Effect of in ovo feeding of vitamin C on antioxidation and immune function of broiler chickens

In ovo sericin suppresses hepatic DNA demethylation in broilers at hatch

Over the years, the rearing period of the commercial broilers to attain the slaughter weight has reduced significantly. Hence, it emphasizes the importance of the period of embryonic development. It has been shown that inadequate nutritional supply to the embryo at the later phases can lead to various abnormalities. This adversely affects the hatchability and further the post-hatch performance of the chicks. This study attempted to study the effect of in ovo feeding of sericin on the developing Ross-308 embryos. Fertile eggs (n = 210) at 17.5 days of embryonic development (ED) were equally divided into five treatments based on the concentration of sericin fed. The treatments were: uninjected control (UCON), followed by different concentrations of sericin injected groups as 0SER (0 % sericin), 1.5SER (1.5 % sericin), 3.0SER (3.0 % sericin), and 4.5SER (4.5 % sericin). Hatch parameters across treatments did not differ significantly. Similarly, the organ (liver, yolk sac, gizzard, proventriculus and heart) indices and plasma antioxidant markers such as 2,2-Diphenyl-1-picrylhydrazyl - radical scavenging activity % (DPPH-RSA%) and malondialdehyde (MDA) content did not differ significantly across treatments. The hepatic mRNA expression of superoxide dismutase (SOD) was higher in 3.0SER treatment in comparison to 4.5SER. On the other hand, in ovo sericin downregulated the hepatic gene expression of DNA demethylation-related enzymes such as ten-eleven translocation methylcytosine dioxygenase 3 (TET3, p = 0.028) and methyl-CpG-binding domain protein 4 (MBD4, p = 0.007) compared to 0SER. Pearson's correlation analyses revealed a significant correlation between the hepatic gene expression of NADPH oxidase (NOX) related genes and DNA-demethylation-related genes (p < 0.01). Hence, in ovo sericin might not be potentially beneficial in improving the hatchability of broilers. Also, no notable effects on the antioxidant capacity of plasma was recorded. However, in ovo sericin downregulated the mRNA expression of some DNA demethylation-related genes which were significantly correlated with the expression of NOXs. Therefore, in ovo sericin feeding could suppress DNA demethylation which could in turn be beneficial to alleviate oxidative stress at hatch.

Effects of in ovo feeding of vitamin C on embryonic development, hatching process, and chick rectal temperature of broiler embryos

Maternal nutritional status plays a crucial role in embryonic development and has persistent effects on postnatal chicks. Vitamin C (VC) plays an important role in embryonic and postnatal development involved in nutri-epigenetics. The present study was conducted to investigate the effects of in ovo feeding (IOF) of VC on embryonic development, egg hatching time, and chick rectal temperature. Trial 1 was conducted under normal incubation conditions without the IOF procedure and was designed to analyze the characteristics of embryonic development and establish the scoring standards for yolk absorption and the rupture of the shell membrane. The results showed that the relative weight of the embryo and residual yolk and the organ indexes were reliable indicators of embryonic development. Yolk absorption was scored 0, 1, 2, 3, and 4, with a higher score indicating more complete absorption. In addition, the rupture of the shell membrane was divided into two cases: YES and NO. Trial 2 included three groups, control (CON), normal saline (NS), and vitamin C (VC), and was designed to detect the effects of IOF of VC on the indicators in trial 1, as well as the plasma biochemical indicators. At embryonic age 11 (E11), each egg in the CON group was non-injected, each egg in the NS group was injected with 0.1 mL of sterile normal saline, and each egg in the VC group was injected with 0.1 mL of sterile normal saline containing 3 mg vitamin C. The whole day of E21 was evenly divided into three time periods: early (incubation hours 480-488), middle (incubation hours 488-496), and late (incubation hours 496-504). Among the CON, NS, and VC groups, the percentages of the early-hatched chicks (egg hatching time) were 29.31, 12.00, and 33.90%, respectively. The proportions of early and middle hatched chicks in these groups were 51.72, 42.00, and 38.27%, respectively. The rectal temperature of chicks was lower (p < 0.05) in the VC group than in the CON and NS groups. Compared to the NS group, the plasma biochemical indicators in the VC group showed significantly lower levels of alkaline phosphatase (ALP), total protein (TP), albumin (ALB), GLB, total bilirubin (TBIL), TBA, uric acid (UA), high-density lipoprotein cholesterol (HDL-C), and corticosterone (CORT) (p < 0.05). Additionally, alanine aminotransferase (ALT) had an increasing trend (p = 0.059) in the VC group. In conclusion, our data demonstrated that VC accelerated the hatching process and reduced chicks' rectal temperature, which may be related to the improvement of liver function and changes in metabolism, as indicated by blood biochemical indicators.

Early-life environmental effects on birds: epigenetics and microbiome as mechanisms underlying long-lasting phenotypic changes

Although the long-lasting effects of variation in early-life environment have been well documented across organisms, the underlying causal mechanisms are only recently starting to be unraveled. Yet understanding the underlying mechanisms of long-lasting effects can help us predict how organisms will respond to changing environments. Birds offer a great system in which to study developmental plasticity and its underlying mechanisms owing to the production of large external eggs and variation in developmental trajectories, combined with a long tradition of applied, physiological, ecological and evolutionary research. Epigenetic changes (such as DNA methylation) have been suggested to be a key mechanism mediating long-lasting effects of the early-life environment across taxa. More recently, changes in the early-life gut microbiome have been identified as another potential mediator of developmental plasticity. As a first step in understanding whether these mechanisms contribute to developmental plasticity in birds, this Review summarizes how changes in early-life environment (both prenatal and postnatal) influence epigenetic markers and the gut microbiome. The literature shows how both early-life biotic (such as resources and social environment) and abiotic (thermal environment and various anthropogenic stressors) factors modify epigenetic markers and the gut microbiome in birds, yet data concerning many other environmental factors are limited. The causal links of these modifications to lasting phenotypic changes are still scarce, but changes in the hypothalamic-pituitary-adrenal axis have been identified as one putative pathway. This Review identifies several knowledge gaps, including data on the long-term effects, stability of the molecular changes, and lack of diversity in the systems studied, and provides directions for future research.

