Strategies to combat heat stress in poultry production-A review

The effects of heat stress (HS) caused by high temperatures continue to be a global concern in poultry production. Poultry birds are homoeothermic, however, modern-day chickens are highly susceptible to HS due to their inefficiency in dissipating heat from their body due to the lack of sweat glands. During HS, the heat load is higher than the chickens' ability to regulate it. This can disturb normal physiological functioning, affect metabolism and cause behavioural changes, respiratory alkalosis and immune dysregulation in birds. These adverse effects cause gut dysbiosis and, therefore, reduce nutrient absorption and energy metabolism. This consequently reduces production performances and causes economic losses. Several strategies have been explored to combat the effects of HS. These include environmentally controlled houses, provision of clean cold water, low stocking density, supplementation of appropriate feed additives, dual and restricted feeding regimes, early heat conditioning and genetic selection of poultry lines to produce heat-resistant birds. Despite all these efforts, HS still remains a challenge in the poultry sector. Therefore, there is a need to explore effective strategies to address this long-lasting problem. The most recent strategy to ameliorate HS in poultry is early perinatal programming using the in ovo technology. Such an approach seems particularly justified in broilers because chick embryo development (21 days) equals half of the chickens' posthatch lifespan (42 days). As such, this strategy is expected to be more efficient and cost-effective to mitigate the effects of HS on poultry and improve the performance and health of birds. Therefore, this review discusses the impact of HS on poultry, the advantages and limitations of the different strategies. Finally recommend a promising strategy that could be efficient in ameliorating the adverse effects of HS in poultry.

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.

Effects of the In Ovo Administration of L-ascorbic Acid on the Performance and Incidence of Corneal Erosion in Ross 708 Broilers Subjected to Elevated Levels of Atmospheric Ammonia

Effects of the in ovo injection of various levels of L-ascorbic acid (L-AA) on the performance and corneal erosion incidence in Ross 708 broilers exposed to 50 parts per million (ppm) of atmospheric ammonia (NH₃) after hatch were determined. A total of 1440 Ross 708 broiler embryos were randomly assigned to 4 treatments: non-injected (control), 0.85% sterile saline-injected (control), or saline containing 12 or 25 mg of L-AA. At hatch, 12 male chicks were randomly assigned to each of 48 battery cages with 12 replicate cages randomly assigned to each treatment group. All birds were exposed to 50 ppm of NH₃ for 35 d and the concentration of NH₃ in the battery cage house was recorded every 20 s. Mortality was determined daily, and mean body weight (BW), BW gain (BWG), average daily BW gain (ADG), and feed intake, as well as feed conversion ratio (FCR), were determined weekly. From 0 to 35 d of post-hatch age (doa), six birds from each cage were selected and sampled for eye erosion scoring. Incidences of corneal erosion were significantly higher at 21 and 28 doa in comparison to those at 14 and 35 doa, and at 21 doa, birds in the saline-injected group exhibited a higher incidence of corneal erosion compared to all other treatment groups. The in ovo injection of 12 mg of L-AA increased BWG (p = 0.043) and ADG (p = 0.041), and decreased FCR (p = 0.043) from 0 to 28 doa in comparison to saline-injected controls. In conclusion the in ovo administration of 12 mg of L-AA may have the potential to improve the live performance of broilers chronically exposed to high aerial NH₃ concentrations, but further study is needed to determine the physiological and immunological factors that may contribute to this improvement.

