During the past decade, the number of cases of gastroenteritis due to Salmonella subspecies enterica serovar Enteritidis (SE) infections has increased markedly in the United States. SE is invasive in poultry and therefore has the potential to contaminate eggs by transovarian transmission following colonization of the intestinal tract. Periodic clusters of contaminated eggs produced by laying hens may be related to stress incurred from specific management practices such as molting. Feed withdrawal has been the primary method used in the layer industry to induce molting and stimulate multiple egg-laying cycles in hens. However, the stress associated with feed withdrawal increases SE colonization, decreases fermentation in the gut, and increases SE organ invasion. Ideally, a molting approach is needed by the poultry industry that is as easy as simple feed deprivation but avoids the disruption of the protective microflora in the gastrointestinal tract and promotion of physiological stress to the bird during molting.
Research Studies Combining a Prebiotic with an Alfalfa Molting Diet to Reduce Hen Stress and Salmonella Invasion
The key to inducing a molt that minimizes pathogen infection and stress of laying hens is to use a low energy molt diet that not only supports optimal egg production but maximizes gut bacterial fermentation activities antagonistic to pathogens.
As animal welfare concerns directed toward feed withdrawal molting increase, alternative molt diets such as the alfalfa diet initially developed by us at Texas A&M University need to be demonstrated to limit SE colonization and bird stress during molting. Although our preproposal USPOULTRY data suggested that 100 percent ad libitum alfalfa diets would potentially limit SE colonization, the detectable SE levels in some birds indicated an inconsistency in the promotion of gut microflora antagonistic to SE.
For this US Poultry & Egg Association project, we examined different physical forms (ground meal versus crumble) of our alfalfa molting diet and either combined with layer ration (90 percent alfalfa + 10 percent layer ration), a prebiotic fructooligosaccharide (FOS) + 100 percent alfalfa or an antimicrobial dietary supplement, experimental chlorate product (ECP) + 100 percent alfalfa.
(1) Alfalfa in all physical forms (meal and crumble) and alfalfa + layer ration stopped egg production and effectively initiated molt induction while birds continued to consume the diet.
(2) Alfalfa + layer ration limited stress in laying hens during molt when measured as behavior and physiological responses.