HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Obeidat, B. S. Articles by Hernandez, J. A. Search for Related Content PubMed PubMed Citation Articles by Obeidat, B. S. Articles by Hernandez, J. A.

Effects of locoweed on serum swainsonine and selected serum constituents in sheep during acute and subacute oral/intraruminal exposure¹

B. S. Obeidat^*, J. R. Strickland^,2, M. L. Vogt^*, J. B. Taylor, C. R. Krehbiel, M. D. Remmenga^*, A. K. Clayshulte-Ashley^*, K. M. Whittet^*, D. M. Hallford^* and J. A. Hernandez^*

^* New Mexico State University, Las Cruces 88003; and Forage-Animal Production Research Unit, ARS, USDA, Lexington, KY 40546; and U.S. Sheep Experiment Station, ARS, USDA, Dubois, ID 83423; and and Oklahoma State University, Stillwater, OK 74078

² Correspondence: N-220F Ag Science North, UK Campus (phone: 859-257-1647; fax: 859-257-3334; e-mail: jstrickland{at}ars.usda.gov).

A study was conducted to evaluate the effects of acute and subacute locoweed exposure on serum swainsonine concentrations and selected serum constituents in sheep. Thirteen mixed-breed wethers (BW = 47.5 ± 9.3 kg) were assigned randomly to 0.2, 0.4, or 0.8 mg of swainsonine•kg BW^–1•d^–1 treatments. During acute (24 h) and subacute (19 d) exposure, serum swainsonine was detected in all treatments and was greatest (P < 0.03) in the 0.8 mg treatment. Serum alkaline phosphate (ALK-P) activity was increased (P < 0.01) for the 0.8 mg treatment compared with baseline (0 h) by 7 h and continued to increase throughout the initial 22 h following acute exposure to locoweed. A linear increase (P < 0.01) in serum ALK-P activity was noted, with the rate being 3.00 ± 0.56 U•L^–1•h^–1. Serum ALK-P activity was increased (P < 0.05) across treatments on d 7 over d –19, –12, 0, 1, 21, and 26; on d 14 over d –19, –12, 0, and 26; and on d 19 over d –19, –12, 0, 1, 21, and 26. By d 20, approximately 48 h after last exposure to swainsonine, serum ALK-P activities were no longer different (P = 0.13) than baseline (d –19, –12, and 0), and by d 26 values had generally returned to baseline. No linear (P = 0.98), quadratic (P = 0.63), or cubic effects of swainsonine with time from exposure were noted for serum aspartate aminotransferase. Similar to serum ALK-P activities, serum aspartate aminotransferase activities were increased (P < 0.05) across treatment levels on d 7, 14, 19, 20, 21, and 26 over those on d –19, –12, 0, and 1. Total serum Fe was decreased (P < 0.05) within the initial 22 h following the swainsonine exposure. On d 21 (48 h after swainsonine feeding ended), serum Fe increased to 472 mg/L. Concentrations of ceruloplasmin were lower (P < 0.10) on d 14 and 19 following exposure to locoweed. Recovery of ceruloplasmin levels coincided with similar changes in serum Fe. There was a linear (slope = 0.33 mg•dL^–1•d^–1; P < 0.01) effect with time of exposure to locoweed (i.e., swainsonine) on serum triglyceride concentrations. Rapid changes in serum ALK-P and Fe concentrations without parallel changes in other damage markers indicate that acute exposure to swainsonine induces metabolic changes that may impair animal production and health before events of cytotoxicity thought to induce clinical manifestation of locoism.

Key Words: Acute Exposure • Locoweed • Sheep • Subacute Exposure • Swainsonine