Evaluation of commercially manufactured animal feeds to determine presence of Salmonella, Escherichia coli, and Clostridium perfringens

Unveiling a Listeria monocytogenes Outbreak in a Rabbit Farm: Clinical Manifestation, Antimicrobial Resistance, Genomic Insights and Environmental Investigation

Listeria monocytogenes poses a threat to both human and animal health. This work describes an L. monocytogenes outbreak in a Portuguese rabbit farm, detailing the isolates' clinical manifestations, necropsy findings, and phenotypic and genomic profiles. Clinical signs, exclusively observed in does, included lethargy and reproductive signs. Post-mortem examination of does revealed splenomegaly, hepatomegaly with a reticular pattern, pulmonary congestion, and haemorrhagic lesions in the uterus, with thickening of the uterine wall and purulent greyish exudates. Positive L. monocytogenes samples were identified in fattening and maternity units across different samples, encompassing does and environmental samples. Core-genome Multi Locus Sequence Typing (cgMLST) analysis confirmed the outbreak, with the 16 sequenced isolates (lineage II, CC31, and ST325) clustering within a ≤2 allelic difference (AD) threshold. Antimicrobial susceptibility testing for five antibiotics revealed that 15 out of 19 outbreak isolates were resistant to sulfamethoxazole-trimethoprim (SXT). Concordantly, all SXT-resistant sequenced isolates were found to exclusively harbour a plasmid containing a trimethoprim-resistance gene (dfrD), along with loci linked to resistance to lincosamides (lnuG), macrolides (mphB), and polyether ionophores (NarAB operon). All sequenced outbreak isolates carried the antibiotic resistance-related genes tetM, fosX, lin, norB, lmrB, sul, and mprF. The outbreak cluster comprises isolates from does and the environment, which underscores the ubiquitous presence of L. monocytogenes and emphasizes the importance of biosecurity measures. Despite limited data on listeriosis in rabbit farming, this outbreak reveals its significant impact on animal welfare and production.

Sensitivity of broiler performance, organ weights and plasma constituents to amino acid supplementation and reused litter exposure using ideal protein-formulated rations

Effects of amino acid supplementation to ideal protein (IP) formulated rations were investigated on growth performance, plasma metabolites and organ weights of broilers placed on 100% recycled (reused) litter. Day-old Ross308 male broilers were raised on either clean or reused litter and fed for three weeks on one of five isoenergetic diets, where an IP-based control diet (C) was compared with diets containing threonine (T) or arginine (A) at 25% above requirements, or with 1% supplemented glutamine (G), or with each amino acid added (TAG). Litter and diet treatments did not strongly interact on outcomes. Reused litter placement resulted in greater weight gain, smaller feed conversion ratio and heavier bursal weights (P < 0.05) compared to clean litter placement. Relative to C and T birds, TAG birds reduced weight gain and feed intake (P < 0.05). Plasma uric acid levels in G birds were greater than in C, T and A birds (P < 0.001). Collectively, since the outcomes of placement on reused litter increased performance and the control diet was IP formulated, the absence of increased growth performance in response to amino acid supplementation would be consistent with amino acids tested being excess to requirements.

Buffering Capacity Comparison of Tris Phosphate Carbonate and Buffered Peptone Water Salmonella Pre-Enrichments for Manufactured Feed and Feed Ingredients

Various culture-based methods to detect Salmonella in animal feed have been developed due to the impact of this bacterium on public and animal health. For this project, tris phosphate carbonate (TPC) and buffered peptone water (BPW) buffering capacities were compared as pre-enrichment mediums for the detection of Salmonella in feed ingredients. A total of 269 samples were collected from 6 feed mills and mixed with the pre-enrichments; pH was measured before and after a 24 h incubation. Differences were observed when comparing pH values by sample type; DDGS and poultry by-product meal presented lower initial pH values for TPC and BPW compared to the other samples. For both TPC and BPW, meat and bone meal presented higher final pH values, while soybean meal and peanut meal had lower final pH values. Furthermore, for BPW, post cooling, pellet loadout, and wheat middlings reported lower final pH values. Additionally, most feed ingredients presented significant differences in pH change after 24 h of incubation, except DDGS. From meat and bone meal samples, four Salmonella isolates were recovered and identified: three using BPW and one using TPC. TPC provided greater buffer capacity towards neutral pH compared to BPW, but BPW was more effective at recovering Salmonella.

