This narrative review with structured literature screening combines comprehensive research on the rapid adoption of object detection computer vision models, particularly “You Only Look Once” (YOLO), used alone or in conjunction with other machine learning models, to advance Precision Poultry Farming (PPF), which refers to the application of data-driven and automated technologies to monitor, manage, and optimize poultry health, welfare, and production efficiency. A literature search across search engines, such as Google Scholar, was used because of its broad interdisciplinary coverage, allowing retrieval of literature spanning animal science, computer vision, and agricultural engineering, which are often indexed across different publications venues, on October 15 2024, which revealed 408 results when searching with search expression “YOLO + broilers + layers” and publications dated from 2015 to October 15, 2024. We removed 200 articles during screening, and 126 articles were excluded after eligibility evaluation, resulting in 82 eligible research papers to be included for this review. The YOLO object detection models have evolved from YOLOv1 to YOLO11 by 2024, progressively improving in model performance, speed, accuracy, and robustness through the refinement of key architectural components, including backbone networks, detection heads, and loss functions. This review highlights how YOLO models have been applied to broiler chickens and laying hens across diverse housing systems to support key tasks such as identification, behavior detection, counting, tracking, health and disease monitoring, flock distribution pattern, and calculating activity index, often in combination with other machine vision models. The analysis shows that it took 4 years to apply YOLO models for the object detection task in poultry since the release of the first version of the YOLO model in 2015. The application of YOLO models in poultry from 2019 to 2021 was very slow and sporadic while it took rapid growth in publications since 2021, led primarily by research groups in China and the USA, and mainly concentrated in journals such as Computers and Electronics in Agriculture (10), Institute of Electrical and Electronics Engineers (IEEE) Conference (10), Poultry Science (9), Animals (6), and AgriEngineering (5). Major opportunities and challenges are identified around deploying these models for reliable, real-time decision support on commercial farms, particularly for animal welfare assessment, disease and wild bird detection, and integration with complementary sensing and analytics frameworks.

Mislaid eggs are management and economic challenges in Cage-free (CF) housing systems, producing about 10-15 % floor eggs, although approximately 40 % of table egg laying hens are now in CF production systems. Ramps may ease the use of nesting boxes by minimizing physical extension to hens, thereby reducing floor eggs, and increasing the number of eggs laid in the nest box. The objective of our study was to develop a deep learning method for monitoring hens’ ramp use and the potential impact of ramp access to the nest box on the number of floor eggs and the number of eggs laid in the nest boxes. A total of 600 Lohmann LSL Lite hens were raised from day 1 to 413 in three identical research rooms (7.3 m L × 6.1 m W × 3 m H) following the Lohmann LSL Lite management guide. Each study room had four nest boxes placed at the four corners of the room. Two nest boxes were provided with ramp access (R), and two nest boxes had no ramp access (NR) in each study room and were replicated among three study rooms. The ramp use was video recorded at 15 frames per second (fps). We trained two You Only Look Once (YOLO) models, YOLOv5u and YOLO11, object detection models for 200 epochs each. A total of 2,000 images were used for training (70 %), validation (20 %), and testing (10 %) for the model. All models achieved a precision, recall, and mean average precision at 0.50 intersection over union (mAP@0.50) of at least 0.94. YOLO11n(nano) achieved the highest precision (0.9940), recall (0.9934), and mAP@0.50 (0.9848). Our best model provides a baseline for automatic ramp use detection with 0.99 precision. Ramp access did not lower the floor egg production statistically (p = 0.5468). Across bird weeks, ramp access (R) and no ramp access (NR) revealed opposite patterns in floor and nest-box egg production. Ramp access generally resulted in significantly higher floor egg production in several weeks (52, 54, 58), but also produced higher nest-box egg counts in other weeks (49, 51, 52, 54, 56, 58), whereas no-ramp access showed more nest-box access in weeks when ramp access floor egg were high (48, 50, 53, 55, 57, 59). Overall, ramp access did not consistently increase or decrease egg laying in either location, but shifted the proportion of eggs between the floor and nest-boxes depending on bird age (week). Future studies are warranted to investigate the effect of ramp use on nesting behavior and floor eggs from egg laying to the end of the laying cycle. Data on floor eggs and nest box eggs with ramp access to the nest box from commercial aviary systems, as well as the CF system, also need to be compared.

