Bermudagrass management in the Southern Piedmont USA. V: Gastrointestinal parasite control in cattle.

Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae.

Bermudagrass management in the Southern Piedmont USA: VI. Soil-profile inorganic nitrogen.

Fate of applied N in forage-based agricultural systems is important to long-term production and environmental impacts. We evaluated the factorial combination of N fertilization targeted to supply 20 g N m 2 yr(-1) and harvest strategies on soil-profile inorganic N during the first 5 yr of 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.

Bermudagrass management in the Southern Piedmont U.S. IV. Soil surface nitrogen pools.

The fate of nitrogen (N) applied in forage-based agricultural systems is important for understanding the long-term production and environmental impacts of a particular management strategy. We evaluated the factorial combination of three types of N fertilization (inorganic, crimson clover [Trifolium incarnatum L.] cover crop plus inorganic, and chicken [Gallus gallus] broiler litter pressure and four types of harvest strategy (unharvested forage, low and high cattle [Bos Taurus] grazing pressure, and monthly haying in summer) on surface residue and soil N pools during the first 5 years of 'Coastal' bermudagrass (Cynodon dactylon [L.

Putative temporal variability of Escherichia coli ribotypes from yearling steers.

Escherichia coli is a ubiquitous component of the intestinal microflora of warm-blooded animals, and is an indicator of fecal contamination of surface waters. Ribotype profiling of E. coli is one of several genotypic methods that has been developed to determine the host origin of fecal bacteria.

Particulate and non-particulate fractions of soil organic carbon under pastures in the Southern Piedmont USA.

Pasture management can be effective at sequestering soil organic C. We determined the depth distribution of particulate organic C (POC), non-particulate organic C (NPOC), particulate-to-total organic C (POC-to-TOC) ratio, and particulate organic C-to-N (POC-to-N) ratio under pastures near Watkinsville, GA, USA. POC was highly related with total organic C (TOC), but became an increasingly larger portion of TOC near the soil surface, where both pools were greatest.

Ergot alkaloid transport across ruminant gastric tissues.

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.

Anti-inflammatory effects of ergotamine in steers.

The objective of this experiment was to investigate whether the ergot alkaloid, ergotamine (ET), an alkaloid used to model fescue toxicosis in cattle, modifies the response of cattle to endotoxin (LPS) challenge. Steers (n = 16) were divided into the following treatment groups: control (C), ergotamine (ET), endotoxin (LPS), and ET + LPS. ET and ET + LPS groups received a single bolus intravenous injection of ET (40 microg.

Urinary alkaloid excretion as a diagnostic tool for fescue toxicosis in cattle.

Fescue toxicosis research studies have often included serum prolactin as a physiologic index of the disorder. Serum prolactin has not been used as a clinical measure of fescue toxicosis because of variation associated with sex and physiologic condition of the animal and climatic and seasonal factors. The primary excretory route of the alkaloids responsible for this toxicosis is the urine.

Increased responsiveness to intravenous lipopolysaccharide challenge in steers grazing endophyte-infected tall fescue compared with steers grazing endophyte-free tall fescue.

Fescue toxicosis in cattle occurs as a result of consumption of ergot alkaloids in endophyte-infected (E+, Neotyphodium coenophialum) tall fescue (Festuca arundinacea). The condition is characterized by pyrexia, decreased weight gains, rough hair coats, and decreased calving rates. The objective of this experiment was to investigate whether steers grazing E+ fescue have altered host response to lipopolysaccharide (endotoxin, LPS) challenge compared with steers grazing endophyte-free (E-) fescue.

Behavior of steers grazing monocultures and binary mixtures of alfalfa and tall fescue.

Spectral analysis was used to relate dietary quality and herbage species to the behavior of grazing steers. Four .3-ha paddocks were established with either 'AU-Triumph' tall fescue (F; Festuca arundinacea Schreb.

Vaccination against ergot alkaloids and the effect of endophyte-infected fescue seed-based diets on rabbits.

Three sequential experiments were conducted with rabbits to 1) determine the effect of endophyte-infected (E+) tall fescue seed on rabbit performance and examine the effect of anti-ergot alkaloid immunization on rabbit performance and protectiveness against fescue toxicosis, 2) compare immunogens designed to elicit systemic anti-ergot alkaloid antibodies, and 3) select a superior adjuvant. In Exp. 1, rabbits (n = 6/treatment) fed E+ fescue seed diets (20%, 340 ppb total ergot alkaloids) had reduced (P < .

Urinary and biliary excretion of ergot alkaloids from steers that grazed endophyte-infected tall fescue.