Biosecurity and Mitigation Strategies to Control Swine Viruses in Feed Ingredients and Complete Feeds

No system nor standardized analytical procedures at commercial laboratories exist to facilitate and accurately measure potential viable virus contamination in feed ingredients and complete feeds globally. As a result, there is high uncertainty of the extent of swine virus contamination in global feed supply chains. Many knowledge gaps need to be addressed to improve our ability to prevent virus contamination and transmission in swine feed. This review summarizes the current state of knowledge involving: (1) the need for biosecurity protocols to identify production, processing, storage, and transportation conditions that may cause virus contamination of feed ingredients and complete feed; (2) challenges of measuring virus inactivation; (3) virus survival in feed ingredients during transportation and storage; (4) minimum infectious doses; (5) differences between using a food safety objective versus a performance objective as potential approaches for risk assessment in swine feed; (6) swine virus inactivation from thermal and irradiation processes, and chemical mitigants in feed ingredients and complete feed; (7) efficacy of virus decontamination strategies in feed mills; (8) benefits of functional ingredients, nutrients, and commercial feed additives in pig diets during a viral health challenge; and (9) considerations for improved risk assessment models of virus contamination in feed supply chains.

Pond water quality and its relation to fish yield and disease occurrence in small-scale aquaculture in arid areas

The study was conducted to determine the associations between water availability and management practises with pond water parameters in small-scale aquaculture in arid areas. Further, the study determined the associations between fish yield and disease incidence with the pond water parameters. We visited 36 tilapia farmers in Dodoma, a semi-arid region in Tanzania, for interviews and measurements of pond water parameters. The interviews collected information about pond type, pond age, water sources, feed type, pond fertilisation, stocking density, and disease incidences. The sources of water for the aquaculture activities were tap water, boreholes, and shallow wells. The source of water and management practises were linked to the parameters of the pond water. On the other hand, the parameters of the pond water were associated with fish yield and the likelihood of disease occurrence. Fish yield had a non-linear relationship with DO, turbidity, salinity, and stocking density and a linear association with pH. To expand aquaculture development in arid areas, efficient use of water through integrated aquaculture is recommended. Training farmers in good management practises and integration is necessary to ensure sustainable aquaculture development in arid areas.

Prevalence and antimicrobial resistance of Escherichia coli and Salmonella spp. in animal feed in Colombia

Objective

To determine the prevalence and antimicrobial resistance of Escherichia coli and Salmonella spp. in animal feed samples collected between 2018 and 2021 in Colombia.

Methods

This was a laboratory-based cross-sectional study using routine data from the program for inspection, surveillance, and control of animal feed at the Colombian Agriculture Institute. Samples of animal feed for swine, poultry, canine, feline, leporine, piscine, and equine species were processed for detection of E. coli and Salmonella spp. using enrichment and selective culture methods. Isolates were tested for antimicrobial susceptibility using an automated microdilution method.

Results

Of 1 748 animal feed samples analyzed, 83 (4.7%) were positive for E. coli and 66 (3.8%) for Salmonella spp. The presence of E. coli and Salmonella spp. was highest in feed for poultry (6.4% and 5.5%) and swine (6.1% and 4.3%). Antimicrobial resistance testing was performed in 27 (33%) E. coli isolates and 26 (39%) Salmonella isolates. Among E. coli, resistance was most frequently observed to ampicillin (44.5%) followed by cefazolin (33.3%), ciprofloxacin (29.6%), ampicillin/sulbactam (26%), and ceftriaxone (11.1%). The highest resistance levels in Salmonella spp. isolates were against cefazolin (7.7%) and piperacillin/tazobactam (7.7%).

Conclusions

This is the first study from Colombia reporting on the prevalence and antimicrobial resistance of E. coli and Salmonella spp. in animal feed samples. Its results establish a baseline over a wide geographical distribution in Colombia. It highlights the need to integrate antimicrobial resistance surveillance in animal feed due to the emergence of resistant bacteria in this important stage of the supply chain.