Animal manure is a desirable fertilizer because of its rich nitrogen, but it also contains a large and diverse reservoir of antimicrobial resistance (AMR) genes (ARGs). To reduce this AMR reservoir, five treatments (passive aeration, forced aeration, static or anaerobic incubations, autoclaving) were assessed for their impact on the poultry litter resistome. Bacterial DNA was extracted from the litter and the qPCR-estimated copy number of 16S rrs, class1 integrons (intI1) and associated resistance genes (aadA, sul1). Then, 16S amplicon metagenomic sequencing was used to determine community diversity and composition. Depending on incubation conditions, class 1 integrons and their associated ARGs were reduced by 0.5 to 1.0 Log10/g poultry litter. Only autoclaving reduced integrons and associated AMR genes by three Log10. Changes in AMR abundance reflected fluctuations in litter bacteriome composition at the family, genus, and sequence variant level. There was a negative correlation between class 1 integron and AMR genes, with genera belonging to Actinobacteria, Firmicutes, and Proteobacteria phyla. While these poultry litter treatments failed to reduce AMR abundance, aerobic and anaerobic treatments reduced taxons that contained pathogenic species. The approach to remediating resistance in poultry litter may be more effective if is focused on reducing bacterial pathogens.

High leucine levels and an imbalanced branched-chain amino acid (BCAA) ratio in the diet can trigger BCAA antagonism, negatively affecting chicken growth. The current study investigated how additional valine and isoleucine could mitigate the negative effects of imbalanced BCAA diets in broilers. The control and additional isoleucine groups experienced significantly decreased body weight gain (BWG) and feed efficiency compared to the additional valine and valine with isoleucine groups (P < 0.001). The additional isoleucine group significantly reduced BWG and feed intake (FI) compared to the control group (P < 0.001). The additional isoleucine group had the lowest carcass weight, breast muscle weight, lean and fat weights, bone mineral density and content, tight junction-related gene expression levels, and villus height values among the groups (P < 0.05). The additional isoleucine group had the highest levels of breast muscle BCAA catabolism-related enzyme and gene expression among the groups (P < 0.05). However, the gene expression levels in breast muscle decreased when valine and isoleucine were provided together. In conclusion, adding isoleucine alone to a BCAA-imbalanced diet can further exacerbate the negative effects of BCAA antagonism and deficiency, impairing growth performance unless additional valine is also provided.

The increasing demand for cage-free (CF) poultry farming raises concern regarding air pollutant emissions in these housing systems. Previous studies have indicated that air pollutants such as particulate matter (PM) and ammonia (NH3) pose substantial risks to the health of birds and workers. This study aimed to evaluate the efficacy of electrostatic particle ionization (EPI) technology with different lengths of ion precipitators in reducing air pollutants and investigate the relationship between PM reduction and electricity consumption. Four identical CF rooms were utilized, each accommodating 175 hens of 77 wk of age (WOA). A Latin Square Design method was employed, with 4 treatment lengths: T1 = control (0 m), T2 = 12 ft (3.7 m), T3 = 24 ft (7.3 m), and T4 = 36 ft (11.0 m), where room and WOA are considered as blocking factors. Daily PM concentrations, temperature, and humidity measurements were conducted over 24 h, while NH3 levels, litter moisture content (LMC), and ventilation were measured twice a week in each treatment room. Statistical analysis involved ANOVA, and mean comparisons were performed using the Tukey HSD method with a significance level of P <= 0.05. This study found that the EPI system with longer wires reduced PM2.5 concentrations (P <= 0.01). Treatment T2, T3, and T4 led to reductions in PM2.5 by 12.1%, 19.3%, and 31.7%, respectively, and in small particle concentrations (particle size >0.5 mu m) by 18.0%, 21.1%, and 32.4%, respectively. However, no significant differences were observed for PM10 and large particles (particle size >2.5 mu m) (P < 0.10), though the data suggests potential reductions in PM10 (32.7%) and large particles (33.3%) by the T4 treatment. Similarly, there was no significant impact of treatment on NH3 reduction (P = 0.712), possibly due to low NH3 concentration (<2 ppm) and low LMC (<13%) among treatment rooms. Electricity consumption was significantly related to the length of the EPI system (P <= 0.01), with longer lengths leading to higher consumption rates. Overall, a longer-length EPI corona pipe is recommended for better air pollutant reduction in CF housing. Further research should focus on enhancing EPI technology, assessing cost-effectiveness, and exploring combinations with other PM reduction strategies.

