Posthatch Chicks Research Articles

Effects of Incubation Light on Behaviour, Growth Performance, Blood Parameters, and Digestive Enzymes in Post-Hatch Layer Chicks.

Manipulation of light during incubation may have an effect on post-hatch chicks through the role of prenatal stage. The effects of providing different wavelengths of light (white, blue, and green lights, dark as control) during incubation on the growth performance, organ development, immune response, stress related hormones, digestive enzymes and behaviour of post-hatch chicks were investigated for 1-42 days. A total of 60 chicks per light treatment in three batches were used in this study. The results showed that the percentage of chicks accessing to feed and water resources appeared not to be affected by incubation light. Chicks hatched under white light were found to have a growth advantage (p < 0.05). The weight of organs (except thymus), IgA, IgY, IgM and heterophil to lymphocyte (H/L) ratio for post-hatch chicks were not affected by incubation light (p > 0.05). Thymus weight was reduced in chicks incubated under blue light compared to dark incubation (p < 0.05). The jejunum amylase and ileum lipase activities were significantly affected by the light treatments (p < 0.01). All light incubation chicks had stable plasma corticosterone levels and may have better ability to cope with environmental changes. Hence, white light photoperiod incubation may have potential to improve post-hatch chicks' growth performance and environmental adaptability.

Strand-Specific RNA Sequencing Reveals Gene Expression Patterns in F1 Chick Breast Muscle and Liver after Hatching.

Heterosis refers to the phenomenon where hybrids exhibit superior performance compared to the parental phenotypes and has been widely utilized in crossbreeding programs for animals and crops, yet the molecular mechanisms underlying this phenomenon remain enigmatic. A better understanding of the gene expression patterns in post-hatch chickens is very important for exploring the genetic basis underlying economically important traits in the crossbreeding of chickens. In this study, breast muscle and liver tissues (n = 36) from full-sib F1 birds and their parental pure lines were selected to identify gene expression patterns and differentially expressed genes (DEGs) at 28 days of age by strand-specific RNA sequencing (ssRNA-seq). This study indicates that additivity is the predominant gene expression pattern in the F1 chicken post-hatch breast muscle (80.6% genes with additivity) and liver (94.2% genes with additivity). In breast muscle, Gene Ontology (GO) enrichment analysis revealed that a total of 11 biological process (BP) terms closely associated with growth and development were annotated in the identified DEG sets and non-additive gene sets, including STAT5A, TGFB2, FGF1, IGF2, DMA, FGF16, FGF12, STAC3, GSK3A, and GRB2. Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation presented that a total of six growth- and development-related pathways were identified, involving key genes such as SLC27A4, GLUL, TGFB2, COX17, and GSK3A, including the PPAR signaling pathway, TGF-beta signaling pathway, and mTOR signaling pathway. Our results may provide a theoretical basis for crossbreeding in domestic animals.

Impact of In Ovo Leptin Injection and Dietary Protein Levels on Ovarian Growth Markers and Early Folliculogenesis in Post-Hatch Chicks (Gallus gallus domesticus).

Genetically bred for rapid growth, broiler breeder hens develop obesity and ovarian dysfunction when fed ad libitum, resembling a condition that resembles human polycystic ovary syndrome (PCOS). Nutritional control applies to post-hatched chicks from one week onward to prevent the development of a PCOS-like phenotype in adult broilers. This study investigated the impact of a growth marker, leptin, and post-hatch nutritional intake on early-life ovarian function. Fertile broiler eggs were injected in ovo with physiological saline solution or 5 µg of leptin and then incubated. After hatching, female chicks were fed ad libitum a diet containing low protein (17% low crude protein (LP)) or standard protein (22% standard crude protein (SP)). Tissues were collected from 7- and 28-day-old chicks for RT-qPCR and histological analysis. In contrast to the LP diet, the SP diet suppressed the mRNA expression of ovarian growth markers essential for folliculogenesis in post-hatched chicks. Leptin injection did not influence ovarian growth markers but increased pituitary gonadotropin transcripts in 7-day-old chicks fed with LP diet. No treatment effects on follicle activation were noted on day 7, but by day 28, in ovo leptin-treated LP-fed chicks exhibited a higher percentage of primary follicles. These changes may have resulted from the early upregulation of genes by leptin during the first week, including pituitary gonadotropins and ovarian leptin receptors. The decline in ovarian growth markers with the SP diet highlights the importance of precise post-hatch protein calculation, which may influence future ovarian function in animals. These findings may contribute to future dietary strategies to enhance broiler reproduction.

