|Byrd, James - Allen|
|Nisbet, David - Dave|
Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2004
Publication Date: 12/20/2004
Citation: Ricke, S.C., Park, S.Y., Moore, R.W., Kwon, Y.M., Woodward, C.L., Byrd II, J.A., Nisbet, D.J., Kubena, L.F. 2004. Feeding low calcium and zinc molt diets sustains gastrointestinal fermentation and limits Salmonella enterica serovar enteritidis colonization in laying hens. Journal of Food Safety. 24:291-300. Interpretive Summary: It is estimated that about 4 million people in the United States get sick each year from food-borne bacteria called Salmonella, with about 25% of these illnesses caused by one group of bacteria called Salmonella enteritidis (SE). The SE can infect the internal organs, including the ovaries, of laying hens and contaminate eggs that are consumed by humans. Chickens and other avian species undergo a natural process called molting, where feathers are lost, the reproductive tract shrinks, and the hens quit laying eggs. This is followed by the growth of a new set of feathers, an increase in the size of the reproductive tract, and the beginning of a second cycle of egg production. In commercial egg production, the hens do not experience molting until the end of a long laying period and the number of eggs and the quality of the eggs decreases as the hens get older. Compared with non-molted hens, molted hens have increased productivity, better feed efficiency, and decreased death. The most commonly practiced method of molt induction is by withdrawing feed for a period of several days. This is an efficient method; however, this practice has raised concerns over issues related to animal stress during this period and may also cause an increase in the number of hens that become infected with SE. In the present study, laying hens experimentally infected with SE and molted by a molt induction diet containing low calcium and moderate zinc concentration had decreased SE colonization, when compared with hens force molted by withdrawing feed. This is important because the results of this study suggest that feeding of such diets has the potential to be used as an alternative method for forced molting, thus allowing the producers to benefit economically from a second productive egg-laying cycle without increasing the risk of producing SE contaminated eggs that may be consumed by humans.
Technical Abstract: Aims: To determine whether alternative molting diets would minimize S. Enteritidis (SE) colonization in molting hens. Methods and Results: Hens were randomly assigned to four treatment groups of 12 hens either full-fed (non-molt, NM), molted by feed withdrawal (molt, M), a low calcium (LC containing 800 mg calcium), or LC diet supplemented with 110 mg zinc/kg of diet (LC-ZN) in 2 trials. All hens were challenged orally with 10**5 SE on day 4 of experiment. Hen body weight loss was significantly (P < 0.05) increased and ovarian weight was significantly (P < 0.05) decreased in hens fed the LC or LC-ZN diets compared to NM. Cecal lactic acid concentrations were significantly (P < 0.05) increased in hens fed alternative molting diets. M hens exhibited significantly (P < 0.05) more SE positive and SE CFU crop, cecal, and organ colonization than NM, LC, and LC-ZN hens. Conclusions: Alternative molt diets retain sufficient fermentative activity to limit SE colonization. Significance and Impact of the Study: Alternative molting dietary regimes avoid the risk of increasing SE colonization associated with feed withdrawal.