As global demands on the poultry production and welfare both intensify, the precision poultry farming technologies such as computer vision-based cybernetics system is becoming important in addressing the current issues related to animal welfare and production efficiencies. The integration of computer vision technology has become a catalyst for transformative change in precision farming, particularly concerning productivity and welfare. This review paper delineates the central role of computer vision in precision poultry farming, focusing on its applications in non-contact monitoring methods that employ advanced sensors and cameras to enhance farm biosecurity and bird observation without disturbance. We delved into the multifaceted advancements such as the utilization of convolutional neural networks (CNNs) for behavior analysis and health monitoring, evidenced by the high accuracy sorting of eggs and identification of health concerns within target-dense farm environments. The review paper underscores advancements in precision agriculture, including accurate egg weight estimation and egg classification within cage-free systems, paralleling the poultry sector’s evolution towards more ethical farming practices. Moreover, it addresses the progress in poultry growth monitoring and examines case studies of commercial farms, showcasing how these innovations are being practically applied to enhance productivity and animal welfare. Challenges remain, particularly in terms of environmental variability and data annotation for deep learning models. Nevertheless, the review emphasizes the scope for future innovations like voice-controlled robotics and virtual reality applications, which have the potential to enhance poultry farming to new levels of efficiency, humanity, and sustainability. The insights assert that the continued exploration and development in computer vision technologies are not only instrumental for the poultry sector but also offer a blueprint for agricultural enhancement at large.

Perching is one of the essential natural behaviors for avian species. Providing an optimal perching design (e.g., shape, dimension, and materials) for commercial poultry production is critical for maintaining bird health, welfare, and production efficiency. This review paper summarized poultry perching studies and discussed the relationship between perch design, bird welfare, and production efficiency. Providing perches at an early stage may ensure optimum use during adulthood, reduce perching accidents, and lower the risk of floor eggs in cage-free (CF) hen houses. Therefore, a perch space of 15 cm per bird is recommended for the CF hen house. Similarly, rectangular perches are preferred to circular perches as the rectangular perch provides hens with an excellent tendon-locking mechanism to prevent slipping. In addition, perches with softer materials such as polyurethane and rubber coverings are recommended to increase the contact surface on the chicken’s toes. Perching behavior (PB) promotes a musculocutaneous system and reduces the incidences of footpad dermatitis and lesions. Generally, providing perching may reduce aggression and stress in birds and improve welfare and production efficiency. In the case of broilers, it is found that the broiler perches less during the latter stage of their lives because they are comparatively heavier and exhibit a more inactive lifestyle. Studies have investigated the effect of the surface temperature of the perch on broilers’ welfare. Perches with lower temperatures help improve performance and welfare by relieving heat stress and leg issues. Overall, PB is required to improve bird health and welfare.

