Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2003
Publication Date: March 20, 2003
Citation: McMurtry, J.P., Allen, P.C., Richards, M.P., Poch, S.M., Brocht, D. 2003. Eimeria acervulina infection elicits an elevation in plasma ghrelin and changes in other metabolic hormones [abstract]. Poultry Science. v.82:84.
One of the most costly enteric parasitic diseases of broilers is coccidiosis. Impaired feed consumption is a major consequence of coccidiosis, which negatively impacts growth and feed efficiency. The cause of the suppression of appetite in coccidial infected birds is unknown. Ghrelin is a recently discovered peptide hormone that has unique properties separate from mammals. In birds, ghrelin is mainly produced in the proventriculus, and has been shown to inhibit feed intake. This study was conducted to monitor plasma ghrelin and other metabolic hormones during a coccidial infection. At 24 days of age, male chicks were inoculated with 500,000 sporulated oocysts of E. acervulina (strain #12) per chick (I). A control (C) group received vehicle. Blood and tissue samples were taken prior to inoculation (day 0), and on days 4, 8, and 14 post infection. Feed consumption was determined daily. Body weights were determined at sampling. The extent of infection was confirmed by histology. Plasma levels of ghrelin, IGF-I and -II, GLP-1, glucagon and thyroid hormones were determined by RIA. At 4 days post infection, ghrelin levels in the I chicks were 3-fold higher than in the C group. This is also the period when feed intake was suppressed to the greatest extent. By day 8, ghrelin levels were similar in both groups. On day 4 glucagon levels were greater in the I group compared to the C birds. Conversely, IGF-I and triiodothyronine concentrations were lower in the I birds on day 4. By day 8 post infection, any changes in circulating hormone levels were not different between the two groups, and remained similar through day 14. Infection did not alter IGF-II, GLP-1or thyroxine levels. It is evident from this study that coccidial infection elicits a dramatic increase in circulating ghrelin, and with the concomitant decrease in feed intake, strongly suggests that ghrelin may be the causative factor. However, confirmation of this association awaits further study.
Key Words: coccidiosis, feed intake