Concurrent ivermectin and Solanum spp. toxicosis in a herd of horses.

BACKGROUND: Representatives from a herd of horses with acute onset of neurologic signs after administration of ivermectin presented for evaluation and treatment. OBJECTIVES: Describe clinical signs of horses intoxicated by ingestion of Solanum sp. and administered ivermectin. ANIMALS: Six of 11 affected unrelated horses presented for evaluation and treatment. The remaining 5 affected horses were treated at the farm. Four additional horses, housed separately, were unaffected. METHODS: Case series is presented. Serum ivermectin concentrations were evaluated in the 6 hospitalized horses. The remnants of the tubes of ivermectin paste were analyzed for ivermectin concentration. The hay fed to the affected horses was analyzed for the presence of toxic plants. RESULTS: Serum ivermectin concentrations were higher than expected, given the dosage of ivermectin administered. The ivermectin concentration remaining in the administration tubes did not exceed specifications. The hay was heavily contaminated by 2 Solanum species. All horses returned to normal neurologic function with supportive care. CONCLUSIONS AND CLINICAL IMPORTANCE: Horses might exhibit signs of ivermectin toxicity after appropriate dosing of the drug if they concurrently consume toxic plants of the Solanum family.

Influence of crambe meal as a protein source on intake, site of digestion, ruminal fermentation, and microbial efficiency in beef steers fed grass hay.

Four ruminally and duodenally cannulated beef steers (558 +/- 37 kg) were arranged in a 4 x 4 Latin square to evaluate the influence of crambe meal as a protein source on intake, digestion, and microbial efficiency. Steers were offered chopped (10.2 cm) brome hay (6.2% CP) for ad libitum consumption and one of four supplements. Protein sources used were soybean and crambe meals (CM). Protein sources were blended to provide four levels of supplemental CM protein (0, 33, 67, and 100%). Protein supplements were fed to provide similar amounts of protein and energy. Amounts of supplements fed were 831, 885, 950, and 996 g of DM/steer daily for 0, 33, 67, and 100% CM treatments, respectively. Crambe meal represented 0, 2.00, 3.83, and 5.88% of the DM intake for respective treatments. Steers were allowed a 21-d adaptation to diets before each collection period. Supplements were offered at 0800 and forage at 0830. Crambe meal had no influence (P > .10) on forage and total DM intake (grams/kilogram of BW). Apparent total tract, ruminal, and postruminal digestion of OM, NDF, ADF, and N were unaffected (P > .10) by CM supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of yeast culture supplementation and advancing season on steers grazing mixed-grass prairie in the northern Great Plains: I. Dietary composition, intake, and in situ nutrient disappearance.

Twelve beef steers (368 +/- 25.3 kg) and four beef heifers (559 +/- 79.5 kg) fitted with ruminal cannulas were used to evaluate effects of yeast culture (YC) and advancing season on dietary chemical composition, intake, and in situ CP and NDF degradation. Treatments were control and YC supplementation (28.4 g.steer-1.d-1 dosed ruminally). Steers grazed from late June to early November 1991 on mixed-grass prairie. Experimental periods consisted of 10 d for adaptation and a 13-d collection phase. Forage samples collected from YC-supplemented steers had greater (P < .10) soluble N and in vitro OM disappearance than forage from controls throughout the grazing season. Organic matter intake was greater (P < .10) by YC-supplemented steers during June. Fecal output and OM intake increased (P < .10) from June to September. Increases (P < .10) in in situ NDF disappearance were noted at 8, 16, and 24 h in June, at 8, 48, and 72 h in July, and at 8 h in August for the YC treatment group. Supplemental YC did not affect (P > .10) rate or lag time of NDF disappearance. In situ CP disappearance (ISCPD) was greater (P < .10) at all times except 48 h in June, at 48 and 72 h in July, and at 0, 4, 8, and 12 h in August for YC-supplemented steers. Steers supplemented with YC had an increased extent (P < .10) of ISCPD in July and an increase in CP degradation rate in June; however, total CP degradation was greater (P < .10) during June for control than for YC steers.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of yeast culture supplementation and advancing season on steers grazing mixed-grass prairie in the northern Great Plains: II. Ruminal fermentation, site of digestion, and microbial efficiency.

Twelve ruminally and duodenally cannulated beef steers (initial BW 368 +/- 25.3 kg) and four ruminally cannulated beef heifers (initial BW 559 +/- 79.5 kg) were used to evaluate the effects of yeast culture (YC) and advancing season on ruminal fermentation, microbial protein synthesis, ruminal fluid kinetics, and site of digestion. Treatments were control and YC supplementation (28.4 g.steer-1.d-1 dosed ruminally). Steers grazed from late June to early November 1991 on mixed-grass prairie. Ruminal pH decreased (P < .10) from late July to early October. Fluid dilution rate decreased (P < .10) as the grazing season advanced, whereas ruminal fluid volume and flow rate increased (P < .10) from late July to early October. Ruminal ammonia concentration (milligrams/deciliter) was lower (P < .10) during late July and late August than during late June and early October at 4, 8, 12, and 16 h after sunrise in YC-supplemented steers. Molar proportions of propionate and butyrate were greater (P < .10) in control than in YC-supplemented steers at 0, 4, 12, and 24 h and 0, 4, and 12 h after sunrise, respectively, during late July. Acetate (mol/100 mol) was greater (P < .10) during late July and late August than in late June and early October for YC-supplemented steers at 0, 4, and 8 h after sunrise. True ruminal OM digestion was greatest (P < .10) in late June, intermediate in late July and late August, and least in early October. Supplementation with YC increased (P < .04) true ruminal OM digestion in late June and late July. Steers receiving YC had greater (P < .07) duodenal bacterial N flow in late July. These data indicate that yeast culture supplementation can increase true OM digestibility early in the grazing season. Advancing season seems to result in increased ruminal fluid volume, lower true ruminal OM digestion, and greater microbial efficiency.