Embryo thermal manipulation modifies development and hepatic lipid metabolism in post-hatch layer-type chicks.

Incubation temperature is a crucial environmental factor affecting embryonic development and chick quality. Metabolism during the embryonic stage, particularly liver lipid metabolism, is essential for the growth and development of poultry. This study aimed to investigate the effects of embryo thermal manipulation with high (TMH, 39.5 °C, 65% RH, 8h/d) and low (TML, 20 °C, 65% RH, 1h/d) temperatures during 8th to 15th embryonic age on hatching performance and liver lipid metabolism in layer chicks. Additionally, the duration of TM effects was evaluated through a short-term feeding trial. The results indicated that TMH accelerated the hatching process without significantly affecting hatchability and growth performance. In contrast, TML delayed hatching time and significantly reduced hatchability and chick quality. After hatching, TML also increased residual yolk weight and reduced the relative liver weight in relation to body weight and yolk-free body mass. Moreover, lipid droplets in the liver were stained with Oil Red O, and the lipid content in the liver and serum was further detected. TMH had no significant impact on triglyceride (TG) and total-cholesterol (TCHO) content in the liver and serum but upregulated the expression of lipogenesis-related genes ACC, Fas, and Fatp1 compared to the TML group. Conversely, TML significantly reduced liver TG content, enhanced lipoprotein lipase (LPL) activity, and promoted the expression of lipid oxidation-related genes CPT-1, PGC-1α, and PPARα. At 7 d of age, liver LPL activity was significantly increased in the TMH group. However, there were no significant changes in the content of TG and TCHO in the liver and the expression of lipid metabolism-related genes in the TML group. Overall, these results indicate that embryonic TM alters hatching performance and liver lipid metabolism in layer chicks. TML reduces TG content by increasing liver lipid oxidation capacity. However, this effect is not long-lasting, as the influence of TM diminishes as the chicks develop.

Effect of in ovo lactoferrin injection in Fayoumi chicken eggs on immune response and some physiological parameters in posthatch chicks.

The effects of in ovo lactoferrin (Lf) injection on some physiological parameters and immune response of posthatch chicks were investigated. Live embryonated Fayoumi chicken eggs (n = 600) were randomly allocated into four groups. The first group as a control was noninjected eggs, the secondgroup was only injected with 0.1 mL of NaCl 0.75% solution, and the thirdand fourthgroups were injected with 50 and 100 µL Lf dissolved in 0.1 mL saline solution respectively. The eggs were injected on Day 15 of incubation in the amnion. The results illustrated that the hatchability of eggs in two Lf groups was significantly higher than in the control, NaCl groups. The residual yolk in chicks injected with Lf (100 µL/egg) was significantly lower than the control group (p < 0.05). In ovo Lf injection improved lipid profile, liver function, antioxidant indices, blood haematology, serum immunoglobulins and jejunum histomorphometry compared to the control group (p < 0.05). In ovo injection of Lf decreased significantly (p < 0.001) of pathogenic bacteria in residual yolk such as Salmonella,Shigellaand Coliform compared to the control group. In conclusion, in ovo Lf injection can improve the hatchability, lipid profile, immune response and antioxidant indices and decline pathogens in the residual yolk, thus boosting the health status of newly hatched Fayoumi chicks.

Effect of thermal manipulation on embryonic development, hatching process, and chick quality under heat-stress conditions

