Endophyte-infected Fescue Research Articles

Prolonged gestation, decreased triiodothyronine concentration, and thyroid gland histomorphologic features in newborn foals of mares grazing Acremonion coenophialum-infected fescue

SUMMARY Newborn foals of mares grazing on Acremonium coenophialum-infected fescue pasture throughout gestation or from gestation day 300 to parturition had increased gestation duration and decreased serum triiodothyronine concentration. Pregnant mares were allotted to 4 treatments: grazing continuously on endophyte-free (E−) fescue, grazing continuously on endophyte-infected (E+) fescue, grazing on E+ fescue from gestation day 300 to parturition, and grazing on E+ fescue from conception to gestation day 300. Morphometric studies indicated that foals born to mares exposed to endophyte late in gestation had large, distended thyroid follicles lined by flat cuboidal epithelial cells. Mean triiodothyronine concentration in foals exposed to endophyte (395.2 ng/dl) was decreased (P < 0.01), compared with mean values in control foals (778.0 ng/dl). Thyroxine and reverse triiodothyronine concentrations were not significantly different among groups. Foal organ weight as a percentage of foal body weight was not significantly different among experimental groups.

Economic Analysis of Grazing and Subsequent Feeding of Steers from Three Fescue Pasture Alternatives

Cattle grazing tall fescue (Festuca arundinacea Schreb.) infected with the endophytic fungus, Acremonium coenophialum, typically experience toxicity symptoms, resulting in poor animal performance. However, potential exists for compensatory gains during subsequent finishing. This study provides an economic analysis of three grazing alternatives along with subsequent feedlot performance. The pasture alternatives were endophyte-infected »Kentucky 31« tall fescue (IF); IF interseeded with ladino clover (Trifolium repens L., IFL); and endophyte-free »Missouri 96« tall fescue (MO). Three years of agronomic data from pastures and animal performance data from steers (Bos taurus) were collected

Efficacy of domperidone and sulpiride as treatments for fescue toxicosis in horses

Summary We evaluated the effectiveness of 2 dopamine antagonists as treatments for fescue toxicosis in horses. Sixteen gravid mares were assigned by breed and expected foaling date to 1 of 3 treatment groups; endophyte-infested control; 1.1 mg of domperidone/kg of body weight/d; and 3.3 mg of sulpiride/kg/d. Mares were pastured on endophyte-infected fescue and received 0.454 kg of a corn and dried molasses carrier containing the drug treatment. Treatment started 30 days prior to expected foaling date and continued until parturition. Blood samples were collected, and mammary gland scores were recorded every 5 days. Body weight and body condition scores were obtained every 28 days. Serum was analyzed for prolactin, progesterone, and estradiol-17β concentrations. Domperidone-treated mares had shorter (P = 0.09) gestation duration and foaled closer (P = 0.07) to their expected parturition date than did control mares. Mammary gland scores were higher (P < 0.05) for domperidone-treated mares than for control mares. By 4 and 9 days after the start of treatment, serum prolactin concentration was higher (P < 0.05) in domperidone-treated mares and sulpiride-treated mares, respectively, than in control mares. Domperidone- and sulpiride-treated mares had higher (P < 0.05) serum progesterone and lower (P < 0.01) estradiol-l7β concentrations than did control mares. These results indicate that domperidone may offer considerable potential as a treatment for fescue toxicosis in horses.

