Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Maternal Ingestion of Locoweed. Ii. the Ability of Intoxicated Ewes to Discriminate Their Own Lamb

Authors
item Astorga, J. - UNIV. TECNICA ALTIPLANA
item PFISTER, JAMES
item STEGELMEIER, BRYAN

Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 12, 2005
Publication Date: June 29, 2005
Citation: Astorga, J.B., Pfister, J.A., Stegelmeier, B.L. 2005. Maternal ingestion of locoweed (oxytropis sericea). ii. the ability of intoxicated ewes to discriminate their own lamb. Small Ruminant Research, 65:64-69.

Interpretive Summary: Livestock that eat locoweeds (Oxytropis sericea) often show aberrant behaviors and may show reductions in ability to move and to discriminate other animals and objects. This study examined the ability of ewes exposed to locoweed during gestation and/or lactation to discriminate their own from an alien lamb. Ewes (n=6 per treatment group) were fed a 10% locoweed pellet during 1) gestation (day 100 to 130)(LC) but not during lactation; 2) lactation (day 10 to 50 postpartum)(CL) but not gestation; and 3) both gestation and lactation (LL); controls (CC) were fed alfalfa hay. Ewe behavior was examined in a two-lamb choice test on days 20, 40, and 50 after birth (days 10, 30, and 40 of locoweed feeding). Locoweed feeding increased blood AST activity (an enyzme indicating intoxication) and blood swainsonine concentration compared to controls, indicating moderate intoxication. Feeding locoweed during gestation had little effect on lamb discrimination by ewes. Ewes not receiving locoweed during lactation (CC, LC) were initially (postpartum day 20) slower to approach their own lambs, but on days 40 and 50 had faster approach times to their own lambs compared to CL and LL ewes. Intoxicated ewes were nervous and hypersensitive. As a result, these lactating ewes spent a greater percentage of time with their lambs after contact than did controls on postpartum day 50. If clinical signs of toxicity are not severe, culling intoxicated ewes for behavioral reasons may not be warranted.

Technical Abstract: Consumption of locoweed (Oxytropis sericea) by sheep causes neurotoxicity, but specific behavioral effects have been given little attention. We examined the ability of ewes exposed to locoweed during gestation and/or lactation to discriminate their own from an alien lamb. Ewes (n=6 per treatment group) were fed a 10% locoweed pellet during 1) gestation (day 100 to 130)(LC) but not during lactation; 2) lactation (day 10 to 50 postpartum)(CL) but not gestation; and 3) both gestation and lactation (LL); controls (CC) were fed alfalfa hay. Ewe behavior was examined in a two-lamb choice test on postpartum days 20, 40, and 50 (days 10, 30, and 40 of locoweed feeding). Locoweed feeding increased (P < 0.05) serum AST activity and swainsonine concentration compared to controls, indicating moderate intoxication. Discrimination of lambs was not adversely affected by locoweed exposure. Locoweed intoxication during gestation decreased (P = 0.06) ewe approach times to the first lamb, while locoweed exposure during lactation increased (P < 0.03) approach times to the first lamb. Ewes not receiving locoweed during lactation (CC, LC) were initially (postpartum day 20) slower to approach their own lambs, but on days 40 and 50 had faster approach times to their own lambs compared to CL and LL ewes. Intoxicated ewes displayed an apparent locoweed-induced hypersensitivity and nervousness; these lactating ewes spent a greater percentage of time with their lambs after contact than did controls on postpartum day 50. If clinical signs of toxicity are not severe, culling intoxicated ewes for behavioral reasons may not be warranted.

Last Modified: 8/27/2014
Footer Content Back to Top of Page