Thermal stress is a risk that threatens poultry welfare and productivity. Thermal manipulation during egg incubation is considered a prevention strategy used to mitigate the detrimental effects of high ambient temperatures on birds. This study aimed to investigate the impact of thermal manipulation, applied to chicken breeder's eggs during the incubation period, on embryonic development, hatching characteristics, and chick quality, as well as posthatch thermotolerance and performance. A total of 1,200 fertile eggs were randomly and equally assigned into 2 groups of 3 replicates (200 eggs/replicate), using a randomized experimental design followed by t test. The first group eggs (G1) were subjected to a commercial setter temperature of 37.5°C with 55% relative humidity (RH) throughout the incubation period (1-18 d) and served as a control, while the second group eggs (G2) were treated the same commercial setter conditions until the 11th day of the incubation, then the eggs were exposed to a higher temperature of 39.5°C with 60% RH for 4 h daily from the 12th to the 18th day of incubation. All eggs in both groups were exposed to the same temperature condition of 37.2°C with 70% RH from the 19th to the 22nd days of the incubation (hatching period). Three hundred hatched female chicks per each treatment group were transferred into a closed-system house and distributed randomly into 20 floor pens (15 birds per pen). At the 8th week of age, birds were exposed to a daily heat challenge by raising the temperature to 35°C for 6 h until the 18th week of the chick's age. According to the results, thermal manipulation at 12 to 18 d of egg incubation positively (P ≤ 0.05) affected several studied traits. It improved some embryonic development traits, such as embryonic weight and tibia length, as well as some hatching parameters, such as hatching time and pipped eggs. It also improved hatched chick quality traits, including the chick's weight, length, and activity. In addition, it enhanced the posthatch chick's thermotolerance and body weight. Hatched chicks of G2 had significantly (P ≤ 0.05) higher total protein, albumin, IgM, glucose, calcium, total antioxidant, and T3 than G1 chicks. They also had significantly (P=0.001) higher body weight (23%) at the 18th week of age than G1, as well as a lower feed conversion ratio (20.71%) than G1 chicks at 8 to 18 wk of age. Therefore, it is recommended to apply thermal manipulation during egg incubation, particularly at 12 to 18 d, for its positive effects on the pre- and posthatch performance.

Exploring the Confluence of In-Ovo Mineral Supplementation and Hatching Attributes in Broiler Chick Progeny: A Symphony of Nutritional Enrichment and Broiler Chicks Development

Embryonic nutrition is a key factor that influences broiler progeny performance with long-lasting nutritional adequacies or insufficiencies in the developmental phase. Objective: To explores the effects of in-ovo mineral supplementation or day in-ovo feeding on the hatching attributes and chick quality in broiler breeders. Methods: About 1400 hatching eggs of broiler breeders were selected, categorized into seven experimental groups: one control group, three macro mineral (P, Mg, and Ca) groups, and three micro-mineral (Zn, Mn, and Cu) groups. During the 12th and 18th day of incubation, eggs received in-ovo injections of their respective mineral (5% of the total mineral content in a 50g egg) solutions, prepared by dissolving the corresponding salts in deionized water. Post-injection, eggs were placed in the setter, and upon completion of incubation, hatching trays were removed to evaluate hatchability performance and chick quality parameters for each group. Results: The results showed that Zn, Ca, and Mg-supplemented eggs demonstrated the highest (P&lt;0.05) hatchability rates for settable and fertile eggs at day 12 of in-ovo feeding. The chick weight, hatch window, and hatchling size were significantly influenced (P&lt;0.05) by in-ovo feeding and the day of in-ovo feeding. However, no effect of in-ovo mineral feeding and day of in ovo feeding was observed on chick quality (chick grades, navel area, retracted yolk, and membrane score) and post-hatch chick activities (activity, down-appearance, vitality, eye score, and gait score). Conclusions: In conclusion, Zn, Ca, and Mg in ovo feeding improve the hatchability traits when administered at day 12 of incubation.

Distribution of importin-α isoforms in poultry species and their tissue- and age-related differences

While importin-α is well studied in mammals, the knowledge in avian species is still limited. In this study, we compared the mRNA expression patterns of five importin-α isoforms in the respiratory tract, liver, and spleen of chickens, turkeys, and pekin ducks in two different age-groups. In addition, we determined the distribution of importin-α in selected tissue of conchae, trachea, and lung of post-hatch chickens at all cellular levels by immunohistochemical staining. Our results indicate that importin-α3 is the most abundant isoform in the respiratory tract of chickens, turkeys, and pekin ducks. Moreover, importin-α is expressed as a gradient with lowest mRNA levels in the conchae and highest levels in the lung. The mRNA expression levels of most isoforms were higher in tissues from post-hatch chickens and turkeys in comparison to the corresponding embryos. In contrast to that, duck embryos mostly show higher mRNA expression levels of importin-α than post-hatch ducks.

