|Solis DE Los Santos, Fausto - UNIVERSITY OF ARKANSAS|
|Farnell, Morgan - TEXAS A&M UNIVERSITY|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2006
Publication Date: April 1, 2007
Citation: Huff, G.R., Huff, W.E., Rath, N.C., Solis De Los Santos, F., Farnell, M.B., Donoghue, A.M. 2007. Influence of hen age on the response of turkey poults to cold stress, Escherichia coli challenge, and treatment with a yeast extract antibiotic alternative. Poultry Science. 86:(4):636-642. Interpretive Summary: Two trials were conducted to test the effects of a yeast extract antibiotic alternative for its ability to protect turkey poults from the effects of cold stress and infection with bacteria. In the first trial the product was effective at increasing body weights during the first week. Cold stress and bacterial challenge at 7 days of age decreased body weights and feed conversion efficiency and the yeast extract protected the turkeys from these changes. In the second trial, first week body weights were also improved, but there was no effect of cold stress and bacterial challenge on body weights and feed conversion and thus no protection due to the yeast extract. While experimental conditions were identical in these two trials, it was determined that the turkeys in the first trial were hatched from eggs obtained from young hens in their second week of lay, while the turkeys in the second trial were hatched from eggs obtained from older hens in their eighth week of lay. As these were the only apparent differences between the two trials, it is suspected that the age and laying experience of the hen may affect the stress response of her progeny and may be an important variable to control during study of the effects of stress on poultry.
Technical Abstract: 1. Two duplicated battery trials were conducted to evaluate a standardized Yeast Extract feed supplement, (Alphamune™) in a cold stress-Escherichia coli challenge of one-week-old turkeys. Trial 1 used day-old male Hybrid Converter poults from 33-week-old hens in their 2nd week of lay. Trial 2 used male poults of the same line from 40 week-old hens in their 8th week of lay. 2. In both trials poults were fed a standard unmedicated turkey starter diet or the same diet with either 1 lb/ton or 2 lb/ton Alphamune™. 3. Challenged birds were exposed to intermittent cold stress (12-16C) during weeks 1-3 and respiratory E. coli challenge at 1 week of age. Unchallenged controls were neither stressed nor inoculated. 4. In both trials, pre-challenge (week 1) body weight was increased by Alphamune™ supplementation. In Trial 1, challenged, control fed birds had significantly decreased week 3 body weight and feed conversion efficiency (FC) whereas in Trial 2, these parameters were not affected. In Trial 1, week 3 body weight and FC of challenged poults were protected by both levels of supplementation. In Trial 2, challenge had no effect on control-fed birds, however Alphamune™ decreased body weights of challenged birds. 5. In Trial 1, total leukocyte numbers (WBC) were decreased by challenge of control-fed birds only, and there was no effect of challenge on the heterophil/lymphocyte (H/L) ratio. In Trial 2, the WBC was decreased and the H/L ratio was increased in challenged control-fed birds. Supplementation with Alphamune™ resulted in increased basal H/L ratios of unchallenged birds, but there was no further increase due to challenge of the supplemented birds. 6. Percent mortality and air sacculitis scores were not affected by challenge in Trial 1, however in Trial 2 mortality was increased by challenge of control-fed birds and those fed 1 lb/ton Alphamune™. 7. These results suggest that poults from very young breeder hens may have a differential response to stress compared to those from older hens, and that Alphamune™ supplementation may protect poults from young breeder flocks from the production losses due to cold stress and E. coli infection.