Review of litter turning during a grow-out as a litter management practice to achieve dry and friable litter in poultry production

Broiler litter moisture and trace metals contribute to the persistence of Salmonella strains that harbor large plasmids carrying siderophores

Broiler litter sampling has proven to be an effective method for determining the Salmonella status of a broiler chicken flock and understanding the ecology of Salmonella prior to harvest. In this study, we investigated the ecology of Salmonella within the litter (n = 224) from two commercial broiler houses in the United States. We employed culture enrichment methods and quantitative polymerase chain reaction to determine the prevalence and load of Salmonella and utilized antimicrobial susceptibility testing and whole-genome sequencing (WGS) to characterize select isolates. Additionally, we applied machine learning algorithms and in vitro experiments to identify environmental selective pressures that may contribute to the persistence of Salmonella in litter. Our findings indicate that the prevalence and abundance of Salmonella in broiler litter are influenced by the downtime between flocks as well as by the flock raised on the litter. A Decision Tree Classifier model developed demonstrated that the moisture in the caked part of litter was the most influential environmental parameter for predicting the prevalence of viable Salmonella. WGS analysis revealed that Typhimurium, Infantis, and Kentucky strains that harbored large self-conjugative plasmids encoding fitness factors for iron siderophore production were the dominant Salmonella population found in litter, and exposure to iron-limiting and copper-enriched culture media affected Salmonella growth. Our results suggest that trace metals may select for siderophores harbored on plasmids, and interventions that reduce litter moisture can potentially curtail the persistence of Salmonella in pre-harvest environments.IMPORTANCEBroiler chicken meat is the most consumed protein worldwide, and global poultry imports are projected to reach 17.5 million tons by 2031. To raise billions of chickens, litter is reused multiple times by the top global producers and exporters of chicken (Brazil and the United States). Chickens are in continuous contact with litter and depend on it for warmth and coprophagy. Consequently, litter serves as a major route for pathogens such as Salmonella to infect chickens, making it crucial to understand the environmental and genetic selective pressures that might explain why certain Salmonella strains persist on broiler farms more than others. In this study, we demonstrated that Salmonella strains that harbored siderophores on large conjugative plasmids persisted in litter and suggested that reducing litter moisture would significantly control Salmonella prevalence. However, a complete eradication of persisting Salmonella strains will require novel, innovative, and multifaceted approaches.

Impact of Growth Rate on the Welfare of Broilers

Selection for the more efficient production of broilers has resulted in rapid growth rates. The aim was to review the existing knowledge on the effect of growth rate on broiler welfare. Genotypes with faster growth rates consistently demonstrate poorer gait scores and increased prevalence of disorders affecting their legs than slower-growing genotypes. Reduced mobility places faster-growing broilers at an increased risk of developing contact dermatitis, as they spend increased durations sitting in contact with litter. Poor walking ability, heavy body weights, and conformational differences such as proportionally larger breast muscle in genotypes with faster growth can impact a bird's ability to walk and navigate the environment, making it difficult to access resources and express natural behaviors. Faster growth has also been associated with poor cardiovascular health, increased susceptibility to heat stress, increased prevalence of mortality, ascites, as well as multiple breast muscle myopathies. Feed restriction, a practice associated with hunger and frustration, may be used to control the growth of broiler breeders, with birds having higher growth potential typically experiencing higher restriction levels. Overall, there is strong evidence that fast growth rates negatively impact welfare, and that slower-growing genotypes show significantly improved welfare. Furthermore, some evidence suggests that even minor reductions in growth rate can lead to welfare improvements.