The welfare of laying hens in conventional caged houses has become an increased public concern, leading primary food chains, restaurants, and grocers in the United States to pledge to source only cage-free (CF) eggs by 2025 or 2030. Cage-free housing systems have been considered as a more humane alternative; however, they still come with certain challenges. One of the primary challenges with CF housing is the poor indoor air quality due to the high levels of ammonia (NH3) and particulate matter (PM). Despite the importance of air quality in animal welfare, most studies have focused on the egg-laying stage, thereby leaving a significant knowledge gap in the pullet phase. Addressing this gap is essential to ensure the well-being of laying hens in CF housing and to help producers and researchers identify effective strategies to mitigate the impact of poor indoor air quality on the bird’s health and welfare. Therefore, the objective of this study was to (a) examine the effect of the pullets’ age on NH3 and PM levels, and (b) find the effect of housing, litter moisture content (LMC), and relative humidity (RH) on air pollutant concentrations. The results show that the PM levels of PM2.5, PM10, and total suspended particles (TSP) increased significantly with the growth of birds from 1 to 16 weeks of age (WOA) (p < 0.01). For instance, PM2.5, PM10, and TSP levels were measured at 0.023 ± 0.003, 0.031 ± 0.004, and 0.058 ± 0.013 mg m−3 in the first week, and these levels increased to 1.44 ± 0.58, 2.723 ± 1.094, and 6.39 ± 2.96 mg m−3, respectively, by 16 WOA. In addition, PM levels measured near the perch were found to be three times higher than other locations inside the rooms (e.g., between the feeder and drinker or near the exhaust fan) (p < 0.01), as perching is one of the primary reasons for dust generation. Furthermore, a significant interaction between the age of the pullets and PM levels was found (p < 0.01), as the litter quality and the behaviors of birds were changing over time. For NH3 levels, average daily concentrations were lower than 1 ppm at 16 WOA for all rooms due to dry litter conditions (i.e., 9–10% LMC). Additionally, RH has been shown to have a significant effect on air pollutant concentration. Overall, the results indicate that the bird’s age significantly affects PM generation and PM variation within the rooms. The variation of PM was directly affected by RH inside the house. Therefore, this research will provide valuable information for both researchers and producers to control air pollutant emissions from the pullet stage in CF housing to ultimately improve the health and welfare of hens.

Cage-free (CF) layer houses tend to have high particulate matter (PM) levels because of bedding/litter floor and the birds’ activities, such as perching, dustbathing, and foraging on it. It has been reported that optimizing bedding management can potentially suppress PM levels in CF houses. The objectives of this study were to (1) test the effect of the top application of new bedding materials (BMs) on PM levels and (2) compare different BM PM reduction efficiencies. Small flake shavings (SFS), large flake shavings (LFS), and aspen wood chips (AWC) were top-dressed on the surface of the original litter (33-week-old litter) evenly in each of the BM treatment rooms at 20% volume of the original litter floor. The initial litter depths in the control, SFS, LFS, and AWC rooms were 4.6 ± 0.6, 4.8 ± 0.8 cm, 4.8 ± 0.8 cm, and 4.6 ± 0.9 cm, respectively. One room was used as a control without adding new BM. The results indicate that the top application of new bedding suppressed PM levels in all treatment rooms (p < 0.01). The PM2.5 reductions in the SFS, AWC, and LFS treatment rooms were 36.5%, 34.6%, and 28.9% greater than in the control room, respectively. The mitigation efficiencies were different between PM sizes. For instance, PM2.5, PM10, and TSP in the SFS room were lower than in the control room by 36.5%, 39.4%, and 38.7%, respectively. For litter quality, the moisture content was 18.0 ± 2.8, 20.0 ± 3.1, 20.6 ± 2.4, and 19.7 ± 4.2% in the control, SFS, LFS, and AWC rooms, respectively. Treatment rooms with 20% new BM had 10% higher litter moisture than the control room. The findings of this study reveal that the top application of new bedding on old litter is a potential strategy for reducing PM generation in CF houses. Further studies are warranted, such as regarding the effect of different ratios of new bedding on PM reduction, cost analysis, and verification tests in commercial CF houses.

