Risk of nutritional deficiencies for dogs on a weight loss plan.

OBJECTIVES: To determine how general practice veterinarians make weight loss recommendations for dogs and if nutrients become deficient when following these recommendations. MATERIALS AND METHODS: A questionnaire of general practice veterinarians was conducted to characterise weight loss recommendations made to clients. Using this data, progressive levels of caloric restriction were applied to top-selling commercial non-therapeutic adult maintenance diets and non-therapeutic weight management diets. Nutrient intakes were compared to the National Research Council's Recommended Allowances for metabolic body weight using a theoretical current weight and ideal body weight for an obese dog. Nutrient intakes were also compared to recommendations from the Association of American Feed Control Officials using current body weight. RESULTS: Several nutrients were found at risk of deficiency, including choline, methionine, cysteine, selenium, eicosapentanoic acid, docosahexanoic acid, riboflavin, pantothenic acid and cobalamin in both non-therapeutic adult maintenance diets and non-therapeutic weight management diets. CLINICAL SIGNIFICANCE: Caution is warranted when making weight loss recommendations using commercial diets until further research on the nutrient needs of obese dogs undergoing weight loss is undertaken. Restriction of commercial diets to achieve weight loss in dogs may result in nutrient deficiencies.

The effect of an oral probiotic containing lactobacillus, bifidobacterium, and bacillus species on the vaginal microbiota of spayed female dogs.

BACKGROUND: Recurrent urinary tract infections (UTIs) are often difficult to treat. Vaginal colonization with lactic acid-producing bacteria (LAB) is associated with reduced frequency of recurrent UTIs in women. Oral probiotics might help increase the prevalence of vaginal LAB and decrease the frequency of recurrent UTIs in dogs. HYPOTHESIS: Administration of an oral probiotic supplement containing Lactobacillus, Bifidobacterium, and Bacillus species will increase the prevalence of LAB in the vagina of dogs. ANIMALS: Thirty-five healthy, spayed female dogs without history of recurrent UTIs. METHODS: Prospective, controlled study. Enrolled dogs received an oral probiotic supplement for 14 or 28 days. A vaginal tract culture was obtained from each dog before and after oral probiotic administration. Twenty-three dogs received the oral probiotic supplement daily for a period of 14 days and 12 dogs received the oral probiotic supplement daily for a period of 28 days. RESULTS: Lactic acid-producing bacteria were isolated from 7 of 35 dogs prior to probiotic administration. After the treatment course, 6 of 35 dogs had LAB isolated. Only one of these dogs had LAB (Enterococcus canintestini) isolated for the first time. Enterococcus canintestini was the most common LAB isolated from all dogs in this study, although it was not included in the probiotic supplement. CONCLUSIONS AND CLINICAL IMPORTANCE: Lactic acid-producing bacteria are not a common isolate from the vaginal vault of dogs. Administration of this oral probiotic supplement for a 2- or 4-week period did not increase the prevalence of vaginal LAB in dogs.

Relationship between gastrointestinal transit time and anesthetic fasting protocols in the captive chimpanzee, Pan troglodytes.

BACKGROUND: Lengthy social separation and prolonged fasting time contribute to increased risks associated with anesthesia in captive primates. This study is an initial attempt to identify a safe pre-anesthetic fasting procedure by identifying gastric emptying time (GET) and gastrointestinal transit time (GTT) of captive chimpanzees, Pan troglodytes. METHODS: Seven adult chimpanzees at the North Carolina Zoo immobilized for annual physical examinations were fed barium-impregnated polyethylene spheres to measure GET. Eleven animals were individually fed a color dye marker and fecal passage was observed to determine GTT. RESULTS: Gastric emptying time (GET) was approximated to be >3 hours but <16 hours. The mean GTT was 16.5 hours. CONCLUSIONS: This study indicates that a fasting time of 3 hours would allow for complete gastric emptying and could potentially replace the current overnight fast (≥16 hour) to help minimize complications associated with pre-anesthetic fasting in captive primates.

Influence of endophyte consumption and heat stress on intravaginal temperatures, plasma lipid oxidation, blood selenium, and glutathione redox of mononuclear cells in heifers grazing tall fescue.

