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1.
Thirty mares in late gestation were used in a 3-yr study to assess effects of the tall fescue endophyte Acremonium coenophialum on serum prolactin (PRL) and progesterone. Two paddocks of each treatment, 0 or 100% infected 'Kentucky 31' tall fescue, were grazed by the mares for 21 d. Blood was collected three times per week until parturition. At 7-d intervals, mares were challenged with thyrotropin-releasing hormone (TRH) while grazing and blood was collected postinjection. Mares grazing 100% infected tall fescue (E+) had decreased serum PRL compared with mares grazing the 0% infected tall fescue (E-) in 2 of 3 yr. Within 8 d postgrazing, serum PRL for E+ mares equaled or surpassed values of the E- mares. Serum PRL was not different during the 3rd yr. In response to TRH, serum PRL rate of increase was similar between treatments but remained elevated (P less than .01) in the E+ mares at the 180-, 240-, and 300-min sample times. Serum progesterone was lowered (P less than .05) by E+ but increased to control values within 10 d postgrazing. It is concluded that serum PRL and progesterone in the gravid mare were decreased by the presence of A. coenophialum in 'Kentucky 31' tall fescue grass but normal levels were reestablished within 2 to 3 wk.  相似文献   

2.
Tall fescue (Festuca arundinacea Schreb.) infected with the endophyte Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin) causes fescue toxicosis in cattle grazing the forage, but effects of the endophyte were considered to be abated soon after removal of the animals from pastures. Tasco-Forage, a proprietary extract from the brown seaweed Ascophyllum nodosum, is a known source of cytokinins and has increased antioxidant activity in both plants and the animals that graze the forage. Tasco was applied at 0 and 3.4 kg/ha to infected and uninfected tall fescue pastures in Virginia and Mississippi. Forty-eight steers grazed the pastures at each location during each of 2 yr (n = 192) before being transported to Texas for feedlot finishing. On arrival at the feedlot, steers from Tasco-treated pastures had higher (P < 0.01) monocyte phagocytic activity and tended (P < 0.07) to have higher major histocompatibility complex class II expression than steers that grazed the untreated pastures. A depression (P < 0.05) in monocyte immune cell function due to grazing infected fescue was detected throughout the feedlot finishing period but was reversed by Tasco. Rectal temperatures were elevated (P < 0.07) in steers that had grazed the infected tall fescue when they arrived in Texas, but by d 14 no difference was detected. However, by d 28 the temperature effects of infected tall fescue were reversed. Steers that had grazed infected fescue had lower (P < 0.01) rectal temperatures on d 112 of the feedlot period, demonstrating a much longer-lasting effect of the endophyte on thermoregulatory mechanisms than previously thought. Steers that had grazed Tasco-treated pastures had higher (P < 0.01) rectal temperatures on d 56 than steers that had grazed untreated fescue. Steers that had grazed the Tasco-treated pastures had higher marbling scores (P < 0.05) regardless of the endophyte, but no effect of Tasco or endophyte on gain was measured. Our data suggest that Tasco application to tall fescue pastures alleviated some of the negative effects of tall fescue toxicity.  相似文献   

