proliferation and differentiation in the small intestinal epithelium of chicks

Nutritional stimulation of the developing small intestine of chick embryos can be conducted by in-ovo feeding (IOF). We hypothesized that IOF of glutamine and leucine can enhance small intestinal development by promoting proliferation and differentiation of multipotent small intestinal epithelial cells. Broiler embryos (n = 128) were subject to IOF of glutamine (IOF-Gln), leucine (IOF-Leu), NaCl (IOF-NaCl) or no injection (control) at embryonic d 17 (E 17). Multipotent, progenitor and differentiated cells were located and quantified in the small intestinal epithelium between E 17 and d 7 after hatch (D 7) in all treatment groups by immunofluorescence of SRY-box transcription factor 9 (Sox9) and proliferating cell nuclear antigen (PCNA), in-situ hybridization of leucine-rich repeat containing G-protein coupled receptor 5 (Lgr5) and peptide transporter 1 (PepT1) and histochemical goblet cell staining. The effects of IOF treatments at E 19 (48 h post-IOF), in comparison to control embryos, were as follows: total cell counts increased by 40%, 33% and 19%, and multipotent cell counts increased by 52%, 50% and 38%, in IOF-Gln, IOF-Leu and IOF-NaCl embryos, respectively. Only IOF-Gln embryos exhibited a significance, 36% increase in progenitor cell counts. All IOF treatments shifted Lgr5+ stem cell localizations to villus bottoms. The differentiated, PepT1+ region of the villi was 1.9 and 1.3-fold longer in IOF-Gln and IOF-Leu embryos, respectively, while goblet cell densities decreased by 20% in IOF-Gln embryos. Post–hatch, crypt and villi epithelial cell counts were significantly higher IOF-Gln chicks, compared to control chicks (P < 0.05). We conclude IOF of glutamine stimulates small intestinal maturation and functionality during the peri-hatch period by promoting multipotent cell proliferation and differentiation, resulting in enhanced compartmentalization of multipotent and differentiated cell niches and expansions of the absorptive surface area.

Exogenous Linoleic Acid Intervention Alters Hepatic Glucose Metabolism in an Avian Embryo Model

In the present study, developmental changes of gluconeogenesis and glycolysis in an avian model were measured, and then the intervention effects of in ovo feeding (IOF) linoleic acid (LA) on hepatic glucose metabolism were evaluated. In Experiment 1, thirty fertilized eggs were sampled on embryonic days (E) of 16, 19, 22, 25, 28, 31, and thirty newly-hatched ducklings at hatch (E34 and E35). In Experiment 2, a total of 120 fertilized eggs (60 eggs for each group) were injected into the yolk sac with PBS as the control group and LA as the IOF LA group on E25. Twelve eggs were selected for sample collection on E28 and E31. Serum contents of glucose, pyruvate, and lactate increased ( p < 0.05) linearly or quadratically from E16 to hatch, as well as hepatic glycogen and pyruvate contents. Hepatic mRNA expression related to energy homeostasis, gluconeogenesis, and glycolysis increased ( p < 0.05) in embryogenesis, and the plateau period was presented on E25–E31. IOF LA decreased ( p < 0.05) serum contents of glucose, triacylglycerol, cholesterol, and hepatic oleic acid, unsaturated fatty acids on E28, as well as the gene expression relative to gluconeogenesis. IOF LA increased ( p < 0.05) pyruvate content in serum and liver, and hepatic gene expression relative to glycolysis on E31. In summary, hepatic gluconeogenesis and glycolysis were enhanced to meet the increasing energy demands of embryonic development during E25 – hatch. Exogenous LA intervention on E25 could inhibit hepatic gluconeogenesis and enhance glycolysis during the later developmental period, disrupting glucose embryonic homeostasis and energy status.

Influences of L-Arginine In Ovo Feeding on the Hatchability, Growth Performance, Antioxidant Capacity, and Meat Quality of Slow-Growing Chickens

Simple Summary

The nutrition and health status of the embryo in the hatching process directly influence the hatchability and chicken performance post-hatch in poultry production. The in ovo feeding (IOF) technique provides a viable way to improve the embryonic development and chicken performance post-hatch. Thus, the hypothesis of this study was that supplementing L-arginine (Arg) into embryos could positively affect the hatchability, growth performance, antioxidant capacity, and meat quality of slow-growing chickens. The results of this study demonstrate that IOF of Arg positively affected the antioxidant capacity of the breast muscle in the starter period, and there was no effect on the hatchability, growth performance, carcass traits, and meat quality. Overall, our findings suggest that IOF of Arg may have beneficial effects on chicken health without compromising the hatchability, subsequent growth, and meat quality.