Investigation of the effects of in ovo taurine injection on hatching characteristics and stress reduction potential

BACKGROUND

In ovo application is the process of administering some nutrients or components into the egg. The main purpose of this application is to ensure that some nutrients are provided to chicks with a short incubation period. Few studies were conducted with taurine in fertile eggs; especially, no observation of hatchability and chick quality has been found. In addition, taurine has an anti-stress impact that fights oxidative factors.

OBJECTIVE

To assess the hatchability and chick quality after in ovo taurine administration. To determine the stress that may occur as a result of in ovo application and whether taurine has a stress-reducing effect.

METHODS

A total of 1200 fertile eggs from a 34-week-old broiler breeder (Ross 308) flock were categorized into 4 groups with 75 eggs per replicate: control (uninjected), taurine group (0.30 mL dissolved taurine in distilled water), sham control (sterile distilled water) and perforation (eggs perforated and then waxed). On day 14 of incubation, an in ovo injection was administered to the albumen. Data on hatching parameters and hepatic HSP70 levels were obtained using relevant formulas and western blotting, respectively.

RESULTS

Control chicks exhibited higher hatchability than other groups, with the taurine group showing the lowest hatchability. The HSP70 levels were the highest in the perforation group compared to the control group. An increase of 21.37% in the taurine group and 83.45% in the sham control group was observed compared to the control group.

CONCLUSIONS

The findings suggest that in ovo application may induce increased stress, whereas taurine may have positive effects in mitigating the stress caused by in ovo application.

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.

Embryonic modulation through thermal manipulation and in ovo feeding to develop heat tolerance in chickens

Healthy chickens are necessary to meet the ever-increasing demand for poultry meat. Birds are subjected to numerous stressful conditions under commercial rearing systems, including variations in the environmental temperature. However, it is difficult to counter the effects of global warming on the livestock industry. High environmental temperature is a stressful condition that has detrimental effects on growth and production performance, resulting in decreased feed intake, retarded growth, compromised gut health, enhanced oxidative stress, and altered immune responses. Traditional approaches include nutritional modification and housing management to mitigate the harmful effects of hot environments. Currently, broiler chickens are more susceptible to heat stress (HS) than layer chickens because of their high muscle mass and metabolic rate. In this review, we explored the possibility of in ovo manipulation to combat HS in broiler chickens. Given their short lifespan from hatching to market age, embryonic life is thought to be one of the critical periods for achieving these objectives. Chicken embryos can be modulated through either temperature treatment or nourishment to improve thermal tolerance during the rearing phase. We first provided a brief overview of the harmful effects of HS on poultry. An in-depth evaluation was then presented for in ovo feeding and thermal manipulation as emerging strategies to combat the negative effects of HS. Finally, we evaluated a combination of the two methods using the available data. Taken together, these investigations suggest that embryonic manipulation has the potential to confer heat resistance in chickens.

Research Note: Responses of broiler chickens to in ovo feeding with clove and cinnamon extract under hot-humid environments

An experiment was carried out to evaluate the responses of broiler chickens to in ovo injection of aqueous extracts of clove and cinnamon under a hot-humid environment. The study involved the use of seven hundred hatching eggs from broilers (Ross 308) which were incubated with the use of standard protocol (37.8°C). The incubating eggs (100 each) were randomly selected and assigned to 7 treatments on day 17.5 of incubation, viz.: un-injected eggs (UE), eggs injected with 0.5 mL distilled water (DW), 2 mg clove (CL2), 4 mg clove (CL4), 2 mg cinnamon (CN2), 4 mg cinnamon (CN4), and 3 mg ascorbic acid (AA).Data on physiological parameters, hatchability, chick quality, and anatomical characteristics of the chicks were collected and analyzed using one-way analysis of variance. The results obtained revealed that the hatchability of eggs of AA and CN2 was higher compared to DW and UE. However, the hatchability of DW and UE was higher than those of CN4. The total chick quality scores of the control were similar to the other groups. Chick weights at hatch were similar in CL2, CN2, and AA but heavier than CN4, CL4, UE, and DW. The chick-to-egg ratio in AA was comparable to CL2 and CN2 but higher than UE, DW, CN4, and CL4. Total scores for chick quality of AA birds were similar to those of UE, CL2, and CL4 birds but higher than DW, CN2, and CN4 birds.

Effect of In Ovo Vitamin C Injection against Mobile Phone Radiation on Post-Hatch Performance of Broiler Chicks

This study aimed to investigate the effect of in ovo injection of vitamin C to reduce the harmful effects of electromagnetic waves (EMWs) emitted from mobile phones on chicken embryos. In this study, a total of 750 fertilized eggs of Ross 308 were exposed to EMWs for 1050 min during the incubation period. On the 17th day of incubation, the eggs were divided into three groups and solutions were injected into the amnion sac of embryos. The chicks were housed separately in accordance with in ovo treatments for 5 wk after hatching. An in ovo vitamin C injection resulted in a lower hatching weight. The post-hatch mortality or production efficiency factor of birds in the in ovo vitamin C injection group and the intact egg group were comparable, and were better than that of the other negative control group. In ovo vitamin C injection in eggs subjected to EMWs significantly increased their body weight gain, carcass weight, abdominal fat weight, and AST levels, but reduced spleen weight and PON-1 levels. In conclusion, an in ovo vitamin C injection in eggs subject to mobile phone EMWs improved the post-hatch performance of chicks, but low PON and high AST activities indicate an increase in oxidative damage among broiler chicks.

