Poultry, Volume 2, Issue 1 (March 2023) – 11 articles

The purpose of this study was to determine if adding β-mannanase to the diet can improve the quality of storage eggs from laying hens. Lightweight laying hens (36 weeks old), housed in cages with four birds each, were randomly assigned to one of two treatments: control group (diet without additives), or birds fed with 300 g/ton of β-mannanase. The experiment was carried out on a commercial farm (14 thousand birds). The study took 84 days to be completed, and each of its three productive phases lasted 28 days. On the final day of each phase, 125 eggs were randomly collected. The quality of the fresh eggs was assessed, and after each storage interval, the remaining eggs were kept and randomly divided to evaluate their quality (7, 14, 21, 28, 35, and 42 days). Analysis of variance was used to compare means considering differences at 5 and 10%. When compared to the control group, β-mannanase was able to prevent the loss of egg weight and albumen weight during storage (p < 0.05). Yolk color (palette) also improved by 2.5% (p < 0.001), while lightness, red intensity, and yellow intensity all increased in comparison to the control group by 1.9% (p < 0.001), 7.7% (p < 0.001), and 4.10% (p < 0.001). Additionally, compared to the control treatment, β-mannanase was able to lower the yolk pH and TBARS levels by 2.4% (p < 0.001). As a result, adding β-mannanase to laying hen diets is a successful method for enhancing egg quality. Full article

Billions of poultry are slaughtered globally each year to provide protein for a rapidly expanding human population. The large number of birds produced in conventional systems presents animal welfare issues during production, transport, and at the time of slaughter. While we recognise the significance of welfare issues during rearing and transport, this paper highlights the welfare of poultry at the time of slaughter. The impacts of manual handling, inversion and shackling, use of inappropriate electrical stunning parameters, and the use of aversive gas mixtures during controlled atmosphere stunning are some of the evident welfare lapses; if the entrance to the water bath is wet and not isolated, bird welfare can also be compromised during water bath stunning because of pre-stun shocks. We also highlight the use of aversive stunning methods such as carbon dioxide gas at high concentrations, which has been shown to compromise bird welfare. In conclusion, we offer some reflections on ways to improve the welfare of birds during pre-slaughter handling, stunning, and neck cutting. Full article

As previously reported, inflammatory activity initiated by intradermal injection of multiple growing feather (GF)-pulps of a chicken with lipopolysaccharide, and the subsequent periodic sampling of GFs and blood, enables the longitudinal evaluation of in vivo tissue- and systemic-inflammatory activities by ex vivo laboratory analyses. To demonstrate the suitability of this two-window approach to monitor and assess vaccine responses, two groups of chickens were immunized by intramuscular injection of mouse IgG (mIgG), mIgG in alum adjuvant (Alum&mIgG), or PBS-vehicle (Group I and II at 7- and 7- and 11-weeks, respectively). Plasma levels of mIgG-specific antibodies were monitored by ELISA for 28 days post-primary- and secondary-immunizations. To examine the cellular responses, 20 GF-pulps per bird were injected with mIgG on Day-10 or Day-5 post-primary- or -secondary-immunization, respectively. Two GFs were collected before- and at various times (0.25 to 7 days) post-injection for leukocyte population- and cytokine mRNA expression-analyses. The observed primary- and secondary-antibody response profiles were as expected for a T-dependent antigen. Leukocyte- and cytokine-profiles established in GF-pulps revealed temporal, qualitative, and quantitative differences in local naïve, primary, and secondary leukocyte-effector responses to antigen. This study demonstrates the unique opportunity in the avian model to monitor both cell- and antibody-mediated immune responses using minimally invasive techniques. Full article

This study evaluated the effects of a Bacillus direct-fed microbial and microencapsulated calcium butyrate fed individually and in combination, as compared to an antibiotic growth promoter, on growth performance, processing characteristics, intestinal morphology, and intestinal microbiota of Ross 708 broilers reared from 0 to 47 d post-hatch. Dietary treatments included: (1) a negative control with no antimicrobial (NC), (2) a positive control diet containing bacitracin methylene disalicylate (PC), (3) a diet containing a Bacillus direct-fed microbial (CS), (4) a diet containing microencapsulated calcium butyrate (BP), and (5) a diet containing both CS and BP. Treatments were replicated with 10 pens of 20 birds each. From 0 to 15 d post-hatch, the FCR of broilers fed the PC, CS, BP, and CS + BP diets were lower (p < 0.05) than those fed the NC diet, but treatment effects (p > 0.05) were not observed on subsequent performance. BP supplementation improved (p < 0.05) total breast meat weight and yield at processing. Intestinal histology was not influenced (p > 0.05) by the treatment. Analysis of the jejunal microbiota collected at 15 d post-hatch revealed that the genus SMB53 was significantly lower for the CS group, and Sporanaerobacter was lower in the CS and CS + BP groups compared with the NC (p < 0.05). The jejunal microbiota from broilers in the CS + BP group had higher (p < 0.05) alpha and beta diversities compared with broilers fed the NC and CS diets. The results reflected synergistic effects between CS and BP in modulating the jejunal microbiota at 15 d that may have been related to enhanced feed efficiency (i.e., lower FCR) observed during this period. Full article