In vitro and in vivo release of metoclopramide from a subdermal diffusion matrix with potential in preventing fescue toxicosis in cattle

An auricular implant (0.5 × 3.7 cm) containing metoclopramide was developed for use in cattle as a therapeutic aid in antagonizing the harmful effects associated with grazing of endophyte-infected fescue pastures. The implant matrix was prepared from the biodegradable polymer, polyhydroxybutyrate and its copolymer polyhydroxyvalerate using compression-melt and solvent-evaporation compression techniques. Fabrication variables evaluated in in vitro dissolution studies included concentration of copolymer, drug payload, salt form vs. free base form of drug, and degree of compression. The optimal system consisted of a matrix containing 24% copolymer with a 50% drug payload that was prepared with the compression-melt technique. An in vivo study in cattle was conducted to assess biocompatibility and verify the dissolution rate in the whole animal. No adverse reactions occurred. The metoclopramide implant had a dissolution rate of 12 mg/day and was vascularized by the surrounding connective tissue. The matrix sham had no observable vascularization. An additional study used twelve pairs (one implanted, the other control) of steers placed on four different endophyte/nitrogen grazing treatments. The total ergot content (0.2–2.2 μg/g) of the twelve fescue paddocks was measured by HPLC, and fraction of Acremonium endophyte infection (23–67%) was determined by aniline stain. The implant resulted in an improvement in suppressed tail temperature ( P < 0.01) among all endophyte/nitrogen treatments, and cholesterol ( P < 0.01) among the high endophyte/nitrogen treatments.

Influence of endophyte-infected tall fescue on cyclicity, pregnancy rate and early embryonic loss in the mare

The effects of grazing endophyte-infected tall fescue on luteal function, pregnancy rates, and embryonic loss rates were compared between treated mares (n=18) and untreated controls (endophyte-free, n=12). Mares grazing endophyte-infected fescue demonstrated significantly (P<0.01) prolonged luteal function (22.9 vs 15.8 d) than those grazing endophyte-free fescue. Continuous grazing of endophyte-infected fescue resulted in a decreased (P=0.30) per cycle 14-d viable pregnancy rate (14/31, 45.2%) compared with that of endophyte-free grazing (12/16, 75.0%). Early embryonic death rates were higher (P=0.20) in the endophyte-infected group (6/20, 30.0%) than the endophyte-free group (1/13, 7.7%). Cumulative pregnancy rates after a 60-d breeding period did not differ between the 2 groups. Embryonic development based on mean vesicle height at 14-d was not significantly different between treatment groups for embryos that maintained viability. Embryos that underwent early embryonic death were smaller (P<0.10) at Day-14 than embryos that maintained viability. Mean plasma progesterone concentrations were significantly (P<0.01) greater at Day-21 postovulation in endophyte-infected mares in which the embryo remained viable (15.8 ng/ml) than in endophyte-free mares that experienced early embryonic death (9.8 ng/ml) or that demonstrated prolongation of luteal function (11.2 ng/ml). The results of this study suggest that grazing endophyte-infected tall fescue can have a detrimental effect on reproductive efficiency in the mare due to an increase in cycles bred per pregnancy rate, increased early embryonic death rate and prolongation of luteal function.

Growth and ovarian function of weanling and yearling beef heifers grazing endophyte-infected tall fescue pastures

Growth and ovarian function of crossbred beef heifers grazing low and high endophyte-infected tall fescue pastures were studied for 2 successive years. In April of each year, 20 weanling and 20 yearling heifers were included in the study. All heifers were weighed at 28-d intervals for 112 d. Blood samples were collected from each heifer on Day 0 and +7 of each of five 28-d periods and analyzed for progesterone concentration. Heifers with progesterone concentrations ≥ 1.5 ng/ml on either or both Day 0 and +7 were classified as having normal cyclic ovaries. High endophyte-infected fescue pastures adversely altered the ovarian activity (P < 0.05) of weanling heifers in both years. In each trial, average weight gains were lower (P < 0.05) in yearling and weanling heifers grazing the high endophyte-infected pastures than in heifers grazing low endophyte-infected pastures. In 1992, heifers were synchronized with PGF2α administered on Days 101 and 112. Blood samples were collected on 0, 4, 8 and 12 d after the second PGF2α injection for progesterone analysis. Heifers grazing high and low endophyte-infected pastures were pastured separately with 4 bulls each and were given heatmount detectors. At 96 h, less estrus activity was observed (P < 0.10; power=0.63) in weanling heifers grazing the high vs. low endophyte pastures although pregnancy rates were similar for all groups. Progesterone concentrations suggested that weanling heifers on the high endophyte pastures had a higher incidence of luteal dysfunction after PGF2α synchronization. In summary, high endophyte-infected pastures decreased growth in both weanling and yearling heifers, ovarian activity and luteal function were adversely altered in weanling heifers with subsequent decreased estrus response to estrus synchronization.