Influence of in-ovo vitamin E and ascorbic acid injections on chick development, hatching performance and antioxidant content in different tissues of newly-hatched quail chicks

This study determined the influence of in ovo (IO) vitamin E and ascorbic acid injections on hatching performance, chick development, and antioxidant content of different tissues in day-old quail chicks. The experiment compared a control group (C: non-injection group) and injection groups, which had the yolk sac injected with 3.75 mg α- tocopherol (T1), or had the amniotic sac injected with 0.9% saline solution (T2), 2.5 mg ascorbic acid containing 0.9% saline solution (T3), and 2.5 mg ascorbic acid solution (T4), respectively.Mean relative asymmetry (RA) of bilateral lengths increased in the T2, T3 and T4 groups, whereas it decreased in the T1 group compared to C. The highest total carotene content in the residual yolk sac (RYS) was seen for the T1 group, which was significantly higher compared to T2, T3, and T4 groups. The highest total carotene concentration in liver was in the T1 group.The concentrations of delta-tocopherol, gamma-tocopherol and total vitamin E in RYS tissue were significantly higher in the T1 group than T2, T3, and T4 groups. Alpha-tocopherol and total vitamin E levels in the liver were significantly higher in the T2 and T4 groups than C.In ovo injections of vitamin E and ascorbic acid to different embryonic sacs caused antioxidant-specific effects on developmental stability of bilateral traits, RYS absorption, concentrations of total carotene and derivatives of vitamin E in newly-hatched quail chicks.

Effects of the In Ovo Injection of L-Ascorbic Acid on Broiler Hatching Performance

Simple Summary

Previous studies have shown positive effects of the use of supplementary L-ascorbic acid (L-AA) to mitigate various stressors such as heat and ammonia exposure in the broiler industry. The aim of the current study was to determine the effects of L-AA administrated by in ovo injection on various hatch variables and the embryonic serum L-AA concentrations of Ross 708 broilers. At 18 days of incubation (doi), the following four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA were administrated. An automated multi-egg injector accurately delivered 100 μL solution volumes into the amnion. The in ovo injection of high levels of L-AA (12 and 25 mg) did not affect hatchability, but 12 mg of L-AA in saline and saline alone resulted in a reduction in embryonic mortality. Additionally, serum L-AA did not differ between the in ovo injected treatments at any time period; however, the serum L-AA concentration was numerically higher in males as compared to female hatchlings. In conclusion, the automated in ovo injection of high levels of L-AA may not be detrimental to hatchling quality but may promote embryonic livability.

Abstract

Effects of the in ovo injection of various concentrations of L-ascorbic acid (L-AA) on the hatchability and retention levels of L-AA in the serum of broiler embryos were investigated. A total of 960 Ross 708 broilers hatching eggs were randomly divided into four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA. At 18 days of incubation (doi), injected eggs received a 100 μL volume of sterile saline (0.85%) alone or containing one of the two L-AA levels. Percentage egg weight loss was also determined from 0 to 12 and 12 to 18 doi. Hatch residue analysis was conducted after candling to determine the staging of embryo mortality. At approximately 21 doi, hatchability of live embryonated eggs (HI) and hatchling body weight (BW) were determined. Blood samples were taken at 6 and 24 h after L-AA in ovo injection to determine serum L-AA concentrations. Serum L-AA concentrations, HI, and hatchling BW did not differ among all treatment groups. However, chicks in the non-injected group had a higher (p = 0.05) embryonic mortality at hatch in comparison to those in the 12 mg of L-AA in saline and saline alone treatment groups. These results suggest that the in ovo injection of high levels of L-AA (12 and 25 mg) does not negatively affect HI or serum concentrations of L-AA but has the potential to promote embryonic livability. Further research is needed to determine the retention time of L-AA in the other tissues of broilers, including the cornea of the eye, in response to different levels of supplemental L-AA.

The application of ascorbic acid as a therapeutic feed additive to boost immunity and antioxidant activity of poultry in heat stress environment

Ascorbic acid, widely known as vtamin C, is an essential nutrient for animals such as poultry. Ascorbic acid in poultry feed improves animal health and thus increases the growth performance of birds. Ascorbic acid can be used in the form of synthetic products or can be naturally obtained from fruits and plants. It is soluble in water and can be easily administered in drinking water and the diet. Poultry can synthesize ascorbic acid in the body. However, the performance of the animals can be improved by adding ascorbic acid to their diet. In addition, ascorbic acid is called an antioxidant and an anti-inflammatory. This increases their resistance to disease during the transition season. Ascorbic acid supplementation positively affects the stress response, especially during the dry season in tropical countries. Furthermore, supplementing ascorbic acid in the poultry’s diet improves resistance to diseases, regulates stress, and helps in the body’s oxidation process. Ultimately, this enhances the laying rate, egg hatch performance, and higher poultry productivity. For layers at the end of the laying period, it helps increase the quality of the eggshell and reduces the proportion of broken eggs. Ascorbic acid has a strong relationship with other vitamins such as vitamin E and other substances such as zinc, safflower oil, folic acid, and a fibrous diet. This review aims to synthesize all the information of ascorbic acid in the poultry’s diet, thereby providing the general role of ascorbic acid for the poultry industry.

Effects of in ovo feeding and dietary addition oils on growth performance and immune function of broiler chickens

This study aimed to investigate the effects of in ovo feeding (IOF) and dietary addition (DA) oils on growth, development and immune function of broiler chickens. In experiment 1, a total of 500 eggs were randomly assigned to 3 treatments: non-injected group (CON) with 100 eggs; soybean oil injected group (SO) with 200 eggs and linseed oil injected group (LO) with 200 eggs. Results showed that there were no detrimental effects of IOF of oils on embryonic development. In experiment 2, a two factor experimental design was adopted. After hatching, 120 chicks which came from each oil-injected group were divided into 2 treatments with 6 replicates, and chickens were fed soybean oil diet and linseed oil diet, respectively. The results showed that DA linseed oil increased final body weight (FBW) of broilers at d 21 post hatch, IOF of linseed oil decreased average daily feed intake (ADFI) and feed conversion ratio (FCR) of broilers from d 1 to 21 (P < 0.05), while the plasma leptin level of 21-day-old broilers was increased by IOF or DA linseed oil (P < 0.05). Main effect analysis showed that DA linseed oil increased the spleen index and mRNA expression of IFN-γ in spleen of broilers at 7 d of age (P < 0.05). IOF of linseed oil upregulated the mRNA expression of IFN-γ in the spleen of chicks at 1 d and mRNA expression of IL-2 and IL-4 in spleen of broilers at 21 d (P < 0.05), and the interaction effect showed that IOF and DA linseed oil synergically increased the expression of IL-2 and IL-4 in spleen of broilers at 21 d. Compared with SO group, LO increased the Shannon index of hatching-day cecum microflora (P < 0.05). Principal co-ordinates analysis (PcoA) showed that LO group clearly separated from CON and SO groups. Finally, Spearman correlation analysis also manifested that Alkalicoccus was significantly correlated with spleen index and mRNA expression of IL-2, and Phreatobacter was significantly correlated with the mRNA expression of IL-2 and IFN-γ in spleen, Acinetobacter had a positive correlation with thymus index (P < 0.05). In conclusion, IOF of linseed oil reduced the ADFI and FCR of broilers and increased the species diversity and changed the structure of cecal microflora of chicken embryos at the 19th day of incubation (E19). Immune function of broilers spleen was also regulated by IOF and DA linseed oil.

