Metabolic Gene Expression in the Muscle and Blood Parameters of Broiler Chickens Stimulated In Ovo with Synbiotics

Growth performance, carcass composition, and qualitative meat features of broiler chickens after galactooligosaccharides and sodium butyrate in ovo administration

The study aimed to analyze the growth performance, feed indicators, and quantitative and qualitative physicochemical features of carcass and meat from broiler chickens after rearing, stimulated in ovo on d 12 of incubation with various substances. In the experiment, 1,200 hatching eggs from meat-type hen Ross 308 parental flock were incubated. On d 12, the injection was performed. Group CON-0 was noninjected. Group CON-S was injected with saline. In the GOS group, the procedure was performed in ovo with galactooligosaccharides (dissolved 3.5 mg of GOS in 0.2 mL of NaCl). In the SB group, butyric acid sodium salt was administered in a 0.3% SB dissolved in 0.2 mL NaCl. After hatching, 336, 1-day-old chicks per group were transferred to the broiler house and kept in 7 pens with 12 chickens per group for 42 d. The body weight and feed intake indicators were calculated. Next, 40 birds were selected (n = 10 per group) and taken to analyze carcass composition and meat quality (pH, color, WHC, drip loss, chemical composition). Compared to the experimental groups, the highest body weight indicators were found in groups CON-0 and CON-S. The feed conversion ratio was the lowest in the SB group on d 36 to 42 (P < 0.05). The European Efficiency Production Factor in groups GOS and SB was lower than in group CON-S (P = 0.005). The GOS group showed higher pH24hours in the pectoral muscles than the CON-S group (P = 0.011). The leg muscles showed better WHC in the CON-S, GOS, and SB groups than in the CON-0 group (P < 0.001). A lower intramuscular fat of the pectoral and leg muscle content was demonstrated, especially in the SB group. Injection of galactooligosaccharides and sodium butyrate in ovo adversely affected broiler production but did not alter carcass composition. It varied pectoral muscles' pH and chemical composition and improved water holding capacity and chemical composition in leg muscles.

Exploring Evolutionary Adaptations and Genomic Advancements to Improve Heat Tolerance in Chickens

Climate change poses a significant threat to the poultry industry, especially in hot climates that adversely affect chicken growth, development, and productivity through heat stress. This literature review evaluates the evolutionary background of chickens with the specific genetic characteristics that can help chickens to cope with hot conditions. Both natural selection and human interventions have influenced the genetic characteristics of the breeds used in the current poultry production system. The domestication of chickens from the Red junglefowl (Gallus gallus) has resulted in the development of various breeds with distinct genetic differences. Over the past few years, deliberate breeding for desirable traits (such as meat production and egg quality) in chickens has resulted in the emergence of various economically valuable breeds. However, this selective breeding has also caused a decrease in the genetic diversity of chickens, making them more susceptible to environmental stressors like heat stress. Consequently, the chicken breeds currently in use may possess a limited ability to adapt to challenging conditions, such as extreme heat. This review focuses on evaluating potential genes and pathways responsible for heat tolerance, including heat shock response, antioxidant defense systems, immune function, and cellular homeostasis. This article will also discuss the physiological and behavioral responses of chicken varieties that exhibit genetic resistance to heat, such as the naked neck and dwarf traits in different indigenous chickens. This article intends to review the current genomic findings related to heat tolerance in chickens that used methods such as the genome-wide association study (GWAS) and quantitative trait loci (QTL) mapping, offering valuable insights for the sustainability of poultry in the face of global warming.

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.

MicroRNA expression in immune tissues of adult chickens after embryo stimulation with bioactive substances

The microbiota has a profound impact on the host organisms. The interaction between the host and its microbiota has an epigenetic mode of action. In poultry species, gastrointestinal microbiota might be stimulated before hatching. This stimulation with bioactive substances has a broad spectrum and long-term effects. This study aimed to examine the role of miRNA expression stimulated by host-microbiota interaction via administering a bioactive substance at the stage of embryonic development. This paper is a continuation of earlier research in the field of molecular analyzes in immune tissues after in ovo administration of bioactive substances. Eggs of Ross 308 broiler chicken and Polish native breed chicken (Green-legged Partridgelike) were incubated in the commercial hatchery. On day 12 of incubation, eggs were injected: the control group with saline (0.2 mM physiological saline), probiotic-Lactococcus lactis subsp. cremoris, prebiotic-galactooligosaccharides, and synbiotic-mentioned above prebiotic with probiotic. The birds were intended for rearing. miRNA expression analysis was performed using the miRCURY LNA miRNA PCR Assay in the spleen and tonsils of adult chickens. Six miRNAs differed significantly, at least between one pair of treatment groups. The most miRNA changes were observed in the cecal tonsils of Green-legged Partridgelike chickens. At the same time, only miR-1598 and miR-1652 showed significant differences between the treatment groups in the cecal tonsils and spleen of Ross broiler chickens. Only two miRNAs showed significant GeneOntology (GO)enrichment with the ClueGo plug-in. gga-miR-1652 target genes showed only 2 GOs significantly enriched: chondrocyte differentiation and early endosome. gga-miR-1612 target genes, the most significant GO was regulating the RNA metabolic process. The enriched functions were associated with gene expression or protein regulation, the nervous system, and the immune system. Results suggest that early microbiome stimulation in chicken might regulate the miRNA expression in different immune tissues in a genotype-dependent manner.