Viral respiratory diseases, such as avian influenza, Newcastle disease, infectious bronchitis and infectious laryngotracheitis, have considerable negative economic implications for poultry. Ensuring the virus-free status of premises by environmental sampling after cleaning and disinfection is essential for lifting a quarantine and/or safely restocking the premises following an outbreak. The objectives of this study were to identify optimal sample collection devices and to determine the locations in poultry housing which are best for poultry respiratory virus sample collection. Chickens exposed to infectious bronchitis virus, which was used as a representative virus for enveloped poultry respiratory viruses, were housed in floor-pens in either a curtain-sided wood framed house or a cement block house. Foam swabs, cellulose sponges, polyester swabs, dry cotton gauze and pre-moistened cotton gauze were evaluated for comparative efficiency in recovering viral RNA. Cotton gauze pre-moistened with the viral transport media had the highest sensitivity among the devices (wood-framed house: 78% positive, geometric mean titre [GMT] of 2.6 log(10) 50% egg infectious doses [EID50] equivalents/ml; cement block houses: 55% positive, GMT of 1.7 log(10) EID50 equivalents/ml). Targeting virus deposition sites is also crucial for efficient virus elimination procedures and subsequent testing; therefore, 10 locations within the houses were compared for virus detection. In both housing types, the highest viral RNA loads were recovered from the tops of drinker lines within the pen. Places the chickens could contact directly (e.g., feeder rim) or were contacted by caretaker feet (hallway floor) also yielded higher levels of viral RNA more consistently. These results will facilitate the establishment of efficient environmental sampling procedures for respiratory viruses of poultry.

Antimicrobial resistance spread is a worldwide health challenge, stemming in large part from the ability of microorganisms to share their genetic material through horizontal gene transfer. To address this issue, many countries and international organizations have adopted a One Health approach to curtail the proliferation of antimicrobial-resistant bacteria.

Antimicrobial resistance (AR) spread is a worldwide health challenge, stemming in large part, from the ability of microbes to share their genetic material through horizontal gene transfer (HGT). Overuse and misuse of antibiotics in clinical settings and in food production have been linked to this increased prevalence and spread of AR. Consequently, public health and consumer concerns have resulted in a remarkable recent reduction in antibiotics used for food animal production. This is driven by the assumption that removing this selective pressure will favor the recovery of antibiotic susceptible taxa and will limit AR sharing through HGT, allowing the currently available antibiotic arsenal to be effective for a longer period. In this study we used broiler chicks raised antibiotic-free and Salmonella enterica serovar Heidelberg (SH), as a model food pathogen, to test this hypothesis. Our results show that neonatal broiler chicks challenged with an antibiotic susceptible SH strain and raised without antibiotics carried susceptible and multidrug resistance SH strains 14 days after challenge. SH infection perturbed the microbiota of broiler chicks and gavaged chicks acquired antibiotic resistant SH at a higher rate. We determined that the acquisition of a plasmid from commensal Escherichia coli population conferred multidrug resistance phenotype to SH recipients and carriage of this plasmid increased the fitness of SH under acidic selection pressure. These results suggest that HGT of AR shaped the evolution of SH and that antibiotic use reduction alone is insufficient to limit antibiotic resistance transfer from commensal bacteria to Salmonella . Importance The reported increase in antibiotic resistant bacteria in humans have resulted in a major shift away from antibiotics use in food animal production. This has been driven by the assumption that removing antibiotics will select for antibiotic susceptible bacterial taxa, and this in turn will allow the currently available antibiotic arsenal to be more effective. This shift in practice has highlighted new questions that need to be answered to assess the effectiveness of antibiotic removal in reducing the spread of antibiotic resistance bacteria. This research demonstrates that antibiotic susceptible Salmonella Heidelberg strains can acquire multidrug resistance from commensal bacteria present in the gut of neonatal broiler chicks, even in the absence of antibiotic selection. We demonstrate that exposure to acidic pH drove the horizontal transfer of antimicrobial resistance plasmids and suggests that simply removing antibiotics from food-animal production might not be sufficient to limit the spread of antimicrobial resistance.