3.
Cattle grazing tall fescue (Festuca arundinacea Schreb.) often develop fescue toxicosis. This condition is thought to be caused by ergot alkaloids produced by the endophyte Neotyphodium coenophialum. Endophytes from wild tall fescue plants, which do not produce ergot alkaloids, were transferred into the endophyte-free tall fescue germplasm, HiMag. The novel associations also lacked the ability to produce ergot alkaloids. Our objective was to determine whether cattle grazing these novel endophyte associations showed signs of fescue toxicosis. At the Fayetteville, Arkansas location, tester steers (n = 72) were assigned to one of four pasture treatments: endophyte-free HiMag tall fescue (HiMag-); 'Kentucky-31' tall fescue infected with its native, toxic endophyte (KY+); and two novel endophyte-infected tall fescue associations, HiMag4 and HiMag9. At the Mount Vernon, Missouri location, steers (n = 54) were used to test three of the four cultivars (HiMag9 was not tested). Ergot alkaloid concentrations in the forage of HiMag4 and HiMag9 were low or undetectable. Respiration rate, rectal temperature, ADG, and hair scores were measured during the grazing period. Blood was collected via jugular venipuncture and used for prolactin, aspartate aminotransferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), cholesterol, triglyceride, and creatinine analysis. Weight gains by steers grazing HiMag4 and HiMag9 did not differ from those of steers grazing HiMag-, but were greater than gains (P < 0.05) by steers on the KY+ treatment. Steers grazing KY+ had higher (P < 0.05) respiration rates, rectal temperatures, and hair scores than did steers grazing novel endophyte and HiMag- pastures. Prolactin, ALP, cholesterol, LDH, and triglycerides all were suppressed (P < 0.05) in steers grazing KY+ compared with steers grazing novel endophyte and HiMag- pastures. Steers grazing the novel endophyte tall fescues did not suffer from the decreased weight gains and toxicities associated with fescue toxicosis, resulting in enhanced animal production.  相似文献   

4.
A 2-yr grazing experiment was conducted with crossbred steers (8 to 10 mo and with initial BW of 304 kg ± 34 kg in 2008 and 277 kg ± 24 in 2009) to evaluate animal performance and pasture responses of a late maturing tall fescue [Lolium arundinaceum (Schreb.) Darbysh; KYFA9301] population infected with the AR584 novel, non-toxic endophyte (Neotyphodium coenophialum; NE9301) as compared with Kentucky 31 fescue infected with the common toxic endophyte strain (KY31), 'Jesup' MaxQ fescue infected with the AR542 endophyte (MaxQ), and endophyte-free KYFA9301 (EF9301). Treatments were assigned for seeding in 1.0-ha pastures in a randomized complete block design with 3 replications. Pastures were grazed from 6 May to 23 July in 2008 (76 d) and 2 April to 25 June in 2009 (84 d). Each pasture was grazed with 4 tester steers and put-and-take steers were used to maintain forage mass at 2,500 ± 250 kg DM/ha. Shrunk BW was taken at initiation and termination of grazing each year. Rectal and skin temperatures were recorded, and jugular blood was collected each year at approximately d 28, 56, and study completion. Forage samples were collected at 2-wk intervals for analyzing CP, IVDMD, ADF, and NDF. Responses were analyzed with mixed models, and preplanned orthogonal contrasts were used to compare KY31 with non-toxic fescues, EF9301 vs. novel endophyte fescues, and NE9301 vs. MaxQ. All steer responses were similar (P > 0.10) among the non-toxic fescues. Average daily gains and total BW gain/ha for the 3 non-toxic fescues were greater (P < 0.001) than for KY31. Rectal/skin temperatures for the 3 non-toxic fescues were less (P < 0.001) and serum prolactin concentrations were greater (P < 0.01) than for KY-31. Pasture carrying capacity was greater (P = 0.003) for KY31 than the 3 non-toxic fescues and was greater for EF9301 (P = 0.017) than the 2 novel endophyte fescues. However, stocking rates (kg BW/ha) at the initial and midpoint days of grazing were similar (P > 0.40) among endophyte-fescue combinations, but by the end of the grazing season, stocking rate was greater (P < 0.001) for KY31 than for the non-toxic fescues and was greater (P = 0.053) for NE9301 than for MaxQ. Results indicated that NE9301 is as effective as EF9301 and MaxQ in improving BW gain and alleviating fescue toxicosis and that NE9301 can provide greater carrying capacities than MaxQ in late June and July.  相似文献   

