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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #100703
Title: LOCOWEED BITE COUNT CORRELATION WITH SERUM SWAINSONINE LEVELS IN CATTLE

Author
item DOHERTY, D - CSU
item VAAD, J - CSU
item GREATHOUSE, G - CSU
item KNIGHT, A - CSU
item Geary, Thomas
item Ralphs, Michael

Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1999
Publication Date: N/A
Citation: DOHERTY, D.R., VAAD, J., GREATHOUSE, G., KNIGHT, A.P., GEARY, T.W., RALPHS, M.H. LOCOWEED BITE COUNT CORRELATION WITH SERUM SWAINSONINE LEVELS IN CATTLE. WESTERN SECTION OF ANIMAL SCIENCE PROCEEDINGS. 1999. v. 50. p. 24-26.

Interpretive Summary: Locoweed consumption by livestock decreases animal performance and can cause death. Swainsonine, the principle toxic alkaloid in locoweed, acts by inhibiting alpha-mannosidase which affects oligosaccharide metabolism. Primiparous cows (n=16) were used to evaluate the correlation between locoweed consumption (as measured by bite counts) and serum swainsonine, alpha-mannosidase, and aspartate aminotransferase (AST), a liver enzyme indicative of mitochondrial damage. The heifers were randomly divided into two groups and fed either grass hay or alfalfa hay for 70 d prior to exposure to locoweed infested pastures to determine whether legume hay affected locoweed-feeding preference. There was no difference (P>.1) in locoweed preference. Blood samples were collected weekly to determine the level of swainsonine, AST, and alpha- mannosidase activity. Bite counts were recorded twice a day, 5 days per week, for 5 weeks on each animal. The concentration of swainsonine in the serum was positively correlated (P<.05) with the weekly locoweed bites (r=.645) and with AST concentrations (r=.415). Serum swainsonine concentrations were not correlated (P>.1) to alpha-mannosidase activity (r=-.051). Also, alpha-mannosidase was not correlated (P>.1) to either bite counts (r=-.082) or AST values (r=-.15). Legume feeding does not appear to predispose cows to eating locoweed. Bite counts appear to accurately reflect serum swainsonine and AST concentrations, but not alpha-mannosidase activity. The alpha-mannosidase activity seemed low at the beginning of this study and remained low. It is possible that serum swainsonine concentrations were not elevated for a sufficient length of time to depress alpha-mannosidase activity.

Technical Abstract: Locoweed consumption by livestock decreases animal performance and can cause death. Swainsonine, the principle toxic alkaloid in locoweed, acts by inhibiting alpha-mannosidase which affects oligosaccharide metabolism. Primiparous cows (n=16) were used to evaluate the correlation between locoweed consumption (as measured by bite counts) and serum swainsonine, alpha-mannosidase, and aspartate aminotransferase (AST), a liver enzyme indicative of mitochondrial damage. The heifers were randomly divided into two groups and fed either grass hay or alfalfa hay for 70 d prior to exposure to locoweed infested pastures to determine whether legume hay affected locoweed-feeding preference. There was no difference (P>.1) in locoweed preference. Blood samples were collected weekly to determine the level of swainsonine, AST, and alpha- mannosidase activity. Bite counts were recorded twice a day, 5 days per week, for 5 weeks on each animal. The concentration of swainsonine in the serum was positively correlated (P<.05) with the weekly locoweed bites (r=.645) and with AST concentrations (r=.415). Serum swainsonine concentrations were not correlated (P>.1) to alpha-mannosidase activity (r=-.051). Also, alpha-mannosidase was not correlated (P>.1) to either bite counts (r=-.082) or AST values (r=-.15). Legume feeding does not appear to predispose cows to eating locoweed. Bite counts appear to accurately reflect serum swainsonine and AST concentrations, but not alpha-mannosidase activity. The alpha-mannosidase activity seemed low at the beginning of this study and remained low. It is possible that serum swainsonine concentrations were not elevated for a sufficient length of time to depress alpha-mannosidase activity.