Tall fescue utilization by exercised - yearling horses

Summary Little information has been published concerning the effects of endophyte-infected tall fescue consumption on performance of young growing horses. Therefore, this study evaluated exercise performance and growth by yearlings fed endophyte-infected fescue. Twelve Quarter Horse yearlings (12-16 months of age) were blocked by age and sex and randomly assigned to one of three groups. Group I received native prairie hay (P), Group II received endophyte-free fescue hay (EF) and, Group III received endophyte infected fescue hay (EI). Rectal temperatures were monitored daily and growth parameters (weight, hip and wither heights, and body fat) were measured at the start of the study (d 0) and every 2 weeks throughout the 106 d study. Additionally, blood samples were collected on d 0 and every 28 d for the duration of the study to monitor blood concentrations of calcium, phosphorus, prolactin (PRL), thyroxine (T 4 ), and triiodothyronine (T 3 ). Horses were exercised twice a week for 10-30 min. Respiration, heart rate, and rectal temperature were measured at the start and 5, 30, and 60 min postexercise. Growth parameters and daily rectal temperatures were not different (P >.05) among grdups. No differences (P >.05) occurred among groups in concentrations of serum calcium, phosphorus, PRL, T 3 , and T 4 . Respiration rates were lower (P

Impacts of Endophyte-Infected Fescue on Cow/Calf Production

AbstractCow-calf performance on endophyte (Acremonium coenphialum)-free fescue (EFF) and endophyte-infected fescue (EIF) were evaluated. Four groups of 15 cows each (60 total) were used and allotted to groups on the basis of breed (Hereford and Angus), age, weight, and body condition. Pregnancy rate, cow and calf weights, milk production, milk-fat, lactose, protein and solids-non-fat were measured. Cows grazing EFF had a higher (P<.05) palpated pregnancy rate (88%) than those grazing EIF (58%). Calf grade, body type, and condition score were higher (P<.05) for calves from cows grazed on EFF (13.7, 3.6, and 7.4, respectively) than for those grazed on EIF (12.6, 3.1, and 6.9). Weaning weight and milk production per day were higher (P<.05) for animals on EFF (231 and 3.65 kg, respectively) than for those on EIF (188 and 1.25 kg). Economic analysis indicated that cows grazed on EFF returned an estimated profit of $89.63 per cow in comparison to a loss of $54.44 per cow when cows and calves were grazed on EIF. Fescue stand percentage of EFF pastures was less than 10% at the end of 4yr of continuous grazing.

Milk production in Brahman and Angus cows on endophyte-infected fescue and common bermudagrass

Daily milk yield and milk fat were estimated by method of milking machine in 60 Angus and 60 Brahman cows grazing common bermudagrass or endophyte-infected fescue during a 3-yr period. Averaged over monthly estimates, there was evidence (P < .05) of a dam breed x forage interaction in daily milk yield. Tall fescue decreased milk yield more in the Angus (1.64 kg/d, P < .01) than in the Brahman (.53 kg/d, P > .15). There were significant dam breed effects on both percentage of milk fat and daily milk fat yield; Brahman exceeded Angus by .68% (P < .01) and 34.3 g/d (P < .01), respectively. There were significant forage effects for both percentage of milk fat and daily milk fat yield; common bermudagrass exceeded tall fescue by .5% (P < .01) and 62.3 g/d (P < .01), respectively. These data indicate that incorporation of Brahman germplasm into a grazing system that uses endophyte-infected fescue may be beneficial in daily milk yield but will probably not prevent decreases in milk fat production associated with grazing endophyte-infected tall fescue.