Thyroid hormone manipulation influences development of endothermy and hatching in white leghorn chickens (Gallus gallus)

Chickens experience rapid change in their physiology and metabolism during hatching. We propose that thyroid hormones play a major role in regulating the developmental changes associated with attaining endothermy. To better understand the role thyroid hormones play in hatch timing and development of thermogenic capacity and metabolic rate we manipulated plasma thyroid hormone levels in chicken embryos beginning at 80% development (day 17 of a 21-day incubation) with either a single dose of triiodo-L-thyronine (T3) or the thyroperoxidase inhibitor methimazole (MMI). Manipulation of thyroid hormones altered the timing of hatching, accelerating hatching under hyperthyroid conditions, and prolonging hatching with hypothyroid conditions. Effect sizes comparisons of morphological variables between treatment groups revealed larger heart and body masses in hyperthyroid 1-day post hatch animals. Thyroid hormone manipulation influenced the thermal neutral zone for O2 consumption and body temperature during gradual cooling from 35 to 15 °C of externally pipped embryos and 1-day post hatch chicks. Hyperthyroid EP animals had a wider thermal neutral zone during cooling when compared to control animals. At the temperatures tested, the hypothyroid animals did not exhibit a thermal neutral zone. Similar differences between treatments in the breadth of the thermal neutral zone carried through to 1-day post hatch chickens. These findings suggest that thyroid manipulations influence the timing and development of the animal’s thermogenic response to cooling.

Short communication: In ovo injection of all-trans retinoic acid causes adipocyte hypertrophy in embryos but lost its effect in posthatch chickens.

The regulation of adipose deposition in broiler chickens is an important factor for production efficiency to poultry producers and health concerns to customers. Although vitamin A and its metabolite [all-trans retinoic acid (atRA)] have been used for studies on adipogenesis in mammals and avian, effects of embryonic atRA on adipose development in embryonic (E) and posthatch (D) ages in broiler chickens have not been studied yet. Different concentrations of atRA (0M-2μM) were injected in broiler eggs at E10, and adipose tissues were sampled at E16. Percentages of adipose tissues in chicken embryos were significantly increased in the group injected with 500nM of atRA compared to the 0M group (P<0.05). In addition, the adipocyte cross-sectional area (CSA) was significantly greater by in ovo injection of 500nM atRA compared to the injection of 0M (P<0.01). Moreover, in ovo atRA-injected embryos were hatched and BWs were measured at D0, D7, and D14. BWs were not different from those of the 0M group. Percentages of adipose tissues and CSA of the in ovo atRA-injected group (500nM) were not different from those of the 0M group at D14. Taken together, the current study clearly showed that in ovo injection of atRA promoted adipose deposition with hypertrophy during embryonic development, but its effects were not maintained in early posthatch age in broiler chickens, implying that embryonic atRA has an important role in the regulation of adipose development in chicken embryos.

The effect of storage periods and SPIDES on embryonic mortality, hatching characteristics, and quality of newly hatched chicks in broiler eggs

sEgg storage duration can affect embryo mortality, hatching characteristics, hatching time, and post-hatch chick quality. In order to assess these effects, the impact of storage duration (5 days, 10 days, 15 days) and short incubation period during egg storage (SPIDES) investigated further 18, 900 eggs of broiler breeder (ROSS 308) in 3 × 2 factorial arrangement design. In the SPIDES treatment, the egg shell temperature was raised from its storage temperature (18 °C) and held at 100 °F for 3.5 h. Storage periods could significantly (P < 0.05) influence on embryo mortality (total, early, middle, and late), hatchability of both the total eggs and fertile eggs. The SPIDES treatment had a significant (P < 0.05) impact on a lower embryonic death rate and improved egg hatchability. Eggs stored for 5 days and eggs treated with SPIDES significantly (P < 0.001) shorten hatching time, batch’s 90% hatching time (T 90% H), mean hatching time (MHT), maximal hatching period (MHP), and hatching window (HW). Chick quality was also determined, whereas storing eggs for 5 days and using the SPIDES treatment resulted in enhanced (P < 0.001) chick weight relative to egg weight (CW/EW), activity (AC), and chick quality score (CQS). The residual yolk sac weight (RYSW), unhealed navel (UHN %), and dirty feather (DF%) recorded the lowest (P < 0.001) values compared to long storage periods and control group. Finally, stored for 5 days treated by SPIDES positively affected the hatchability characteristics, the shortening hatching time, and the quality of chicks. Regarding the results, it was confirmed that using the SPIDES treatment to prevent the harmful effects of broiler eggs being stored for an extended period of time is a viable option.