Effects of in ovo injection of nicotinamide riboside on high-yield broiler myogenesis

The objective of this study was to determine the effects of in ovo injection of high-yield broiler embryos with nicotinamide riboside (NR) on pectoralis major muscle (PMM) development, growth, and gene expression. Fertilized Cobb 700 broiler eggs were randomly assigned to one of four treatments within a 2 × 2 factorial design. Factor 1 consisted of NR dose (DOS) with eggs receiving 0 or 2.5 mM NR. Factor 2 consisted of injection location (LOC), with treatments injected into either the yolk sac or albumen. At day 10 of incubation, 100 μL of the assigned NR dose was injected into the yolk sac of the developing embryo and chicks were euthanized within 24 h of hatching. Chick PMM and individual fiber morphometrics, and expression of genes associated with cell cycle progression were analyzed. There were DOS × LOC interactions for hatched chick PM weight and length (P < 0.04). When NR was injected into the albumen, PMM weight decreased (P < 0.05); when NR was injected into the yolk, PMM weight increased (P < 0.05). Pectoralis major length was not affected (P > 0.05) when NR was injected into the albumen but was increased (P < 0.05) when NR was injected into the yolk. There was a DOS × LOC interaction (P = 0.04) for muscle fiber density and tended to be a DOS × LOC interaction (P = 0.07) for muscle fiber CSA. Pectoralis major muscle fiber density was not affected when NR was injected into the albumen (P > 0.05), but density increased when NR was injected into the yolk (P < 0.05). There were DOS × LOC interactions for hatched chick COXII, cyclin D, and SIRT1 expression (P ≤ 0.04), which may indicate NR improves skeletal muscle development and growth by enhancing myoblast proliferation during embryonic development.

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.

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.

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.

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.

Effects of the in ovo injection of vitamin D3 and 25-hydroxyvitamin D3 in Ross 708 broilers subsequently fed commercial or calcium and phosphorus-restricted diets. II. Immunity and small intestine morphology1,2,3

Effects of the in ovo injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on the immunity and small intestine morphology of broilers fed calcium and phosphorus-restricted diets were investigated. At 18 d of incubation (doi), live embryonated Ross 708 broiler hatching eggs were in ovo-injected with a 50 μL solution of one of the following treatments using an Inovoject multiegg injector: 1) diluent (control); diluent containing either 2) 2.4 μg D₃; 3) 2.4 μg 25OHD₃; or 4) 2.4 μg D₃ + 2.4 μg 25OHD₃. At hatch, 18 randomly selected male broilers belonging to one of the 4 in ovo injection treatments were placed in each of 12 floor pens and were fed either a commercial diet or a diet restricted by 20% in calcium and available phosphorus (ReCaP) content for the starter, grower and finisher dietary phases. Concentrations of plasma IgG and IgM at 14 d of age (doa) and α-1-acid glycoprotein at 40 doa were determined. Bursa, liver, spleen, duodenum, jejunum, and ileum weights were recorded at 7, 14, and 40 doa and small intestine histology was evaluated at 14 and 40 doa. Blood and organ samples were randomly collected from 1 bird in each of the 6 replicate pens within each of the 8 (4 in ovo x 2 dietary) treatment groups. Plasma IgG levels were higher in 25OHD₃ than in diluent or D₃ in ovo-injected birds. At 14 doa, a higher jejunal villus length (VL) to crypt depth (CD) ratio (RVC) was observed in birds that were in ovo-injected with 25OHD₃ alone as compared to all other in ovo injection treatments. At 40 doa, ileal VL increased and jejunal CD decreased in commercial diet-fed birds compared to ReCaP diet-fed birds. In conclusion, the in ovo injection of 25OHD₃ alone increased the immune response and improved the small intestine morphology and subsequent nutrient uptake of Ross 708 broilers. However, a ReCaP diet was observed to be detrimental to their small intestine morphology.

Centennial Review: Effects of vitamins A, D, E, and C on the chicken immune system

Vitamins are nutritional elements which are necessary for essential activities such as development, growth, and metabolism of cells. In addition to these conventional functions, vitamins A, D, E, and C have vital roles in normal function of the immune system as their deficiency is known to impair innate and adaptive host responses. By altering transcription of multiple immune system genes and contributing to antioxidant activities, these vitamins influence the immune system in different ways including modulation of cell-mediated and antibody-mediated responses, immunoregulation, and antiinflammatory effects. Furthermore, supplementation of these vitamins to poultry may assist the immune system to combat microbial pathogens while reducing detrimental effects associated with stress and enhancing responses to vaccines. In this article, the relationship between the chicken immune system and vitamins A, D, E, and C is reviewed, and evidence from the literature pertaining to how these vitamins exert their antiinflammatory, regulatory, and antimicrobial effects is discussed.