Erysipelas is a re-emerging disease in different poultry species. Antibiotic treatment is crucial to combat outbreaks in poultry flocks, but only very limited data on susceptibility are available. Recently, the Clinical and Laboratory Standard Institute established standardized guidelines and minimal inhibitory concentration breakpoints for E. rhusiopathiae when using the broth microdilution method. In the present investigation, these guidelines were applied to evaluate the antimicrobial susceptibility of 30 E. rhusiopathiae isolates derived from field outbreaks in poultry flocks towards penicillins, macrolides, lincosamides and fluoroquinolones. All isolates were identified by MALDI-TOF MS. The majority of isolates belonged to two serovars, 1b and 5. More than 40% of the isolates proved resistant to penicillin G, with values ranging from 0.25 to 8 µg/mL. Furthermore, the majority of isolates were found resistant to erythromycin (76.7%; MIC 2–4 µg/mL) and enrofloxacin (60.0%; MIC ≥ 2 µg/mL), altogether limiting treatment options. In contrast, most of the isolates proved susceptible to ampicillin and ceftiofur with MICs ≤ 0.25 µg/mL and ≤2 µg/mL, respectively. A great variety of antimicrobial resistance patterns was found, and multidrug resistance was detected in one-third of the isolates. The presented data are helpful to raise awareness for the antimicrobial resistance of a zoonotic pathogen in context of the One Health concept. Full article

The pH of pre-enrichment media containing feed/ingredients can become acidic during incubation due to bacterial utilization of feed carbohydrates. This decrease in pH can result in cell injury or death, negatively impacting the detection of Salmonella. Our objective was to evaluate a new triple buffered peptone (TBP) against buffered peptone water (BPW) and lactose broth (LB) for the recovery of Salmonella from feed. Liquid cultures of nalidixic acid resistant strains of Salmonella (Enteritidis, Heidelberg, Kentucky or Typhimurium) were added to the pre-enrichment media alone, to pre-enrichment media containing feed or to artificially inoculated feed stored 1 or 7 d to evaluate the effect of the medium on the recovery of Salmonella. Three replicates per treatment were conducted. After incubation at 37 °C for 24 h, the pH of the medium was measured prior to plating onto brilliant green sulfa agar plates supplemented with 200 ppm nalidixic acid (BGS_NA). Plates were incubated and evaluated for presence of typical Salmonella colonies. The experiment was replicated. TBP was observed to exhibit significantly better buffering capacity than BPW or LB. Additionally, TBP was able to recover Salmonella 100% of the time compared to BPW (97.9%) and LB (61.5%). TBP shows promise to maintain neutral pH during pre-enrichment which may allow for a more accurate detection of Salmonella in feed. Full article

There is growing pressure to find a way to eradicate or reduce the levels of foodborne pathogens such as Campylobacter in broiler chickens, whilst limiting the use of antimicrobials. For Campylobacter, there is currently no vaccine and on-farm biosecurity alone is insufficient to prevent colonization of broiler chicken flocks. Dipteran flies are proven carriers of Campylobacter and their entry into broiler houses may contribute to its transmission to broiler chickens. As there is currently no experimental vector transmission model for Campylobacter and chickens, we decided to examine experimentally whether Galleria mellonella could be used as vector to transmit Campylobacter to broiler chickens. More recently, the use of live insect feed has been proposed both for its nutritional qualities and improving bird welfare through the encouragement of natural foraging behaviours and it is unclear any risk this poses in terms of pathogen transmission. In this study, day-old chicks (n = 29) were obtained from a commercial hatchery. At three weeks of age, birds were split into 4 This groups; Group 1 was infected via oral gavage with 10⁶ cells of C. jejuni-M1, Group 2 was fed Galleria mellonella infected with 10⁶ cells of C. jejuni-M1, Group 3 was fed uninfected Galleria mellonella, whilst the remaining group was unchallenged. Cloacal swabs were taken at 2, 4, and 6 days post-infection (dpi) to follow transmission and at 8 dpi birds culled and C. jejuni load quantified in the caeca and liver. At 8 dpi, all birds in both the Campylobacter gavage group and those in the group fed the Campylobacter infected Galleria mellonella were Campylobacter positive, whereas those fed uninfected Galleria mellonella and the control group were all Campylobacter negative. The mean caecal Campylobacter load in the Campylobacter gavage group was 1.7 × 10¹⁰ per gram compared with 8.6 × 10⁹ in the group fed the Campylobacter-infected Galleria mellonella. No liver positives were found in any of the groups. Our findings indicate that feeding broiler chickens with the vector Galleria mellonella infected with C. jejuni-M1 is sufficient to establish colonisation with C. jejuni. We propose that Galleria can be used as an easy and flexible model for vector transmission of foodborne pathogens in chicken. Full article

