Incidence of Salmonella serovars isolated from commercial animal feed mills in the United States and serovar identification using CRISPR analysis

Microbiome analyses of poultry feeds: Part II. Comparison of different poultry feeds

Within the realm of poultry feed mill operations, the persistent concern over microbial feed quality necessitates the establishment of a robust baseline for enhancing and sustaining the standards of commercial feeds. This dual-phase investigation, comprising Parts I, was previously published, and the current study presented here as Part II aimed to illuminate this baseline using 16S rRNA gene sequencing. In Part II, nine distinct commercial poultry feeds formulated as starters, growers, starter/growers, or supplements, the selected feeds underwent genomic DNA extraction, amplification with custom dual-indexed primers, and subsequent Illumina MiSeq sequencing. Through data analysis in QIIME2-2021.4 and R Studio, the study unveils alpha (Kruskal-Wallis) and beta (ANOSIM) diversity, taxonomic differences (ANCOM), and core microbiomes (core_members), deeming main and pairwise effects statistically significant at p < 0.05 and Q < 0.05. Notably, the investigation identified 30% common core microbial members across the nine feed types, shedding light on potential foodborne poultry pathogens such as Helicobacter and Campylobacter. Probiotic-associated feeds exhibited distinct microbial communities, emphasizing the need to explore their impact on the early poultry gastrointestinal tract (GIT) further.

CRISPR and CRISPR-MVLST reveal conserved spacer distribution and high similarity among Salmonella enterica serovar Infantis genomes from Brazil and other countries

Salmonella enterica serovar Infantis (S. Infantis) is a globally distributed non-typhoid serovar infecting humans and food-producing animals. Considering the zoonotic potential and public health importance of this serovar, strategies to characterizing, monitor and control this pathogen are of great importance. This study aimed to determine the genetic relatedness of 80 Brazilian S. Infantis genomes in comparison to 40 non-Brazilian genomes from 14 countries using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-Multi-Locus Virulence Sequence Typing (CRISPR-MVLST). CRISPR spacers were searched using CRISPR-Cas++ and fimH and sseL alleles using BLAST and MEGA X. Results were analyzed using BioNumerics 7.6 in order to obtain similarity dendrograms. A total of 23 CRISPR1 and 11 CRISPR2 alleles formed by 37 and 26 types of spacers, respectively, were detected. MVLST revealed the presence of five fimH and three sseL alleles. CRISPR's similarity dendrogram showed 32 strain subtypes, with an overall similarity ≥ 78.6. The CRISPR-MVLST similarity dendrogram showed 37 subtypes, with an overall similarity ≥ 79.2. In conclusion, S. Infantis strains isolated from diverse sources in Brazil and other countries presented a high genetic similarity according to CRISPR and CRISPR-MVLST, regardless of their source, year, and/or place of isolation. These results suggest that both methods might be useful for molecular typing S. Infantis strains using WGS data.

Salmonella in eggs and egg-laying chickens: pathways to effective control

Eggs contaminated with Salmonella have been internationally significant sources of human illness for several decades. Most egg-associated illness has been attributed to Salmonella serovar Enteritidis, but a few other serovars (notably S. Heidelberg and S. Typhimurium) are also sometimes implicated. The edible interior contents of eggs typically become contaminated with S. Enteritidis because the pathogen's unique virulence attributes enable it to colonize reproductive tissues in systemically infected laying hens. Other serovars are more commonly associated with surface contamination of eggshells. Both research and field experience have demonstrated that the most effective overall Salmonella control strategy in commercial laying flocks is the application of multiple interventions throughout the egg production cycle. At the preharvest (egg production) level, intervention options of demonstrated efficacy include vaccination and gastrointestinal colonization control via treatments such as prebiotics, probiotics, and bacteriophages, Effective environmental management of housing systems used for commercial laying flocks is also essential for minimizing opportunities for the introduction, transmission, and persistence of Salmonella in laying flocks. At the postharvest (egg processing and handling) level, careful regulation of egg storage temperatures is critical for limiting Salmonella multiplication inside the interior contents.

Thermal inactivation of Salmonella Typhimurium and surrogate Enterococcus faecium in mash broiler feed in a laboratory scale circulated thermal bath