Effects of cooled perch and different floor types on animal- and management-based welfare indicators, heterophil/lymphocyte ratio, and perching behavior in broiler chickens reared at high ambient temperature

This study aims to analyze the impact of cooled perches and different floor types on broiler chicken welfare under high ambient temperatures. The experiment was designed as a 2 × 3 factorial arrangement with 234 male broiler chickens. They were randomly assigned to two perch treatments (cooled and non-cooled) and three-floor treatments (slatted floor, zeolite, and wood shavings) with three replicates consisting of 13 broiler chickens each. The presence of cooled perches increased (P < 0.0001) the incidence of foot pad dermatitis. The incidence of foot pad dermatitis and hock burn in the treatment of slatted floor was higher (P < 0.0001). The litter moisture concentration was lower in the zeolite treatment at the end of the trial (P < 0.0001). Cooled perch availability in hot weather reduced (P = 0.006) the heterophil-lymphocyte ratio, indicating reduced stress levels. No significant effect of the floor types on stress levels was observed. Notably, an increase in perch-contacting behavior was observed in the presence of cooled perches (3rd, 4th, and 5th weeks P < 0.0001). In brief, cooled perches increased perch-contacting behavior and mitigated stress but increased foot pad dermatitis. Slatted floors negatively impacted footpad and hock health.

Lignite reduces carbon and nitrogen loss from litter in commercial broiler housing

The loss of carbon and nitrogen from broiler litter limits nutrient recycling and is damaging to the environment. This study investigated lignite, a low-rank brown coal, as an amendment to reduce the loss of carbon and nitrogen from broiler litter over 3 consecutive grow-out cycles, November 2021 to May 2022, at a commercially operated farm in Victoria, Australia. Lignite-treated litter contained significantly more carbon and nitrogen, with an increase of 70.1 g/bird and 12.6 g/bird for carbon and nitrogen, respectively. Lignite also reduced aerobic microbial respiration, with a 46.0% reduction in CO2 flux recorded in week 7 of the study, resulting in reduced mass loss. It is expected that this is a key mechanism responsible for nutrient retention in litter following treatment with lignite. Furthermore, lignite treatment lowered litter moisture content by 7, 6 and 3 percentage points for grow-out 1, 2 and 3, respectively. These findings present lignite as a beneficial litter amendment for increasing the nutrient value of waste and reducing carbon dioxide emissions. The study highlights the potential of lignite to reduce the environmental impact of poultry production and presents an alternative use for lignite as an existing resource.

Effect of different bedding depths of rice hulls on growth performance and carcass traits of White Pekin ducks

Duck meat is recognized as a healthier poultry product that contains higher amounts of unsaturated and essential fatty acids, iron, and excellent amounts of protein. It has been found to possess the ability to reduce low-density lipoprotein cholesterol and subsequently, blood pressure in the human body; and improve the immunity system. The current study investigated the appropriate bedding depths of rice hulls as a preferred bedding material by evaluating the growth performance and carcass traits of White Pekin ducks raised for 42 days. A total of 288 one-day-old White Pekin ducklings were randomly allotted to floor cages with one of four bedding depths at 4 cm, 8 cm, 12 cm, and 16 cm. Ducklings were fed standard duck starter (days 1-21) and finisher (days 22-42) diets. The birds were stocked at a rate of 6 birds/m2 with 6 replicates per treatment. Growth performance evaluation for the body weight, average daily gain, and average daily feed intake were measured to calculate the weekly feed conversion ratio. Breast, leg, and carcass yield were assessed as carcass traits. The muscle color and proximate composition were also analyzed for meat quality. Footpad dermatitis was also evaluated on day 42. Ducks reared on 16 cm bedding depth over the 42 days recorded higher (p < 0.05) body weight, average daily, average daily feed intake, and improved feed conversion ratios compared to other groups. The crude fat in breast meat also lowered (p < 0.05) in ducks reared at 16 cm (1.02%) when compared to ducks raised at 4 cm bedding depth (2.11%). Our results showed improved redness (p < 0.05) when the depth of bedding materials was elevated. Except for the breast meat fat, the dissimilar bedding depths did not affect (p < 0.05) the breast and leg meat composition, footpad dermatitis, and mortality for the current study. In conclusion, this study indicated that the bedding depths would directly or indirectly affect the growth performance and meat color of White Pekin ducks; and the bedding depth of rice hulls at 16 cm improved the growth performance of White Pekin ducks for 42 days.

