Search

Consumption of endophyte-infected tall fescue during summer months can result in severe hyperthermia in cattle. Six heifers (296 [+ or -] 8.3 kg BW) were used to determine changes in body temperature control that occur with consumption of an endophyte-infected tall fescue diet during controlled heat challenge. All animals were exposed in five separate periods to a step increase in ambient temperature ([T.sub.a]) from 21 to 31 [degrees] C while fed E+ (5 [micro]g ergovaline [multiplied by] [kg.sup.-1] [multiplied by] [d.sup.-1]) or endophyte-free (E-) diets. Core body temperature ([T.sub.core]) was monitored continuously using implanted, telemetric temperature transmitters. Heat production and heat loss were also measured at selected times to identify primary effects of E+ on thermal balance. Pretreatment [T.sub.core] exhibited a diurnal rhythm at a constant [T.sub.a] of 21 [degrees] C, with high and low values at 2300 and 1300, respectively. An increase in daily averaged [T.sub.core] (P [is less than] 0.001) occurred with an increase in [T.sub.a] from 21 to 31 [degrees] C. Likewise, all phases of the daily cycle increased equally during this challenge. This increase at 31 [degrees] C was associated with higher levels of respiration rate, skin temperature, respiratory vaporization, and skin vaporization (P [is less than] 0.05) and lower blood levels of thyroxine (P [is less than] 0.05). Intake of the E+ diet further elevated [T.sub.core] in heifers during the short-term heat challenge (2 d), and the effect was most pronounced at 0000 to 0300 and declined thereafter. The increase in [T.sub.core] during E+ treatment was associated with an increase in respiration rate (P [is less than] 0.05), whereas metabolic heat production, skin temperature, skin vaporization and respiratory vaporization were unaffected. These results show that consumption of an E+ diet during continuous heat challenge results in a marked increase in core body temperature, especially during nighttime exposure to heat stress, due primarily to a reduction in cutaneous heat transfer, with no effect on heat production or other measured avenues of heat loss. Key Words: Cattle, Circadian Rhythm, Endophytes, Heat

Purple coneflower [Echinacea purpurea (L.) Moench] is an increasingly popular crop because of its value in the U.S. botanical industry. At present, there is no rapid method of analyzing it for chicoric acid, the predominant phenolic acid associated with immunostimulation in humans. The objective of this study was to quantify chicoric acid in purple coneflower roots by near infrared (NIR) reflectance spectroscopy. One hundred sixty-nine plants were harvested and their root tissues analyzed for chicoric acid by high performance liquid chromatography (HPLC). Root samples were scanned between 1100 and 2498 nm and reflectance data recorded. The HPLC data were regressed against infrared spectra to develop empirical prediction equations. The optimum prediction equation produced coeffecients of determination for calibration and cross validation of 0.90 and 0.86, respectively. The mean chicoric acid concentration was 8.29 g kg [DM.sup.-1] and the standard errors of calibration and cross validation were 0.89 and 1.06 g kg [DM.sup.-1], respectively. We conclude that NIR reflectance spectroscopy can accurately quantitate chicoric acid in purple coneflower., PURPLE CONEFLOWER is a crop gaining popularity for its value as a dietary supplement. This species is grown, extracted, and made into dietary supplements that currently rank among the highest [...]