Effect of Chick Quality on Viability, Performance Traits and Meat Quality Characteristics of Broiler Chickens

The chick quality in broiler production is a major factor that has a direct impact on the profitability of both hatcheries and producers. In recent years, there has been considerable interest in the correlations between chick quality, which is measured by quantitative or qualitative methods, and yield characteristics. This study aims to compare the viability, performance traits, and meat quality characteristics of broiler chickens classified into two chick quality categories based on the Tona score method. In the study, broilers in the first-grade group had a lower mortality rate of 1.67%, while the average mortality rate of those with poor chick quality was 23.33% (P&amp;lt;0.05). There were no statistically significant correlations between post-hatch performance and chick quality characteristics such as Tona score, chick weight, chick length (all P&amp;gt;0.05). According to the Tona score, there were no differences between the mean values of body weight, feed efficiency, Gompertz growth curve parameters, slaughter carcass traits, and meat quality characteristics of first- and second-grade broiler chickens (all P&amp;gt;0.05). Although there is no difference between high and low quality chicks in terms of performance characteristics, it is possible that the use of low quality chicks in conventional broiler production will increase the general mortality of the flock. Due to their superior yield potential, it is recommended that low-quality chicks be utilized in more suitable production systems without culling, rather than in conventional broiler production.

Retinal Gene Expression of Selective Genes and Histological Stages of Embryonic and Post-Hatch Chickens (Gallus gallus).

Chickens are excellent models for the study of retinal development and function. Gene expression at the correct time is crucial to retinal development and function. The present study aimed to investigate retinal gene expression and morphology in locally grown chickens at various developmental stages. RNA was extracted from the retina at the embryonic and post-hatch stages, and the retinal layers were stained with haematoxylin and eosin (H&E). RT-PCR and RT-qPCR were used for gene expression analysis of 14 selected genes. The results showed that all the retinal genes were expressed at different developmental stages. However, there were slight noticeable variations in expression patterns. At the morphological level, all retinal layers were well observed, except for the outer plexiform layer that became visible in the fifteen-day chick embryo. The current study provides a baseline for standard retinal gene expression of 14 genes and retinal histological staining. The selected genes have different roles in retinal development and function, and most of these genes are associated with retinal diseases. The results obtained here can be applied to molecular retinal research and retinal diseases with genetic factors in retina animal models or human diseases.

The Effect of Gum Arabic Supplementation on Growth Performance, Blood Indicators, Immune Response, Cecal Microbiota, and the Duodenal Morphology of Broiler Chickens.

Simple SummaryGum Arabic (GA) is considered a natural prebiotic because it contains soluble and indigestible fibers that can stimulate the growth and activity of commensal bacteria through fermentation. Administration of GA in broiler diets may promote early growth as well as the development and health of the intestine and immune functions. However, studies on the mechanism of GA on broiler chickens to improve growth performance and intestinal health are scarce. This study aimed to evaluate the growth performance, internal organs, immune-related gene expression, microbiota, and histological changes of broiler chickens fed with increasing levels of GA. We suggest that GA (0.25 to 0.75%) positively affects the performance, microbiota, immune response, morphology, and gut health of post-hatched chickens. Gum Arabic (GA) belongs to the Fabaceae family and contains indigestible soluble fibers (80–85%) that could be fermented by commensal bacteria to enhance performance, immune response, and intestinal integrity. This study aimed to investigate the effects of GA on performance, serum biochemical indicators, microbiota, immune-related gene expression, and histological changes in chickens. Six GA levels (0.0, 0.12, 0.25, 0.5, 0.75, 1.0%) were allocated using a total of 432 1-day-old male chickens (12 replicates with 6 chickens each). Growth performance was evaluated on days 10 and 24 of age. Blood parameters, organ pH levels, and intestinal health were determined on day 10 of age. Results showed that GA at 0.12% increased weight gain and 0.12 to 1.0% decreased feed intake but was best in feed conversion ratio and production efficiency except for 1.0% on day 1–10 of age. There was an increase in the thymus weight at GA level 0.25 to 0.75%. GA decreased the pH value of the proventriculus (at 0.50 and 1.0%) as well as the duodenum and cecum (at 0.12 and 1.0%). Chickens fed GA between 0.25 to 1.0% had higher protein and HDL, but lower cholesterol, LDL, and creatinine. Globulin was increased at 0.50% GA, while glucose and triglycerides were decreased (at 0.25 and 0.75% GA, respectively). The immune-related gene expression was reduced, except for 0.25% GA, which increased IL-10. Furthermore, chickens fed GA (0.25 to 0.75%) had higher Lactobacillus spp. and lower Salmonella spp. and Escherichia coli. When chickens received GA, the villus length and length to crypt ratio were higher, which also improved the integrity of intestinal epithelial cells and early duodenal development. We conclude that using GA (0.25 to 0.75%) as a natural prebiotic positively affects the performance, microbiota, immune response, morphology, and gut health of post-hatched chickens. More studies are needed to determine the potential mechanism of GA on broiler chickens.