In Ovo Inoculation of Vitamin A Modulates Chicken Embryo Immune Functions

Vitamin A mediates many important biological functions in humans and animals. Presence of vitamin A receptors on immune system cells emphasizes their role in immune functions. To assess the effects of in ovo inoculation of vitamin A on the immune system of chicken embryos, 18 days old embryonated eggs were inoculated with 3 different concentrations of retinoic acid (the active form of vitamin A) at 30, 90, and 270 μmol/egg via the amniotic sac. After 6, 18, and 24 h, the spleen and bursa of the embryos were collected for RNA extraction and real-time polymerase chain reaction. The results were dose dependant. After 24 h, inoculation with 270 μmol/egg downregulated relative expression of interferon IFN-α, IFN-β, IFN-γ, interleukin (IL)-1β, IL-2, CXCLi2, IL-12, and IL-13 compared to control in the spleen, indicating an anti-inflammatory effect at this concentration. In comparison, 90 μmol/egg induced greater expressions of the above genes at the same timepoint compared to the 270 μmol. The results of this study indicate that in ovo inoculation of vitamin A can modulate immune functions of the chicken embryo, which might be beneficial for induction of immune responses by in ovo vaccines.

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.

Chicken embryo development: metabolic and morphological basis for in ovo feeding technology

Broiler embryonic development depends on the nutrients that are available in the egg, which includes mostly water, lipids, and proteins. Carbohydrates represent less than 1%, and free glucose only 0.3%, of the total nutrients. Considering that energy requirements increase during incubation and metabolism is shifted toward the use of glycogen stores and gluconeogenesis from amino acids, extensive muscle protein degradation in the end of incubation can compromise chick development in the initial days after hatch. Significant prehatch changes occur in embryonic metabolism to parallel the rapid embryonic development. Oral consumption of the amniotic fluid begins around 17 d of incubation and promotes rapid development of the intestinal mucosa, which is characterized by morphological changes and increased expression and activity of enzymes and transporters. Furthermore, ingested substrates are stored as nutritional reserves to be used during hatching and in the first week after hatch. At hatch, this limited-nutrient store is directed to the functional development of the gastrointestinal tract to enable assimilation of exogenous nutrients. In ovo feeding is an alternative to deliver essential nutrients to chick embryos at this critical and challenging phase. The improved nutritional status and physiological changes triggered by in ovo feeding can resonate throughout the entire rearing period with significant health and economic gains. The present review addresses the main changes in metabolism and intestinal development throughout incubation, and also addresses scientific advances, limitations and future perspectives associated with the use of in ovo feeding that has been regarded as an important technology by the poultry industry.

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 L-ascorbic acid on growth performance, carcass composition, plasma antioxidant capacity, and meat quality in broiler chickens1,2,3

