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.

Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide, with an estimated 1.5 million human infections occurring annually in the United States alone. With chickens being considered the primary reservoir and source of infection in humans, developing effective vaccination strategies is crucial for preventing Campylobacter transmission to humans. This study aimed to examine the immunogenicity and protective efficacy of a multi-antigen subunit vaccine, consisting of C. jejuni outer membrane proteins (OMPs) and cytosine-phosphorothioate-guanine oligodeoxynucleotides (CpG ODN), in layer breeders and its potential to enhance the levels of C. jejuni-specific maternal antibodies in their offspring. Four groups of layer breeders were subcutaneously vaccinated with 200 μg C. jejuni OMPs and 50 μg CpG-ODN, individually or combined, or with PBS as a negative control. C. jejuni shedding and antibody levels were monitored in breeders for up to ten weeks post-vaccination. At the peak of antibody levels (the fourth week post-primary vaccination), fertilized eggs were collected and incubated in a sensitized egg incubator until hatching. Maternally derived antibodies (MDA) were measured in the serum of hatched chicks for five weeks post-hatch. The results revealed that breeders vaccinated with the combination of C. jejuni OMPs and CpG ODN exhibited a significant reduction in C. jejuni shedding by up to 1.37 log₁₀. This group also showed significantly higher serum and egg yolk IgY and IgM levels compared to the non-vaccinated negative control group, and notably, their chicks maintained significantly higher serum IgY, IgM, and IgA levels for five weeks post-hatch compared to the negative control group. Overall, these outcomes suggest that a combination of C. jejuni OMPs and CpG ODN could offer a promising vaccine strategy to reduce Campylobacter colonization in breeders and to boost and sustain high levels of C. jejuni-specific MDA in hatched chicks. Further research is needed to evaluate the protective effects of vaccine-associated MDA against Campylobacter infection in a commercial broiler model.

Laying hens usually have 16 h of light and 8 h of darkness during egg laying, with eggshell formation primarily occurring during darkness when dietary calcium is lacking, leading to bone calcium resorption and osteoporosis. This study examined how interrupting the dark phase affects bone health in 396 Hy-line W36 hens assigned to control (C) or treatment groups (W1 and W2). All hens received 16 h of light and 8 h of darkness daily in different variations of scotophase interruption. Blood samples were taken at weeks 20, 30, 50, and 70, serum calcium was measured during darkness at two timepoints (SRT and END), and bone demineralization markers were examined using enzyme concentrations (TRACP-5b and CTX-I). Across weeks, tibias were CT-scanned for density (mg/cm³) and area (mm²), then used for breakage strength analysis (N) and ash%. No SRT Ca level differences emerged, but C hens had lower END Ca levels compared to W1 and W2 hens across all weeks, while W1 and W2 hens showed no significant differences. C hens displayed higher TRACP-5b and CTX-I concentrations across all weeks compared to W1 and W2 (all p ≤ 0.05). At week 70, C hens had the lowest cortical bone cross-sectional area and mineral density compared to W1 and W2 (all p ≤ 0.05). Tibiotarsi bone breakage strength was lower in C hens compared to W1 and W2. C hens had significantly lower ash% than treatment birds. Interrupting the scotophase period improved overall bone health in Hy-line W36 laying hens.

Laying hens are commonly provided with 16 h of continuous light and 8 h of continuous darkness, with eggshell calcification largely developing during dark hours when dietary calcium is depleted simultaneously with the daily fasting period in laying hens. This phenomenon is thought to be the leading cause of osteoporosis in modern commercial flocks. This trial examined how disrupting the midnight phase affected egg quality in Hy-line W36 hens assigned to control (C) or treatment groups (W1 or W2) from 20 to 70 weeks of age. C hens received 16 h of light and 8 h of dark. W1 hens received 1 h of scotophase interruption, whereas W2 hens received 2 h of scotophase interruption. Across weeks, performance, production, and egg quality measures were measured (p < 0.05). Scotophase interruption displayed a positive effect on the treatment groups in terms of HDEP (week 50: p = 0.028, 0.016; week 70 = 0.031,0.022), damaged eggs (week 50: p = 0.012, 0.021, week 70: p = 0.019, 0.025), eggshell weight (week 30: p = 0.021, 0.027; week 50: p = 0.022, 0.024; week 70; p = 0.018, 0.019), eggshell thickness (week 30: p = 0.017, 0.022; week 50: p = 0.018, 0.031; week 70; p = 0.029, 0.033), ash percent week 30: p = 0.027, 0.021; week 50: p = 0.012, 0.014; week 70; p = 0.031, 0.034), and eggshell strength (week 30: p = 0.025, 0.023; week 50: p = 0.019, 0.021; week 70; p = 0.029, 0.015) in W1 and W2 birds compared to C birds.