5.
The objective of the current study was to delineate changes that occur in serum analytes and blood cellular elements in cattle that graze endophyte-infested (Neotyphodium coenophialum) tall fescue. Tall fescue is grown on more than 35 million acres (14.2 million ha) of pasture in the United States, and three-fourths of the pastures are infected with the endophyte at a 60% or greater level. Tall fescue toxicosis caused by endophyte-produced ergot alkaloids continues to be the most important grass-related disease in the United States, in terms of economic loss to animal producers. However, the agronomic attributes of tall fescue make it an attractive forage species because of its ability to withstand cool temperatures, drought, poor soil conditions, and intensive defoliation from herbivore species, including insects. Tall fescue toxicosis is a complex disease and the need exists to understand the mechanisms of the toxic effects in order to institute effective, prophylactic control measures. Our group previously reported changes that occur in serum biochemical analytes of cattle that graze endophyte-infected tall fescue. An additional year's worth of data have been added, strengthening and corroborating these data. Consistent and significant changes associated with tall fescue toxicosis during the 3-yr study included decreased serum concentrations of cholesterol, globulin (increased albumin/globulin ratio), prolactin, total protein, and copper. The activity of alanine aminotransferase was decreased in serum, whereas an increase in serum concentrations of creatinine and total bilirubin occurred. The present report also documents comparative hemograms of cattle that grazed endophyte-infected or endophyte-free tall fescue over a prolonged period. The mean erythrocyte counts were increased in cattle that grazed endophyte-infected tall fescue, whereas mean corpuscular hemoglobin and mean corpuscular volume were decreased, as were mean eosinophil counts. Thus, repeatable changes have been identified that occur in serum biochemical and blood cellular values of cattle grazing endophyte-infected tall fescue that will aid in understanding the pathogenesis of the disease. In addition, these consistently altered parameters can be used to assess the effectiveness of potential prophylactic treatments.  相似文献   

6.
Livestock grazing endophyte (Acremonium coenophialum Morgan-Jones and Gams)-infected tall fescue (Festuca arundinacea Schreb.) perform poorly due to tall fescue toxicosis, especially when animals are under heat stress. In order to determine whether thiamin promotes recovery from tall fescue toxicosis, 1 or 0 g of thiamin per day, as mononitrate, was fed orally to adult Angus (Bos taurus) cows (380 +/- 8 kg) grazing either tall fescue pasture with and without endophyte or alfalfa (Medicago sativa L.). A tethered grazing system employing a split-plot design was used to estimate intake and components of ingestive behavior. No significant differences attributable to thiamin supplements were seen in rates of intake and biting, grazing time and intake per bite when cows grazed endophyte-infected tall fescue during the first 4 d of exposure. When cows grazed endophyte-infected (greater than 95%) tall fescue with 2,091 micrograms/g loline alkaloids after 4 d of exposure, the untreated animals ingested herbage dry matter (DM) at 1.19 kg/h, whereas the cows receiving thiamin ate 1.57 kg/h (P less than .05). Cattle achieved these rates of DM intake by forming bites of 1.0 and 1.2 g DM at 24 and 26 bites/min when treated with 0 and 1 g of thiamin per day, respectively. Thiamin supplements had no effect on ingestive behavior of cows grazing endophyte-free tall fescue or alfalfa after exposure to these forages for 4 d. Responses to thiamin generally were greater when cattle grazing endophyte-infected tall fescue were exposed to heat stress. Oral thiamin supplementation may alleviate tall fescue toxicosis of beef cattle during warm weather.  相似文献   

7.
OBJECTIVE: To determine whether ingestion of fescue seed infected with the endophyte Neotyphodium coenophialum would alter thyroid function in adult horses. DESIGN: Original study. ANIMALS: 4 adult mares that were not pregnant and 6 adult geldings. PROCEDURE: Thyrotropin releasing hormone stimulation tests were performed while horses received a standard diet and after infected seed (2.3 kg/d [5 lb/d]) had been fed for 1 and 2 months. Serum prolactin concentrations were measured to verify endophyte absorption. RESULTS: Serum prolactin concentrations indicated that at least 8 of 10 horses absorbed the endophyte. Baseline concentrations of thyroid stimulating hormone, total and free triiodothyronine, and total and free thyroxine and the change in hormone concentrations in response to administration of thyrotropin releasing hormone (1 mg, i.v.) were not altered by ingestion of endophyte-infected fescue seed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that ingestion of fescue seed infected with the endophytic fungus N. coenophialum for 2 months has little effect on thyroid function in adult horses that are not pregnant.  相似文献   