The current study was designed to investigate the effects of the in ovo injection of different dosages of L-ascorbic acid (AA) on posthatch growth performance, carcass characteristics, plasma antioxidant capacity, and meat quality in broiler chickens. A total of 2,220 Ross 708 broiler hatching eggs containing live embryos at 17 D of incubation were subjected to 1 of 6 treatments (trt): non-injected control, saline-injected control, or saline containing 3, 6, 12 or 36 mg of AA. An Inovoject m semi-automatic multi-egg injector was used to inject a 100 μL volume of sterile saline (0.85%) alone or containing the different AA dosage into each egg. After hatch, 14 male hatchlings from each trt group were randomly selected and placed in each of 10 replicate floor pens for growth performance evaluation through 45 D posthatch. Chicks from the 3 and 6 mg AA trt groups had a higher average daily BW gain and a higher feed intake compared to the saline-injected control group during the grower phase. Chicks in the 12 mg AA trt group exhibited a better feed efficiency in the late finisher phase and the entire growing phase than those in the saline-injected control group. Higher thigh and leg percentages were observed in chicks from the 3 and 6 mg AA trt groups than in the non-injected control group. Compared to the non-injected or saline-injected control groups, birds in the 12 mg AA trt group were observed to have a lower plasma malondialdehyde content during the grower and finisher phases, and breast muscle tenderness was elevated in chicks from the 36 mg AA trt group. Taken together, these results suggest that the in ovo injection of AA (3 to 12 mg per egg) have lasting positive effects on the posthatch growth, leg muscle development, and systemic antioxidant capacity of broilers. Higher injected dosages of AA (36 mg per egg) may also have the potential to improve broiler meat quality.

In ovo injection of flavanone on bone quality characteristics, biochemical parameters and antioxidant enzyme status of blood in daily chicks

In ovo injection (IOI) of Naringin (N), flavanone was examined on post-hatch blood biochemical parameters, antioxidant status and bone characteristics. Fertile eggs (n = 700) were distributed in seven groups with 100 eggs. On 14th and 17.5th days of incubation, four groups were injected using 15 or 30 mg active ingredient levels of naringin/0.5 ml saline/egg, low and high level, into amnion sac. Controls include sham (injected normal saline, 0.5 ml/egg on day 14 and 17.5th) and un-injected group. IOI of high naringin and saline on 14th day of incubation resulted in lower hatchability and then higher mortality in last week of embryonic life. On day hatch, high levels of injected groups more body weight compared to the control. Chick length was increased at high levels of naringin on day 17.5th compared to control and saline injected. Quality traits of bones were improved in naringin-injected groups compared to control. IOI of naringin influenced thyroid hormones on 14th day of incubation. Naringin groups influenced the Alkaline phosphatase (ALP), Calcium (Ca), superoxide dismutase (SOD), blood biochemical and lipids. Totally, amniotic IOI of naringin in last days of developing embryo may be useful for hatched chick, development of leg long bone or effect on biochemical metabolites by levels of flavanone that it needs more research.

In ovo applications in poultry: A review,

The various methods employed for the in ovo administration of different materials for promoting the health and productivity of poultry are discussed in this review article. The amnion has proven to be an effective site for injection and the timing of in ovo injection has commonly occurred at transfer. However, the volumes and dosages or concentrations of the materials administered vary depending on bird type, egg size, timing and site of injection, incubation system and regimen, and the type of material. Both manual and automated injections have been shown to be effective. Nevertheless, commercial application mandates automation. Materials described in the literature over the past 20 years or more for in ovo use in avian species include vaccines, drugs, hormones, competitive exclusion cultures and prebiotics, and supplemental nutrients. Vaccines approved for in ovo delivery include those for Marek's disease, infectious bursal disease, fowl pox, Newcastle disease, and coccidiosis. Some of the materials listed above have been shown to be viable candidates for enhancing immunity and for promoting embryonic and posthatch development. Several reports have indicated that probiotics may be effectively used to fight intestinal bacterial infections, and folic aid, as well as egg white protein and various amino acids, including L-arginine, L-lysine, L-histidine, HMB, and threonine alone or in combination, have been shown to benefit embryonic development or posthatch performance. Furthermore, CpG oligodeoxynucleotides, vitamins C and E, and thyme and savory have the potential to enhance immunity, carbohydrates can be used to increase tissue glycogen stores, and creatine can be used to promote muscle growth. Trace minerals and vitamin D3 have shown potential to improve bone strength, and potassium chloride may be an effective alternative electrolyte in vaccine diluent. The in ovo application of these and other materials will continue to expand and provide further benefits to the poultry industry.