Effects of a synbiotic as an antibiotic alternative on behavior, production performance, cecal microbial ecology, and jejunal histomorphology of broiler chickens under heat stress

Differential effects of synbiotic delivery route (feed, water, combined) in broilers challenged with Salmonella Infantis

Salmonella enterica subsp. enterica serovar Infantis (S. Infantis) presents a persistent and multi-drug-resistant threat to poultry production, highlighting the need for effective control strategies. This study evaluated the impact of a S. Infantis infection in broiler chickens across various parameters, including organ colonization, gut microbiota, and immune function. We also assessed the mitigation potential of a synbiotic, multispecies feed additive, administered via three routes applicable for the field: feed only, drinking water only, and a combination of both. Our results demonstrated that the combined administration route yielded notably positive effects on several parameters, followed by the drinking-water only administration. This approach resulted in significant improvements in gut microbiota health, characterized by increased levels of beneficial microbes such as Lactobacillus, Ligilactobacillus, and Butyricicoccus, and a decrease in potentially harmful genera from the Proteobacteria phylum. Reduction of S. Infantis load was observed in caecum, ileum, and spleen over time albeit shedding was not influenced. The drinking water-only administration showed a significant reduction of S. Infantis colonization in the caecum on the last sampling day. Immune response analysis indicated no significant differences in serum antibody levels between control and treatment groups. These findings underscore the impact of both combined and drinking water-only synbiotic, multispecies feed additive administration on the gut microbiota and a possible route for reducing S. Infantis in poultry production. The obtained data provide valuable guidance for optimizing synbiotic use in commercial poultry management, enabling enhanced pathogen control and improved gut health.

Different sound exposures causes alterations in stress-related serum indicators, behaviors, and cecal microbiota of green-shell egg-laying chickens under different stocking densities

Sound and stocking density are two common factors which influence the performance and welfare of layers. Accumulated studies have been conducted on the impacts of the two factors on production performance, while knowledge regarding the impacts of the two factors and their interactions on stress-related serum indicators, behaviors, and cecal bacterial communities in laying hens is still limited. A 3 × 3 factorial design with three sound sources (natural sound (NS), instrumental music (IMS), or mixed road noise (MRS)) and three stocking densities (low density (LD), medium density (MD), and high density (HD)) was used in this 24-day experiment, in which 378 30-week-old Xiandao green-shell layers were randomly distributed into nine treatments with six replicates per treatment. At the 3rd, 12th, and 24th experimental day, we evaluated the serum levels of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) and recorded stress-related animal behaviors. At the end of the experiment, 16S rRNA gene amplicon sequencing of the cecal bacterial communities was performed. Our results confirmed that MRS and HD induced significantly elevated serum ACTH and CORT levels, and were correlated with significantly increased feather pecking behavior. IMS and LD were associated with enhanced preening behavior and reduced feather pecking behavior. LD significantly increased the Firmicutes/Bacteriodetes ratio and IMS significantly enriched the beneficial Lactobacillus population. Based on the obtained results we proposed that music exposure and reduced stocking density were helpful in reducing stress and improving cecal bacterial profile, which were beneficial for improving layers' health status and welfare.

Influence of using synbiotics by various routes on Mandarah male chicks: intestinal bacterial counts, gut morphology and histological status

This experiment investigated the influence of different synbiotic processing methods on the intestinal bacterial count, morphology and histological status of developed male Mandarah chicks. Two hundred and ten male Mandarah line chicks aged 1 d were randomized to receive one of 7 chicks. The method and dose for 1-time synbiotics administration to the day-old chicks were as follows: G1: chicks on basal diet received no treatment (control); G2: 0.25 mL synbiotics sprayed; G3: 0.50 mL synbiotics sprayed; G4: 0.25 mL of synbiotics are added to drinking water; G5: 0.50 mL of synbiotics are added to drinking water; G6: 0.25 mL of synbiotics dripped into the mouth; and G7: 0.50 mL of synbiotics dripped into mouth drops. Lactic acid bacteria(LAB) were significantly increased (P<0.0001) compared to the control group and other treated groups and had the maximum values after the use of synbiotics via drinking water (0.25 or 0.50 mL). Furthermore, when comparing the treated birds (G4, G5) with the control birds, the Escherichia coli concentration in the drinking water containing synbiotics was significantly lower. In addition, treated chickens at (G7) showed a higher duodenum, ileum villus height (VH), and VH. - Ileum crypt depth (CD) ratio compared to other groups. In addition, birds treated with 0.50 mL of synbiotics in drinking water (G5) performed better in duodenum, ileum, CD and VH. - CD ratio than the other groups. Meanwhile, intestinal tract length and visceral pH did not differ significantly between groups. It can be concluded that the use of 0.25 mL of synbiotics in drinking water can improve the overall health of birds.