Leptin Promotes Primordial Follicle Activation by Regulating Ovarian Insulin-like Growth Factor System in Chicken.

Leptin and insulin-like growth factor 1 (IGF-1) regulate follicle development and reproduction in vertebrates. This study investigated the role played by leptin and IGF-1 in primordial follicle activation in the ovary of 7-day-old chicks. Different doses of leptin were intraperitoneally administrated to female layer chicks, and further analyses were performed. While leptin administration did not affect hepatic leptin receptor (LEPR), growth hormone receptor (GHR), or IGF-1, the lower dose of leptin significantly increased the messenger RNA (mRNA) expression of IGF-1, IGF-1 receptor, and IGF-binding protein (IGFBP)-2 and attenuated anti-Müllerian hormone (AMH) gene expression in the ovary. Furthermore, the ovaries of the same age chicks were challenged with leptin and/or IGF-1 in vitro. Leptin at a lower dose increased the mRNA expression of IGF-1, LEPR, and leptin; 100 ng/mL leptin and 10 ng/mL IGF-1 alone or combined with leptin reduced IGFBP-2 mRNA expression. AMH gene expression was also reduced by all doses except 10 ng/mL leptin. Histological studies showed that a lower dose of leptin injection induced the primordial follicle growth in the ovary in vivo, and the number of primordial follicles was higher in all leptin treatments over control in vitro. Moreover, the luciferase assay revealed that leptin enhanced IGF-1 promoter activity in LEPR-expressing CHO-K1 cells. Collectively, these results indicate that leptin directly affects the IGF-1/IGFBP system and promotes primordial follicular growth in the ovary of early posthatch chicks. In addition, the follicular development by leptin-induced IGF-1 is, at least in part, caused by the suppression of AMH in the ovary.

Effect of Partial Replacement of Yellow Corn by Mango Seed Kernel on Productive Performance, Egg Quality, and Blood Constituents of Laying Hens

Corn is the main energy source in most poultry feed. Due to rapid climate change, corn production cannot keep up with the demand for food and industrial applications. This necessitated the search for alternatives, such as agro-industrial by-products like mango seed kernel, which is a good source of carbohydrates and protein and can wholly or partly replace corn. The purpose of this study was to investigate the effect of partial replacement of yellow corn (YC) with soaked mango seed kernel (SMSK) on productive and reproductive performance, egg quality, blood biochemistry, hematological parameters, and antioxidants status of local laying hens. A total of 120 local Gimmizah breeds (108 females and 12 males) at 32 weeks of age were randomly assigned to four dietary treatments with three replicates (9 hens + 1 male per replicate). The treatments were YC replaced by SMSK at 0, 10, 15, and 20% levels in the hen diets for 12 weeks. Replacing YC with SMSK increased egg production, weight and number of eggs, and egg mass, and improved feed conversion ratio, but feed intake was not affected. Replacement of yellow corn with SMSK did not affect egg quality parameters. The hens in the SMSK 10% and SMSK 15% groups had the highest fertility, hatchability, post-hatch chick weight, and number followed by those in the SMSK 20% group. Groups given varying levels of SMSK had the lowest rate of embryonic mortality. Carcass weight and dressing percentage were positively affected by the 10% and 15% SMSK diet, except for the heart, pancreas, and spleen. Hematological indices were not influenced by dietary SMSK except for higher platelets in the SMSK 20% group. Total protein, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels were similar among treatments. In SMSK groups, serum total cholesterol, triglycerides, and malondialdehyde levels decreased significantly, whereas IgG and catalase levels increased. These findings indicated that SMSK up to 20% could be considered a successful nutritional and health approach and can be partially substituted for YC with no adverse impact on the productive, reproductive and physiological performance of laying hens.