Effects of in ovo feeding of disaccharide and/or methionine on hatchability, growth performance, blood hematology, and serum antioxidant parameters in geese

A completely randomized design employing a 2 × 2 factorial experiment was designed in this study to evaluate the effects of in ovo injection of disaccharide (DS) and/or methionine (Met) on hatchability, growth performance, blood hematology, and serum antioxidant parameters in geese. A total of 600 fertilized geese's eggs containing live embryo were randomly assigned into 4 groups with 6 replicates and 25 eggs per replicate. Factors in four groups comprised noninjection, DS injection (25 g/L maltose + 25 g/L sucrose + 7.5 g/L NaCl), Met injection (5 g/L Met + 7.5 g/L NaCl), or DS plus Met injection (25 g/L maltose + 25 g/L sucrose + 5 g/L Met + 7.5 g/L NaCl), respectively. We found that the administration of DS in embryo increased hatching time, yolk sac-free carcass weight, yolk sac-free carcass indexes and decreased assisted hatching ratio, yolk sac weight, yolk sac indexes, but did not affect hatchability and mortality. Moreover, higher body weight and serum glucose concentrations in DS injection group compared with noninjection group were observed on day of hatching. The body weight and average daily gain (ADG) of geese in DS injection group were higher than noninjection group after incubation. In ovo injection of Met increased hatching time and yolk sac-free carcass indexes, but decreased yolk sac indexes. In addition, the strategy of in ovo feeding of Met led to higher body weight, ADG, serum uric acid, glutathione (GSH), and glutathione peroxidase concentrations, as well as lower GSSG/GSH ratio, serum glutathione disulfide (GSSG), and malondialdehyde (MDA) concentrations than the noninjection group on day of hatching. The post-hatching body weight, ADG, serum total protein, albumin, and uric acid concentrations increased, whereas post-hatching serum GSSG and MDA concentrations and GSSG/GSH ratio decreased when injected with Met. In addition, synergistic effects of in ovo injection of DS plus Met on hatching time as well as post-hatching body weight and ADG were observed. Therefore, in ovo injection of DS plus Met was demonstrated to be a way to improve the development of geese during early incubation stages.

Yeast β-Glucan Altered Intestinal Microbiome and Metabolome in Older Hens

The prebiotics- and probiotics-mediated positive modulation of the gut microbiota composition is considered a useful approach to improve gut health and food safety in chickens. This study explored the effects of yeast β-glucan (YG) supplementation on intestinal microbiome and metabolites profiles as well as mucosal immunity in older hens. A total of 256 43-week-old hens were randomly assigned to two treatments, with 0 and 200 mg/kg of YG. Results revealed YG-induced downregulation of toll-like receptors (TLRs) and cytokine gene expression in the ileum without any effect on the intestinal barrier. 16S rRNA analysis claimed that YG altered α- and β-diversity and enriched the relative abundance of class Bacilli, orders Lactobacillales and Enterobacteriales, families Lactobacillaceae and Enterobacteriaceae, genera Lactobacillus and Escherichia–Shigella, and species uncultured bacterium-Lactobacillus. Significant downregulation of cutin and suberin, wax biosynthesis, atrazine degradation, vitamin B6 metabolism, phosphotransferase system (PTS), steroid degradation, biosynthesis of unsaturated fatty acids, aminobenzoate degradation and quorum sensing and upregulation of ascorbate and aldarate metabolism, C5-branched dibasic acid metabolism, glyoxylate and dicarboxylate metabolism, pentose and glucuronate interconversions, steroid biosynthesis, carotenoid biosynthesis, porphyrin and chlorophyll metabolism, sesquiterpenoid and triterpenoid biosynthesis, lysine degradation, and ubiquinone and other terpenoid-quinone biosyntheses were observed in YG-treated hens, as substantiated by the findings of untargeted metabolomics analysis. Overall, YG manifests prebiotic properties by altering gut microbiome and metabolite profiles and can downregulate the intestinal mucosal immune response of breeder hens.

Alterations on vitamin C synthesis and transportation and egg deposition induced by dietary vitamin C supplementation in Hy-Line Brown layer model

In ovo feeding of vitamin C (VC) has positive effects on the growth performance, immune and antioxidant function in poultry, which indicates that increasing VC content in eggs may be of benefit. This study was to investigate the effects of dietary VC supplementation on VC synthesis and transportation and egg deposition. In Exp. 1, in order to select a suitable animal model, VC content was detected in different eggs from different layer species. Vitamin C content was lower in ISA Brown breeder eggs and Hy-Line Brown layer eggs (P < 0.05) then in Arbor Acres breeder eggs. In Exp. 2, a total of 24 Hy-Line Brown layers (42-week-old) were randomly divided into 3 treatments with 8 replicates and fed a basal diet with VC at 0, 200 and 400 mg/kg. Sodium-dependent VC transporter 1 and 2 (SVCT1 and SVCT2) expressions were higher in ileum than in duodenum and jejunum (P < 0.05). SVCT1 expression was higher but SVCT2 expression was lower in the magnum than in the ovary (P < 0.05). L-Gulonolactone oxidase (GLO) and SVCT1 expressions were higher but SVCT2 was lower in the kidney than in the liver (P < 0.05). Dietary VC supplementation at 400 mg/kg increased SVCT1 expression in duodenum, ovary and magnum, but decreased GLO and SVCT1 expression in liver (P < 0.05). Dietary VC supplementation at 200 and 400 mg/kg increased SVCT2 expression in duodenum, but decreased GLO and SVCT1 expression in kidney and SVCT2 expression in liver (P < 0.05). Dietary VC supplementation promoted VC absorption in duodenum and jejunum, but reduced endogenous VC synthesis in liver and kidney. Although dietary VC supplementation enhanced VC transportation in ovary and magnum, it did not increase VC deposition in produced eggs.

