FAILURE OF DIETARY BENTONITE CLAY, SILENT HERDER(R) MINERAL SUPPLEMENT, OR PARENTERAL BANAMINE(R) TO ALLEVIATE LOCOWEED TOXICOSIS IN RATS

To evaluate treatments purportedly beneficial for livestock grazing lo coweeds (LW), growing rats were fed diets containing 10 or 20% whole-p lant Oxytropis sericea (LW) with and without Silent Herder(R) mineral mix (1.5% of diet) or bentonite clay (1.5% of diet). Pregnant female r ats fed 10% LW were treated i.m. with Banamine(R) (a prostaglandins su ppressor) or saline. The LW contained swainsonine (430 mu g/g DM) and elicited toxicosis within 10 d at intake of 2 mg/kg BW. In Trial 1, 96 immature male Sprague-Dawley rats (BW approximately 100 g) were fed c ommercial rat feed (CRF) with and without LW, as follows: 100% CRF, fr ee choice; 100% CRF, restricted intake to equal average intake of rats consuming 10 and 20% LW; 90% CRF + 10% LW free choice; and 80% CRF 20% LW free choice. Diets with LW contained either no supplement or su pplemental mineral mixture (Silent Herder, 1.5% of diet) or added bent onite clay (1.5% of diet). Twelve rats received each of eight dietary regimens through 28 d. Locoweed depressed (P < .05) feed intake and BW gain, increased (P < .05) relative size of liver, kidneys, heart, spl een, and testes, and altered blood serum components (P < .05) indicati ng toxicosis. Dietary provision of Silent Herder or bentonite failed t o benefit rats that ingested approximately 4 or 8 mg of swainsonine/kg BW daily through 28 d. In Trial 2, 68 young adult female Sprague-Dawl ey rats (approximately 230 g BW) were mated and directly assigned to t hree diets (100% CRF, free choice, 100% CRF, intake restricted slightl y below average intake of diet by rats consuming LW, or 90% CRF + 10% LW free choice) and two treatments (i.m. saline or i.m. Banamine at .2 5 mg/kg BW daily for 10 d) in a 3 x 2 factorial arrangement. Approxima tely half (31 of 68) of the impregnated rats were killed at d 10, when Banamine was discontinued, but diets were continued until the remaini ng females gave birth. Ingested LW provided approximately 2 mg swainso nine/kg BW daily and elicited toxicosis in 10 d, but LW failed to affe ct numbers of live concepti at d 10 (P > .5) or numbers of offspring a t parturition (P > .10). Banamine did not alleviate LW toxicosis of da rns (P > .10). Provision of Silent Herder or bentonite in the diet or Banamine i.m. had no benefit for rats fed toxic locoweed.