The role of feeds in the transmission of chicken pathogens in Dodoma Urban District, Tanzania

Chicken production is an important economic activity in Tanzania. Indigenous chickens are kept in rural areas, while exotic breeds are kept in urban areas. Due to their high productivity, exotic breeds are becoming important sources of protein in fast-growing cities. Dodoma is one of the cities growing very fast in Tanzania. As a result, production of layers and broilers has increased dramatically. However, diseases remain the major challenge to chicken production despite the efforts of livestock officers to educate people on good management practices. This has made farmers think that feeds may be the source of pathogens. The study's objectives were thus to identify the major diseases affecting broiler and layer chickens in the Dodoma urban district, as well as the potential role of feeds in pathogen transmission to chickens. A household survey was conducted to identify common diseases affecting chickens in the study area. Thereafter, locally prepared feed samples were collected from twenty shops available in the district to determine the presence of Salmonella and Eimeria parasites. The presence of Eimeria parasites in the feeds was determined by raising day-old chicks in a sterile environment for 3 wk while feeding them the feed samples collected. Fecal samples from the chicks were analyzed for the presence of Eimeria parasites. Salmonella contamination of the feed samples was determined in the laboratory through the culture method. The study found that coccidiosis, Newcastle disease, fowl typhoid, infectious bursal disease, and colibacillosis are the main diseases affecting chickens in the district. After 3 wk of rearing, 3 out of 15 chicks developed coccidiosis. In addition, about 31.1% of the feed samples showed the presence of Salmonella spp. The prevalence of Salmonella was highest in limestone (53.3%), followed by fishmeal (26.7%), and maize bran (13.3%). It has been concluded that feeds are potential carriers of pathogens. To reduce economic losses and the continuous use of drugs in chicken production, health authorities should assess the microbial quality of poultry feeds.

Survival of Escherichia coli in Airborne and Settled Poultry Litter Particles

Airborne Escherichia coli (E. coli) in the poultry environment can migrate inside and outside houses through air movement. The airborne E. coli, after settling on surfaces, could be re-aerosolized or picked up by vectors (e.g., caretakers, rodents, transport trucks) for further transmission. To assess the impacts of airborne E. coli transmission among poultry farms, understanding the survivability of the bacteria is necessary. The objective of this study is to determine the survivability of airborne E. coli, settled E. coli, and E. coli in poultry litter under laboratory environmental conditions (22–28 °C with relative humidity of 54–63%). To determine the survivability of airborne E. coli, an AGI-30 bioaerosol sampler (AGI-30) was used to collect the E. coli at 0 and 20 min after the aerosolization. The half-life time of airborne E. coli was then determined by comparing the number of colony-forming units (CFUs) of the two samplings. To determine the survivability of settled E. coli, four sterile Petri dishes were placed on the chamber floor right after the aerosolization to collect settled E. coli. The Petri dishes were then divided into two groups, with each group being quantified for culturable E. coli concentrations and dust particle weight at 24-h intervals. The survivability of settled E. coli was then determined by comparing the number of viable E. coli per milligram settled dust collected in the Petri dishes in the two groups. The survivability of E. coli in the poultry litter sample (for aerosolization) was also determined. Results show that the half-life time of airborne E. coli was 5.7 ± 1.2 min. The survivability of E. coli in poultry litter and settled E. coli were much longer with the half-life time of 15.9 ± 1.3 h and 9.6 ± 1.6 h, respectively. In addition, the size distribution of airborne E. coli attached to dust particles and the size distribution of airborne dust particles were measured by using an Andersen impactor and a dust concentration monitor (DustTrak). Results show that most airborne E. coli (98.89% of total E. coli) were carried by the dust particles with aerodynamic diameter larger than 2.1 µm. The findings of this study may help better understand the fate of E. coli transmitted through the air and settled on surfaces and evaluate the impact of airborne transmission in poultry production.

