Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2006
Publication Date: 11/12/2006
Citation: Aiken, G.E., Mcclanahan, L. 2006. Steer Weight Gain and Physiological Responses to Feeding Soybean Hulls on Toxic Tall Fescue: Dilution of Ergot Alkaloids or Additive Effect on Weight Gain. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting. 266-12. Interpretive Summary:
Technical Abstract: Stocker cattle grazing toxic tall fescue (Festuca arundinacea Schreb.) consume ergot alkaloids produced by an endophyte that can lead to the “fescue toxicosis” malady. One approach to alleviating fescue toxicosis is to dilute the alkaloids by interseeding clovers or by feeding concentrates; however, it is unknown if dilution of the alkaloids is sufficient to completely alleviate toxicosis. A 2-yr grazing experiment was conducted to determine if feeding pelleted soybean hulls (SBH) at approximately 1% of BW/day can increase weight gain and reduce the severity of toxicosis. Steers grazed during the summer for 112 days in 2004 and 102 days in 2005 on five, 3.0-ha pastures of ‘KY-31’ tall fescue in a completely randomized design. Pastures were assigned treatments of either SBH (n = 2) or pasture-only (n = 3). Average daily gain (ADG) and serum prolactin (PROL) were measured at approximately 28-d intervals. Rectal temperatures (RTEMP) and hair coat scores (HCS) were recorded on the final weigh day in both years. Feeding SBH increased ADG (P < 0.001) and there was a year effect (P < 0.001), but no interaction (P > 0.10) between the two variables. Prolactin decreased (P < 0.05) over the grazing season in both years but remained unaffected by treatment (P > 0.10). Rectal temperatures were not influenced (P > 0.10) by either treatment or year. Haircoats were predominately rough by the conclusion of grazing in both years and there was no treatment effect (P > 0.10) in either year. Results indicate that feeding SBH to steers on E+ fescue increases ADG as compared to stockers grazing only E+ fescue, but does not reduce the severity of toxicosis.