The overuse and misuse of antibiotics in clinical settings and in food production have been linked to the increased prevalence and spread of antimicro-bial resistance (AR). Consequently, public health and consumer concerns have resulted in a remarkable reduction in antibiotics used for food animal production. However, there are no data on the effectiveness of antibiotic removal in reducing AR shared through horizontal gene transfer (HGT). In this study, we used neonatal broiler chicks and Salmonella enterica serovar Heidelberg, a model food pathogen, to test if chicks raised antibiotic free harbor transferable AR. We challenged chicks with an antibiotic-susceptible S. Heidelberg strain using various routes of inoculation and determined if S. Heidelberg isolates recovered carried plasmids conferring AR. We used antimicrobial susceptibility testing and whole-genome sequencing (WGS) to show that chicks grown without antibiotics harbored an antimicrobial resistant S. Heidelberg population at 14 days after challenge and chicks challenged orally acquired AR at a higher rate than chicks inoculated via the cloaca. Using 16S rRNA gene sequencing, we found that S. Heidelberg infection perturbed the microbiota of broiler chicks, and we used metagenomics and WGS to confirm that a commensal Escherichia coli population was the main reservoir of an IncI1 plasmid acquired by S. Heidelberg. The carriage of this IncI1 plasmid posed no fitness cost to S. Heidelberg but increased its fitness when exposed to acidic pH in vitro. These results suggest that HGT of plasmids carrying AR shaped the evolution of S. Heidelberg and that an-tibiotic use reduction alone is insufficient to limit antibiotic resistance transfer from commensal bacteria to Salmonella enterica. IMPORTANCE The reported increase in antibiotic-resistant bacteria in humans has resulted in a major shift away from antibiotic use in food animal production. This shift has been driven by the assumption that removing antibiotics will select for anti-biotic susceptible bacterial taxa, which in turn will allow the currently available anti-biotic arsenal to be more effective. This change in practice has highlighted new questions that need to be answered to assess the effectiveness of antibiotic removal in reducing the spread of antibiotic resistance bacteria. This research demonstrates that antibiotic-susceptible Salmonella enterica serovar Heidelberg strains can acquire multidrug resistance from commensal bacteria present in the gut of neonatal broiler chicks, even in the absence of antibiotic selection. We demonstrate that exposure to acidic pH drove the horizontal transfer of antimicrobial resistance plasmids and suggest that simply removing antibiotics from food animal production might not be sufficient to limit the spread of antimicrobial resistance.

Running Title: Commensal bacteria can competitively exclude Salmonella Heidelberg 3 Adelumola Oladeinde, Zaid Abdo, Benjamin Zwirzitz , Reed Woyda, Steven M. 4 Lakin, Maximilian O. Press, Kimberly Cook, Nelson A. Cox, Jesse C. Thomas IV, 5 Torey Looft, Michael J. Rothrock, Gregory Zock, Jodie Plumblee Lawrence, Denice 6 Cudnik, Casey Ritz and Samuel E. Aggrey 7 Authors’ Affiliation 8 U.S. National Poultry Research Center, USDA-ARS, Athens, GA, USA. Department of 9 Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, 10 Colorado, USA. Institute of Food Safety, Food Technology and Veterinary Public 11 Health, University of Veterinary Medicine, Vienna, Austria. Austrian Competence 12 Centre for Feed and Food Quality, Safety, and Innovation FFoQSI GmbH, Tulln, 13 Austria.Phase Genomics Inc, Seattle, WA, 98109, USA. Office of National Programs, 14 USDA-ARS, Beltsville, Maryland, USA. Division of STD Prevention, National Center for 15 HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Center for Disease and Control, 16 Atlanta, Georgia, USA. National Animal Disease Center, USDA-ARS, Ames, IA, 17 USA,Poultry Science Dept, University of Georgia, Athens, GA, USA 18 Corresponding authors* ade.oladeinde@usda.gov; zaid.abdo@colostate.edu 19 ¶ These authors contributed equally to this work. 20

Ammonia (NH3) has been used as a target gas for nuisance complaints to restrict or close poultry operations near encroaching rural development. There are conflicting data on NH3 emissions from broiler production across the United States. The purpose of this research is to compare emission rates from a Georgia broiler operation across seasons and with other geographical areas in the United States. Comparison of seasonal and geographical emission rates showed large seasonal variation in NH3 emissions for eastern U.S. sites but little seasonal variation in the semi-arid region of the United States. Differences in production management practices, ambient temperature, and animal density did not appear to explain differences in emissions between regions; however, the climatic influence of ambient humidity and litter management practices are thought to be key factors in the generation of emissions.