Proteome changes upon in ovo stimulation with Lactobacillus synbiotic in chicken liver

The liver, as the main metabolic organ, plays a key role in many vital processes, including nutrient metabolism, fat digestion, blood protein synthesis, and endocrine management. As one of the immune organs, it has a remarkable ability to adequately activate the immune cells in response to metabolic signals. The anatomy of the liver ensures its close interaction with the gut so that nutrients and gut microbiota contribute to normal metabolism. In chickens, the intestinal microbiota plays an important role in supporting health and improving production parameters. The most effective method of stimulating the microbiota is to administer an appropriate bioactive compound during embryonic development. In ovo stimulation on d 12 of egg incubation involves the delivery of the substance into the air chamber. The aim of the study was to analyze the changes at the protein level after in ovo administration of the synbiotic on d 12 of egg incubation. Our study is the first to conduct a proteome analysis in liver after the administration of a Lactobacillus synbiotic in ovo. Eggs of broiler chickens were injected with a synbiotic—Lactobacillus plantarum with raffinose family oligosaccharides (RFO). On d 21 posthatching liver was collected. We performed analyses based on two-dimensional electrophoresis, matrix-assisted laser desorption/ionization (MALDI) time-of-flight, and MALDI Fourier-transform ion cyclotron resonance to obtain a global view of the hepatic proteome changes in response to in ovo injection. A representative pattern of significantly altered liver proteins was observed after stimulation with the synbiotic. A total of 16 protein spots were differentially expressed, with 5 downregulated and 11 upregulated spots. We conclude that the in ovo synbiotic treatment had the potential to accelerate the major energy-yielding metabolic pathways in the liver of adult broilers.

Molecular Response in Intestinal and Immune Tissues to in Ovo Administration of Inulin and the Combination of Inulin and Lactobacillus lactis Subsp. cremoris

Intestinal microbiota are a key factor in maintaining good health and production results in chickens. They play an important role in the stimulation of immune responses, as well as in metabolic processes and nutrient digestion. Bioactive substances such as prebiotics, probiotics, or a combination of the two (synbiotic) can effectively stimulate intestinal microbiota and therefore replace antibiotic growth promoters. Intestinal microbiota might be stimulated at the early stage of embryo development in ovo. The aim of the study was to analyze the expression of genes related to energy metabolism and immune response after the administration of inulin and a synbiotic, in which lactic acid bacteria were combined with inulin in the intestines and immune tissues of chicken broilers. The experiment was performed on male broiler chickens. Eggs were incubated for 21 days in a commercial hatchery. On day 12 of egg incubation, inulin as a prebiotic and inulin with Lactobacillus lactis subsp. cremoris as a synbiotic were delivered to the egg chamber. The control group was injected with physiological saline. On day 35 post-hatching, birds from each group were randomly selected and sacrificed. Tissues (spleen, cecal tonsils, and large intestine) were collected and intended for RNA isolation. The gene panel (ABCG8, HNF4A, ACOX2, APBB1IP, BRSK2, APOA1, and IRS2) was selected based on the microarray dataset and biological functions of genes related to the energy metabolism and immune responses. Isolated RNA was analyzed using the RT-qPCR method, and the relative gene expression was calculated. In our experiment, distinct effects of prebiotics and synbiotics following in ovo delivery were manifested in all analyzed tissues, with the lowest number of genes with altered expression shown in the large intestines of broilers. The results demonstrated that prebiotics or synbiotics provide a potent stimulation of gene expression in the spleen and cecal tonsils of broiler chickens. The overall number of gene expression levels and the magnitude of their changes in the spleen and cecal tonsils were higher in the group of synbiotic chickens compared to the prebiotic group.

Hepatic DNA Methylation in Response to Early Stimulation of Microbiota with Lactobacillus Synbiotics in Broiler Chickens

DNA methylation inhibits DNA transcription by the addition of methyl residues to cysteine within the CpG islands of gene promoters. The process of DNA methylation can be modulated by environmental factors such as intestinal microbiota. In poultry, the composition of the intestinal microbiota can be stimulated by in ovo delivery of synbiotics. The present study aims to determine the effect of Lactobacillus synbiotics delivered in ovo on the level of hepatic DNA methylation in broiler chickens. In ovo stimulation was performed on day 12 of egg incubation. Bioactive compounds delivered in ovo included (S1)—Lactobacillus salivarius with GOS and (S2)—Lactobacillus plantarum with RFO. Samples were collected from six individuals from each group on day 42 post-hatching. DNA methylation of five genes selected on the basis of the transcriptome data were analyzed using the qMSP method. Significant changes were observed in DNA methylation of genes in liver including ANGPTL4 and NR4A3, after S2 delivery. The obtained results confirm that the downregulation of metabolic gene expression in the liver mediated by in ovo stimulation had epigenetic characteristics.