Systematic review on microbiome-related nutritional interventions interfering with the colonization of foodborne pathogens in broiler gut to prevent contamination of poultry meat

This systematic review aimed to compile the available body of knowledge about microbiome-related nutritional interventions contributing to improve the chicken health and having an impact on the reduction of colonization by foodborne pathogens in the gut. Original research articles published between 2012 and 2022 were systematically searched in Scopus and PubMed. A total of 1,948 articles were retrieved and 140 fulfilled the inclusion criteria. Overall, 73 papers described 99 interventions against colonization by Escherichia coli and related organisms; 10 papers described 15 interventions against Campylobacter spp.; 36 papers described 54 interventions against Salmonella; 40 papers described 54 interventions against Clostridium perfringens. A total of 197 microbiome-related interventions were identified as effective against one or more of the listed pathogens and included probiotics (n = 80), prebiotics (n = 23), phytobiotics (n = 25), synbiotics (n = 12), organic acids (n = 12), enzymes (n = 4), essential oils (n = 14) and combination of these (n = 27). The identified interventions were mostly administered in the feed (173/197) or through oral gavage (11/197), in the drinking water (7/197), in ovo (2/197), intra amniotic (2/197), in fresh or reused litter (1/197) or both in the feed and water (1/197). The interventions enhanced the beneficial microbial communities in the broiler gut as Lactic acid bacteria, mostly Lactobacillus spp., or modulated multiple microbial populations. The mechanisms promoting the fighting against colonization by foodborne pathogens included competitive exclusion, production of short chain fatty acids, decrease of gut pH, restoration of the microbiome after dysbiosis events, promotion of a more stable microbial ecology, expression of genes improving the integrity of intestinal mucosa, enhancing of mucin production and improvement of host immune response. All the studies extracted from the literature described in vivo trials but performed on a limited number of animals under experimental settings. Moreover, they detailed the effect of the intervention on the chicken gut without details on further impact on poultry meat safety.

Alternative approaches to therapeutics and subtherapeutics for sustainable poultry production

The world population is growing rapidly and thus its demand for food is growing as well. To meet the demand of the ever-increasing number of consumers, the poultry industry and both of its main sectors-conventional and organic/cage-free farming-are expanding in parallel. Due to increasing demand of poultry products and higher mortality rate of chicks (an average 0.3% increase of mortality over last 5 yr), both conventional and organic poultry farming systems struggle with various issues; animal welfare, environmental sustainability, and antibiotic resistance of the prevailing zoonotic/enteric pathogens are common issues for conventional farming whereas slow growth rate, higher costs, inefficient land use, different diseases of the chicken, and cross-contamination with bacterial pathogens into the final products are the major issues for organic poultry farming. On top of these issues, the use of subtherapeutic antibiotics was recently banned in conventional farming systems and by definition the organic farming system cannot use the antibiotics/synthetic chemicals even for therapeutic use. In conventional farming system, use of therapeutic antibiotics may result in residuals antibiotics in the final products. As a result, sustainable alternatives are in demand to mitigate the prevailing issues for both conventional and organic farming. Potential alternatives may include bacteriophages, vaccination, probiotics, plant-derived prebiotics, and synbiotics. These alternatives have beneficial attributes and shortcomings of their use in both conventional and organic poultry production system. In this review, we'll discuss the scope of these potential alternatives as therapeutics and subtherapeutics in sustainable poultry production and ways to improve their efficacy.

Effects of cumin (Cuminum cyminum L.) essential oil and chronic heat stress on growth performance, carcass characteristics, serum biochemistry, antioxidant enzyme activity, and intestinal microbiology in broiler chickens

This study was conducted on 600 one-day-old male broiler chicks, using a 2 × 6 factorial design (ambient temperature, A x feed additive, F), for a period of 42 days. The chicks assigned to different groups were exposed to thermoneutral (TN, 24 ± 1 °C) and constant heat stress (HT, 36 ± 1 °C) conditions, and were only fed on a basal diet, and a basal diet supplemented with either 100 mg/kg chloramphenicol, 50 IU/kg α-tocopherol, or 200, 400, and 600 mg/kg of cumin essential oil (CEO). The results showed that heat stress adversely affected performance and carcass characteristics, and increased both the mortality rate and footpad lesions. Moreover, constant chronic heat stress showed negative effects on serum biochemistry and the intestinal microbiota, increased antioxidant activity in both the plasma and breast meat, and increased counts of the pathogenic microorganisms in the small intestine. On the other hand, dietary CEO supplementation positively affected these parameters. CEO had a slight effect on performance, carcass characteristics, mortality rate and the incidence of footpad lesions. When compared to the control group, it was determined that CEO generally had a positive effect on lipid peroxidation in the plasma and tissues and decreased antioxidant enzyme activity. Furthermore, CEO positively affected serum biochemistry and counts of beneficial microorganisms in the small intestine.