In ovo feeding of vitamin C regulates splenic development through purine nucleotide metabolism and induction of apoptosis in broiler chickens

Nutrition in early life has a long-term influence on later health. In order to the explore effects of in ovo feeding (IOF) of vitamin C on splenic development, splenic metabolism and apoptosis were detected in embryo, adult chickens and in vitro. A total of 360 fertile eggs were selected and randomly assigned to control (CON) and vitamin C (VC) groups which were injected with saline and vitamin C on embryonic day 11, respectively. Functional enrichment of differentially expressed genes by transcriptome on embryonic day 19 suggested that purine nucleotide metabolism might be a potential pathway for the IOF of vitamin C to regulate spleen development. Additionally, the IOF of vitamin C significantly increased splenic vitamin C content on post-hatch day 21. Meanwhile, the splenic expression of adenosine deaminase, serine/threonine kinase 1 and proliferating cell nuclear antigen was down-regulated, whereas the expression of cysteinyl aspartate specific proteinase 9 was up-regulated in the VC group. On post-hatch day 42, the IOF of vitamin C significantly down-regulated the splenic expression of B-cell lymphoma 2 and increased the mRNA level of cysteinyl aspartate specific proteinase 9. The IOF of vitamin C could regulate the expression of genes related to adenylate metabolism and increased the apoptosis rate in vitro, which is consistent with the result in vivo. In conclusion, the IOF of vitamin C regulated splenic development and maturation by affecting purine nucleotide metabolism pathway and promoting apoptosis.

Efficacy of in ovo delivered resveratrol (Trans 3, 4, 5-trihydroxystilbene) on growth, carcass weights, and blood metabolites of broiler chicks

This research aimed to determine the impact of in ovo resveratrol (RV) (Trans.3, 4, 5-trihydroxystilbene) injection on performance, carcass weights, and blood constituents in Cobb chicks. A total of 300 fertile broiler breeder eggs were divided into five treatments as 60 eggs in each group, with 6 replicates (10 eggs each). The groups were as follows: (1) negative control (without additive), (2) positive control (saline injection), (3) 1.5 mg RV, 4) 3.0 mg RV, and (5) 4.5 mg in ovo RV injections. Significant changes were found in the amount of forage consumed per day, and the feed conversion ratio between treatment groups. RV injection significantly altered the parameters of the complete lipid profile, including total cholesterol, triglycerides, low-density lipoproteins, and very low-density lipoproteins, in plasma. RV injection significantly affected blood biochemical parameters, including total protein, albumin, and globulin in broiler chicken plasma. Liver and kidney functions were influenced by the injection of RV eggs into broiler chickens. The antioxidant enzymes also changed significantly after RV injection. Moreover, in egg injection from RV the immunogenicity (IgG and IgM) in broiler chickens were significantly altered. In conclusion, in ovo injection with RV significantly improved liver and kidney functions, antioxidant activity, and immune function in Cobb broilers.

Exploring the effectiveness of in ovo feeding of vitamin C based on the embryonic vitamin C synthesis and absorption in broiler chickens

BACKGROUND

Many researches about in ovo feeding (IOF) of vitamin C (VC) are gradually carried out to explore physiological development in chicken, but little studies focus on VC synthesis capacity of the embryo itself, the selection of injection site and the effectiveness of IOF of VC. This study aims to explore the above problems.

RESULTS

Kidney and yolk sac were the main organs for VC synthesis and L-gulonolactone oxidase (GLO) expression was lower during pre-hatch development than that during post-hatch development. Sodium-dependent vitamin C transporter 1 (SVCT1) expression was increased continuously in yolk sac from embryonic age 19 (E19) to post-hatch day 1 (D1) and in intestine (duodenum, jejunum and ileum) from E17 to D1. Plasma VC content was higher at D1 than that at D21 and D42. IOF of VC significantly reduced GLO expression in liver, kidney and yolk sac as well as SVCT1 expression in duodenum, jejunum and ileum, but increased the VC content in plasma, brain, kidney and liver. In addition, IOF of VC obviously reduced the embryonic morality and increased the hatchability under heat stress.

CONCLUSIONS

This study suggested that IOF of VC at E11 in yolk was effective for embryonic VC supplementation. These findings provide a theoretical reference about the method of embryonic VC supplementation and effective methodology on embryonic VC nutrition in broiler chickens.

Effects of in ovo feeding of vitamin E or vitamin C on egg hatchability, performance, carcass traits and immunity in broiler chickens

The effect of in ovo feeding of different levels of vitamins C and E on egg hatchability, immune response, growth and carcass traits of broiler chickens were investigated. A total of 672 fertilized eggs were assigned to one of eight experimental groups having three replicates with 28 eggs as follows: (1) negative control (not injected); (2) positive control (injected with 0.2 mL deionized water); (3) vitamin C at 1 mg; (4) vitamin C at 3 mg; (5) vitamin C at 6 mg; (6) vitamin E at 0.5 IU; (7) vitamin E at 0.75 IU; and (8) vitamin E at 1.0 IU. At the end of incubation, the number of chicks hatched, and their individual body weight were recorded. Among hatched birds, a total of 240 mixed chicks were randomly selected (30 subject per group equally shared in three pen floors). Chicks were vaccinated against Avian Influenza, Gumboro, Bronchitis, and Newcastle disease virus. Performance parameters were weekly evaluated until 42 days of age. At days 28 and 42, broiler serum and spleen and Bursa of Fabricius relative weight were assessed as well as on day 42 the carcass traits. From results, in ovo injection with 3 mg of vitamin C or 0.75 IU of vitamin E, increased significantly (p < .05) the embryos hatchability when compared to the negative control. However, body weight at hatch and growth performance parameters showed no differences among treatments. Similarly, in ovo concentrations of vitamins C or E showed no differences on carcass traits, immunity-related organs weight or immune response for anti-Newcastle disease hemagglutination-inhibition and total immunoglobulins against sheep red blood cells (SRBC) when compared to the control groups. Based on findings, it can be concluded that in ovo feeding vitamins E and C supported positively chicken embryos hatchability demonstrating the key-role as antioxidant agents; however, further studies are currently being evaluated.

