Automated enumeration of Eimeria oocysts in feces for rapid coccidiosis monitoring.

Coccidiosis represents a major driver in the economic performance of poultry operations, as coccidia control is expensive, and infections can result in increased feed conversion ratios, uneven growth rates, increased co-morbidities with pathogens such as Salmonella, and mortality within flocks. Shifts in broiler production to antibiotic-free strategies, increased attention on pre-harvest food safety, and growing incidence of anti-coccidial drug resistance has created a need for increased understanding of interventional efficacy and methods of coccidia control. Conventional methods to quantify coccidia oocysts in fecal samples involve manual microscopy processes that are time and labor intensive and subject to operator error, limiting their use as a diagnostic and monitoring tool in animal parasite control. To address the need for a high-throughput, robust, and reliable method to enumerate coccidia oocysts from poultry fecal samples, a novel diagnostic tool was developed. Utilizing the PIPER instrument and MagDrive technology, the diagnostic eliminates the requirement for extensive training and manual counting which currently limits the application of conventional microscopic methods of oocysts per gram (OPG) measurement. Automated microscopy to identify and count oocysts and report OPG simplifies analysis and removes potential sources of operator error. Morphometric analysis on identified oocysts allows for the oocyst counts to be separated into 3 size categories, which were shown to discriminate the 3 most common Eimeria species in commercial broilers, E. acervulina, E. tenella, and E. maxima. For 75% of the samples tested, the counts obtained by the PIPER and hemocytometer methods were within 2-fold of each other. Additionally, the PIPER method showed less variability than the hemocytometer counting method when OPG levels were below 100,000. By automated identification and counting of oocysts from 12 individual fecal samples in less than one hour, this tool could enable routine, noninvasive diagnostic monitoring of coccidia in poultry operations. This approach can generate large, uniform, and accurate data sets that create new opportunities for understanding the epidemiology and economics of coccidia infections and interventional efficacy.

Pilot Study: Colostomy and Urine Collection Protocol for Investigating Potential Inciting Causes of Hen Diuresis Syndrome.

Hen diuresis syndrome has emerged over the past 5 yr as a significant cause of mortality in the U.S. broiler breeder industry. The condition affects hens in production and is characterized by transient muscle weakness in the vent region, transient diuresis, and often urate deposits on the skin below the vent. Affected hens are often seen straining to lay an egg, which suggests oviduct contraction is also impaired. Related hen mortality, often reaching 1% or more a week, is believed to be primarily the result of male aggression of the vent region (Turner et al., "Investigating Causes of Excessive Urate Production in Broiler Breeder Hens Associated with Peritonitis and Cannibalism Mortality," Oral Presentation at The American Association of Avian Pathologists Annual Meeting, p. 139, 2010). The exact association between the cause of mortality and this syndrome is unknown, but it may be the consequence of transient partial to full oviduct prolapse, which predisposes or stimulates cannibalism and aggression. Based on unpublished work done prior to this study (Turner et al., ibid.), the evidence suggests the underlying problem is metabolic. We feel that urine collection and analysis is an essential component to understanding this condition. This study serves as a pilot study for future investigations that attempt to identify the nature and cause of the metabolic disturbance through paired urine and serum collection and analysis. For the purpose of this study, a small sample of 10 affected and 10 unaffected birds was used for sample collection. In order to collect pure urine, the birds were surgically colostomized. Colostomy did prove to be a useful means of collecting urine free of feces, and for the purposes of our study it yielded adequate urine samples for analysis. There were statistically relevant urine values observed. Affected birds had a higher presence of blood in the urine, a lower uric acid excretion rate (mg/hr), higher concentration (mEq/L) of urine Na+, and a lower concentration (mEq/L) of urine K+ than unaffected birds. This pilot study helps to address some of the pitfalls previously associated with colostomy and to determine when collection can begin postoperatively so that we can better understand when and how to begin our sampling in future trials to address the etiology of this condition.

Effects of broiler feed medications on Salmonella.