Effects of the In Ovo Vaccination of the ts-11 Strain of Mycoplasma gallisepticum in Layer Embryos and Posthatch Chicks.

Simple SummaryMycoplasma gallisepticum (MG) is responsible for reductions in egg production and other economic losses in the poultry industry. In this study, the potential application of in ovo vaccination of the ts-11of MG vaccine (ts-11MGV) in layer embryos for the subsequent early protection as well as live performance of pullets were investigated. The use of various dosages of live attenuated ts-11MGV ranging from 3.63 × 101 to 3.63 × 104 cfu that were delivered in ovo at 18 days of incubation were evaluated. The results of current study revealed that the in ovo injection of various dosage of ts-11MGV had no negative impacts on any hatch variables. Additionally, the higher dosage of ts-11MGV (3.63 × 104) resulted in a reduction in body weight gain in three-week-old pullets in comparison to all other treatments. Furthermore, MG DNA remained undetectable for hatchling and three-week-old pullets and no serological response was observed at 3 weeks posthatch. Total flock protection from field-strain MG infections is facilitated by the prior systemic establishment of vaccine strains in pullets. Therefore, it is concluded that the ts-11MGV may not be an appropriate candidate for in ovo injection due to the lack of its presence in hatchlings and posthatch chicks subsequent to its in ovo administration.The transmission of the ts-11 strain of Mycoplasma gallisepticum (MG) vaccine (ts-11MGV) between incubated eggs and between hatchlings that was administrated via in ovo injection, and its subsequent effects on their posthatch performance were evaluated. Marek’s disease diluent alone (sham-injected) or containing either 3.63 × 101, 102, 103, or 104 cfu of ts-11MGV was manually in ovo-injected into the amnion on 18 days of incubation. Egg residue analysis, percentage incubational egg weight loss, hatchability of viable injected eggs, and hatchling body weight (BW) were assessed. Selected hatchlings from each treatment replicate group were swabbed in the choanal cleft for MG DNA detection. Female chick live performance was also assessed through 21 days of posthatch age. Unexposed control sentinel chicks were allocated to each treatment replicate group to assess horizontal transmission. Birds were later swabbed and bled respectively, for detection of MG DNA and IgM production at 21 days posthatch. In all birds, no MG DNA was detected and SPA tests for IgM were negative. Among all variables, only 0 to 21 day BW gain was significantly affected by treatment and was lower in the 3.63 × 104 ts-11 MGV treatment in comparison to all the other treatments. Because ts-11MGV does not exhibit vertical or horizontal transmission capabilities under commercial conditions, it may not be a good candidate for in ovo injection.

Synergy Between Dietary Quercetin and Vitamin E Supplementation in Aged Hen's Diet Improves Hatching Traits, Embryo Quality, and Antioxidant Capacity of Chicks Hatched From Eggs Subjected to Prolonged Storage.

The current study aims to investigate the effects of the synergy between quercetin and vitamin E in aged hen’s diet on hatchability and antioxidant levels of the embryo and newly hatched chicks from prolonged storage eggs. A total of 400 breeder laying hens of 65 weeks of age were selected and randomly divided into 4 groups. Birds were fed a basal diet alone (Control), and basal diets supplemented with quercetin (Q) (0.4 g/kg) and vitamin E (VE) (0.2 g/kg) alone and their combination (0.4 g/kg Q + 0.2 g/kg VE) for 14 weeks, respectively, to determine their effects on yolk antioxidant status, fertility, embryonic mortality, hatchability, antioxidant status of embryonic tissues, as well as the antioxidant status of the newly hatched chicks. The results showed that the hen’s dietary Q + VE increased the yolk weight, as well as increased the antioxidant status of the egg yolk (p < 0.05). Compared with the control group, the supplementation of Q + VE significantly increased the hatchability of set-fertile eggs and decreased early embryonic mortality in eggs stored for 7 and 14 days, respectively (p < 0.05), and also improved the antioxidant capacity of the embryos obtained from eggs stored for 14 days (before incubation) (p < 0.05). Moreover, Q + VE increased the levels of SOD, GSH-Px, T-AOC, T-SOD, and CAT in the liver, heart, and pectoral muscle of the embryo, 1-day-old and 14-day-old chicks (p < 0.05), as well as upregulated the antioxidant related genes (GPx-1, GPx-2, GPx-4, DIO-1, and SOD-1) in the liver of the embryo, 1-day-old and 14-day-old chicks hatched from 14-days storage eggs (p < 0.05). Meanwhile, the MDA levels were decreased by the Q + VE in the embryo and post-hatched chicks (p < 0.05). In conclusion, these findings suggested that maternal dietary Q + VE exerts beneficial synergistic effects on the antioxidant capacity of the egg yolk, embryo, and chicks during prolong egg storage, therefore, Q + VE could be used as a dietary measure to enhance hatchability and chick quality in poultry production.

