An update on the epidemiology of contact dermatitis in commercial broilers

Potential contaminants and hazards in alternative chicken bedding materials and proposed guidance levels: a review

Bedding material or litter is an important requirement of meat chicken production which can influence bird welfare, health, and food safety. A substantial increase in demand and cost of chicken bedding has stimulated interest in alternative bedding sources worldwide. However, risks arising from the use of alternative bedding materials for raising meat chickens are currently unknown. Organic chemicals, elemental, and biological contaminants, as well as physical and management hazards need to be managed in litter to protect the health of chickens and consequently that of human consumers. This requires access to information on the transfer of contaminants from litter to food to inform risk profiles and assessments to guide litter risk management. In this review, contaminants and hazards of known and potential concern in alternative bedding are described and compared with existing standards for feed. The contaminants considered in this review include organic chemical contaminants (e.g., pesticides), elemental contaminants (e.g., arsenic, cadmium, and lead), biological contaminants (phytotoxins, mycotoxins, and microorganisms), physical hazards, and management hazards. Reference is made to scientific literature for acceptable levels of the above contaminants in chicken feed that can be used for guidance by those involved in selecting and using bedding materials.

Effects of a partially perforated flooring system on animal-based welfare indicators in broiler housing

Alternative flooring designs in broiler housing have been the subject of intensive research. Research comparing different floor types with a focus on animal-based welfare indicators might be of special interest to meet the animal's needs. This case-control study investigated the effect of a partially perforated vs. a littered flooring system on health- and behavior-based welfare indicators of fast-growing Ross 308 broilers. Furthermore, production performance was assessed. The experimental barn was partially (50%) equipped with a perforated floor directly underneath the feeders and water lines accessible by perforated ramps. Conventional wood shavings were used in the control barn, as usual in practice. There were 4 fattening periods (repetitions) of 31 to 32 D performed with 500 animals per barn (final density of 39 kg m-2). Beside the flooring system, management conditions were identical. Health- and behavior-based welfare indicators were assessed weekly. Production performance indicators were measured continuously during animal control. During the avoidance distance test, animals were less fearful on day 21 (P = 0.010) and tended to be less fearful on day 28 (P = 0.083) in the barn with the partially perforated flooring system compared to the littered control barn. More animals around the novel object were also assessed in the barn with the partially perforated flooring system during the novel object test on day 1 (P < 0.001) and a tendency was found on day 28 (P = 0.064). Results showed that the partially perforated flooring system had a positive influence on foot pad dermatitis from day 14 (all P ≤ 0.007) and hock burn on day 28 (P < 0.001). With regard to the production performance, animals showed no differences in final body weight for both floor types. In this study, the partially perforated flooring system had a positive effect on animal health and behavior as indicated by welfare indicators without a reduction in production performance.

Identification of production chain risk factors for slaughterhouse condemnation of broiler chickens'

Slaughterhouse condemnation of broiler chickens results from identification of polymorphic pathological conditions during meat inspection from arrival and on the slaughter line. While conditions that result in condemnation are multifactorial, identification of factors that are common for a number of categories could be valuable for developing strategies to reduce total condemnation. This study aimed to identify those condemnation categories that were most common in batches of broiler chickens and to determine and compare associated risk factors. In the first step, retrospective meat inspection records for 55,918 broiler batches from one large broiler integrator for 2015-2017 were used for association rules analysis. Results identified a network of nine associated condemnation categories: whole carcass condemnation for ascites, abnormal colour, perihepatitis, cellulitis, hard breast, tumours and dead on arrival, and liver only and heart only most often associated with hepatitis and pericarditis, respectively. Secondly, a longitudinal study collected data on 109 explanatory variables from broiler parental flocks to slaughterhouse characteristics between January 2015 and December 2017. Condemnation outcome data were obtained from meat inspection records for 539 broiler batches participating in the study. Parental flock-, rearing farm-, shed- and transport-level risk factors were assessed for each outcome using mixed-effects multivariable Poisson regression including shed and farm as random effects. A Poisson regression tree method was used as the first step to identify variables most relevant for analysis and comparison across the outcomes. No single production factor was associated with all nine of the condemnation outcomes investigated in this study, although some were shared across multiple outcomes: age of parental flock at time of lay, flock-level Campylobacter spp. frequency, broiler chick weight at seven days of age, weight at slaughter, type of broiler removal (i.e. thinning, final depopulation), catcher team, number of birds per transport crate, slaughterhouse shift number, and type of slaughterhouse line. Broiler chickens removed during final depopulation were at greatest risk of condemnation. Condemnation rates for cellulitis and tumours were found to be higher in broilers inspected by night shift at the slaughterhouse. Discovery of an apparent protective effect of a higher number of broilers per transport crate was unexpected. These findings provide information for the broiler industry on production chain factors that might be amenable to targeted intervention to improve future efforts for control of condemnation.

