Thermoregulatory ability of beef heifers following intake of endophyte-infected tall fescue during controlled heat challenge.

Consumption of endophyte-infected tall fescue during summer months can result in severe hyperthermia in cattle. Six heifers (296+/-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 (Ta) from 21 to 31 degrees C while fed E+ (5 microg ergovaline x kg(-1) x d(-1)) or endophyte-free (E-) diets. Core body temperature (Tcore) 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 Tcore exhibited a diurnal rhythm at a constant Ta of 21 degrees C, with high and low values at 2300 and 1300, respectively. An increase in daily averaged Tcore (P < 0.001) occurred with an increase in Ta 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 < 0.05) and lower blood levels of thyroxine (P < 0.05). Intake of the E+ diet further elevated Tcore 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 Tcore during E+ treatment was associated with an increase in respiration rate (P < 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.

Vacuum-assisted wound closure provides early fascial reapproximation in trauma patients with open abdomens.

BACKGROUND: Damage control and decompressive laparotomies salvage severely injured patients who would have previously died. Unfortunately, many of these patients develop open abdomens. A variety of management strategies exist. The end result in many cases, however, is a large ventral hernia that requires a complex repair 6 to 12 months after discharge. We instituted vacuum-assisted wound closure (VAWC) to achieve early fascial closure and eliminate the need for delayed procedures. METHODS: For 12 months ending June 2000, 14 of 698 trauma intensive care unit admissions developed open abdomens and were managed with VAWC dressing. This was changed every 48 hours in the operating room with serial fascial approximation until complete closure. RESULTS: Fascial closure was achieved in 13 patients (92%) in 9.9 +/- 1.9 days, and 2.8 +/- 0.6 VAWC dressing changes were performed. There were 2 wound infections, no eviscerations, and no enteric fistulas. CONCLUSIONS: Use of VAWC can safely achieve early fascial closure in more than 90% of trauma patients with open abdomens.

Effects of environmental heat and intake of tall fescue seed infested with Acremonium coenophialum on the acid-base status of young bulls.

Effects of high environmental temperature and dietary intake of tall fescue (Festuca arundinacea) seed containing the endophyte Acremonium coenophialum on bovine acid-base status were studied using 3 groups of bull calves (2 Simmental, 1 Angus). Experimental animals were housed in controlled-climate chambers and subjected to gradual increases in environmental temperature, first while being fed an endophyte-free diet and then while being fed a diet containing 17% endophyte-infested fescue seed. Marked acid-base disturbances were not observed in any animals. In general, Pco2, HCO3-, base excess, and arterial blood pH values were reduced in response to heat stress, both with endophyte-free and endophyte-containing diets. In most individuals anion gap increased. These results reflected metabolic compensation for mild chronic alveolar hyperventilation and retention of organic acids. These findings suggest that, under conditions similar to those found during the summer in central Missouri, normal cattle should not be at great risk of developing respiratory alkalosis or other severe acid-base disturbances as a result of heat stress and/or intake of tall fescue endophyte.

Temperature-dependent responses of rats to ergovaline derived from endophyte-infected tall fescue.

Ergovaline, found in Acremonium coenophialum-infected tall fescue, is considered to be responsible for many symptoms associated with fescue toxicosis. Rats were tested to determine time-related thermoregulatory responses to acute treatment with ergovaline during specific thermal challenges. Isolated ergovaline was administered to rats (15 micrograms/kg body mass, i.p.) at controlled ambient temperatures (Ta) of 7 to 9 degrees C (cold) and 31 to 33 degrees C (hot). Treatment at cold Ta resulted in a decrease in rectal temperature (Tre) from 38.0 to 37.0 degrees C at 50 min after injection (P < .05) without complete return to preinjection value at 100 min. Tail temperature (Ttail) exhibited a concomitant 1C degree decrease (P < .05) after ergovaline injection at cold Ta. Also, metabolic heat production decreased from 15.7 to 11.7 W/kg at 20 min after injection of ergovaline (P < .05), with return to normal value at 40 min after injection. Injection of ergovaline at hot Ta increased Tre from 39.0 to 40.6 degrees C at 80 min after injection (P < .05), with no return to preinjection value at 100 min. This was attributed to a reduction in heat transfer across the tail as indicated by the decrease in Ttail from 37.1 to 36.4 degrees C at 40 min after injection (P < .05) and an initial increase in metabolic heat production from 8.4 to 9.4 W/kg at 3 min after injection (P < .05). Ambient temperature was found to be a major determinant of ergovaline response, which included alterations in both thermogenic and thermolytic mechanisms that control thermal balance.