This pilot analysis was conducted with data from 52 conventional grow-out broiler flocks in a prospective field observational study in the southeastern United States during 2003-2006. Each flock was sampled for Salmonella 1 wk before the end of grow-out, upon arrival at the processing plant, and during processing (prior to and immediately after carcass chilling). The broiler litter was sampled on the day of bird harvest. The grow-out feeding programs, including the medications delivered in feed, were surveyed with questionnaires completed by the broiler managers and feedmill managers. Each detail of the feeding program was tested for statistical association with the frequency of Salmonella in the flock at each sampling point, after accounting for variation in Salmonella frequency between the farms, broiler complexes, and companies. Significant associations were found between Salmonella frequency in the broiler flock pre- and postharvest and the inclusion of feeds containing individual coccidiostats and other antimicrobial growth promoters, days on feed, and total consumption of feeds containing these products, as well as with practices such as a mash feed and a nonmedicated withdrawal feed. The analysis provided testable hypotheses for how broiler feed medications impact the frequency of Salmonella in the flocks.

Factors associated with introduction of infectious laryngotracheitis virus on broiler farms during a localized outbreak.

We analyzed factors involved in the introduction of infectious laryngotracheitis (ILT) virus (ILTV) onto broiler farms during a localized outbreak in an immunologically naive broiler population. The outbreak occurred in the state of Mississippi, United States in 2002-2003. From the responses to a retrospective survey questionnaire administered via personal interviews, 181 farm-level risk factors were defined and analyzed for their association with ILTV introduction using logistic regression. There were 27 case farms (93% of all the infected broiler farms) and two sets of controls: farms matched to the cases by location and those randomly selected among the broiler farms in Mississippi. We found that farm suppliers such as gas company representatives, who are likely to visit other farms, and farm-workers who visit other chicken farms, are likely vehicles of ILTV introduction onto broiler farms. These risks can be greatly reduced by following biosecurity procedures, in particular if farm workers bathe and change footwear prior to entering broiler houses on their own farm. Footbaths for farm visitors can provide a false sense of security during an ILT outbreak when, indeed, other practices such as plastic boots or changing boots are more effective in preventing ILTV transmission. Sharing of equipment used for removal of caked broiler litter between subsequent flocks may also serve as an important vehicle of ILTV transmission. During the 2002-2003 outbreak, shared litter removal equipment was associated with ILTV transmission despite a requirement being put in place for litter decontamination. We also found that tunnel-ventilated broiler houses with inlets toward a neighboring poultry farm are more likely to get infected with ILTV. In addition to this analysis, the data collected provide a good overview of the actual practices and deficiencies of biosecurity undertaken on broiler farms in this part of the United States.

Lighting during grow-out and Salmonella in broiler flocks.

BACKGROUND: Lighting is used during conventional broiler grow-out to modify bird behaviour to reach the goals of production and improve bird welfare. The protocols for lighting intensity vary. In a field study, we evaluated if the lighting practices impact the burden of Salmonella in broiler flocks. METHODS: Conventional grow-out flocks reared in the states of Alabama, Mississippi and Texas, USA in 2003 to 2006 were sampled 1 week before harvest (n = 58) and upon arrival for processing (n = 56) by collecting feathered carcass rinsate, crop and one cecum from each of 30 birds, and during processing by collecting rinsate of 30 carcasses at pre-chilling (n = 56) and post-chilling points (n = 54). Litter samples and drag swabs of litter were collected from the grow-out houses after bird harvest (n = 56). Lighting practices for these flocks were obtained with a questionnaire completed by the growers. Associations between the lighting practices and the burden of Salmonella in the flocks were tested while accounting for variation between the grow-out farms, their production complexes and companies. RESULTS: Longer relative duration of reduced lights during the grow-out period was associated with reduced detection of Salmonella on the exterior of birds 1 week before harvest and on the broiler carcasses at the post-chilling point of processing. In addition, starting reduced lights for > or = 18 hours per day later in the grow-out period was associated with decreased detection of Salmonella on the exterior of broilers arriving for processing and in the post-harvest drag swabs of litter from the grow-out house. CONCLUSIONS: The results of this field study show that lighting practices implemented during broiler rearing can impact the burden of Salmonella in the flock. The underlying mechanisms are likely to be interactive.