|Anthony, N - University Of Arkansas|
|Nestor, K - The Ohio State University|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2015
Publication Date: 2/12/2015
Citation: Huff, G.R., Huff, W.E., Rath, N.C., Anthony, N.B., Nestor, K.E. 2015. Ascorbic acid differentially affects the response and resistance to Colibacillosis in turkeys from genetic lines differing in growth rate. Avian Diseases. 59(2):323-328.
Interpretive Summary: Genetic selection for fast-growth can affect the ability of male turkeys to cope with stress resulting in decreased immunity to common bacteria in the environment. The purpose of this study was to compare the effects of vitamin C (ascorbic acid, AA) on the stress response in birds selected for fast growth (F-line) with their slow-growing parent line (RBC2). At 5 weeks of age, AA (1200 ppm, (Stabilized-C, Alpharma) was provided in drinking water for a 24 hour period, during which all birds were weighed. After 24 hours of AA treatment the challenged group was subjected to transport stress that included disruption of the social group, catching, loading, and movement to another building, and a 12 hour feed and water withdrawal. Six hours after the start of transport, birds were also inoculated with Escherichia coli into the airsac. At the end of the transport stress birds were returned to their original pens and provided feed and water. The following morning 4 birds from each pen were bled and all birds were weighed and examined 2 days later. Body weight (BW) and gain after transport stress was decreased in the F-line but not the RBC2 line and there were no AA effects on BW. The weight of the bursa of Fabricius, an organ involved in the immune response, was higher in the RBC2 line, was decreased by transport stress, and was not affected by AA. The heterophil/lymphocyte ratio, which is a way to measure stress in birds, was higher in the stressed F-line birds as compared to the stressed RBC2 birds and was decreased by AA only in the stressed F-line . The levels of a stress hormone, Corticosterone (C), were increased by transport stress only in the F-line and AA decreased C levels only in the RBC2 line. The challenge strain of E. coli was cleared from the airsac in all treatments except the AA-treated F-line challenged birds. These results suggest that transport stress and E. coli challenge at 5 wks of age had a more harmful effect on the fast-growing F-line than on its slow-growing parent line, AA treatment had different effects in the two lines, and AA may have decreased resistance to E. coli in the transport stressed F-line birds.
Technical Abstract: Genetic selection for fast-growth can affect the ability of male turkeys to cope with stressors resulting in decreased immunity to opportunistic bacterial infection. The purpose of the current study was to compare the effects of ascorbic acid (AA) on the stress response and resistance to Escherichia coli challenge of birds selected for increased 16-wk-BW (F-line) with their randombred parent line (RBC2). Male turkeys were raised in duplicate floor pens in a 2 line x 2 AA treatment x 2 stress challenge (SC) design. At 5 wk of age, AA (1200 ppm) was provided in drinking water for a 24 h period, during which all birds were weighed. After AA treatment, the SC group was subjected to a transport stress protocol. Six h after the start of transport, SC birds were also inoculated in the thoracic airsac (AS) with 1 x 104 cfu of E. coli. The following morning 4 birds from each pen were bled and all birds were weighed and necropsied 2 days later. Body weight and gain after SC was decreased in the F-line but not the RBC2 line and there were no AA effects on BW. The weight of the bursa of Fabricius relative to BW was higher in the RBC2 line than the F-line, was decreased by SC, and was not affected by AA. The heterophil:lymphocyte ratio was higher in the SC F-line as compared to the SC RBC2 and was decreased by AA only in the SC F-line. Corticosterone (C) levels were increased by SC only in the F-line and AA decreased C levels only in the RBC2 line. The challenge strain of E. coli was only detected in the airsac and liver of the AA-treated F-line SC birds and in the liver of the non-challenged F-line birds. These results suggest that SC at 5 wk of age had a more deleterious effect on the fast-growing F-line than on its parent line and AA may have increased susceptibility to colibacillosis in the SC F-line birds.