8.
Livestock grazing endophyte (Acremonium coenophialum)-infected tall fescue (Festuca arundinacea Schreb. cv. Kentucky 31) at high ambient temperatures may suffer from fescue toxicosis. Adult Angus cows (Bos taurus) were fed 0 to 1 kg/d of 70% infected tall fescue seed containing about 4.4 g of loline alkaloids in factorial combination with thiamin at 0 or 1 g/d. Cows assigned to the zero level of tall fescue seed received a supplement of equivalent energy and protein. Ingestive behavior was measured at 1330 to 1430 EDT during two 4-d periods in two consecutive weeks in August on alfalfa (Medicago sativa L.) pastures using a tethered grazing system. Alfalfa intake per measured grazing session of cows given tall fescue seed declined linearly (P less than .01) as air temperatures during grazing increased above 25 degrees C, largely because of shorter grazing meals. Thiamin increased alfalfa intake per measured grazing session by extending grazing time. Alkaloids in ingested endophyte-infected tall fescue induce thiamin deficiencies in cattle that result in symptoms of tall fescue toxicosis.  相似文献   

9.
The 1st outbreak of fescue toxicosis in South Africa was recently confirmed in a Brahman herd at Perdekop, near Standerton, in Mpumalanga province, South Africa. Within 3 weeks of being placed on a fescue pasture in mid-winter, 50 of 385 cattle developed lameness and/or necrosis of the tail. The farmer had established Festuca elatior L. (tall fescue, Iewag variety) on c. 140 ha for winter grazing. Fescue may be infected by an endophyte, Neotyphodium coenophialum, which produces ergot alkaloids, in particular ergovaline. Ergovaline concentrations in basal leaf sheaths and grass stems collected during the outbreak ranged from 1720-8170 ppb on a dry-matter basis.  相似文献   

10.
Effects of fescue toxicosis on reproduction in livestock.   总被引：3，自引：0，他引：3  
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.  相似文献   

11.
Most of the tall fescue pastures in the United States are infected by an endophyte, N. coenophialum. The fungus derives nutrients from the plant while supplying the plant with toxins for defense. The most detrimental toxins for animals in tall fescue are ergopeptine alkaloids, especially ergovaline. Ergovaline functions as a dopamine D2 agonist and alters prolactin and several other hormones in the body. Pregnant mares are most susceptible during their last month of gestation. Clinical signs include prolonged gestation, dystocia, retained placentas, agalactia, and dysmature foals that are either stillborn or weak.  相似文献   