Performance, forage utilization, and ergovaline consumption by beef cows grazing endophyte fungus-infected tall fescue, endophyte fungus-free tall fescue, or orchardgrass pastures.

Two 120-d trials (May to September, 1988 and 1989) determined the effects of grazing tall fescue (two varieties) or orchardgrass on forage intake and performance by beef cows. Each summer, 48 cow-calf pairs grazed endophyte-infected Kentucky-31 tall fescue (KY-31), endophyte-free Mozark tall fescue (MOZARK), or Hallmark orchardgrass (OG) pastures (16 pairs/treatment). Forage OM intakes and digestibilities were determined during June and August each year. Cow and calf BW and milk production were determined every 28 d. During June of both years, OM intakes did not differ (P greater than .10) among treatments. During August of 1988, intakes were 18% lower (P less than .05) by KY-31 cows (1.6% of BW) than by MOZARK or OG cows (average 1.95% of BW); however, no differences (P greater than .10) were measured in August of 1989. Estimates of ergovaline consumption during June from KY-31 were between 4.2 (1988) and 6.0 mg/d (1989), whereas August estimates were between 1.1 (1988) and 2.8 mg/d (1989). Ergovaline in MOZARK estrusa was below detection limits, except in August of 1989. Cows that grazed KY-31 lost three times (P less than .01) more BW than cows that grazed MOZARK or OG (42 vs 9 and 13 kg, respectively). Milk production by KY-31 cows was 25% lower (P less than .01) than that by cows that grazed MOZARK or OG (6.0 vs average of 8.0 kg/d). Similarly, slower (P less than .01) calf gains were noted for KY-31 than for MOZARK or OG (.72 vs .89 and .88 kg/d, respectively). Cows grazing KY-31 experienced accelerated BW loss and reduced milk production and weaned lighter calves than did cows grazing MOZARK or OG. Decreased performance was not explained by consistently reduced forage intakes; hence, altered nutrient utilization was suspected.

Performance, body composition and carcass characteristics of finishing steers as influenced by previous forage systems.

To evaluate effects of previous forage systems on feedlot performance, yearling Hereford steers (average initial weight of 249 kg) were grazed on tall fescue (TF), smooth bromegrass-red clover (BG-RC) or orchardgrass-red clover (OG-RC) pastures before finishing. Serial slaughter was utilized during the first 2 yr of this study to determine changes in carcass characteristics throughout finishing, while steers were slaughtered at approximately 29% body fat during the third year. Steers grazing TF entered the feedlot at lighter weights and maintained lighter weights throughout finishing (P less than .05) even though dry matter intakes and feed conversions were similar (P greater than .05) among treatments. Steers that previously grazed TF had less (P less than .05) body fat, body protein, fat thickness and marbling, smaller (P less than .05) ribeye areas and lower (P less than .05) USDA yield and quality grades than than those that grazed BG-RC and OG-RC. However, linear contrasts indicated that steers grazing TF were compensating in ribeye area, marbling and quality grade as days in feedlot increased. This was confirmed in the third-year study, since carcass characteristics were similar among all steers. During the third year, linear and quadratic contrasts indicated that steers that grazed TF partially compensated in body protein. As days in feedlot increased, live and hot carcass weights, body fat, fat thickness, kidney, pelvic and heart fat, marbling, and USDA yield and quality grades increased (P less than .05), while ribeye area and body protein plateaued. Although carcass characteristics were similar among treatments, steers backgrounded on TF entered the feedlot at lighter weights, and partially compensated in weight after 134 d of finishing.

Influence of forage level on passage rate, digestibility and performance of cattle.