Epidemiology of influences on the performance in broiler flocks--a field study in Germany

To establish which factors influence performance and bird welfare during a fattening period and to identify those factors to be investigated during routine monitoring of farms by veterinary authorities, a questionnaire-based field study was conducted in districts of Lower Saxony, Germany, with the highest density of broiler chickens. Mortality and BW of farms with different stocking densities (≤33, 33.1-39, and >39 kg/m(2)) were investigated. Analyses of 79 farms with 176 stables and 634 fattening periods revealed that flock mortality and BW appeared to be greatly influenced by weather conditions and litter material. In general, it is an advantage to grow broilers under warm weather conditions. However, the longer the fattening period lasts the more important it becomes that the outside weather conditions are not too warm. Therefore, weather conditions should be considered when determining the length of the fattening period, especially before the background of the growing demands of broilers regarding ventilation, absorption of feces by the litter material, and so on. Apart from the length of the fattening period, the weather conditions determine the choice of the litter material, as well. Under cold-humid weather conditions, it is better to use litter material other than wood shavings. In particular in older buildings it is not possible to provide the required conditions, which results in a lower weight gain the longer the fattening period lasts. The study identified differences in the final BW of flocks, which indicate different (farm) management policies. Regardless of the underlying policy, the performance of a fattening period can be improved by optimizing the farm management according to the prevalent conditions. Future routine monitoring, which should be cost effective regarding personnel and finance, should be generally risk based and consider weather conditions, litter material, the age of the building, and the length of the fattening period.

Assessment of frequent litter amendment application on ammonia emission from broilers operations

Litter amendments have been used to control the ammonia (NH3) emission from the broiler litter during the brooding period. One of the commercially available litter amendments, sodium bisulfate, was frequently applied on the litter with two different rates on weekly basis in a laboratory setup and with a single rate on biweekly basis under field conditions. Repeated application ofsodium bisulfate led to significant reduction in NH3 emissions from broilers. The magnitude of NH3 emission reduction increases with the application rate of sodium bisulfate. The reduction rates of cumulative emissions with 366 g/wk-m2 (75 lb/wk-1000 ft) rate (from 14% to 64.5%) were higher than the reduction rate of 183 g/wk-m2 (37.5 lb/wk-1000 ft2) rate (from 0% to 55%) from 28 to 61 days of age. The cumulative NH3 emission was reduced by 51.7% with 244 g/2 wk-m2 (50 lb/2 wk-1000 ft2) rate over a three-flockperiod (8-wk average grow-out per flock) under field production conditions. Sodium bisulfate application showed no significant difference on body weight and feed conversion efficiency. However, footpad quality was significantly improved by sodium bisulfate application. Litter pH and ammonia nitrogen level of the litter were decreased by sodium bisulfate application with both rates. Organic and total nitrogen contents in the litter were higher, whereas less nitrogen was emitted as NH3. The laboratory-scale findings of emission reduction by the additives should be considered to be preliminary if the additives are to be applied under commercial production settings.

IMPLICATIONS

This work demonstrated that frequent litter amendment application can be used to reduce NH3 emissions from broiler houses, with no adverse effect on the animal production performances. The NH3 reduction rates could vary with different application frequencies and rates. Using litter amendment during broiler grow-out to lower NH3 emissions should be applicable to boiler production systems. The results of this study also contribute to the baseline data for improving the national air emissions inventory for livestock and poultry production facilities.

Broiler chickens can benefit from machine learning: support vector machine analysis of observational epidemiological data

Machine-learning algorithms pervade our daily lives. In epidemiology, supervised machine learning has the potential for classification, diagnosis and risk factor identification. Here, we report the use of support vector machine learning to identify the features associated with hock burn on commercial broiler farms, using routinely collected farm management data. These data lend themselves to analysis using machine-learning techniques. Hock burn, dermatitis of the skin over the hock, is an important indicator of broiler health and welfare. Remarkably, this classifier can predict the occurrence of high hock burn prevalence with accuracy of 0.78 on unseen data, as measured by the area under the receiver operating characteristic curve. We also compare the results with those obtained by standard multi-variable logistic regression and suggest that this technique provides new insights into the data. This novel application of a machine-learning algorithm, embedded in poultry management systems could offer significant improvements in broiler health and welfare worldwide.

Factors affecting the prevalence of foot pad dermatitis, hock burn and breast burn in broiler chicken

1. Standardised data on flock husbandry were recorded on 149 broiler farms during the 4 d prior to slaughter. 2. Birds were examined at the slaughterhouse for contact dermatitis lesions. Foot pad dermatitis score (FPDS) and hock burn score (HBS) were measured on five point scales. Carcase rejection data were also collected. 3. The mean percentage of birds in each flock with: moderate or severe foot lesions was 11.1% (range 0-71.5%); moderate or severe hock burn was 1.3% (range 0-33.3%); and, breast burn was 0.02%. 4. A general linear model was developed to examine factors associated with mean flock FPDS. Assuming a linear relationship, within the range of data collected and with all other factors remaining the same, every 1% increase in the proportion of Genotype A birds in the flock was associated with an increase in mean FPDS of 0.003, every one-point increase in litter score was associated with a 0.326 increase in mean FPDS and every one-point increase in flock mean HBS was associated with a 0.411 increase in mean FPDS. Flock mean FPDS was associated with feed supplier and was higher in winter. 5. The general linear model developed for flock mean HBS, found that every one-point increase in mean FPDS increased mean HBS by 0.090, every one-point increase in litter score increased HBS by 0.119 and, every 1% increase in small/emaciated birds decreased mean HBS by 0.333. Reduced HBS was also associated with increased final litter depth, younger slaughter age and an increased percentage of dietary wheat. For every 1% increase in Genotype A birds, a decrease in flock mean HBS of 0.003 would be expected. 6. An effect of hatchery was also identified.