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.

Mitigating the Growth, Biochemical Changes, Genotoxic and Pathological Effects of Copper Toxicity in Broiler Chickens by Supplementing Vitamins C and E

Simple Summary

Copper (Cu) is a trace element necessary for biological utility; nevertheless, it can produce significant harmful impacts when existing in abundance. This study examined the efficiency of vitamin C and vitamin E in alleviating the biochemical, genotoxicity, and pathological alterations in the liver induced by copper sulfate (CuSO₄) toxicity in chickens. The broilers were fed on five experimental diets; basal diet with no additives or basal diets supplemented with 300 mg CuSO₄/kg, CuSO₄ + 250 mg Vit. C/kg diet, CuSO₄ + 250 mg Vit. E/kg diet, CuSO₄ + 250 mg Vit. C/kg diet + 250 mg Vit. E/kg diet for six weeks. The obtained results suggested that addition of vitamin C and E, especially in combination, was beneficial for alleviating the harmful effects of CuSO₄ toxicity on growth performance and liver histoarchitecture in broiler chickens.

Abstract

This experiment was carried out to explore the efficiency of an individual or combined doses of vitamin C (Vit. C) and vitamin E (Vit. E) in alleviating biochemical, genotoxicity, and pathological changes in the liver induced by copper sulfate (CuSO₄) toxicity in broiler chickens. Two hundred and fifty-one-day-old broiler chicks were haphazardly allotted into five groups (five replicates/group, ten chicks/replicate). The birds were fed five experimental diets; (1) basal diet with no additives (CON), (2) basal diets supplemented with 300 mg CuSO₄/kg diet (CuSO₄), (3) basal diets supplemented with 300 mg CuSO₄/kg diet + 250 mg Vit. C /kg diet, (4) basal diets supplemented with 300 mg CuSO₄/kg diet +250 mg Vit. E /kg diet, (5) basal diets supplemented with 300 mg CuSO₄/kg diet + 250 mg Vit. C /kg diet + 250 mg Vit. E /kg diet for six weeks. The results displayed that CuSO₄-intoxicated birds had significantly (p < 0.05) decreased bodyweight, weight gain, and feed intake with increased feed conversion ratio from the 2nd week till the 6th week compared with the CON. However, these changes were minimized by single or combined supplementation of vitamin C and E. The FCR was insignificantly different in birds-fed diets complemented with vitamin C and E singly or in combination from the 3rd week of age compared to the CON. Serum aminotransferases (ALT, AST) and alkaline phosphatase (ALP) were elevated in CuSO₄-intoxicated birds (p < 0.05). Additionally, they showed a drop in serum total protein (TP), albumin, globulins, triglycerides (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein-cholesterol (VLDL-C), and high-density lipoprotein-cholesterol (HDL-C) levels compared to the CON (p < 0.05). Concomitantly, histopathological and DNA changes were perceived in the liver of CuSO₄-intoxicated birds. Co-supplementation of Vit. C and Vit. E single-handedly or combined with CuSO₄-intoxicated chickens enhanced the performance traits and abovementioned changes, especially with those given combinations of vitamins. From the extant inquiry, it could be established that supplementation of vitamin C and E was beneficial for mitigating the harmful effects of CuSO₄ toxicity on growth performance and liver histoarchitecture in broiler chickens.

Alleviating Effects of Vitamins C and E Supplementation on Oxidative Stress, Hematobiochemical, and Histopathological Alterations Caused by Copper Toxicity in Broiler Chickens

Simple Summary

Excessive copper in diets is associated with numerous disadvantageous impacts on poultry. The current study evaluated the efficacy of vitamin C and vitamin E in mitigating oxidative stress, hematobiochemical, and histopathological changes in the kidney induced by copper sulfate (CuSO₄) toxicity in broiler chickens. The birds were assigned to five experimental groups: 1st group—basal diet with no additives (control group), 2nd group—basal diet complemented with CuSO₄ (300 mg/kg diet), 3rd group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin C (250 mg/kg diet), 4th group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin E (250 mg/kg diet), and 5th group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin C (250 mg/kg diet) + vitamin E (250 mg/kg diet). The current study’s findings showed the possible preventive impacts of dietary antioxidants on hematobiochemical alterations, oxidative stress, and kidney damage induced by CuSO₄ toxicity.