A grazing experiment was conducted to assess the effects of wild-type endophyte-infected (E+) tall fescue consumption and elevated ambient temperatures on intravaginal temperatures, plasma lipid peroxidation, and glutathione redox of peripheral blood mononuclear cells. Angus heifers (n = 34) were allotted by BW to 4 blocks consisting of E+ and endophyte-free (E-) fescue pastures. Monthly, in June, July, and August, temperature loggers were fixed into blank controlled internal drug releasers and inserted into a subsample of heifers (n = 16) for 2 d. After 48 h, heifers were weighed, and blood (30 mL) was collected via jugular venipuncture. Peripheral blood mononuclear cells were isolated for analysis of glutathione peroxidase activity, glutathione reductase activity, and reduced:oxidized glutathione. Plasma malondialdehyde was evaluated as a marker of lipid peroxidation, and whole blood Se concentration was determined. Serum prolactin was assayed after the grazing period. Heifer ADG was greatest in August and least in July (P < 0.001). In August, heifers grazing E+ fescue exhibited greater (P < 0.05) afternoon intravaginal temperatures and temperature fluctuations than heifers grazing E- fescue. In July and August, all heifers had greater afternoon temperatures (P < 0.02) and less reduced:oxidized glutathione (P < 0.0001) than in June. Glutathione reductase activity of all heifers was greater in June (P = 0.03) than in July. Similarly, all heifers exhibited decreased glutathione peroxidase activity (P < 0.0008) in July, whereas whole blood Se was reduced (P < 0.0001) in July and August. No treatment or date effects were detected for malondialdehyde, but serum prolactin was reduced at the end of the grazing period (P = 0.008) in heifers stocked on E+ fescue. Using these markers, differences in oxidative stress were not detected between heifers consuming E+ fescue and those consuming E- fescue. Date effects indicating altered glutathione redox and enzyme activity may have been related to heat stress and nutritional limitations.

Brown seaweed- (Tasco) treated conserved forage enhances antioxidant status and immune function in heat-stressed wether lambs.

Twenty-seven wether lambs were utilized to evaluate select innate immunity and oxidative stress in response to diet and heat stress. Dietary treatments were: (i) control (tall fescue) hay = no Tasco (tradename for the extract of the brown seaweed, Ascophyllum nodosum, Acadian Sealants Ltd, Nova Scotia, Canada); (ii) pre-harvest Tasco-Forage-treated hay and (iii) control hay + post-harvest Tasco-EX. Tasco-Forage and Tasco-EX are two forms of the Tasco extract that are either applied to foliage or used for direct feeding, respectively. All lambs were supplemented with soyabean meal and trace mineralized salt. Heat stress was applied for 10 days with measurements obtained at days 0, 4 and 10. A heat x treatment interaction indicated hay with Tasco enhanced monocyte oxidative burst through short duration (p < 0.05) and long duration (p < 0.10) heat stress. Phagocytic activity was influenced by days of heat stress (p < 0.001) and treatment (p = 0.02) with post-harvest Tasco lambs exhibiting the greatest immune enhancement (p < 0.05). Red and white blood cell glutathione peroxidase increased by heat stress day 10 in Tasco lambs. Superoxide dismutase activity was increased and lipid hydroperoxide metabolites minimized (p < 0.01) through long duration heat stress in the pre-harvest Tasco group. Tasco treatment of tall fescue hay prior to harvest appears to provide residual effects on animal antioxidant availability in short-duration heat stress. Tasco supplementation to post-harvest fescue hay enhances immune function and protects against prolonged heat-induced oxidative stress.

Antioxidant supplementation and subsequent oxidative stress of horses during an 80-km endurance race.

This study tested the development of oxidative stress and the effects of antioxidant supplementation in an 80-km ride. A precompetition survey revealed that no competitor would participate without vitamin E supplementation; therefore, 46 horses were paired for past performances and randomly assigned to two groups of 23 each for 3 wk of supplementation before the ride. One group (E) was orally supplemented with 5,000 IU of vitamin E per day; the other group (E+C) received that dose of vitamin E plus 7 g/d of vitamin C. Blood samples, temperature, and heart rate were taken the day before the race, at 21 and 56 km during the ride, at completion, and after 20 min of recovery. Plasma was assayed for lipid hydroperoxides, alpha-tocopherol, total ascorbate, albumin, creatine kinase (CK), and aspartate aminotransferase (AST). Total glutathione and glutathione peroxidase activity were determined in red blood cells and white blood cells. Thirty-four horses completed the race, 12 horses (six in E and six in E+C) did not finish for reasons including lameness, metabolic problems, and rider option. Plasma ascorbate was higher (P = 0.045) in the E+C group than in the E group. Other than ascorbate, neither antioxidant status nor CK and AST activities were affected by supplementation with E+C vs. E. Red blood cell glutathione peroxidase, white blood cell total glutathione, lipid hydroperoxides, CK, and AST increased, and red blood cell total glutathione and white blood cell glutathione peroxidase activity decreased with distance (P < 0.001). Positive correlations were found for plasma lipid hydroperoxides on CK (r = 0.25; P = 0.001) and AST (r = 0.33; P < 0.001). These results establish an association between muscle leakage and a cumulative index of oxidative stress.