Ergot alkaloids cause fescue toxicosis when livestock graze endophyte-infected tall fescue. It is generally accepted that ergovaline is the toxic component of endophyte-infected tall fescue, but there is no direct evidence to support this hypothesis. The objective of this study was to examine relative and potential transport of ergoline and ergopeptine alkaloids across isolated gastric tissues in vitro. Sheep ruminal and omasal tissues were surgically removed and placed in parabiotic chambers. Equimolar concentrations of lysergic acid, lysergol, ergonovine, ergotamine, and ergocryptine were added to a Kreb's Ringer phosphate (KRP) solution on the mucosal side of the tissue. Tissue was incubated in near-physiological conditions for 240 min. Samples were taken from KRP on the serosal side of the chambers at times 0, 30, 60, 120, 180, and 240 min and analyzed for ergot alkaloids by competitive ELISA. The serosal KRP remaining after incubation was freeze-dried and the alkaloid species quantified by HPLC. The area of ruminal and omasal tissues was measured and the potential transportable alkaloids calculated by multiplying the moles of transported alkaloids per square centimeter of each tissue type by the surface area of the tissue. Studies were conducted to compare alkaloid transport in reticular, ruminal, and omasal tissues and to determine whether transport was active or passive. Ruminal tissue had greater ergot alkaloid transport potential than omasal tissue (85 vs 60 mmol) because of a larger surface area. The ruminal posterior dorsal sac had the greatest potential for alkaloid transport, but the other ruminal tissues were not different from one another. Alkaloid transport was less among reticular tissues than among ruminal tissues. Transport of alkaloids seemed to be an active process. The alkaloids with greatest transport potential were lysergic acid and lysergol. Ergopeptine alkaloids tended to pass across omasal tissues in greater quantities than across ruminal tissues, but their transport was minimal compared to lysergic acid and lysergol. Key Words: Ergot Alkaloids, Festuca, Rumen Mucosa, Toxicity

Abstract: Theories suggest that incorporating alfalfa (Medicago sativa L.; Alf) or birdsfoot trefoil (Lotus corniculatus L.; BFT) into endophyte‐infected tall fescue (Festuca arundinaceas Schreb.; E+TF) pasturelands may improve livestock production. We investigated how planting configuration might influence plant secondary metabolites (PSM) and nitrogen concentration in these forages. Total nitrogen (N), in addition to condensed tannins (CT), saponins and ergovaline (EV), was compared in BFT, Alf and E+TF, respectively, when forages grew in monocultures and all possible two‐way “mixtures” using a block design with repeated measures in three blocks. Ergovaline (p < .01) and N (p < .001) concentrations in E+TF were greater when growing adjacent to legumes than when growing in monoculture, and N and EV concentrations in E+TF were positively correlated (r = .51; p = .001). No differences in saponins or CT were found when Alf or BFT grew in monoculture or in two‐way mixtures (p > .10). We conducted an in vitro trial to determine whether CT or saponins isolated from BFT and Alf, respectively, would bind to EV in water. Ergovaline bound to saponins to a greater extent (39%; SE = 0.25) than CT (5.1%; SE = 5.13; p < .05). Because EV was lower in E+TF monocultures than in E+TF–legume mixtures, and because CT and saponins may form complexes with EV which may alleviate fescue toxicosis, animals may benefit from systems which allow them to graze monoculture patches of E+TF and Alf or BFT rather than grass–legume mixtures. [ABSTRACT FROM AUTHOR]

The aim of this study was to verify the carryover of aflatoxin B1 from feed to lambari fish. Aflatoxins (AF) were incorporated into feed, checking the levels by HPLC. Treatments were: Control, feed without toxin; A, feed + 10 µg AFB1 kg–1; B, feed + 20 µg AFB1 kg–1; and C, feed + 50 µg AFB1 kg–1. Juveniles of lambari fish were placed in 12 aquariums at a density of 50 fish/m2. Fish were fed twice a day with extruded feed, at 5% of animal biomass. The unit sample was constituted by a pool of 10 fish. AFs B1, B2, G1, G2 and M1 were quantified by HPLC in fish muscle and liver after 30, 60, 90 and 120 days of experiment. There was accumulation of AFs is fish liver and muscle, mainly after 90 days. Fish from treatment C had higher levels of AFB1 in muscle when compared with the others, and AFB1 in muscle at 120 days was similar to the levels in feed. Therefore, when lambari fish is exposed on a daily and long-term basis to AFs in feed, the regulation limits for AFs in animal feed do not guarantee safety for consumers. [ABSTRACT FROM AUTHOR]