Ergot alkaloids cause fescue toxicosis when livestock graze endophyte-infected (E+) tall fescue. Little is known about the bioavailability of the ergot alkaloid classes (lysergic acid, lysergic acid amides, or ergopeptine alkaloids) in livestock, and this hampers development of pharmacological strategies to ameliorate the toxicosis. One method used to determine bioavailability of ergot alkaloids is to examine urinary and biliary excretion patterns.

The effectiveness of a single treatment with doramectin or ivermectin in the control of gastrointestinal nematodes in grazing yearling stocker cattle.

Four studies were conducted to a similar experimental design in the U.S. to evaluate the effectiveness of doramectin injectable administered to yearling stocker cattle in the control of gastrointestinal nematodiasis over the subsequent grazing period.

Efficacy of a pour-on formulation of eprinomectin (MK-397) against nematode parasites of cattle, with emphasis on inhibited early fourth-stage larvae of Ostertagia spp.

Objective: To evaluate efficacy of topically applied eprinomectin against inhibited early fourth-stage larvae (IL4) of Ostertagia spp in calves.

Animals: 4 groups (n = 6 [replicates]) for dose titration; 2 groups (n = 8 calves [replicates]) for dose confirmation.

Procedure: 2 dose titration studies-0, 125, 250, and 500 micrograms of eprinomectin/kg of body weight-Louisiana and Georgia- and 2 dose confirmation studies of selected therapeutic dosage (500 micrograms/kg) in Scotland and France.

Bioavailability and pharmacokinetics of metoclopramide in cattle.

The bioavailability of metoclopramide was investigated in three steers following administration of 8 mg/kg by the oral, abomasal (cannula), and intravenous routes, using a Latin square design. The mean (+/- SD) oral and abomasal bioavailabilities were 51.3 +/- 30.

Antibody binding of circulating ergot alkaloids in cattle grazing tall fescue.

Direct evidence linking alkaloids found in endophyte-infected tall fescue forage with the livestock disorder known as fescue toxicosis is lacking. Physiologic effects of fescue toxicosis include reduced serum prolactin concentration in cattle. A monoclonal antibody specific to the lysergic moiety of ergot alkaloids was developed in mice after creating an immunogen by linking lysergol to human serum albumin.

Raising replacement beef heifers in the south-birth to parturition: a review of current practices.

The South of the United States (13 southern states) is ecologically and socioeconomically well suited for reproducing ruminant animals. The South has a broad economic base, its climate is comparatively mild, much of its soil is easily eroded requiring vegetative cover, it receives comparatively abundant rainfall, and a diversity of plant species grow well, enabling a multitude of production and management alternatives. The South currently accounts for 46.

Melatonin and pineal neurochemicals in steers grazed on endophyte-infected tall fescue: effects of metoclopramide.

Plasma and pineal melatonin (MEL) and selected pineal neurochemicals (5-hydroxytryptophan, serotonin, N-acetylserotonin, dopamine, norepinephrine) associated with MEL synthesis were determined in steers grazing Acremonium coenophialum (endophyte)-infected 'Kentucky-31' tall fescue paddocks. Paddock treatments included low (LE, 33%) or high (HE, 74%) endophyte at either low (134 kg.ha-1 x yr-1, LN) or high (335 kg.

Neural dopamine D2 receptors in rats fed endophyte-infected fescue seed.

To study the effect of endophyte (Acremonium coenophialum) on hypothalamic and striatal dopamine D2 receptors, male rats (n = 14/group) were pair-fed diets containing 50% Rat Chow and 50% either endophyte-infected (E+) or noninfected (E-) fescue (Festuca arundinacea Schreb.) seed for 21 days. Concentrations of ergovaline and saturated pyrrolizidines were 1.

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.

Effect of metoclopramide on luteinizing hormone secretion in postpartum anestrous cows.

The effect of metoclopramide (MC), a dopamine antagonist on luteinizing hormone (LH), was examined in anestrous primaparous cows. Metoclopramide has been found to be beneficial in overcoming fescue toxicosis; increasing LH secretion stimulates return to ovulatory function after parturition. Consequently, if MC had negative effect on LH secretion, it would indicate that administration of MC to reproducing animals might be limited.

Effects of metoclopramide and quipazine on serum prolactin concentrations in steers.

The dopamine antagonist metoclopramide monohydrochloride (MC) and the serotonin agonist quipazine maleate (Q) were administered to steers by both the oral and intravenous (i.v.) routes.

Influence of endophyte-infected tall fescue on serum prolactin and progesterone in gravid mares.

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.