Poultry and eggs provide the most valuable protein for human beings and animals. Currently USA is the world‘s largest broiler chicken producer and 2nd largest egg producer. However, poultry & egg production is facing a number of grand challenges associated with environmental quality and animal health. For instance, poultry workers and animals are faced with the challenge of poor air quality in the poultry houses, especially in winter time when house ventilation is limited. Most studies focused on broiler grow-out houses and layer houses in past years, very limited works have been conducted in commercial broiler breeder‘s houses, where parents produce hatchery eggs of broiler chicks. Animals in breeder houses are similar to cage-free or free-range laying hen houses, where animals produce eggs up to 80 weeks of age and can performance natural behaviors such as dustbathing and foraging freely. The objectives of this study were to monitor the dust and ammonia levels in commercial broiler breeder houses in Georgia (the largest broiler production state in the US) and identify the relationship between air quality and production management. Two identical broiler-breeder houses (350 ft L x 40 ft W x 10 ft H; 10,000 Ross breeders per house at around 35 wk old in early 2019) were monitored in Southern Georgia. Results show that two houses had similar air temperature (21-28 °C), relative humidity (40-80%), ammonia (8-12 ppm), and dust level (0.5-1 mg m-3 - PM2.5 and 1-1.5 mg m-3-PM10). Dust monitored at 0.35 m above floor (bird level) was 50% higher than 1 m above floor because bedding floor was the primary source of airborne dust and animals‘ movement led to the increase of dust levels. Ammonia level in breeder houses were lower than published results for broiler grow-out houses in Georgia (e.g., about 50 ppm) as grow-out houses have different ventilation stages from breeder houses. Besides, the current farm included wood chips in bedding that potentially reduced the moisture accumulation on floor, which inhibited the generation of ammonia from litter. This study generated the information for developing on-farm environmental stewardship and best management practices (BMPs) for commercial broiler breeder farms.

The success of poultry litter reuse in U.S. poultry production can be attributed to the efficient treatment methods used by producers during downtimes (the time lapse between consecutive flocks, during which the broiler house is empty). During this period, reused litter may be decaked, tilled/windrowed, or treated with acid-based amendments to reduce ammonia and bacteria levels. Competitive exclusion, pH, and temperature are proposed factors that influence the level of pathogens and the overall litter microbiome during downtimes. We previously reported on the bacterial genetic factors associated with the fitness of two strains of Salmonella enterica serovar Heidelberg (SH) incubated for 14 d in reused litter. Here, we investigated the physicochemical parameters and the microbiome of the litter correlating with SH abundance during this period. We used 16S ribosomal RNA gene sequencing to determine the litter microbiome and whole genome sequencing to characterize bacteria with competitive exclusion potential against SH. The β diversity of the litter microbiome was significantly affected by the duration of incubation, microcosm, and microcosm plus Heidelberg strain combinations. In addition, β diversity was significantly affected by litter parameters, including NH4 , pH, moisture, water activity, and aluminum. The major phyla observed in the reused litter throughout the 14-d incubation experiment were Firmicutes and Actinobacteria, although their abundance differed by microcosm and time. Amplicon-specific variants homologous to the members of the genera Nocardiopsis and Lentibacillus and the family Bacillaceae_2 were found to significantly correlate with the abundance of Salmonella. A consortium of Bacillus subtilis strains isolated from the litter microcosms reduced the growth of SH in vitro.

