Author
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Holt, Peter |
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Submitted to: Feedinfo News Service
Publication Type: Trade Journal Publication Acceptance Date: 5/5/2004 Publication Date: 5/5/2004 Citation: Holt, P.S. 2004. Induced molting and its potential impact on infections by salmonella enterica serovar enteritidis infections in laying hens. Feedinfo News Service. Electronic publication Interpretive Summary: Interpretive Summary not required. Technical Abstract: Induced molting is an important economic tool used by the egg industry to recycle an aging layer flock. It is estimated that approximately 70% of the flocks nationwide and almost 100% in California are molted annually. Considering that there are approximately 240 million hens in production in the United States, a rough estimate of the numbers of hens molted every year would be between 144 and 168 million birds, a substantial number. There are many methods to induce molt but feed removal until the hens drop a specific weight is the most prevalent molt strategy in the U.S. However, experimental studies in our laboratory showed that induced molting via feed removal depresses the immune system of hens and exacerbates a Salmonella enteritidis (SE) problem in a simulated flock situation. Molted hens excreted significantly higher SE numbers in the feces, had higher numbers of SE in internal organs, and exhibited more intestinal inflammation. Molted hens were 100 to1000 fold more susceptible to infection by SE and therefore more readily transmitted the organism to uninfected hens in neighboring cages. With the problems identified, solutions were sought and several were successful in ameliorating the SE issue. Antibiotic therapy, vaccination, and use of low energy, low calcium diets to molt hens all dramatically decreased SE shedding during molt. Egg production parameters of one low energy ration, wheat middlings, was shown experimentally and also in commercial operations to parallel or surpass those of feed withdrawal. All of the solutions provide the producer with many potential answers to the SE food safety issue and still allow them to recycle their hens. |