Abstract

The aim of this study was to evaluate the effects of in ovo feeding (IOF) of L-arginine (Arg) on the hatchability, growth performance, antioxidant capacity, and meat quality of slow-growing chickens. A total of 480 eggs were randomly divided into a non-injected control group (NC group) and a 1% Arg-injected group (Arg group). On day 18 of incubation, 0.5 mL of Arg solution was injected into the embryonic amnion in the Arg group. Upon hatching, 160 mixed-sex chickens were randomly assigned to two groups, with four replicates per group. This experiment lasted for 63 days. The results showed that the hatchability, growth performance, carcass traits, and meat quality were not significantly different (p > 0.05) between the two groups. However, the malondialdehyde (MDA) content was lower (p < 0.05), and the glutathione (GSH) level was higher (p < 0.05) on day of hatching in the Arg group. The total antioxidant capacity (T-AOC) activity was increased (p < 0.05) on day 21 post-hatch in the Arg group compared to that in the NC group. In conclusion, IOF of Arg increased the antioxidant capacity of the breast muscle in the starter period, which may have a positive effect on health status of slow-growing chickens post-hatch.

Managing Gut Microbiota through In Ovo Nutrition Influences Early-Life Programming in Broiler Chickens

The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36-72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

In ovo Feeding as a Tool for Improving Performance and Gut Health of Poultry: A Review

Early growth and development of the gastrointestinal tract are of critical importance to enhance nutrients' utilization and optimize the growth of poultry. In the current production system, chicks do not have access to feed for about 48-72 h during transportation between hatchery and production farms. This lag time affects early nutrient intake, natural exposure to the microbiome, and the initiation of beneficial stimulation of the immune system of chicks. In ovo feeding can provide early nutrients and additives to embryos, stimulate gut microflora, and mitigate the adverse effects of starvation during pre-and post-hatch periods. Depending on the interests, the compounds are delivered to the embryo either around day 12 or 17 to 18 of incubation and via air sac or amnion. In ovo applications of bioactive compounds like vaccines, nutrients, antibiotics, prebiotics, probiotics, synbiotics, creatine, follistatin, L-carnitine, CpG oligodeoxynucleotide, growth hormone, polyclonal antimyostatin antibody, peptide YY, and insulin-like growth factor-1 have been studied. These compounds affect hatchability, body weight at hatch, physiological functions, immune responses, gut morphology, gut microbiome, production performance, and overall health of birds. However, the route, dose, method, and time of in ovo injection and host factors can cause variation, and thereby inconsistencies in results. Studies using this method have manifested the benefits of injection of different single bioactive compounds. But for excelling in poultry production, researchers should precisely know the proper route and time of injection, optimum dose, and effective combination of different compounds. This review paper will provide an insight into current practices and available findings related to in ovo feeding on performance and health parameters of poultry, along with challenges and future perspectives of this technique.

Omics as a Window To Unravel the Dynamic Changes of Egg Components during Chicken Embryonic Development

Chicken egg, as a completely aseptic and self-sufficient biological entity, contains all of the components required for embryonic development. As such, it constitutes not only an excellent model to study the mechanisms of early embryo nutrition and disease origin but can also be used to develop egg-based products with specific applications. Different omics disciplines, like transcriptomics, proteomics, and metabolomics, represent promising approaches to assess nutritional and functional molecules in eggs under development. However, these individual molecules do not act in isolation during the dynamic embryogenic process (e.g., migration, transportation, and absorption). Unless we integrate the information from all of these omics disciplines, there will remain an unbridged gap in the systematic and holistic assessment of the information from one omics level to the other. This integrative review of the dynamic molecular processes of the different chicken egg components involved in embryo development describes the critical interplay between the egg components and their implications in immunity, hematopoiesis, organ formation, and nutrient transport functions during the embryonic process.