12.
Seaweed (Ascophyllum nodosum) is a known source of plant growth regulators, and application to turfgrasses has increased activity of the antioxidant superoxide dismutase (SOD) and specific vitamin precursors. Increased antioxidant activity in both plants and animals diminishes oxidative stress. Two pasture experiments investigated effects of Tasco-Forage (a proprietary seaweed-based product) applied to tall fescue (Festuca arundinacea) on antioxidant activity in plants and in ruminants that grazed the forage. In Exp. 1, fescue was 70 to 100% infected with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Twenty-four wether lambs (initial BW 41 kg; SD = 5) grazed fescue treated with 0, 1.7, or 3.4 kg Tasco/ha applied in April and July, 1994, with four replications per treatment. Grazing occurred for 26 d beginning April 21 and for 22 d beginning July 19. In July, there was a linear increase in daily gains (P < 0.05), and serum vitamin A (P < 0.13) and whole-blood Se (P < 0.10) tended to increase in lambs grazing Tasco-treated fescue. In Exp. 2,48 Angus and Angus x Hereford steers (initial BW 245 kg; SD = 20) grazed infected or uninfected tall fescue in Virginia that was treated (3.4 kg/ ha) or untreated with Tasco in April and July, 1995. Steers that grazed infected tall fescue had lower (P < 0.02) serum vitamin A and E and tended (P < 0.07) to have lower whole-blood Se in September compared with steers that grazed uninfected tall fescue. Tasco decreased (P < 0.06) serum vitamin E but tended to increase whole-blood Se (P < 0.10) in September and serum vitamin A in July (P < 0.12). During 1996 and 1997, the experiment was repeated in Virginia with Angus steers and was replicated at Prairie, MS, where 1/4 Brahman x 3/4 Angus steers were used. Forty-eight steers were included at each location in each year (n = 192 total steers for 1996 and 1997). Steers that grazed infected tall fescue in Mississippi had lower (P < 0.05) serum vitamin E by the end of the grazing season. At both locations Tasco increased (P < 0.05) activity of superoxide dismutase in both infected and uninfected fescue. The endophyte in tall fescue seemed to decrease antioxidant activity in grazing steers, whereas Tasco seemed to increase antioxidant activity in both the forage and the grazing ruminant. Tasco may provide opportunities to reduce oxidative stress in plants and animals.  相似文献   

13.
Effects of applying Tasco-Forage, an Ascophyllum nodosum seaweed-based product prepared by a proprietary process, to endophyte (Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin)-infected and endophyte-free tall fescue (Festuca arundinacea Schreb.) were studied in each of 3 yr (1995, 1996, and 1997) in Virginia and in 1996 and 1997 in Mississippi. There were 48 steers at each location in each year (n = 240) in a 2 x 2 x 2 factorial arrangement with two replications at each location. Steers in Virginia were Angus and Angus x Hereford with initial weights of 245 kg (SD = 20), 234 kg (SD = 9), and 265 kg (SD = 5) in yr 1, 2, and 3, respectively. Steers in Mississippi were 3/4 Angus and 1/4 Brahman and weighed 230 kg (SD = 8) and 250 kg (SD = 2) in yr 2 and 3, respectively. Tasco (3.4 kg/ha) was dissolved in water and applied to pastures in April before grazing was begun and again in July at the same rate. The grazing period was from mid-April to late September or mid-October. Total gains were higher (P < 0.05) for steers grazing uninfected than for those grazing endophyte-infected tall fescue. Rectal temperatures were increased (P < 0.05) due to endophyte infection at both locations; Tasco application decreased temperature of steers grazing infected fescue in Virginia (interaction, P < 0.07) but increased temperatures of steers grazing infected fescue in Mississippi (interaction, P < 0.05). Presence of the endophyte resulted in rough hair coats and loss of hair color, but the effect was partially offset (P < 0.05) by Tasco application in Virginia in 1995. Both monocyte phagocytic activity (all years and locations) and major histocompatibility complex class II expression (1995 only) were decreased (P < 0.05) in steers due to endophyte infection, but this effect was reversed (P < 0.05) by application of Tasco to pastures. Application of the extract from A. nodosum seems to have use in alleviating adverse effects of endophyte on immune function and may improve hair coat condition in cattle grazing infected fescue, but effects on rectal temperature varied due to location.  相似文献   