Effects of pre-incubation storage duration and nonventilation incubation procedure on embryonic physiology and post-hatch chick performance

This study investigated the effects and possible interactions of storage and nonventilation during incubation for eggs from Sasso broiler breeder flock on pre- and post-hatch incubation results.A total of 1,260 Sasso eggs from a 58-wk-old broiler breeder flock were individually numbered, weighed and stored for 7 d or for 18 d in a climate-controlled room (16°C, 75% RH). After storage, eggs were weighed, and randomly assigned equally into 2 incubators. One of the incubators was ventilated (V) for the entire incubation and the second was nonventilated (NV) for the first 12 d. At d 18, the eggs were weighed, candled, and fertile eggs were transferred from the turning trays to hatching baskets. During the last 3 d of incubation, hatching eggs were checked individually every 3 h for hatching events and hatchability of fertile eggs. After pull out at d 21.5, post-hatch performances was determined until 1 wk of age.Results showed that, embryo weights from eggs in NV incubator was significantly higher (P < 0.05) in both stored eggs compared to those from eggs in ventilated incubator, but embryos from eggs stored for 18 d were smaller (P < 0.05) than those from eggs stored for 7 d. Hatchability was higher (P < 0.0001) in NV incubator compared to V incubator in both 7 d and 18 d stored eggs and an interaction was found between incubation ventilation and storage duration on both hatchability and embryonic mortality (P < 0.0001). Chick weights from NV incubator at 7 d post-hatch was greater (P = 0.0009) than those from V incubator. Serum Tri-iodothyronine (T3) and Thyroxin (T4) concentrations were significantly higher (P < 0.05) in NV compare to V group.It was concluded that the effect of long-term pre-incubation storage on embryonic physiology and post-hatch growth interacted significantly with incubation ventilation and that nonventilation can compensate for the negative effects of storage on some hatching and post-hatch performances.

Maternal immunization against myostatin suppresses post-hatch chicken growth.

Myostatin (MSTN) is a negative regulator of skeletal muscle growth, thus it was hypothesized that immunization of hens against MSTN would enhance post-hatch growth and muscle mass via suppression of MSTN activity by anti-MSTN IgY in fertilized eggs. This study investigated the effects of immunization of hens against chicken MSTN (chMSTN) or a MSTN fragment (Myo2) on the growth and muscle mass of offspring. In Experiment 1, hens mixed with roosters were divided into two groups and hens in the Control and chMSTN groups were immunized with 0 and 0.5 mg of chMSTN, respectively. In Experiment 2, hens in the chMSTN group were divided into chMSTN and Myo2 groups while the Control group remained the same. The Control and chMSTN groups were immunized in the same way as Experiment 1. The Myo2 group was immunized against MSTN peptide fragment (Myo2) conjugated to KLH. Eggs collected from each group were incubated, and chicks were reared to examine growth and carcass parameters. ELISA showed the production of IgYs against chMSTN and Myo2 and the presence of these antibodies in egg yolk. IgY from the chMSTN and Myo2 groups showed binding affinity to chMSTN, Myo2, and commercial MSTN in Western blot analysis but did not show MSTN-inhibitory capacity in a reporter gene assay. In Experiment 1, no difference was observed in the body weight and carcass parameters of offspring between the Control and chMSTN groups. In Experiment 2, the body weight of chicks from the Myo2 group was significantly lower than that of the Control or chMSTN groups. The dressing percentage and breast muscle mass of the chMSTN and Myo2 groups were significantly lower than those of the Control group, and the breast muscle mass of Myo2 was significantly lower than that of the chMSTN. In summary, in contrast to our hypothesis, maternal immunization of hens did not increase but decreased the body weight and muscle mass of offspring.