Endophyte-infected, tall fescue hay utilization by exercised, yearling horses (1993)

Fescue toxicity causes substantial production losses in sheep, cattle, and horses. These losses are attributed to an endophyte, Acremonium coenophialum. However, our results indicate that Quarter horse yearlings can be fed endophyte-infected tall fescue hay for at least 106 days with no detrimental effects on either growth or exercise performance. However, these findings have not been substantiated in other classes of horses or in horses consuming endophyte-infected fescue for longer durations.

Effects of feeding diets containing endophyte-infected fescue seed on luteinizing hormone secretion in postpartum beef cows and in cyclic heifers and cows.

Two experiments were conducted to investigate the effect of feeding endophyte (Acremonium coenophialum)-infected fescue (Festuca arundinacea Shreb.) seed on LH secretion in postpartum beef cows and in cycling heifers and cows. In Exp. 1, spring-calving primiparous Angus cows (n = 16) were pair-fed for 75 d diets that contained endophyte-free or endophyte-infected (95%) fescue seed that contained 1.3 micrograms/g of ergovaline and 5.2 mg/g of saturated pyrrolizidines. Serial blood samples for basal and GnRH-stimulated serum LH analysis were obtained on d 7, 28, 42, and 56 of the study. The endophyte had no effect on LH secretion (basal, pulse frequency, and amplitude) or milk production. Average daily gain was decreased (P < .05) in cows that consumed infected fescue seed compared with controls (-.20 vs -.01 kg, respectively). Basal serum prolactin concentrations were reduced (P < .01) in treated compared with control cows (8.9 vs 25.4 ng/mL, respectively) on d 70. In Exp. 2, cycling Angus heifers (n = 8; age = 2 yr) and cows (n = 8; age = 4 yr) stratified by age were pair-fed for 40 d diets that contained the noninfected or the highly infected fescue seed. Estrus was synchronized by prostaglandin F2 alpha (d 18 and 28). Serial blood samples for serum LH analysis were obtained on d 28 (luteal phase) and d 30 (follicular phase). The endophyte did not affect LH (P > .28) or prolactin (P > .16) secretion, whereas ADG was decreased (P < .05) in treated compared with control animals (.32 vs .70 kg/d, respectively).

A preliminary study of growth, serum prolactin and reproductive performance of beef heifers grazing [formula omitted][formula omitted]-infected tall fescue

In an experiment with a 2×2 factorial arrangement of treatments, 32 virgin Angus heifers were used to study effects of tall fescue endophyte Acremonium coenophialum and energy supplementation on reproductive performance. Treatments were feeding of endophyte-free (EF) or endophyte-infected (EI) tall fescue without (0%) and with energy supplementation at one percent group mean body weight (1%). Blood samples were collected at 28-day intervals for prolactin (PRL). Starting 21 days before the breeding season, blood was also collected weekly for progesterone (P 4) and PRL. After 99 days of grazing, heifers received Syncro-Mate-B (SMB) and were then artificially inseminated over a 30-day period. Heifers on EI-0% had a lower (P<0.05) average final body weight. Highest average daily gain was observed in heifers fed EF-1% (0.98 kg/day), whereas, heifers fed EI-0% had lowest average daily gain (0.53 kg/day; P<0.05). Endophyte-infected fescue depressed serum PRL concentrations (171 and 143 ng/ml vs 70 and 85 ng/ml; EF-0% and EF-1% vs EI-0% and EI-1%, respectively; P<0.05). No differences were observed among treatments in luteal activity before or after SMB, in pregnancy rates after a synchronized estrus or in overall pregnancy rates during the 30-day breeding season. Endophyte-infected fescue decreased average daily gain and depressed serum concentrations of prolactin, but had no effect on reproductive performance as measured in this study.