Abstract

The current investigation evaluated the alleviating effects of vitamin C and vitamin E on oxidative stress, hematobiochemical, and histopathological changes in the kidney induced by copper sulfate (CuSO₄) toxicity in chickens. Two hundred and fifty-one-day-old male broiler chicks were randomly allotted into five experimental groups (five replicates/group, ten chicks/replicate): 1st group—basal diet with no additives (control group), 2nd group—basal diet complemented with CuSO₄ (300 mg/kg diet), 3rd group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin C (250 mg/kg diet), 4th group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin E (250 mg/kg diet), and 5th group—basal diet with CuSO₄ (300 mg/kg diet) + vitamin C (250 mg/kg diet) + vitamin E (250 mg/kg diet) for a 42 day feeding period. The results showed a significant reduction in red blood cells (RBCs), hemoglobin (Hb) concentration, and hematocrit values as well as total leukocyte counts (WBCs), lymphocyte, heterophil, and monocyte counts in the CuSO₄-intoxicated birds (2.42 × 10⁶/µL, 9.54 g/dL, 26.02%, 15.80 × 10³/µL, 7.86 × 10³/µL, 5.26 × 10³/µL, and 1.18 × 10³/µL, respectively, at the 6th week) compared to (2.79 × 10⁶/µL, 10.98 g/dL, 28.46%, 21.07 × 10³/µL, 10.84 × 10³/µL, 7.12 × 10³/µL, and 1.60 × 10³/µL, respectively) in the control group. Moreover, CuSO₄-intoxicated birds showed hypoglycemia with a rise in serum uric acid and creatinine levels (122.68, 5.18, and 0.78 mg/dL at the 6th week) compared to (159.46, 4.41, and 0.61 mg/dL) in the control group. The CuSO₄ toxicity in birds induced oxidative stress, indicated by a high serum malondialdehyde level (MDA) and diminished activity of the antioxidant enzymes (glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD)) (2.01 nmol/mL, 37.66 U/mL, and 2.91 U/mL, respectively, at the 6th week) compared to (1.34 nmol/mL, 57.00 U/mL, 4.99 U/mL, respectively) in the control group. High doses of Cu exposure caused severe microscopic alterations in kidney architecture. The addition of vitamins C and E, singularly or in combination, displayed a beneficial effect in alleviating these harmful effects of Cu toxicity. These findings showed the possible mitigating impacts of dietary antioxidants on the hematobiochemical alterations, oxidative stress, and kidney damage induced by CuSO₄ toxicity.

A novel nonenzymatic ascorbic acid electrochemical sensor based on gold nanoparticals-chicken egg white-copper phosphate-graphene oxide hybrid nanoflowers

Au-CEW-Cu₃(PO₄)₂-GO nanoflowers (HNFs), which were assembled of gold nanoparticals (Au NPs), chicken egg white (CEW), copper phosphate (Cu₃(PO₄)₂) and graphene oxide (GO) together to form a flower-like organic/inorganic hybrid nanocomposite, were synthesized through a simple and gentle one-pot co-precipitation method. The prepared samples were well characterized by scanning electron microscope, transmission electron microscope, energy dispersive x-ray spectrometer, x-ray diffraction and Raman spectrometer. The prepared Au-CEW-Cu₃(PO₄)₂-GO HNFs was used to modify glassy carbon electrode to fabricate an electrochemical sensor for detection of ascorbic acid (AA). The electrochemical test results show that the linear range of the developed sensor is 8-300μM and the detection limit is 2.67μM (S/N = 3). While this sensor displays high sensitivity of 6.01 × 10^-3μAμM^-1cm^-2and low detection potential of 35 mV due to the combination of the high conductivity of Au NPs, the larger specific surface area of GO and the intrinsic electrocatalytic activity of CEW-Cu₃(PO₄)₂HNFs. Moreover, the Au-CEW-Cu₃(PO₄)₂-GO HNFs-based sensor was successfully developed for application in electrochemical detection of AA in vitamin C tablets.

Success rates of inoculation of the various compartments of embryonated chicken eggs at different incubation days

Inoculation of embryonated chicken eggs has been widely used during the past decades; however, inoculation success rates have not been investigated systematically. In this study named success rates were assessed in brown eggs incubated between 5 and 19 days, which were inoculated with 0.2 ml methylene blue per egg. Inoculations were performed in a simple and fully standardized way. Five embryonic compartments were targeted blindly (amniotic cavity, embryo, allantoic cavity, albumen and yolk) with needles of four different lengths; albumen and yolk were targeted with eggs in upside down position. Three compartments were inoculated within sight (air chamber, chorioallantoic membrane and blood vessel). Twenty embryos were used per incubation day, intended deposition site and needle length. Success rates were assessed by visual inspection after breaking the eggs. The inoculations targeting albumen, yolk, amniotic cavity and embryo yielded low scores. Magnetic resonance imaging was performed to elucidate the reason(s) for these low success rates: needles used were of appropriate length, but embryo and amniotic cavity had variable positions in the eggs, while albumen and yolk rapidly changed position after turning the eggs upside down. The latter led to adjustment of the inoculation method for albumen and yolk. Failures to inoculate compartments within sight were immediately visible; therefore, these eggs could be discarded. Except for the amniotic cavity, full scores (20/20) were obtained for all compartments although not always on every day of incubation. In conclusion, the present study may serve as a guide to more accurately inoculate the various chicken embryo compartments. RESEARCH HIGHLIGHTS Blind inoculation of embryonated egg compartments was successful, except for the amniotic cavity. MRI showed rapid position change of albumen and yolk after turning eggs upside down. In ovo vaccination against Marek's disease might be improved by using 38 mm needles.

In ovo injection of black cumin (Nigella sativa) extract on hatching and post hatch performance of thermally challenged broiler chickens during incubation

The objective of this study was to investigate the effects in ovo injection of black cumin (BC) extract on chick's quality and response of thermally challenged broiler chickens. A total of 700 hatching eggs of broiler chickens (Marshall) were assigned to 7 treatments of 100 eggs each and incubated using the conventional protocol (37.8°C) for the first 10 d and then exposed to a high temperature (39.6°C) for 6 h daily from day 10 until day 18 of the incubation. At embryonic day 17.5, the eggs were randomly allotted to 7 treatment groups, viz.: eggs without in ovo injection (WA), eggs injected with 0.9% saline solution (SA), 3 mg ascorbic acid (AA), 2 mg BC (TB), 4 mg BC (FB), 6 mg BC (SB), and 8 mg BC (EB) extracts. Experiment was laid out in a Completely Randomized Design. After hatching, the chicks were reared separately according to in ovo treatments for 8 wk. Data were collected on hatchability, chick quality, internal organs, growth performance, plasma superoxide dismutase, malondialdehyde, and triiodothyronine (T₃). The results showed that the hatchability of the eggs in the AA group was similar to that of SB eggs and higher than that of the other treatment groups. The intestinal weights of SB and EB birds were significantly higher (P < 0.05) than those of TB, SA, and WA. The final weights of the birds of SB and AA were higher (P < 0.05) than those of other treatments. The feed conversion ratio of the birds of TB and FB was comparable to that of EB and WA but higher than that of SB and AA. At hatch, the creatinine of the birds in SA and WA was similar to that of EB, FB, and TB but higher (P < 0.05) than that of AA and SB. Also, the plasma malondialdehyde, T₃, and superoxide dismutase of SB and AA birds were better (P < 0.05) than those of the control groups. Overall, it was concluded that 6 mg of BC extract improved the antioxidant status and posthatch performance of thermally challenged broiler chickens.