Welfare of broilers on farm

This Scientific Opinion considers the welfare of domestic fowl (Gallus gallus) related to the production of meat (broilers) and includes the keeping of day-old chicks, broiler breeders, and broiler chickens. Currently used husbandry systems in the EU are described. Overall, 19 highly relevant welfare consequences (WCs) were identified based on severity, duration and frequency of occurrence: 'bone lesions', 'cold stress', 'gastro-enteric disorders', 'group stress', 'handling stress', 'heat stress', 'isolation stress', 'inability to perform comfort behaviour', 'inability to perform exploratory or foraging behaviour', 'inability to avoid unwanted sexual behaviour', 'locomotory disorders', 'prolonged hunger', 'prolonged thirst', 'predation stress', 'restriction of movement', 'resting problems', 'sensory under- and overstimulation', 'soft tissue and integument damage' and 'umbilical disorders'. These WCs and their animal-based measures (ABMs) that can identify them are described in detail. A variety of hazards related to the different husbandry systems were identified as well as ABMs for assessing the different WCs. Measures to prevent or correct the hazards and/or mitigate each of the WCs are listed. Recommendations are provided on quantitative or qualitative criteria to answer specific questions on the welfare of broilers and related to genetic selection, temperature, feed and water restriction, use of cages, light, air quality and mutilations in breeders such as beak trimming, de-toeing and comb dubbing. In addition, minimal requirements (e.g. stocking density, group size, nests, provision of litter, perches and platforms, drinkers and feeders, of covered veranda and outdoor range) for an enclosure for keeping broiler chickens (fast-growing, slower-growing and broiler breeders) are recommended. Finally, 'total mortality', 'wounds', 'carcass condemnation' and 'footpad dermatitis' are proposed as indicators for monitoring at slaughter the welfare of broilers on-farm.

Litter Management Strategies and Their Impact on the Environmental and Respiratory Microbiome Might Influence Health in Poultry

Aerial and respiratory tract-associated bacterial diversity has been scarcely studied in broiler production systems. This study examined the relationship between the environmental air and birds’ respiratory microbiome, considering a longitudinal sampling. Total viable bacteria and coliforms in the air were quantified, and the 16S rRNA gene was sequenced from tracheal and air samples obtained through a novelty protocol. Air results showed a decrease in coliforms over time. However, at week 3, we reported an increase in coliforms (from 143 to 474 CFUc/m3) associated with litter management. Additionally, 16S rRNA gene results indicated a distinctive air microbial community, associated primarily with Bacillota phylum particularly of the Bacilli class (>58%), under all conditions. Tracheal results indicated a predominance of Escherichia coli/Shigella at the beginning of the productive cycle, shifting toward the middle and end of the cycle to Gallibacterium. However, at week 3, the dominance of Escherichia coli/Shigella (>99.5%) associated with litter aeration by tumbling stood out. Tracheal and air samples displayed a statistically different community structure, but shared differentially abundant features through time: Enterococcus, Gallibacterium, and Romboutsia ilealis. These results indicate the impact of production management protocols on the birds’ respiratory system that should be considered a breakpoint in poultry farm health.

Bacterial Detection and Recovery From Poultry Litter

The level of pathogens in poultry litter used for raising broiler chickens is critical to the overall health of a broiler chicken flock and food safety. Therefore, it is imperative that methods used for determining bacterial concentration in litter are accurate and reproducible across studies. In this perspective, we discuss the shortcomings associated with current methods used for bacterial quantification and detection from litter and assess the efficacy of one method for pathogen and commensal (Campylobacter, Salmonella, Escherichia coli, and Enterococcus spp.) recovery. The limit of quantitation and detection for this method differed between pathogens, and the recovery rate (∼138–208%) was higher for Salmonella, E. coli, and Enterococcus compared to Campylobacter (24%). Our results suggest that pathogen recovery from litter is highly variable and pathogen concentrations need to be reported in dry weight before comparisons can be made between studies.