Quail (Coturnix japonica) is processed and marketed as fresh meat, with limited shelf life. The objective of this study was to evaluate the efficacy of antimicrobial interventions during slaughter on reducing Salmonella and Campylobacter contamination and to determine the microbiological shelf life of quail during refrigerated (4°C) storage. Three antimicrobials, peracetic acid (400 ppm; PAA), Citrilow (pH 1.2), and Cecure (cetylpyridinium chloride [CPC], 450 ppm), along with a water and no-treatment control were evaluated. Quail carcasses (n = 75) were inoculated with a cocktail of nalidixic acid–resistant Salmonella Typhimurium and gentamicin-resistant Campylobacter coli. After 30 min of attachment time, quail carcasses were submerged in each antimicrobial solution for 20 s with air agitation. Noninoculated quail carcasses (n = 25) were similarly treated, packaged, and stored under refrigeration (4°C). Aerobic plate counts (APC), psychrotroph counts (PC), Enterobacteriaceae counts (ENT), total coliform counts (TCC), and Escherichia coli counts on quail carcasses were determined on 1, 4, 7, and 10 d. Salmonella and Campylobacter populations were determined by plating on Petrifilm APC supplemented with 200-ppm nalidixic acid and Campy Cefex agar supplemented with 200-ppm gentamycin, respectively. No significant reductions in (P > 0.01 log cfu/mL) in APC, PC, ENT, TCC, and E. coli counts were observed on carcasses submerged in water. However, treatments with PAA, Citrilow, and CPC significantly reduced (P ≤ 0.05) Salmonella and Campylobacter coli contamination. Citrilow showed greater (P ≤ 0.05) reduction in Salmonella and Campylobacter population (1.90 and 3.82 log cfu/mL reduction, respectively) to PAA and CPC. Greater (P ≤ 0.05) reductions in APC, PC, ENT, TCC, and E. coli counts (2.22, 1.26, 1.47, 1.52, and 1.59 log cfu/mL, respectively) were obtained with the application of CPC. Application of antimicrobial interventions resulted in a reduction in Campylobacter and Salmonella, APC, PC, and ENT populations after treatments (day 0) and throughout the storage period (day 10). Use of antimicrobial interventions after slaughter can improve the microbiological safety and shelf life of quail.

Before starting a study with many birds, it helps to know the method of chick inoculation. The objective was to compare 3 methods of Salmonella challenge (oral gavage [OR], intracloacal inoculation [IC], and seeder bird [SB]). Day-old broiler chicks (n = 100) were inoculated with 106 colony forming units (CFU) per chick of a marker strain of Salmonella Heidelberg (SH) with each route of inoculation. Chicks (n = 25) inoculated by each route were placed in floor pens on fresh pine shavings litter. For the seeder batch, 5 colonized chicks, each orally gavaged with 106 CFUs, were placed with 20 pen mates. Two weeks after inoculation, 10 birds from each pen and the 5 inoculated seeder birds were euthanized, the ceca were aseptically removed and macerated with a rubber mallet and weighed, and 3 times (w/v) buffered peptone was added and stomached for 60 s. Serial dilutions were made and plated onto Brilliant Green Sulfa plates containing 200 ppm nalidixic acid. Plates were incubated along with the stomached ceca for 24 h at 37°C. If no colonies appeared on the plates, an additional plate was streaked from the preenriched bag and incubated for 24 h at 37°C. In addition to all seeder birds being positive, the number of SH-positive birds out of 20 sampled in each group was 13, 17, and 7 for OR, IC, and SB, respectively. The level of SH per g of ceca and cecal contents was log (SE) 3.0 (0.7), 2.0 (0.4), and 2.6 (0.4) for OR, IC, and SB, respectively. After enrichment, the number of colonized birds out of 20 was 18, 20, and 10 for OR, IC, and SB, respectively. In conclusion, this study suggests that IC is the method to use to ensure most of the challenged birds are colonized. However, if you prefer to have a smaller percentage of the birds colonized with higher levels, then OR might be better.