Two trials (feedlot and metabolism) were conducted to evaluate the influence of level of chopped tall fescue hay (FH) in high concentrate diets on average daily gain (ADG), liquid and particulate passage rates, digestibility and in situ digestibility of corn. In the feedlot trial, 36 Hereford steers were fed diets containing 15, 30 and 50% FH in combination with 74, 59 and 39% whole shelled corn (WSC) and a soybean meal supplement. Steers offered 15, 30 and 50% FH consumed 9.0, 9.0 and 7.6 kg dry matter (DM) per d; gained 1.19, .89 and .67 kg; and had DM to gain ratios of 7.6, 10.1 and 11.5, respectively. A negative correlation was observed between fecal pH and ADG (r = -.52) and between fecal pH and fecal starch (r = -.40). In a 4 X 4 Latin-square trial, four cannulated steers were fed 4, 8, 16 or 24% FH in combination with 86, 82, 74 or 66% WSC and a soybean meal supplement. After 14 d of adaptation, steers were offered ytterbium (Yb)-labelled WSC and were ruminally pulse-dosed with chromium ethylenediaminetetraacetic acid (Cr-EDTA) on the first day of the collection period. Steers fed 4, 8, 16 or 24% FH had the following particulate passage rates: 2.3, 2.7, 2.7 and 2.9%/h from fecal analyses; 2.3, 1.7, 2.4 and 2.8%/h from ruminal analyses; 6.0, 5.3, 6.3 and 8.1%/h for liquid, respectively. With increasing FH level, liquid passage rate exhibited linear and quadratic effects (P less than .05), while particulate passage rate (rumen sampling) showed linear and cubic effects (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Videothermometry for assay of fescue foot in cattle.

Surface temperatures of hoofs of calves given toxic anion fractions of tall fescue were measured with an infrared sensitive camera. These changes expressed in terms of a weighted average coronary band temperature relate to clinical signs of fescue foot. The weighted average coronary band temperature values for control calves given saline solution were 27 to 31 C; those values of test calves given anion fractions of tall fescue were as low as 22 +/- 1 C. Videothermometry provides an independent, permanent, objective measure that is useful in assessing fescue-foot potential of tall fescue fractions by intraperitoneal injection. Videothermometry may also serve as a clinical means for determining progression of the total fescue foot syndrome.

Non-volatile Organic Acid Profiles of Peas and Carrots Cooked by Microwaves 1.

Frozen peas and frozen carrots were obtained from a local supermarket and cooked in a consumer microwave oven (550 watts of cooking power) and in an institutional microwave oven (1150 watts of cooking power). Non-volatile organic acids of each vegetable were identified and quantitated by gas-liquid chromatography. Lactic, succinic, malic and citric acids were identified in peas. Relative concentrations of these acids increased after cooking, particularly in samples cooked without water in a consumer microwave oven. Only malic acid was identified in carrots. Concentration of this acid was not affected by any cooking treatments used in the study. The non-volatile organic acids found in both peas and carrots were not correlated with the sensory scores for flavor of these vegetables. However, total non-volatile organic acids found in peas tended to be negatively correlated with the total chlorophyll retention of all the cooked pea samples.

Induction of fescue foot syndrome in cattle by fractionated extracts of toxic fescue hay.

Tall fescue (Festuca arundinacea Shreb) hay from a source known to cause "fescue foot" in grazing cattle was extracted with 80% ethanol. The ethanolic extract was further refined and fractionated into cation,nion, and neutral f fractions by ion-exchange chromatography. The cation fraction was partitioned with alkaline-chloroform to give chloroform-extractable cation and residual cation fractions. All fractions plus the crude ethanolic extract were assayed for toxic activity by intraperitoneal injection into 12 calves (weighting 152.4 to 241.3 kg each) over a 14-day period. Clinical signs of fescue foot were observed on the 5th day in calves given the anion and crude ethanolic extracts. Lameness, swelling, and reddening of the rear coronary bands, discoloration of the tip of the tail, and other signs of fescue foot were seen. Microscopically, coronary bands and tail tips of affected calves had blood vessels with thick walls and small lumens.