Avian pathogenic Escherichia coli (APEC) causes colibacillosis in poultry, a leading cause of poultry mortality worldwide. It is crucial to control APEC in broiler breeders as it is vertically transferred to progeny via eggs. However, there is only limited knowledge on the current APEC population in breeders. This study characterized 28 APEC strains isolated from broiler breeders with colibacillosis. The genotypic-virulence characteristics as well as antimicrobial and heavy-metal resistance patterns of the isolates were determined. Results showed that O88 is the most prevalent serogroup and B2 is the predominant phylogenetic group. Among virulence genes, genes for iron acquisition (iroN and iutA), protectins (iss and ompT), and toxin production (hlyF) exhibited the highest prevalence. Further, 93% of the isolates carried at least one antimicrobial resistance gene with highest prevalence for tetracycline gene tetA. Among the isolates, 10.71% exhibited multidrug resistance. All isolates carried at least one heavy-metal resistance gene with the highest prevalence for arsenic gene arsC and the highest resistance towards silver. Our findings provide insight into the characteristics of current APEC populations in broiler breeders in Mississippi. This will help future research on the pathogenesis of APEC and the development of effective prevention and control strategies against APEC in broiler breeders. Full article

Infectious bursal disease virus (IBDV) is a serious poultry pathogen responsible for causing major economic losses to the poultry industry globally. The virus is closely related to several other important viral pathogens of fishes, crabs, and mollusks and evolutionarily related to important viral pathogens of humans. Previously, we demonstrated the inhibition of this virus by the extracts of roots of Withania somnifera Dunal, commonly known as Indian ginseng, both in vitro and in vivo. Furthermore, many studies reported the inhibition of diverse types of viruses by nanoparticles of silver. In the present study, we investigated the inhibitory effect of silver nanoparticles obtained by green synthesized with Indian ginseng extract against IBDV. Conditions for the synthesis of silver nanoparticles were optimized, and the nanoparticles thus obtained (WS AgNPs) were characterized physically. Thereafter, the maximum non-cytotoxic dose of these nanoparticles for treating chicken embryo fibroblasts (CEF) was determined. Treatment of IBDV-infected CEF with the WS AgNPs decreased the infective virus titer by >93%, intracellular viral load by >71%, and virus-induced cytopathy by >51%, demonstrating the strong inhibitory effect of the WS AgNPs against IBDV, and encouraging similar applications against related veterinary and human viruses. Full article

Hatching egg disinfection, as part of the quality assurance system, is a standard procedure in commercial hatcheries. Formaldehyde was and is broadly used but bears high risks for the personnel. In preliminary studies, the spray application of hydrogen peroxide was successfully tested and was chosen to compare its efficacy and impact on hatchability, as well as performance during fattening, and at slaughter, to formaldehyde under field conditions. The trial was set up with hatching eggs from two breeder flocks, running parallelly in three groups (H₂O₂, formaldehyde and non-disinfected control) at four different flock ages (at 38, 39, 56, 57 weeks). No significant differences were noticed in the hatchery, whereas in the rearing period higher 7-day- and total mortalities occurred during trials 1 and 2 in all non-disinfected groups and one formaldehyde-treated group, making an antibiotic treatment necessary. At slaughter, the findings in all groups were comparable. Trials 3 and 4 passed without significant differences between all groups, leading to the conclusion that hatching egg disinfection lowers the risk of infection-related losses. Meanwhile, formaldehyde fumigation and the spraying of hydrogen peroxide produced similar results in all stages. Full article