The awareness of poultry production safety is constantly increasing. The safety of poultry production is defined as biosecurity and the health status of birds. Hence the constant pursuit of developing new strategies in this area is necessary. Biosecurity is an element of good production practices that ensures adequate hygiene and maintaining the health status of poultry production. Poultry production is the world leader among all livestock species. Producers face many challenges during rearing, which depend on the utility type, the direction of use, and consumer requirements. For many years, the aim was to increase production results. Increasing attention is paid to the quality of the raw material and its safety. Therefore, it is crucial to ensure hygiene status during production. It can affect the immune system's functioning and birds' health status. Feed, water, and environmental conditions, including light, gases, dust, and temperature, play an essential role in poultry production. This review aims to look for stimulators and modulators of the poultry immune system while affecting the biosecurity of poultry production. Such challenges in current research by scientists aim to respond to the challenges posed as part of the One Health concept. The reviewed issues are a massive potential for an innovative approach to poultry production and related risks as part of the interaction of the animal-human ecosystem.

Galactooligosaccharides (GOS) are well-known immunomodulatory prebiotics. We hypothesize that GOS supplemented in feed modulates innate immune responses in the skin-associated lymphoid tissue (SALT) of common carp. The aim of this study was to determine the impact of GOS on mRNA expression of the immune-related genes in skin mucosa. During the feeding trial, the juvenile fish (bodyweight 180 ± 5 g) were fed two types of diet for 50 days: control and supplemented with 2% GOS. At the end of the trial, a subset of fish was euthanized (n = 8). Skin mucosa was collected, and RNA was extracted. Gene expression analysis was performed with RT-qPCR to determine the mRNA abundance of the genes associated with innate immune responses in SALT, i.e., acute-phase protein (CRP), antimicrobial proteins (His2Av and GGGT5L), cytokines (IL1β, IL4, IL8, IL10, and IFNγ), lectin (CLEC4M), lyzosymes (LyzC and LyzG), mucin (M5ACL), peroxidase (MPO), proteases (CTSB and CTSD), and oxidoreductase (TXNL). The geometric mean of 40s s11 and ACTB was used to normalize the data. Relative quantification of the gene expression was calculated with ∆∆Ct. GOS upregulated INFγ (p ≤ 0.05) and LyzG (p ≤ 0.05), and downregulated CRP (p ≤ 0.01). We conclude that GOS modulates innate immune responses in the skin mucosa of common carp.

Galactooligosaccharides (GOS) that are delivered in ovo improve intestinal microbiota composition and mitigate the negative effects of heat stress in broiler chickens. Hubbard hybrids are slow-growing chickens with a high resistance to heat. In this paper, we determined the impact of GOS delivered in ovo on slow-growing chickens that are challenged with heat. The experiment was a 2 × 2 × 2 factorial design. On day 12 of incubation, GOS (3.5 mg/egg) was delivered into the egg (n = 300). Controls (C) were mock-injected with physiological saline (n = 300). After hatching, the GOS and C groups were split into thermal groups: thermoneutral (TN) and heat stress (HS). HS (30 °C) lasted for 14 days (days 36–50 post-hatching). The spleen (n = 8) was sampled after acute (8.5 h) and chronic (14 days) HS. The gene expression of immune-related (IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17) and stress-related genes (HSP25, HSP90AA1, BAG3, CAT, and SOD) was detected with RT-qPCR. Chronic HS up-regulated the expression of the genes: IL-10, IL-12p40, SOD (p < 0.05), and CAT (p < 0.01). GOS delivered in ovo down-regulated IL-4 (acute p < 0.001; chronic p < 0.01), IL-12p40, CAT and SOD (chronic p < 0.05). The obtained results suggest that slow-growing hybrids are resistant to acute heat and tolerant to chronic heat, which can be supported with in ovo GOS administration.

