Poultry production has become the fastest-growing sector in global meat supply. However, the intensification of poultry farming has increased the risk of zoonotic transmission of bacterial pathogens such as Salmonella spp., Campylobacter spp., Escherichia coli, Clostridium perfringens, and Listeria monocytogenes. These bacterial agents pose major public health concerns, contributing to millions of human infections annually and substantial economic losses. Historically, antibiotic growth promoters (AGPs) were widely used to mitigate disease burden and improve poultry productivity. Yet, the global shift away from AGPs due to concerns over antimicrobial resistance has spurred interest in antimicrobial alternatives. Among these, probiotics have been explored as a promising preharvest intervention. This review investigates major bacterial foodborne pathogens associated with poultry and evaluates the practical implementation of probiotic-based strategies in modern poultry production systems, with the goal of reducing pathogen load and enhancing overall food safety.

Sperm cryopreservation is of great importance for the poultry industry but still needs to be optimized. The high susceptibility of poultry sperm to cryodamage leads to low fertility rates after cryopreservation. Therefore, the present study aimed at evaluating the effect of including a cryoprotectant, dimethylacetamide (DMA), in the chicken semen freezing extenders at a final concentration of 3%, 6%, or 9% on the post-thawed sperm motility, quality, antioxidant biomarkers, anti-freeze gene expression, and fertilizing ability. Results showed that the total motile sperm, progressivity, and viability were quadratically increased (p < 0.05) in the 6% DMA group. The antioxidant enzyme activity and lipid peroxidation were negatively (p < 0.05) affected by the increase in DMA concentration. Furthermore, some anti-freeze-associated genes such as heat shock protein 70 (HSP70) and ras homolog family member A (RHOA) were linearly and quadratically down-regulated (p < 0.05) with the high concentration of DMA. Finally, the fertility and hatchability rates did not indicate statistical differences between DMA groups. It can be concluded that using the low concentration of 3–6% DMA in the freezing semen extender is preferable to obtain acceptable results in the post-thawed sperm quality and fertility.

Intraepithelial lymphocytes (IEL) reside in the epithelium at the interface between the contents of the intestinal lumen and the sterile environment of the lamina propria. Because of this strategic location, IEL play a crucial role in various immunological processes, ranging from pathogen control to tissue stability. In mice and humans, IEL exhibit high diversity, categorized into induced IEL (conventional CD4 and CD8αβ T cells) and natural IEL (TCRαβCD8αα, TCRγδ, and TCR^neg IEL). In chickens, however, the subpopulations of IEL and their functions in enteric diseases remain unclear. Thus, we conducted this study to investigate the role of IEL populations during necrotic enteritis (NE) in chickens. At 14 days of age, sixty-three Specific-pathogen-free (SPF) birds were randomly assigned to three treatments: Control (sham challenge), Eimeria maxima challenge (EM), and Eimeria maxima + Clostridium Perfringens (C. Perfringens) co-challenge (EM/CP). The EM and EM/CP birds were infected with Eimeria maxima at day 14 of age, and EM/CP birds were additionally orally inoculated with C. perfringens at days 18 and 19 of age. Birds were weighed at days 18, 20, and 26 of age to assess body weight gain (BWG). At 20 days of age (1 day-post C. perfringens infection; dpi), and 26 days of age (7 dpi), 7 birds per treatment were euthanized, and jejunum was harvested for gross lesion scores, IEL isolation, and gene expression. The EM/CP birds exhibited subclinical NE disease, lower BWG and shorter colon length. The Most changes in the IEL populations were observed at 1 dpi. The EM/CP group showed substantial increases in the total number of natural IEL subsets, including TCRαβ⁺CD4^-CD8^-, TCRαβ⁺CD8αα⁺, TCRγδ⁺, TCR^neg and innate CD8α (iCD8α) cells by at least two-fold. However, by 7 dpi, only the number of TCRαβ⁺CD4^-CD8^- and TCRαβ⁺CD8αα⁺ IEL maintained their increase in the EM/CP group. The EM/CP group had significantly higher expression of proinflammatory cytokines (IL-1β and IFN-γ) and Osteopontin (OPN) in the jejunum at 1 dpi. These findings suggest that natural IEL with innate and innate-like functions might play a critical role in the host response during subclinical NE, potentially conferring protection against C. perfringens infection.

