|Byrd Ii, James - Allen|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2004
Publication Date: 1/20/2005
Citation: Woodward, C.L., Kwon, Y.M., Kubena, L.F., Byrd II, J.A., Moore, R.W., Nisbet, D.J., Ricke, S.C. 2005. Reduction of Salmonella enterica serovar enteritidis colonization and invasion by an alfalfa diet during molt in leghorn hens. Poultry Science. 84:185-193.
Interpretive Summary: Salmonella is a food borne bacteria that lives in the gut of chickens and other animals causing an estimated 4 million people in the United States get sick from Salmonella each year. One group of bacteria called Salmonella enteritidis cause about 25% of these illnesses. The SE can get into 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; basically, the hens have a period of rest. 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. Since it is often economically advantageous to add a second productive egg-laying cycle, producers often induce a molt. Feed withdrawal and a reduction in the length of time the hens receive light is the primary method used in the layer industry. Unfortunately, the stress associated with feed withdrawal may cause an increase in the number of hens that become infected with SE and thus increase the risk of human illness from SE contaminated eggs. In the present study, laying hens experimentally infected with SE and fed an alfalfa diet reduced the number of hens testing positive for SE, when compared with hens force molted by feed withdrawal. This is important because the results of this study suggest that an alfalfa diet 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: The standard method for molting to stimulate multiple egg-laying cycles in laying hens is feed deprivation. However, the environmental changes within hens caused by feed deprivation are known to increase susceptibility of the hens to Salmonella Enteritidis (SE) infection. In an effort to develop an alternative method to induce molting without increasing susceptibility to SE, an alfalfa diet was compared with the standard molting method for the level of ovary regression and SE colonization. Hens over 50 wk of age were divided into three treatment groups (12 hens/group); non-molting by normal feeding (NM), molting by feed deprivation (M), and molting by alfalfa diet (A). The individual hens in all treatments were challenged orally with 10**5 cfu of SE on the fourth day after feed changes, and analyzed for ovary weight and SE colonization or invasion in crop contents, cecal contents, liver, spleen, and ovary on the ninth day. In three of the four trials, there was a significant decrease in SE colonization of the crop between the alfalfa diet (A) and the feed deprived molt (M). In most of the 4 trials, there was a significant reduction in SE infected organs in birds fed the alfalfa diet (A) compared to birds undergoing feed deprived molt (M). Most of the trials showed no significant difference in overall SE between A and NM. Therefore, the results of this study suggest that an alfalfa diet has the potential to be used as an alternative method for forced molting, without increasing the incidence of SE in eggs and internal organs.