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Management Issues Addressed by Poultry Vets in Chicago

29 October 2013

Experience with automatic weigh-scales and rising incidence of pendulous crop in turkeys were among the topics covered in the Poultry Management session of the 150th Convention of the American Veterinary Medical Association (AVMA), which was held in Chicago in July 2013.

Use of Automated Bird Scales to Predict Slaughter Weight and Real Time Decision-making in a Vertically Integrated Commercial Turkey Operation

The ability to predict slaughter weights within the turkey industry has been an area of great interest for many years, reported Eric A. Heskett of Elanco. Currently, this process is an invasive and labour-intensive process that does not always yield the desired precision needed in today’s processing environment.

To predict accurately the mean weight of a flock within two per cent of actual weight, with an expected weight of 15.5 pounds and a standard deviation of 2.0 pounds, 543 birds per house would have to be weighed.

The data presented explored the use of 'automated scales' and normal bird activity to predict more  accurately processing weights as precise as 0.1 per cent of actual plant weight with greater than 2,000 birds in a single day being reported.

Dr Heskett added that this data also demonstrated how this method is much less invasive, and operates virtually without any manual processes or human interventions.

Increased Incidence of Pendulous Crops in Commercial Turkeys

A steady increase in pendulous crops has been noted in a commercial turkey operation in the south-eastern United States over the past four years, with a more dramatic increase in 2012, according to David V. Rives of Prestage Farms, Inc. This increase has occurred in all strains and sex/weight categories.

Pendulous crops are a concern due to poor performance of affected birds as well as complications in the processing plant.

A number of factors have been identified as possible contributors to the increase and Dr Rives discussed the changes in various environmental and management parameters over the relevant time period.

A Comparative Assessment of Drop Crop in Commercial Turkeys

The purpose of the study reported by Jocelyn A. Romano of North Carolina State University was to evaluate the affect of drop (pendulous) crop (DC) on different commercial genetic lines.

One thousand strain A and one thousand strain B turkey poults were placed in August 2012 at the North Carolina State University College of Veterinary Medicine Teaching Animal Unit. Strains A and B were identified by differences in toe trimming. All birds were reared using standard commercial practices until they reached approximately 6kg.

Data collected from weekly weights and daily necropsies were used to compare DC and normal birds.

Drop crop was first observed in both strains of birds during week four. Throughout weeks four through nine, DC birds consistently outweighed normal birds by as much as 15 per cent.

In birds with DC, approximately 27 per cent of their bodyweight was composed of crop and crop contents.

Overall, 2.8 per cent of the total flock was affected by drop crop with strain A being more represented than strain B, according to Dr Romano. She added that the pathogenesis of this condition is not fully understood but the potential for significant financial loss is present. 

Comparison of Hatchability Performance and Protection against Marek’s Disease in Broilers Vaccinated with Two in-ovo Vaccination Systems and Two HVT Vaccines

Taylor Barbosa of Zoetis explained that their study aimed to demonstrate the potential differences in hatchability and Marek's Disease protection given by two in-ovo vaccination systems (single-needle and double-needle) and two HVT vaccines.

Hatchability was compared in paired trials (breeder flocks from a single incubator and divided into two equal groups at injection/transfer) and 'week-on week-off' trials (total week production used either one of the injection system).

The Inovoject® System (double-needle) was found to have a numerically higher overall hatch of live than the single-needle system for breeder flocks between 40 and 61 weeks of age.

Inovoject also had higher hatch in 13 out of 22 (59 per cent) of paired trials and higher hatch in 40 out of 55 (73 per cent) of the pairing flocks for the 'week-on week-off' trials.

Additionally, another paired hatchability trial was conducted to test the protection against Marek’s Diseases (MD) challenge.

A single flock of eggs was divided and injected by either in-ovo systems. The groups were sub-divided in half and receive different vaccines (HVT-IBD vector (Vaxxitek, Merial) or a regular HVT (Pfizer Animal Health) vaccine. The study included five different treatments: 1) non-vaccinated controls, 2) single-needle vaccinator with Vaxxitek vaccine, 3) single-needle vaccinator with HVT vaccine, 4) Inovoject with Vaxxitek vaccine and 5) Inovoject with HVT vaccine.

All treatments were commingle in isolator room with 12 birds per treatment (60 birds total). There were 11 replicates of the challenge treatments and two replicates of the non-challenge (controls) treatments. Challenge was done intra-peritoneally with a vMDV (RB1B strain) at three days of age.

Birds vaccinated with the dual-needle device showed greater weight (p≤0.05) than birds vaccinated with the single-needle device at 49 days of age. Protection was determined by the absence of tumors at termination.

The dual-needle system showed significantly higher protection (p≤ 0.05) than the single-needle device. Moreover, there was no difference between the non-vaccinated and the single-needle device groups.

Overall, concluded Barbosa, the dual-needle in-ovo vaccination system demonstrated better efficacy on vaccine application and better protection versus single-needle vaccination method.

Biochemical Evidence for a 'Refeeding Syndrome' in Broiler Breeders at Transfer and its Effect on Mortality and Performance

The modern broiler breeder has to balance a enormous potential for growth and feed conversion with body weight restriction for optimal egg production and fertility.

Daniel Venne of Couvoir Scott ltée explained that restricting bodyweight can limit reserves and favour metabolic changes if fasting occurs especially if the birds are moved from the grower barn to the layer barn.

His paper included presentation of the biochemical analysis of the blood of these hens pre- and post-transportation and showed that phosphorus and AST levels can be used to monitor the effect of fasting and the subsequent re-feeding of these birds.

Dr Venne also discussed management and nutritional supportive treatments.

Effect of Laying Hen Housing on Hen Health: Preliminary Findings

In an effort to determine the effects of laying hen housing systems on all facets of egg production, a coalition of entities sponsored a three-year, two-flock multi-university research project located on a commercial egg laying farm, explained R.M. Fulton of Michigan State University.

Housing consisted of conventional cages, enriched cages and an aviary system. Areas of sustainability evaluated were animal health and well-being, environment, food affordability, food safety, and worker health and safety.

Dr Fulton's presentation focused on animal health and well-being. Each flock was evaluated monthly by veterinarians and causes of mortality in each system, determined by necropsy, was monitored on a routine basis by a trained research-technician.

The aviary system flock had double the mortality of the enriched caged flock and almost four times that of the conventional caged flock. Birds in the aviary system had the most issues related to egg production, in spite of having the lowest number of eggs produced per hen housed.

Aviary birds had the most skeletal issues and the most deaths due to hypocalcaemia.

Egg yolk peritonitis was greatest in conventional caged birds while enriched cage birds had the least amount. Bumblefoot was observed only in the aviary system housed birds.

These findings were preliminary and it will be interesting to see if they are repeated in the second flock, added Dr Fulton.

Field Observations to Determine if Broiler Foot Pad Lesions Correlate with Gait Scores – a Field Trial

A retrospective study was conducted to evaluate the relationship between broiler foot pad lesions and gait scores between 42 and 48 days of age, reported Suzanne Dougherty of Keystone Foods LLC.

The significance of foot pad score evaluation during animal welfare audits as a key performance indicator (KPI) has been debated. The Keystone group assumed that, if foot pad lesion score were meaningful, there would be a correlation between it and gait score, a more widely accepted animal welfare KPI.

Ten birds from every house, on every farm, during every flock, in three broiler complexes were evaluated for both gait score and foot pad lesions between 42 and 48 days of age for one year.

A correlation was run between foot pad lesion scores and gait scores and the results were given during this presentation.

Further Reading

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October 2013

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