The Prevalence of Integument Injuries and Associated Risk Factors Among Canadian Turkeys

Injurious pecking can cause a wide range of damage and is an important welfare and economic issue in turkey production. Aggressive pecking typically targets the head/neck (HN) area, and feather pecking typically targets the back/tail (BT) area; injuries in these separate areas could be used as a proxy for the level of aggressive and feather pecking in a flock. The objective of this study was to identify risk factors for integument injuries in Canadian turkey flocks. A survey containing a questionnaire about housing and management practices and a scoring guide was distributed to 500 turkey farmers across Canada. The farmer scored pecking injuries in two different body areas (HN and BT) on a 0-2 scale on a subset of birds within each flock. Multivariable logistic regression modeling was used to identify factors associated with the presence of HN and BT injuries. The prevalence of birds with integument injuries ranged widely between the flock subsets (HN = 0-40%, BT = 0-97%), however the mean prevalence was low (HN = 6%, BT = 10%). The presence of injuries for logistic regression was defined as flocks with an injury prevalence greater than the median level of injury prevalence in the dataset (3.3% HN and 6.6% BT). The final logistic regression model for HN injuries contained five variables: flock sex, flock age, number of daily inspections, number of different people during inspections, and picking up birds during inspections (N = 62, pR2 = 0.23, α = 0.05). The final logistic regression model for BT injuries contained six variables: flock sex, flock age, litter depth, litter condition, inspection duration, and use of hospital pens for sick/injured birds (N = 59, pR2 = 0.29, α = 0.05). Flock age, and to a lesser extent, sex was associated with both types of injuries. From a management perspective, aggressive pecking injuries appear to be influenced by variables related to human interaction, namely during inspections. On the other hand, the presence of feather pecking injuries, was associated with litter condition and other management factors like separating sick birds. Future research on injurious pecking in turkeys should focus on these aspects of housing and management to better describe the relationship between the identified variables and the prevalence and severity of these conditions.

An industry survey on litter management and re-use practices of Australian meat chicken growers

Litter management is important when rearing meat chickens because litter conditions can affect production as well as chicken health and wellbeing. An industry survey was conducted to gather information from Australian meat chicken growers and integrators about their litter management practices, providing an opportunity to share their knowledge, experiences and perceptions about litter re-use and litter turning. This information was essential for researchers investigating litter management practices because it provided a better understanding about litter preparation and shed configuration to ensure that representative and timely data could be collected. Eighty-four survey responses were received from all major growing regions across Australia. The survey closely reflected the proportions of conventional and free-range production systems of Australian chicken meat industry, with approximately 21% of survey responses representing free range and 80% representing conventional barn housing. Concerning litter management practices, the survey showed that litter re-use is limited (32% of responses), but litter turning is a widespread practice (89% of responses). Litter turning is used to reduce the occurrence of caked litter and to keep litter ‘working’. Maintaining ‘dry and friable’ litter has been shown to reduce the risk of health issues and allows chickens to display behaviours, such as dustbathing, which are believed to be associated with improved welfare. Comments from the survey indicated that litter turning alone does not achieve dry and friable litter, and that proactive ventilation, heater and drinker management are essential. Growers also explained that litter turning is not without its challenges, and can potentially contribute to spikes of dust, ammonia and/or odour. They also expressed concerns relating to operating machinery in poultry houses, particularly when there is high liveweight density. When growers were asked about litter re-use, several reported that it has benefits in reducing production costs and improving moisture holding capacity, but concerns were also expressed about risks relating to ammonia, litter beetle control and disease transmission. Researchers will be able to use these survey results to gain an insight into practices, perceptions, constraints, and challenges relating to the Australian chicken meat industry and ensure that future research relating to litter management reflects local conditions and practices.