Influence of Thermoammoniation and Supplementation on Digestibility of Roughage

Forty-eight H×A steers were used in nine separate digestion studies in a 2×4 factorial arrangement of treatments. Variables measured were DM digestibility (DMD), DE coefficient, and kcal DE/kg DM, percent nitrogen retained (%Nret), and percent N digested (%Ndig). Nine roughages evaluated were: bermudagrass hay (BG), endophyte-infected fescue hay (ElF), johnsongrass hay (JG), ryegrass hay (RG), cottonseed hulls (CSH), soybean stubble (SBS), wheat straw (WS), soybean stubble previously ammoniated under black plastic (SBSBP), and wheat straw previously ammoniated under black plastic (WSBP) ammoniated under black plastic. Roughages were either thermoammoniated (TA) or nonammoniated (NA) and were fed as roughage only (control), supplemented with corn, SBM, or both. TA increased DMD, DE coefficient, and kcal DE/kg DM of BG. TA increased %Nret of RG. TA increased %Nret and %Ndig of SBS. TA increased %Ndig of WS. TA decreased DMD, DE coefficient, kcal DE/kg DM, %Nret, and %Ndig of JG. TA decreased DE coefficient and kcal DE/kg DM of RG and SBS. TA decreased DMD, DE coefficient, and kcal DE/kg DM of WS. T A decreased %Ndig of WSBP. Supplementation of BG, ElF, JG, RG, and SBSBP with corn, SBM, or corn-SBM increased DMD, DE coefficient, and kcal DE/kg DM. Supplementation of SBS with SBM or cornSBM increased DE coefficient and kcal DE/kg DM. Supplementation of JG, CSH, and WS with corn, SBM, or corn-SBM increased %Nret. Supplementation of RG and WSBP with SBM or corn-SBM increased %Nret. Supplementation of all roughages w1th SBM or corn-SBM increased %Ndig. Supplementation of WS with corn decreased DE coefficient and kcal DE/kg DM. Supplementation of SBS with corn decreased %Ndig. TA was beneficial to BG digestibility. Addition of SRM increased %Ndig for all roughages. Supplemental energy appeared to increase %Nret.

Effects of fescue toxicosis on reproduction in livestock.

Fescue toxicosis in livestock is due to ingestion of endophyte (Acremonium coenophialum) -infected tall fescue. Understanding mechanisms responsible for decreased calving and growth rates, delayed onset of puberty, and impaired function of corpora lutea in heifers at puberty consuming endophyte-infected fescue is an emerging field in reproductive toxicology. The condition decreases overall productivity through a reduction in reproductive efficiency, reduced weight gains, and lowered milk production. Reproduction in cattle may be further compromised by winter coat retention, increased susceptibility to high environmental temperatures, and light intolerance. Endocrine effects in steers associated with infected tall fescue include reduced prolactin and melatonin secretions and altered neurotransmitter metabolism in the hypothalamus, the pituitary, and pineal glands. Ewes have decreased prolactin and lengthened intervals from introduction of the ram until conception. The endophyte induces prolonged gestation, thickened placentas, large, weak foals, dystocia, and agalactia in pregnant mares. Ergot peptide alkaloids, produced by the endophyte, are suggested as the primary cause of fescue toxicosis. These compounds reduce prolactin, increase body temperatures, and have powerful vasoconstrictive effects. Neurohormonal imbalances of prolactin and melatonin, with restricted blood flow to internal organs, may be the principal causes of aberrant reproduction, growth, and maturation in livestock consuming endophyte-infected tall fescue.

