Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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“Poster Cases” for the Pitfalls of Niche Market Poultry Production A.A. Bickford, B.R. Charlton, G.L. Cooper, F. Sommer, R. Nordhausen and P. Woolcock California Animal Health and Food Safety Laboratory System Turlock, California INTRODUCTION: In recent years poultry producers have addressed consumer demands for poultry and poultry products that meet special niche market standards. The demands created by these specialty market niches is increasing and more commercial producers are accommodating the prescribed grow-out or egg production standards. In the process they are facing some remarkably different and usually more stringent management practices necessary to avoid calamitous disease problems. Range-rearing of birds can result in increased predation of all types (including human) and a marked increase in infectious diseases spread by fecal-oral transmission. Raising organically grown (“chemical-free”) birds successfully requires the availability of fresh and nutritionally adequate feed and maintenance of outstanding cleanliness and biosecurity with no lapses. Vegetarian rations for laying chickens (with no animal byproducts such as fish, meat, blood or bone meal) must be carefully formulated with knowledge of balance and bioavailability of components in order to avoid nutritional deficiencies. Producers growing for the live markets face two special challenges in maintaining a high level of health in flocks. The first challenge is maintaining strict biosecurity if meat or layer chickens are selected from commercial flocks. If disease agents such as highly pathogenic avian influenza and exotic Newcastle virus (VVND) gain entry to live bird markets they could be readily introduced to flocks via crates, trucks or personnel moving from live markets to the poultry farm. The second challenge is avoidance of management shortcuts such as multi-age broiler grow-out or rearing mixed species (chickens/ducks/game birds) in order to provide a consistent low-volume flow to live markets. These practices were generally discontinued many years ago in the poultry industry due to their propensity to allow persistence of several disease conditions in flocks resulting in unacceptably high mortality rates. If a trend toward growth of niche market continues, diagnostic laboratories will see the return of many of the disease conditions that had all but disappeared with the advent of modern day commercial rearing practices. Some of the problems the laboratory sees in birds raised for niche markets include death due to predator attacks, nutritional diseases, parasitism, fatal cases of coccidiosis, clostridial enteropathies, gangrenous dermatitis and cannibalism. Prevention of these diseases once diagnosed is severely hampered by restrictions on use of parasiticides, coccidiostats and antibiotics in organically grown birds. CCASE REPORTS:Two cases seen over the past few months comprise the basis for this report. Both cases were unique in that they involved Cornish-Cross (broiler-type) chickens grown by small producers for live poultry markets. These birds ranged from 5 to 9 weeks of age and had severe respiratory signs. Riemerella anatipestifer was among several bacteria cultured from the respiratory tract and originally this was the major justification for the case reports. However, further investigation of flock histories indicated that both operations involved multiage grow-out as well as intermingling of avian species including ducks. The problems observed were clearly related to failings frequently associated with efforts to meet the demands of live-bird markets --- thus these cases are presented as “poster cases” for the pitfalls of multiage and multi-species grow-out with relatively little attention to biosecurity and species separation. The most severe case received in August consisted of four Cornish-Cross chickens (2 at 5 weeks of age, 2 at 8 weeks of age) with high mortality (approximately 40%), uneven growth rate and severe respiratory disease. Necrsopy findings included severe mucopurulent conjunctivitis, rhinitis, sinusitis, and tracheitis. Some birds had focal fibrinopurulent to granulomatous pneumonia and all birds had marked hyperplasia of sinus and nasal mucosa. Cultures of various levels of the respiratory tract yielded Hemophilus paragallinarum, Reimerella anatipestifer, Pasteurella gallinarum and Mycoplasma gallisepticum. Virus isolation attempts from trachea were negative but large particles possibly suggesting poxvirus were seen by electron microscopy in the hyperplastic sinus epithelium. An earlier case submitted in June involved 9-week-old Cornish-Cross chickens with respiratory disease and uneven growth rate especially affecting male birds. Necropsy findings included severe tracheitis and chronic airsacculitis with focal lung consolidation. Cultures yielded Mycoplasma gallisepticum, E. coli and Riemerella anatipestifer from tracheas. Virus isolation attempts from tracheas and cecal tonsils were negative. |
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