Molting and Salmonella enterica serovar enteritidis infection: the problem and some solutions

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 U.S., 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 hens lose a specific weight is the most prevalent molt strategy in the U.S. However, experimental studies in our laboratory have shown 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- to 1,000-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. All of the solutions provide the producer with many potential solutions to the SE food safety issue and still allow them to recycle their hens.

Emergence of Salmonella epidemics: The problems related to Salmonella enterica serotyp Enteritidis and multiple antibiotic resistance in other major serotypes

“…For example, the most prevalent molt strategy in the USA is feed removal until hens lose a specific weight. However, hens molted in this way were found to be 100-to 1 000-fold more susceptible to infection by S. Enteritidis and excreted significantly higher numbers in their faeces [75]. Several authors reported that the major risk factors were related to disinfection, hygiene barriers and feedmill [37,69].…”

Zinc Oxide as an Effective Mineral for Induced Moulting: Effects on Post Moult Performance of Laying Hens in the Humid Tropics

“…Moulted birds in T 4 showed greater (P<0.01) percentage loss in body weight (15.41%), than those of moulted hens in T 1 (6.03%) and T 2 (7.17%). The percentage weight loss of moulted hens in T 3 (11.93%) was intermediate among the treatments.…”

“…For instance, researchers and public health authorities have identified the method as a significant risk factor for the infection of laying flocks with Salmonella enteritidis; the most important pathogen inside eggs, and known to be transmitted to humans [3]. Many researchers also subscribed that the practice of feed withdrawal is inhumane, and should be handled with upmost caution [4][5][6]. As an alternative to fasting laying hens as a method of inducing moult, several studies have advocated a non-feed withdrawal method, involving the manipulation of dietary minerals like sodium, calcium, iodine and zinc [6][7][8], etc.…”

Experimental infection of Salmonella Enteritidis in quails submitted to forced molting by feed fasting

“…Molting induced by fasting may compromise the immune system of laying birds, making them more vulnerable to infections by various microorganisms (Holt, 2003). Onbaşılar & Erol (2007) asserted that fasting, because it causes severe physiological stress, is the least suitable method of molting in terms of bird welfare.…”

“…The stress caused by fasting increases corticosterone plasma levels (Webster, 2003), and stress hormones are known to have anti-inflammatory properties, which reduce the effectiveness of the immune system in fighting diseases (Golden et al, 2008). Thus, birds with compromised immune system become susceptible to microorganisms, such as Salmonella Enteritidis (Holt, 2003), and may produce contaminated eggs (Gama et al, 2003), compromising public health.…”