Effect of a commercial product containing canthaxanthin for in ovo feeding to broiler embryos on hatchability, chick quality, oxidation status, and performance

In ovo feeding has been indicated to improve hatchability, newly hatched chick quality, and broiler performance. The aim of this study was to investigate the effect of in ovo feeding of a commercial canthaxanthin product (CCX) containing lignosulphonate, corn starch, canthaxanthin, dextrin (yellow), and ethoxyquin through assessing incubation results, newly hatched quality and oxidation status and broiler performance at 1 to 14 d of age. A total of 780 egg were distributed in a randomized complete block design with 5 treatments (levels of CCX: 0.0, 0.35, 0.45, 0.55, and 0.65 mg/0.5 mL of sterilized and distilled water) and 156 eggs per treatment. The blocking factor was setters. At 17.5 d of embryo development, in ovo injected treatments were applied, using a manual needle. The in ovo feeding of CCX resulted in lower hatching rates (P < 0.05) and a longer hatching window (P < 0.05) as compared with noninjected CCX treatment. The CCX injection did not affect the bursa and spleen percentage of newly hatched chick (P > 0.05). In addition, a higher percentage of chicks with poor physical quality score (<71.0 points) was obtained among the chicks from eggs injected with 0.55 and 0.65 mg of CCX (P < 0.05). There were higher total proteins and catalase activity in the livers of the chicks injected with CCX. Broiler chicks in the control group (0.0 mg of CCX) presented higher BW and BW gain during 1 to 7 and 7 to 14 d of after hatch (P < 0.05). The viability (%) of chicks at 1 to 14 d of after hatch decreased with inoculation greater than 0.45 mg of CCX in ovo (P < 0.05). Although the CCX shown an improvement in oxidation status of chicks, the hatchability and performance of broilers decreased. We concluded that a commercial CCX is not recommended for injection in ovo, and furthers studies should carried out to elucidate the use of pure canthaxanthin.

Effects of in ovo feeding of vitamin C on post-hatch performance, immune status and DNA methylation-related gene expression in broiler chickens

This study aimed to evaluate the effect of in ovo feeding (IOF) of vitamin C at embryonic age 11 (E11) on post-hatch performance, immune status and DNA methylation-related gene expression in broiler chickens. A total of 240 Arbor Acres breeder eggs (63 (sem 0·5) g) were randomly divided into two groups: normal saline and vitamin C (VC) groups. After incubation, newly hatched chicks from each group were randomly divided into six replicates with ten chicks per replicate. Hatchability, average daily feed intake (D21–42 and D1–42), and average daily gain and feed conversion ratio (D1–21) were improved by vitamin C treatment (P < 0·05). IOF of vitamin C increased vitamin C content (D1), total antioxidant capacity (D42), IgA (D1), IgM (D1 and D21), stimulation index for T lymphocyte (D35) and lysozyme activity (D21) in plasma (P < 0·05). On D21, vitamin C increased the splenic expression of IL-4 and DNMT1 and decreased IL-1β, Tet2, Tet3 and Gadd45β expression (P < 0·05). On D42, vitamin C increased the splenic expression of IL-4 and DNMT3A and decreased IFN-γ, Tet3, MBD4 and TDG expression (P < 0·05). In conclusion, the vitamin C via in ovo injection can be absorbed by broiler’s embryo and IOF of vitamin C at E11 improves the post-hatch performance and immune status and, to some extent, the antioxidant capacity of broiler chickens. The expression of enzyme-related DNA methylation and demethylation indicates that the level of DNA methylation may increase in spleen in the VC group and whether the fluctuating expression of pro- and anti-inflammatory cytokines is related to DNA methylation change remained to be further investigated.

Effects of in ovo injection of vitamin C on heat shock protein and metabolic genes expression

Some studies have shown that the excessive metabolic heat production is the primary cause for dead chicken embryos during late embryonic development. Increasing heat shock protein (HSP) expression and adjusting metabolism are important ways to maintain body homeostasis under heat stress. This study was conducted to investigate the effects of in ovo injection (IOI) of vitamin C (VC) at embryonic age 11th day (E11) on HSP and metabolic genes expression. A total of 320 breeder eggs were randomly divided into normal saline and VC injection groups. We detected plasma VC content and rectal temperature at chick's age 1st day, and the mRNA levels of HSP and metabolic genes in embryonic livers at E14, 16 and 18, analysed the promoter methylation levels of differentially expressed genes and predicted transcription factors at the promoter regions. The results showed that IOI of VC significantly increased plasma VC content and decreased rectal temperature (P < 0.05). In ovo injection of VC significantly increased heat shock protein 60 (HSP60) and pyruvate dehydrogenase kinase 4 (PDK4) genes expression at E16 and PDK4 and secreted frizzled related protein 1 (SFRP1) at E18 (P < 0.05). At E16, IOI of VC significantly decreased the methylation levels of total CpG sites and -336 CpG site in HSP60 promoter and -1137 CpG site in PDK4 promoter (P < 0.05). Potential binding sites for nuclear factor-1 were found around -389 and -336 CpG sites in HSP60 promoter and potential binding site for specificity protein 1 was found around -1137 CpG site in PDK4 promoter. Our results suggested that IOI of VC increased HSP60, PDK4 and SFRP1 genes expression at E16 and 18, which may be associated with the demethylation in gene promoters. Whether IOI of VC could improve hatchability needs to be further verified by setting uninjection group.