Effects of the fungal endophyte Acremonium coenophialum in fescue on pregnant mares and foal viability

SUMMARY Effects of the endophyte Acremonium coenophialum in tall fescue on pregnant mares and foal viability were evaluated. Twenty-two mature pregnant mares were randomly chosen to graze either Kentucky-31 tall fescue that was free from A coenophialum (endophyte-free, ef) or tall fescue infected with A coenophialum (endophyte-present, ep) after the first 90 days of pregnancy through parturition. Concentrations of pyrrolizidine and ergopeptine alkaloids were significantly greater in ep grass, compared with ef pasture. Ten of 11 mares grazing ep pasture had obvious dystocia. Mean duration of gestation was significantly greater for the ep group, compared with the ef group. Foal survivability was severely reduced among mares grazing ep fescue with only 1 foal surviving the natal period. Udder development and lactation were low in mares grazing ep grass. The absence of clinical problems in mares grazing ef grass implicated the endophyte as the causative agent of reproductive problems and perinatal foal mortality in pregnant mares grazing endophyte-infected fescue grass. Caution should be exercised in allowing pregnant mares to graze pastures infected with the endophyte A coenophialum.

Effect of level of endophyte infection, nitrogen fertilization rate, grazing period, and paddock exchange on some chemical properties of four bovine tissues.

Three grazing experiments were conducted to determine the effect of level of endophyte infection, rate of N fertilization of tall fescue grass, grazing period, and paddock exchange on selected chemical properties of four bovine carcass tissues. Samples of semitendinosus and longissimus muscle and of subcutaneous and perinephric adipose tissue were excised from the left side of each carcass. In Exp. 1, percentage of stearic acid was higher (P less than .05) and percentages of palmitoleic and oleic acid were lower (P less than .05) in all tissues from steers grazed on LELN Au-Triumph fescue than in tissues from steers grazed on LELN KY-31 fescue. Grazing periods of 175 or 245 d or paddock exchange (Exp. 2) had no significant effect on proximate composition of semitendinosus and longissimus muscles; however, moisture content was higher (P less than .05) in the semitendinosus muscle from steers grazed on 100% (100E) endophyte-infected KY-31 fescue. Forage treatment, grazing period, and paddock exchange (Exp. 2 and 3) had no significant effect on percentage of saturated fatty acids in the subcutaneous, semitendinosus, and longissimus tissue samples. In Exp. 2 and 3, percentages of saturated fatty acids were higher (P less than .05) in subcutaneous and perinephric adipose tissue samples from steers grazed on 100E than in samples from steers grazed on zero endophyte (OE) fescue.(ABSTRACT TRUNCATED AT 250 WORDS)

Variation among Angus cows in response to endophyte-infected fescue seed in the diet, as related to their past calf production.

Production of 18, 12-yr-old Angus cows was summarized as the averaged weaning weight deviations of each cow's calves from their like-aged, like-sexed and similarly managed contemporaries. These cows had spent a large part of their productive lives on pastures dominated by endophyte-infected tall fescue, so differences among them in calf production might have been induced partly by differences in susceptibility to fescue toxicosis. Cows were divided randomly into two groups for a 31-d summer feeding trial. In a crossover design, cows were fed 0 or .9 kg per cow per day of endophyte-infected fescue seed. Various traits were monitored to quantify differences among cows in response to the endophyte-infected fescue seed. Baseline serum prolactin concentration was depressed by fescue seed feeding, but differences among cows in the amount of depression were not related to past calf production. Prolactin release in response to thyrotropin-releasing hormone tended to be depressed by fescue, but the response also was sensitive to factors such as ambient temperature. Serum cholesterol and body weight change did not respond significantly to the fescue challenge. The experiment was not successful in unambiguously differentiating among cows in susceptibility to fescue toxicosis or in relating differential susceptibility to past calf production.

Effects of feeding endophyte-infected fescue hay on portal and hepatic nutrient flux in steers.

