|Byrd Ii, James - Allen|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2008
Publication Date: 8/8/2008
Citation: Callaway, T.R., Dowd, S.E., Wolcott, R.D., Sun, Y., McReynolds, J.L., Edrington, T.S., Byrd II, J.A., Anderson, R.C., Krueger, N.A., Nisbet, D.J. 2008. Evaluation of the bacterial diversity in cecal contents of laying hens fed various molting diets using bacterial Tag-Encoded FLX Amplicon Pyrosequencing (bTEFAP). Poultry Science. 88:298-302.
Interpretive Summary: Hens are starved for up to 10-12 d to induce molting which causes egg production to be refreshed. Starved hens are more susceptible to colonization by the pathogen Salmonella than are fed hens. Alfalfa meal has been used as an alternative to starvation because of animal welfare perceptions and feeding alfalfa as a molting diet reduces hens susceptibility to Salmonella colonization. Researchers have also shown in humans that there is a link between the composition of the microbial population of the gut and obesity, thus understanding what is “normal” in the gut is critical to animal health and production efficiency. In our study, we found that bacterial diversity was lowest in hens that were starved and highest in those fed alfalfa meal, with hens receiving a typical ration being intermediate. Salmonella was only isolated from starved hens in this study. Our data coupled with other research suggests that increased diversity of the gut helps to exclude colonization by Salmonella, although other alternative explanations cannot be ruled out.
Technical Abstract: Laying hens are typically induced to molt in order to begin a new egg-laying cycle by withdrawing feed for up to 12-14 d. Fasted hens are more susceptible to colonization and tissue invasion by Salmonella Enteriditis. Much of this increased incidence in fasted hens is thought to be due to changes in the native intestinal microflora. An alternative to feed withdrawal involves feeding alfalfa meal crumble to hens which is indigestible by poultry but provides fermentable substrate to the intestinal population and reduces Salmonella colonization of hens compared to feed withdrawal. The present study was designed to quantify differences in the cecal microbial population of hens (n=12) fed a typical layer ration, undergoing feed withdrawal, or being fed alfalfa crumble, using a novel tag bacterial diversity amplification method (bTEFAP). Bacteroides, Prevotella, and Clostridium were the most common genera isolated from all diets. Only hens undergoing feed withdrawal (n=4) contained Salmonella in their ceca, but no Lactobacillus were isolated from these same hens. Helicobacter and Campylobacter were isolated from both fed groups, but not from the hens undergoing feed withdrawal group. The number of genera present was highest in the alfalfa crumble-fed group and lowest in the feed withdrawal group (78 vs 54 genera, respectively). Overall, the microbial diversity was lowest and Lactobacillius populations were not found in the hens undergoing feed withdrawal which could explain much of these hens sensitivity to colonization by Salmonella.