Speed associated with plasma pH, oxygen content, total protein and urea in an 80 km race.

To test the hypothesis that endurance performance may be related quantitatively to changes in blood, we measured selected blood variables then determined their reference ranges and associations with speed during an 80 km race. The plan had 46 horses in a 2 x 2 factorial design testing a potassium-free electrolyte mix and a vitamin supplement. Blood samples were collected before the race, at 21, 37, 56 and 80 km, and 20 min after finishing, for assay of haematocrit, plasma pH, pO2, pCO2, [Na+], [K+], [Ca++], [Mg++], [Cl-], lactate, glucose, urea, cortisol, alpha-tocopherol, ascorbate, creatine kinase, aspartate amino transferase, lipid hydroperoxides, total protein, albumin and creatinine, and erythrocyte glutathione and glutathione peroxidase. Data from 34 finishers were analysed statistically. Reference ranges for resting and running horses were wide and overlapping and, therefore, limiting with respect to evaluation of individual horses. Speed correlations were most repeatable, with variables reflecting blood oxygen transport (enabling exercise), acidity and electrolytes (limiting exercise) and total protein (enabling then, perhaps, limiting). Stepwise regressions also included plasma urea concentration (limiting). The association of speed with less plasma acidity and urea suggests the potential for fat adaptation and protein restriction in endurance horses, as found previously in Arabians performing repeated sprints. Conditioning horses fed fat-fortified and protein-restricted diets may not only improve performance but also avoid grain-associated disorders.

Antioxidant status and muscle cell leakage during endurance exercise.

Antioxidant status of 35 endurance horses was studied during an 80 (OD80) or 160 km (OD160) race. Packed cell volume (PCV), total plasma protein (TPP), plasma ascorbic acid (VIT C), plasma alpha-tocopherol (VIT E) and erythrocyte glutathione (GSH) concentrations, erythrocyte glutathione peroxidase (GPX), plasma aspartate aminotransferase (AST) and plasma creatine kinase (CK) activities were measured at 0, 40, 80 km and 60 min of recovery (REC) at OD80, and 0, 64, 106, 142, 160 km and REC at OD160. In both races, no changes were found in plasma VIT E concentration, but VIT C and GSH concentrations decreased (P<0.05), and mean GPX, AST and CK activities increased from 0 km (P<0.05). Indices of muscle cell leakage (plasma AST and CK) were correlated (r = 0.36 to 0.67; P<0.03) with indices of antioxidant status (VIT C, GSH and GPX). Associations between increased muscle leakage and decreased antioxidant status may, in part, reflect oxidative stress and suggest the testing of antioxidant supplements in endurance horses to improve performance and welfare.

Evaluation of a nonradioactive colorimetric assay for analysis of lymphocyte proliferation in healthy cats.

OBJECTIVES: To compare results of a nonradioactive colorimetric microplate assay with results of a traditional radioactive proliferation assay for determination of its use as a reliable and accurate alternative method for determination of proliferative activity of feline lymphocytes. SAMPLE POPULATION: Blood samples from 10 clinically normal domestic shorthair cats. PROCEDURE: Double-density gradient separation was used to isolate mononuclear cells. Isolated cells were stimulated with various concentrations of concanavalin A (Con-A) and cultured for 72 hours. Lymphocyte proliferation was measured by radioactive ([3H]thymidine) and nonradioactive (colorimetric) techniques. Immunophenotypic analysis with feline-specific CD4+ and CD8+ monoclonal antibody was performed, using flow cytometry. RESULTS: Mononuclear cells were successfully isolated (97 to 99% purity and viability) from blood samples. A similar dose-dependent proliferative response to Con-A stimulation was measured with [3H]thymidine incorporation and the colorimetric assay. For both techniques, concentrations of 0.1 and 1.0 microg of Con-A/ml were submitogenic, and 100 microg/ml was toxic to cultured cells. For both techniques, maximal proliferation was observed with 5 microg of Con-A/ml. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that the nonradioactive colorimetric technique is a reliable and accurate method for measuring proliferative activity of feline lymphocytes. Clinically, this assay can be used as part of a screening process to determine immunocompetence of at-risk cats and to evaluate treatments for cats with immune-mediated or T-cell-dependent diseases.