14.
Increased costs of annual establishment of small grain pasture associated with fuel, machinery, and labor are eroding the profitability of stocker cattle enterprises. Interest has therefore increased in development of cool-season perennial grasses that are persistent and high quality. This study occurred on 24 ha (divided into thirty 0.81-ha paddocks) located at the University of Arkansas Division of Agriculture Livestock and Forestry Branch Station, near Batesville. Two tall fescue (Festuca arundinacea Schreb.) cultivars infected with novel endophytes (NE), Jesup infected with AR542 endophyte (Jesup AR542), and HiMag infected with Number 11 endophyte (HM11) were established in September 2002. Jesup AR542 and HM11 were compared with endemic endophyte Kentucky 31 (KY-31) tall fescue; wheat (Triticum aestivum L.) and cereal rye (WR, Secale cereale L.) planted in September 2003, 2004, and 2005; and annual ryegrass [RG, Lolium perenne L. ssp. multiflorum (Lam.) Husnot] planted in September 2004 and 2005. Each year, 3 steers (3.7 steers/ha) were placed on each pasture for fall and winter grazing, and 5 steers (6.2 steers/ha) were placed on each pasture for spring grazing. Animal performance is presented by year in the presence of a year x treatment interaction (P < 0.01). Body weight gain per hectare of steers grazing NE tall fescue was greater (P < 0.01) than those of KY-31 and WR during 2003 to 2004, whereas in 2004 to 2005, BW gain per hectare of steers grazing NE and RG did not differ (P < or = 0.29) and was greater (P < 0.01) than that of WR, which was greater (P < 0.01) than that of KY-31. During 2005 to 2006, BW gain per hectare was greater (P < 0.01) for steers grazing RG than those of NE and WR, which did not differ (P > or = 0.14). Body weight gain per hectare was least (P < 0.01) for steers grazing KY-31. Average net return of NE tall fescue was greater (P < 0.01) than KY-31, but profitability of NE did not consistently differ from cool-season annuals. Across the 3-yr study, NE tall fescue produced net returns per hectare of $219; this level of profitability would require 4 yr for a new planting of NE tall fescue to break even. Novel endophyte tall fescues offer potential benefits related to decreased risk of stand establishment of annual forage crops, longer growing season, and acceptable animal performance.  相似文献   

15.
Ergopeptine alkaloid exposure is common in pregnant mares. Many mares live in geographic areas where Neotyphodium coenophialum-infected tall fescue is the dominant grass in pastures and hay. A variety of grasses and cereal grains can be infected by Claviceps purpurea, and fungal sclerotia can contaminate forage and especially ground and pelleted feed. An understanding of the endocrine alterations associated with ergopeptine alkaloid exposure during pregnancy is necessary for the diagnosis of potential exposure to these compounds and for eective prophylaxis and therapy.  相似文献   

16.
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)  相似文献   

17.
This study was designed to determine the efficacy of a single injection of the long-acting D2-dopamine receptor antagonist, fluphenazine deconoate, on the clinical symptoms and plasma prolactin concentrations of mares grazing endophyte-infected tall fescue. Twelve mares were maintained on an 80% endophyte-infected tall fescue pasture. Group T (n=6) received 25 mg of fluphenazine deconoate i.m. on day 320 of gestation, while group C (n=6) served as untreated controls. Daily plasma samples were obtained and analyzed for prolactin using a homologous equine radioimmunassay. The prolactin data were then grouped according to week after treatment (day 320 to 327=Week 1; day 328 to 335=Week 2) and to week prior to parturition (day 0 to −7=Week −1; day −8 to −14=Week −2). A single injection of fluphenazine had no effect on experiment-wide plasma prolactin concentrations or on prolactin concentrations relative to week of treatment or parturition. However, a treatment by time period interaction was observed. Plasma prolactin concentrations were higher (p<.05) in treated mares (35.6±29.1 ng/ml) on week 2 compared to control mares (14.9±14.2 ng/ml). In addition, there was a trend (p=.09) for fluphenazine treated mares (68.1±64.2 ng/ml) to exhibit higher prolactin concentrations one week prior to parturition when compared to control animals (27.8±27.4 ng/ml). Peak prolactin was higher (p<.05) in fluphenazine treated mares and in mares which foaled normally. Gestation lengths were shorter (p<.05) in group T (330±2.9 days) compared to group C (341±3.2 days). It appeared that treated mares exhibited fewer clinical signs of fescue toxicosis than mares in group C. Four out of six of the untreated mares exhibited at least one of the clinical signs of fescue toxicosis (agalactia, stillbirth, thickened placenta, retained placenta) while only one treated mare showed obvious clinical symptoms. These data indicate that a single injection of a long-acting dopamine receptor antagonist may be beneficial in reducing the effects of fescue toxicosis in pregnant mares grazing endophyte-infected tall fescue pastures. However, additional research is needed to determine the most effective dosage and administration times.  相似文献   