Comparison of an attenuated anticoccidial vaccine and an anticoccidial drug programme in commercial broiler chickens in Italy

A live attenuated anticoccidial vaccine (Paracox) was compared with a nicarbazin-monensin anticoccidial drug shuttle programme in three crops of Italian broilers, comprising a total of 290,405 chickens. All birds received the antibiotic growth promoter avilamycin. No coccidiosis was evident during the trials, but the occurrence of oocysts in the litter demonstrated that a natural challenge was present. Vaccinated birds consistently performed at least as well as those treated with the anticoccidial drug shuttle. The final mean weights of vaccinated birds were significantly greater (P < 0.001) than those of birds treated with anticoccidial drugs, both for females at 36/37 days and males at 56 days. Feed conversion ratios, total mortality including culls, the proportion of rejects at the processing plant, and the moisture content of the litter were not significantly different between the two control methods. Growth curves showed that there was no post-vaccinal growth check in the vaccinated birds and no intolerance of the anticoccidial drug treatment. There was no overall seasonal effect, regardless of treatment, on the performance of the three crops reared from November 1997 to July 1998. These findings suggest that the use of this vaccine is likely to enable the replacement of anticoccidial drug shuttle programmes in broilers reared under conditions similar to those used in these Italian flocks.

Molecular typing of strains of staphylococcus aureus isolated from bone and joint lesions in lame broilers by random amplification of polymorphic DNA

A study was conducted to investigate the relationship between the presence of localized bacterial infection and lameness in broiler fowl (Gallus gallus domesticus). Isolation of bacteria from the proximal femur, proximal tibia, and tibiotarsus from broilers with lameness revealed a probable association between lameness and the presence of Staphlylococcus aureus. Other potential pathogens, including Escherichia coli and DNase-negative staphylococci, were also isolated from sound and lame birds, and their association with pathologies causing lameness was less well defined. After trials with a set of twenty 10-base oligonucleotide primers, a pair of primers giving optimal performance was selected. The S. aureus isolates were typed by random amplification of polymorphic DNA (RAPD) by using the pair of 10-mer primers, and groupings were defined by banding patterns after agarose gel electrophoresis. The putative RAPD groupings may provide a basis for epidemiological studies of S. aureus in broiler production systems.

The efficacy and economic benefits of Paracox, a live attenuated anticoccidial vaccine, in commercial trials with standard broiler chickens in the United Kingdom

The first large-scale broiler trials under modern commercial conditions of Paracox, a live attenuated anticoccidial vaccine administered in the drinking-water, are reported from the United Kingdom. The vaccine, comprising all seven of the species of Eimeria that parasitise the domesticated fowl, was compared with anticoccidial drug shuttles (halofuginone then salinomycin, or nicarbazin then monensin) in nine trials comprising over 936000 chickens, all of which also received the digestive enhancer virginiamycin. No clinical diseases were diagnosed in vaccinated birds in any of the trials. Necrotic enteritis occurred in the medicated controls (anticoccidial drug shuttles) of 2/9 trials and coccidiosis occurred concurrently with one of these outbreaks. Using additional criteria that particularly reflected economic benefits, the vaccine performed overall at least as well as the drug shuttles. The crucial results for vaccinated and medicated birds were: feeding costs (pence per kg liveweight of birds that were processed), 33.9 pence (vaccinated) and 33.7 pence (medicated) (P=0.549); feed conversion ratios, 2.01 (vaccinated) and 1.96 (medicated) (P=0.025); coefficient of variation in mean bird weight before processing, 9.3% (vaccinated) and 9.0% (medicated) (P=0.300); birds found dead, 3.0% (vaccinated) and 3.8% (medicated) (P<0.001); culled birds 4.0% (vaccinated) and 3.8% (medicated) (P=0.483); birds rejected during processing, 1.1% (vaccinated) and 1.2% (medicated) (P=0.271). In addition, the mean total water consumptions per chick were 7.82 L (vaccinated) and 7.76 L (medicated) (P=0.611), whilst the mean percentages of dry matter in the litter were 76.2% (vaccinated) and 75.2% (medicated) (P=0.195). Accumulation of oocysts in the litter of chicks vaccinated at 5 days of age peaked at 21 and 35 days, compared with medicated controls which showed a single higher peak at 35 days. Hence, the use of Paracox vaccine may control clinical coccidiosis in broilers and also achieve performances at least equal to anticoccidial drugs, particularly where drug resistance might result in failure to control disease.