Polyunsaturated fatty acids and epidermal growth factor receptor/mitogen-activated protein kinase signaling in mammary cancer.

Mammary cancer is the second leading cause of cancer death in women, the second most common neoplasm in dogs and the third leading neoplasm in cats. Mammary tumors are similar in morphology and progression in these species, so cats and dogs are good models for determining treatment or prevention modalities for the human population. Epidemiological, in vitro and rodent studies have demonstrated that polyunsaturated fatty acids (PUFA) can influence the growth, progression and metastasis of mammary cancer. Although a role of PUFA in modulating mammary cancer growth has been shown, the mechanisms by which this occurs remain unclear. Recent studies have demonstrated that PUFA may influence the activity of the epidermal growth factor receptor/mitogen-activated protein kinase pathway, which is involved in regulating several oncogenes (c-myc, c-fos, neu/c-erb-b2) involved in the progression of cancer. We review the potential mechanism by which PUFA may modulate the growth of mammary cancer through regulation of the epidermal growth factor receptor/mitogen-activated protein kinase signal transduction cascade.

Tasco-Forage: II. Monocyte immune cell response and performance of beef steers grazing tall fescue treated with a seaweed extract.

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.

Tasco-Forage: III. Influence of a seaweed extract on performance, monocyte immune cell response, and carcass characteristics in feedlot-finished steers.

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.

Acute starvation and subsequent refeeding affect lymphocyte subsets and proliferation in cats.

Although the early identification of patients with suboptimal nutritional status can allow the implementation of nutritional intervention to enhance the ability of the body to fight infection and disease, currently no definitive test of nutritional status exists. Therefore, this study was conducted to identify possible functional indicators of acute nutritional deprivation. The effects of total nutritional deprivation and subsequent refeeding on lymphocyte functions and subpopulations were examined in 23 healthy cats. Peripheral blood samples were analyzed at various times during food deprivation and refeeding periods. During the food deprivation period, decreases were observed in leukocyte number (P: < 0.05), lymphocyte number (P: < 0.05), percentage of CD4(+) cells [before stimulation with concanavalin-A (Con-A); P: < 0.05] and the CD4/CD8 ratio (before stimulation with Con-A; P: < 0.01) compared with d 0. Increases were observed in the percentage of CD8(+) cells [before (P: < 0.05) and after (P: < 0.01) stimulation with Con-A] and in intracellular calcium (P: < 0.01) during acute starvation. During the refeeding period, increases were observed in the percentage of CD4(+) cells (before and after stimulation with Con-A; P: < 0.01), the percentage of CD8(+) cells (before stimulation with Con-A; P: < 0.05) and lymphocyte number (P: < 0.05) compared with d 7. Lymphocyte proliferative capacity tended to decrease (P: = 0.07) during starvation and increased (P: < 0.01) during the refeeding period. These findings suggest that a 7-d starvation period had immunosuppressive effects on cats and that these effects were not completely normalized during 7 d of refeeding. CD4(+)/CD8(+) subset alterations and CD4/CD8 ratio in conjunction with lymphocyte proliferation may be useful as indices of nutritional status.

Duplicated popliteal and superficial femoral veins: incidence and potential significance.

BACKGROUND: Duplication of the popliteal and superficial femoral veins (PV, SFV) is a normal variant previously reported in up to 25% of limbs. Little clinical significance, however, has been attributed to this apparently common anomaly. The present study was designed to determine the incidence of duplications in individuals presenting for venous incompetence studies, and whether their presence could, in theory, act as a predisposing factor to deep venous thrombosis (DVT) formation. METHODS: Duplex ultrasound examinations were performed in which venous duplications were actively searched for and recorded. The diameters of both limbs of any duplicated system and the single vessel immediately distal to it were recorded. Using these measurements, the changes in total cross-sectional area (CSA) associated with these anomalies were calculated. In addition, with the knowledge that the volume flow rate must remain constant, the velocity changes associated with such systems were calculated. RESULTS: A total of 248 limbs from 177 patients was scanned. Duplications were found in 39 (15.7%) of these limbs. Of these, 30 limbs (77%) involved only the SFV, seven (18%) involved both the SFV and PV, and two (5%) involved only the PV. Short-segment SFV duplications were used to calculate the percentage change in total CSA and therefore blood flow velocities. Of the 13 (33%) suitable for such calculations, and calculating for each individual duplicated system, a mean increase in the vessel's total CSA of 42%, which corresponded to a theoretical decrease in blood flow velocity of 36%, was found. CONCLUSION: The present study confirms the significantly high incidence of duplications of the PV and SFV and raises the possibility of the potential for DVT formation secondary to changes in flow velocities.