A healthy gut is one of the main factors influencing bird response. Over the years, efforts have been made to improve intestinal health. One of the supporting methods may be enriching the diet with bioactive ingredients, including sodium butyrate (SB). One of the possible ways of administering such supplementation is in ovo technology. Over the years, research has shown that administering bioactive substances this way has a positive effect on the health status of chickens. The current study aimed to modify the gut microbiota of broiler chickens by in ovo stimulation on d 12 of egg incubation with SB and to determine the changes occurring in intestines. One thousand eggs were incubated and injected with 0.1, 0.3, or 0.5% SB on d 12 of incubation. The control group was injected with physiological saline. Samples collected for analysis were obtained postmortem from 42-day-old ROSS 308 broiler chickens. Growth performance parameters were also monitored during broiler rearing. Gene expression analysis showed significant changes in the levels of IL4, IFNγ, AvBD1, TJAP and MUC6 genes in the ileum. However, the IL8, MUC2 and MUC6 genes were significantly expressed in the cecal mucosa. These changes depended on the administered dose of butyrate. There was no effect of in ovo administration of various doses of SB on digesta pH, SCFA level and histological parameters. However, a significant increase in Bifidobacterium bacteria was detected in the ileum after administration of a dose of 0.5% SB and in the cecum after administration of a dose of 0.3%. Administration of SB in ovo has the potential to support intestinal health in poultry. The effects depend on the administered dose, while the results indicate a dose of 0.3% as the most optimal.

Introduction: Butyrate is one of the three main short-chain fatty acids, and it provides energy, controls the state of the intestinal microbiota and mediates the immune response. Sodium butyrate supplementation improves poultry production and changes the intestinal microbiota dynamically. These changes may affect the liver directly and indirectly through pathways in the gut–liver axis, the bidirectional relationship between the liver and intestines. The study analysed gene expression and methylation in the broiler liver after in-ovo stimulation by sodium butyrate. Material and Methods: Incubated Ross 308 broiler eggs were injected on day 12 with saline as the control group or with sodium butyrate as SB groups at three doses: 0.1%, 0.3% and 0.5%. Chicks’ livers were collected postmortem on day 42 of rearing for RNA and DNA extraction. Gene expression was analysed by reverse-transcription qPCR, and gene methylation by methylation-specific qPCR for a panel of lipid metabolism and immune regulation genes comprising ANGPTL4, CD72, CXCR5, CYR61, IKZF1, KLHL6, NR4A3, SERPING, SYK and TNFRSF14 . Results: Sodium butyrate stimulation changed gene expression levels. Upregulation was noted of ANGPTL4 and NR4A3 in the 0.1% and 0.3% SB groups and downregulation of CYR61 in the 0.5% SB group. The gene-specific DNA methylation also significantly changed under the influence of the sodium butyrate doses for ANGPTL4, CXCR5 and KLHL6 . The level of global methylation did not change significantly, but did decrease with increasing butyrate dose. Conclusion: The obtained results suggest that sodium butyrate affected both gene expression and methylation in the liver, indicating its potential epigenetic effects.

Early-life in ovo interventions are increasingly explored as tools to modulate poultry gut ecosystems and intestinal function. However, high-throughput evidence describing ileal and cecal microbiota responses following embryonic exposure remains limited. This study evaluated whether a single in ovo administration of a prebiotic (galactooligosaccharides) or a short-chain fatty acid donor (sodium butyrate) resulted in differences in gut microbial communities of broiler chickens at day 42 of age. On embryonic day 12, 1,068 fertile Ross 308 eggs were assigned to four treatments: non-injected control, saline-injected control, galactooligosaccharides (3.5 mg/0.2 mL), or sodium butyrate (0.3%/0.2 mL). Birds were reared to day 42, and ileal and cecal digesta were collected from 10 birds per group. Full-length 16S ribosomal RNA gene sequencing was used to characterize microbial composition and diversity. Galactooligosaccharides increased richness and diversity while maintaining dominance of Lactobacillus and promoting Romboutsia and unclassified Peptostreptococcaceae. Sodium butyrate induced a stronger restructuring of the microbiota, accompanied by reduced Lactobacillus abundance and enrichment of multiple Clostridia-associated genera together with representatives of Bacteroidota; community structure differed among treatments. In the cecum, galactooligosaccharides increased diversity and promoted expansion of taxa affiliated with Lachnospiraceae and Ruminococcaceae, including Faecalibacterium, Blautia, Barnesiella, and Sporobacter. In contrast, sodium butyrate reduced microbial diversity while enriching several Clostridia-associated taxa. Discriminant analysis identified distinct marker taxa in the ileum and cecum. In the ileum, sodium butyrate showed a broader range of discriminant taxa, whereas in the cecum most discriminant markers belonged to the class Clostridia. These findings demonstrate that galactooligosaccharides and sodium butyrate differentially modulate microbial communities in the ileum and cecum, highlighting the distinct effects of prebiotic and postbiotic in ovo interventions on gut microbiota composition.