Volatile Organic Compound Profiles Associated with Microbial Development in Feedlot Pellets Inoculated with Bacillus amyloliquefaciens H57 Probiotic

Simple Summary

Our study aimed to confirm that the probiotic, Bacillus amyloliquefaciens strain H57 (H57), manufactured into grain-rich stockfeed pellets, would help maintain the various types of odours of the pellets during an extended storage. Pellets treated with (H57) or without (control, C) were stored either at room temperature or at 5 °C over 3 months. The odours were identified in the pellets, stored at 0, 1, 2 and 3 months, by a gas analysis technique. The change of odour types was greatest in the C pellets stored for 3 months at room temperature (CA3) than all other pellet treatments. The odour types of the H57 pellets aged 2 or 3 months at room temperature were similar to that of C pellets aged 1 or 2 months. Nine odour types of microbial origin were related to the change observed in CA3. These odour types have been previously identified in grains spoiled by mould and thus deserve further evaluation as indicators of the types of mould against which H57 protects as a feed inoculum. These results suggest that H57 can help to maintain the odour of stockfeed pellets, by reducing the rate of microbial spoilage during storage.

Abstract

Mould and bacterial contamination releases microbial volatile organic compounds (mVOCs), causing changes in the odour profile of a feed. Bacillus amyloliquefaciens strain H57 (H57) has the potential ability to inhibit microbial growth in animal feeds. This study tested the hypothesis that H57 influences the odour profile of stored feedlot pellets by impeding the production of mVOCs. The emission of volatile organic compounds (VOCs) of un-inoculated pellets and those inoculated with H57, stored either at ambient temperature (mean 22 °C) or at 5 °C, was monitored at 0, 1, 2, and 3 months by gas chromatography–mass spectrometry. Forty VOCs were identified in all the pellet samples analysed, 24 of which were potentially of microbial and 16 of non-microbial origin. A score plot of the principal component analysis (PCA) showed that the VOC profiles of the pellets stored at ambient temperature changed more rapidly over the 3 months than those stored at 5 °C, and that change was greater in the un-inoculated pellets when compared to the inoculated ones. The bi-plot and correlation loading plots of the PCA indicated that the separation of the un-inoculated pellets from the other treatments over the 3 months was primarily due to nine mVOCs. These mVOCs have been previously identified in grains spoiled by fungi, and could be considered potential markers of the types of fungi that H57 can protect pellets against. These data indicate the ability of H57 to maintain the odour profile and freshness of concentrated feed pellets. This protective influence can be detected as early as 3 months into ambient temperature storage.

Role played by the environment in the emergence and spread of antimicrobial resistance (AMR) through the food chain

The role of food-producing environments in the emergence and spread of antimicrobial resistance (AMR) in EU plant-based food production, terrestrial animals (poultry, cattle and pigs) and aquaculture was assessed. Among the various sources and transmission routes identified, fertilisers of faecal origin, irrigation and surface water for plant-based food and water for aquaculture were considered of major importance. For terrestrial animal production, potential sources consist of feed, humans, water, air/dust, soil, wildlife, rodents, arthropods and equipment. Among those, evidence was found for introduction with feed and humans, for the other sources, the importance could not be assessed. Several ARB of highest priority for public health, such as carbapenem or extended-spectrum cephalosporin and/or fluoroquinolone-resistant Enterobacterales (including Salmonella enterica), fluoroquinolone-resistant Campylobacter spp., methicillin-resistant Staphylococcus aureus and glycopeptide-resistant Enterococcus faecium and E. faecalis were identified. Among highest priority ARGs bla CTX -M, bla VIM, bla NDM, bla OXA -48-like, bla OXA -23, mcr, armA, vanA, cfr and optrA were reported. These highest priority bacteria and genes were identified in different sources, at primary and post-harvest level, particularly faeces/manure, soil and water. For all sectors, reducing the occurrence of faecal microbial contamination of fertilisers, water, feed and the production environment and minimising persistence/recycling of ARB within animal production facilities is a priority. Proper implementation of good hygiene practices, biosecurity and food safety management systems is very important. Potential AMR-specific interventions are in the early stages of development. Many data gaps relating to sources and relevance of transmission routes, diversity of ARB and ARGs, effectiveness of mitigation measures were identified. Representative epidemiological and attribution studies on AMR and its effective control in food production environments at EU level, linked to One Health and environmental initiatives, are urgently required.