Six Holstein steers (313 +/- 10 kg BW) surgically fitted with hepatic portal, mesenteric venous, mesenteric arterial, and hepatic venous catheters were used in a replicated crossover design experiment to evaluate the feeding of Acremonium coenophialum-infected fescue hay on portal-drained visceral and hepatic nutrient metabolism. Only four steers had functional hepatic catheters. Infected (INF) and endophyte-free (EF) fescue hays were harvested on the same day in May, at the soft dough stage of maturity, from a similar location in southeast Kansas. The hay was chopped through a 2.5-cm screen and fed in 12 portions daily. Intake was limited to 5.2 kg of DM/d to equalize consumption. Each experimental period lasted 21 d. Dietary CP concentration was greater for INF than for EF (9.9 vs 8.6%); however, apparent digestibilities of DM (52.6%) and N (37%) were not different. Ruminal total VFA concentrations and molar proportions were not different with the exception of butyrate, which was increased (P less than .10) for steers when they were fed INF. Feeding of INF increased (P less than .05) arterial beta-hydroxybutyrate concentration and decreased (P less than .10) arterial butyrate concentration. Steers fed EF showed a greater (P less than .05) portal-arterial concentration difference for acetate and an increased (P less than .05) net portal flux of acetate (500 vs 620 mmol/h). No differences in net flux were noted for any of the other VFA, glucose, lactate, urea N, insulin, glucagon, or prolactin.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of supplemental ground grain sorghum during grazing of endophyte-infected tall fescue on grazing and subsequent feedlot performance of steers (1991)

Sixty-three crossbred steers (740 lb BW) were used to evaluate the effects of energy supplementation during grazing of endoplyteinfected tall fescue and on their subsequent feedlot performance. Grazing ADG was .53 lb/d for control (no supplementation) vs. .81 and 1.21 lb/d with .25% and .5% of BW as ground sorghum (GS), respectively. Grazing supplementation did not affect (P>.10) feedlot performance. Steers receiving .25% GS were 2.3% and 6.2% more efficient (P<.07) during the feedlot phase than 0% and .5% GS steers, respectively. The .5% GS steers were 3.8% less efficient (P<.07) during the feedlot phase than the 0% GS steers. Steers receiving grazing supplementation had increased (P<.07) adjusted backfat measurements and less desirable (P<.02) yield grades than non-supplemental controls. Supplementing steers grazing endophyte-infected fescue at .25% of BW with ground grain sorghum improved feedlot feed conversion compared to no supplementation and supplementing at .5% BW.

Evaluation of Additives to Endophyte-Infected Fescue Hay on Growth Performance and Body Temperature of Steers

Endophyte-infected fescue hay (EIFH) was harvested during May from a pasture from a 100% Acremonium coenophialum infection. The effects of feeding treatments 1) EIFH, 2) EIFH with lasalocid, 3) ammoniated EIFH, 4) EIFH with acetylsalicylic acid (ASA), 5) EIFH with selenium-zinc-vitamin E (SeZnE), and 6) EIFH with thiabendazole (TBZ) on gain, body temperature, hay consumption, and feed efficiency were evaluated for a 56-d period during September and October. Forty-eight Hereford x Angus steers averaging 207kg were selected for tendency to elevate body temperature when given access to 100% endophyte-infected fescue pasture. Steers were fed individually and hay was offered at a rate of 2.4% of shrunk body weight, which was adjusted after 28 d. Feed consumption was recorded daily and individual body temperatures were taken twice weekly. Steers were supplemented daily with .9kg of ground shelled corn containing the specified treatment compound. A mineral mixture was provided free choice. Steers fed the ammoniated EIFH gained more (P<.05) than those fed EIFH or EIFH with TBZ. Temperatures of steers fed ammoniated EIFH were lower during the second 28 d than for all other treatments and were lower (P<.05) after 56 d than those of steers fed EIFH (control), EIFH with lasalocid, or EIFH with TBZ. Lasalocid, ASA, SeZnE, or TBZ did not increase gain or decrease body temperature when compared to steers fed EIFH.