At day 21 of age, Ross-308 broilers were orally gavaged with 7.5 × 10⁶ CFU/mL S. Typhimurium (n = 30), and another 30 birds were kept as the control. The body weight of birds was recorded on days 0, 2, 7, and 14 days post-infection (dpi) to calculate body weight gains (BWGs). At each time point, seven birds per group were euthanized for sample collection to acquire IELs and lymphocytes from the ileum and spleen for flow cytometric analysis. A reduction in BWGs of the infected groups compared to the control group was observed only at 2 dpi. Additionally, there were no changes in the expression of IFN-γ, IL-1β, and TNF-α in the ileum at 2 and 7 dpi. The number of IELs increased significantly following Salmonella infection in the ileum at 2 and 7 dpi without any changes in spleen lymphocytes. The increase in the total number of IELs was derived from the elevated numbers of conventional CD8αβ⁺TCRαβ⁺ and natural IEL populations (CD4⁻CD8⁻TCRαβ⁺, CD8αα⁺TCRαβ⁺, TCRγδ⁺, non-T cells (TCR^neg, and iCD8α cells)). The increase in regulatory IELs and the stable expression of proinflammatory cytokine genes during the first week of infection suggests the potential role of IELs in modulating intestinal inflammation.

Intestinal intraepithelial lymphocytes (IEL) comprise a diverse population of cells residing in the epithelium at the interface between the intestinal lumen and the sterile environment of the lamina propria. Because of this anatomical location, IEL are considered critical components of intestinal immune responses. Indeed, IEL are involved in many different immunological processes, ranging from pathogen control to tissue stability. However, despite their critical importance in mucosal immune responses, very little is known about the homeostasis of different IEL subpopulations. The phosphoprotein osteopontin is important for critical physiological processes, including cellular immune responses, such as survival of Th17 cells and homeostasis of NK cells among others. Because of its impact in the immune system, we investigated the role of osteopontin in the homeostasis of IEL. In this study, we report that mice deficient in the expression of osteopontin exhibit reduced numbers of the IEL subpopulations TCRγδ⁺, TCRβ⁺CD4⁺, TCRβ⁺CD4⁺CD8α⁺, and TCRβ⁺CD8αα⁺ cells in comparison with wild-type mice. For some IEL subpopulations, the decrease in cell numbers could be attributed to apoptosis and reduced cell division. Moreover, we show in vitro that exogenous osteopontin stimulates the survival of murine IEL subpopulations and unfractionated IEL derived from human intestines, an effect mediated by CD44, a known osteopontin receptor. We also show that iCD8α IEL but not TCRγδ⁺ IEL, TCRβ⁺ IEL, or intestinal epithelial cells, can promote survival of different IEL populations via osteopontin, indicating an important role for iCD8α cells in the homeostasis of IEL. Key Points Osteopontin promotes homeostasis of mouse and human IEL, mediated by its ligand CD44. iCD8α cells produce osteopontin, which impacts the survival of other IEL. Lack of osteopontin renders mice susceptible to intestinal inflammation.

Sperm cryopreservation is an effective technique for conserving animal genetic diversity and transmitting superior genetic backgrounds, maintained via a non-invasive sampling and collection of huge quantities of sperm. Nevertheless, cryopreservation in avian species is not commercially viable because of the rooster sperm’s susceptibility to damage. This study aims to estimate the impact of dimethylacetamide (DMA) as a cryoprotectant at different levels (3%, 6%, or 9%) on the post-thawed sperm quality, motility, antioxidant-biomarkers, and the expression of anti-freeze related genes. Semen samples were collected twice a week from twelve roosters aged 40 wk, weighing 3400 ± 70 g, and belonging to the Cairo-B2 chicken strain. Fresh semen samples were rapidly appraised, pooled, diluted with two volumes of a basic extender, and divided equally into three groups. The diluted groups were chilled at −20 °C for 7 min, then gently supplemented with 3, 6, or 9% pre-cooled DMA and equilibrated at 5 °C for a further 10 min. Semen pellets were formed by pipetting drops 7 cm above liquid nitrogen (LN₂), which were then kept inside cryovials in the LN₂. Thawing was performed 2 months later by taking 3–4 pellets of the frozen semen into a glass tube and warming it in a water bath for 8 s at 60 °C. The results showed that 3% DMA increased the proportion of total motile sperm, progressivity, viability, and plasma membrane integrity (%) compared to the 6% and 9% DMA groups. The lipid peroxidation and antioxidant enzyme activity were improved in the 3% group. At the same time, some anti-freeze-related genes’ (including ras homolog family member A (RHOA), heat shock protein 70 (HSP70), and small nuclear ribonucleoprotein polypeptide A (SNRPA1)) expressions were upregulated within the 3% DMA group relative to other groups. In conclusion, the 3% DMA group maintained higher post-thawed sperm quality than the other tested groups.