18.
Two varieties of chopped grass seed straw, tall fescue (Festuca arundinaces L.) and perennial ryegrass (Lolium perenne L.), were identified as alternative sources to wood sawdust or shavings as bedding for use by Pacific Northwest broiler producers. However, some broiler growers expressed concern that straw may be contaminated with endophytes, symbiotic fungi that are known to be toxic to livestock. The primary toxic compound of concern for livestock in endophyte infected grass straw is ergovaline.Two experiments were conducted to determine if broiler performance was affected by either the feeding of endophyte infected grass seed containing ergovaline, or rearing broilers on endophyte infected grass seed straw. The exposure of broilers to either endophyte-infected chopped straw as bedding and/or feeding endophyte infected ground grass seed in the diet with ergovaline levels as high as 423 ppb, did not significantly affect performance or the micro anatomy of kidney or liver tissues.  相似文献   

19.
The influence of supplemental phenothiazine (P) on growth and physiological criteria was studied in parasite-controlled calves consuming endophyte (Acremonium coenophialum)-infected tall fescue (TF). In Exp. 1, nine Angus heifer calves (312 kg) were supplemented with 227 g corn-mineral (CM) mix twice daily and allowed ad libitum access to either high-endophyte (HE) G1-307 (greater than 90% infected) or low-endophyte (LE) Kenhy (less than 1% infected) tall fescue hay, or HE G1-307 plus 2 g/d P in the daily supplement. Calves were kept in temperature-controlled rooms for 12 d at 21 degrees C followed by 7 d at 34 degrees C. In Exp. 2, 48 Angus steer calves (312 kg) were assigned to treatment groups consisting of calves grazing HE Kentucky-31 (57% infected) or LE Johnstone (less than 1% infected) TF, and supplemented daily with either .91 kg of a control CM mix or .91 kg of the CM mix containing 2 g P. The 112-d experiment was initiated on May 4 with BW and rectal temperature (RT) measurements and blood collected at 28-d intervals. In both experiments, calves receiving HE TF had lower (P less than .01) serum prolactin concentrations (PRL) at elevated ambient temperature and lower (P less than .01) serum alkaline phosphatase activities (AP) but higher (P less than .01) RT than calves consuming LE TF regardless of ambient temperature.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Experiments were conducted with rats and mice to evaluate the effect of the consumption of endophyte (Acremonium coenophialum) and associated toxin(s) infected tall fescue on humoral and cellular aspects of immune function. Treatment diets were: (1) rodent chow (RC) or (2) rodent chow mixed 1:1 (w/w) with endophyte infected (E+) or (3) non-infected (E-) tall fescue seed. Rats fed the E+ diet in experiment 1 (43 days) exhibited a lower (P less than 0.05) serum titer to sheep red blood cell (SRBC) immunization than those fed the E- diet (38.4 vs 131.3). The E+ rats also had lower (P less than 0.01) white cell counts than either RC or E- groups (5225 vs 8959 and 7491/mm3). Spleen cells from mice fed the E+ diet for 37 days exhibited a reduced (P less than 0.05) response to the mitogens Concanavalin A and lipopolysaccharide. Flow cytometric analysis revealed a significant (P less than 0.01) 42% increase in T suppressor cell numbers in spleens of mice fed the E+ vs RC diets.  相似文献   

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