This study compares kinetic parameters of Salmonella and surrogate Enterococcus faecium in mash broiler feed during thermal inactivation. Two-gram samples of mash broiler feed were added into a filtered sample bag and inoculated with nalidixic acid (NaL, 200 ppm) resistant S. Typhimurium or Enterococcus faecium, followed by vacuum-packaging and heating in a circulated thermal water bath at 75°, 85°, and 95°C for 0 to 180 s. Counts of bacterial survival were analyzed on tryptic soy agar and bile esculin agar plus 200 ppm of NaL. Microbial data and thermal kinetic parameters (n = 8, Global-Fit and United States Department of Agriculture [USDA]-Integrated-Predictive-Modeling-Program software) were analyzed by JMP software. Heating mash broiler feed at 75°, 85°, and 95°C decreased (P < 0.05) Salmonella cell counts by >6 log₁₀CFU/g after 180, 60, and 50 s, respectively. Heating E. faecium in feed at 75°, 85°, and 95°C for 180, 120, and 70 s achieved reductions of 3, 6, and >6.5 log₁₀CFU/g, respectively. D-values of linear, Weibull models, and z-value of Salmonella at 75°, 85°, and 95°C were 1.8 to 11.2, 4.2 to 21.8, and 28.6 s, respectively, which were lower (P < 0.05) than those of E. faecium (3.7-18.1, 8.5-34.4, and 34.1 s). Linear with Tail, Linear with Tail and Shoulder, and Weibull with tail equations revealed that E. faecium were more resistant (P < 0.05) to heat than Salmonella as shown by longer "Shoulder-time" (26.5 vs. 16.2 s) and greater "Tail" effect (4.4-4.5 vs. 2.5-2.6 log₁₀CFU/g). Results clearly suggested that E. faecium can be used as a surrogate for Salmonella to validate thermal inactivation during feed manufacture.

Salmonella detection in commercially prepared livestock feed and the raw ingredients and equipment used to manufacture the feed: A systematic review and meta-analysis

Salmonella contamination of livestock feed is a serious veterinary and public health issue. In this study we used a systematic review to assess the prevalence and characterization of Salmonella isolates detected in raw feed components, feed milling equipment and finished feed from 97 studies published from 1955 to 2020 across seven global regions. Eighty-five studies were included in a meta-analyses to estimate the combined prevalence of Salmonella detection and to compare the risk of contamination associated with different sample types. We found the overall combined prevalence estimate of Salmonella detection was 0.14 with a prevalence of 0.18 in raw feed components, 0.09 in finished feed and 0.08 in feed milling equipment. Animal based raw feed components were 3.9 times more likely to be contaminated with Salmonella than plant based raw feed components. Differences between studies accounted for 99 % of the variance in the prevalence estimate for all sample types and there was no effect of region on the prevalence estimates. The combined prevalence of Salmonella detection in raw feed components decreased from 0.25 in 1955 to 0.11 in 2019. The proportion of Salmonella isolates that were resistant to antimicrobials was largest for amikacin (0.20), tetracycline (0.18) streptomycin (0.17), cefotaxime (0.14) and sulfisoxazole (0.11). The prevalence of Salmonella contamination of animal feed varies widely between individual studies and is an ongoing challenge for the commercial feed industry. Control relies on the vigilant monitoring and control of Salmonella in each individual mill.

A comparison of formic acid or monoglycerides to formaldehyde on production efficiency, nutrient absorption, and meat yield and quality of Cobb 700 broilers

After being banned by the European Commission in 2018, the use of formaldehyde as a feed amendment in the United States has come into question. Therefore, this study was conducted to explore alternatives to formaldehyde, such as formic acid and monoglycerides, and their effects on poultry production. In total, 1,728 Cobb 700 broilers were randomly assigned to 96-floor pens on day of hatch (18 birds/pen). Using a randomized complete block design (4 blocks), treatments were assigned to pens with blocking based on location within the barn, with the eastern half of the barn designated for digestibility and the western half designated for production (per experiment: 8 control pens and 10 pens per treatment). All diets were based on a negative control (NC), basal diet. Dietary treatments consisted of: NC, NC + 0.25% formalin (F), NC + 0.25 and 0.50% Amasil NA (AML and AMH; 61% formic acid and 20.5% Na-formate), and NC + SILO Health 104L (SILO; mixture of monoglycerides; 0.5% from 0 to 14 d, 0.4% from 14 to 28 d, and 0.2% from 28 to 42 d). Water and feed were provided ad libitum. Performance data were collected during feed changes on d 0, 14, 28, and 42, with digestibility data collected at d 14 (2 per pen) and carcass quality (6 per pen) assessed at d 46 with a randomly selected group of broilers. A one-way ANOVA followed by Dunnett's multiple comparison, where treatments were evaluated against F were conducted using JMP 14.0 (P ≤ 0.05). Main effect of treatment was significant for performance, nutrient digestibility, and carcass quality. Differences in body weight and ADG were observed from d 14 to d 28, resulting in a trending improvement in lysine digestibility on d 14 and carcass quality on d 46 of birds fed AML and AMH in comparison to those fed F (P < 0.05). Whereas birds fed SILO had reduced digestibility of methionine on d 14 and a decrease in meat quality on d 46 in comparison to those fed F (P < 0.05). Therefore, Amasil NA at 0.25 or 0.50% may be an effective alternative to formaldehyde as a feed amendment for poultry production.