Colour Doppler diagnosis of perigraft flow following endovascular repair of abdominal aortic aneurysm.

BACKGROUND: Endovascular repair of abdominal aortic aneurysm is a relatively new surgical technique which is less invasive than conventional open abdominal surgery but is associated with a significant specific complication of endoleak. The aim of this study was to determine the accuracy of duplex ultrasound imaging, utilising colour Doppler, as the primary method for post surgical monitoring of endovascular aneurysm repair. EXPERIMENTAL DESIGN: a case cohort study of 45 patients undergoing endovascular repair of abdominal aortic aneurysm. SETTING: angiography, CT scanning and surgery performed at Westmead Hospital, a teaching hospital of the University of Sydney; patients followed postoperatively at the Westmead Vascular Laboratory, a dedicated vascular diagnostic ultrasound facility. PATIENTS: Forty males and five females, mean age 69.1 years (range 51 to 84). INTERVENTIONS: patients underwent attempted insertion of an EVT (endovascular prosthesis) for exclusion of abdominal aortic aneurysm (mean diameter 5.3 cm; range 4.0 to 8.4 cm). Conversion to open repair was required in three cases (6.6%). An aorto-biliac graft was inserted in 28 patients, a tube graft in eight and an aorto-unilateral iliac graft with femorofemoral (or ilioilial) crossover graft in six. MEASURES: patients were followed over a period of 53 months (median follow-up time 15 months) with 106 colour Doppler scans of 39 endovascular grafts (mean of 2.9 scans per patient). RESULTS: All aneurysms decreased in diameter (range 0.1 cm to 4.3 cm, mean 0.9 cm). Abnormal flow in the residual aneurysmal sac was found in three patients. In all three cases of endoleak the colour Doppler diagnosis was supported by CT scan and confirmed on angiography. The CT scans did not provide any additional information to that obtained by colour Doppler imaging. CONCLUSIONS: Colour Doppler provides an effective means of non-invasive follow-up assessment of patients who have had endovascular repair of abdominal aortic aneurysms.

Influence of Neotyphodium coenophialum on copper concentration in tall fescue.

Poor performance of livestock that graze tall fescue (Festuca arundinacea Schreb.) has been associated with the endophyte fungus Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Recent evidence suggests lowered Cu status and a depression of Cu-related immune function in steers that graze endophyte-infected (E+) tall fescue. Greenhouse and field studies investigated relationships between the endophyte and Cu concentrations in tall fescue. Seventeen infected 'Kenhy' clones were divided, and one plant of each pair was treated three times with Benomyl to remove the endophyte (E-). Plants were watered with nutrient solution in a greenhouse for 6 mo before sampling. Copper concentrations were greater (P < .001) in E- than in E+ clones (3.4 vs 2.8 microg/g; SE, .06). In the second greenhouse experiment, genetically similar E+ and E- 'Kentucky'-31 (KY-31) and 'Georgia Jessup' were grown from seed and fertilized with nutrient solution to produce mature plants. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (8.6 vs 7.6 microg/g; SE, .3). In a field plot experiment in Texas, E+ and E- KY-31 were grown with 0, 50, and 100% replacement of potential evapotranspiration. By September, Cu concentrations were higher (P < .05) in E- than in E+ tall fescue (7.3 vs 6.6 microg/g; SE, .2). In pasture experiments, KY-31 E+ (> 70% infection level) and E- (< 5% infection level) tall fescue were grown in Virginia at two locations with three rates of N fertilizer. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (4.8 vs 4.5 microg/g; SE, .1) and increased (P < .01) linearly in response to N. Our data demonstrate that the presence of the endophyte is associated with lower Cu concentrations in tall fescue, which may contribute to lowered Cu status in animals and thus contribute to the etiology of fescue toxicity.

Monocyte immune cell response and copper status in beef steers that grazed endophyte-infected tall fescue.

A 3-yr study was conducted to evaluate immune response and Cu status of yearling beef steers as a consequence of grazing tall fescue (Festuca arundinacea Schreb.) infected (E+) with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). During a preliminary study in 1994, 24 weanling Angus and Angus x Hereford steers were blocked by breed and weight (initial BW 271 kg; SD 25) and were randomized to E+ and low endophyte (E-) fescue in pastures at Glade Spring, VA. Grazing began in April and was discontinued in July. In 1995 and 1996, 24 weanling Angus and Angus x Hereford steers (initial BW 249 kg, SD 20 and 240 kg, SD 15, respectively) were randomized to the E+ and E- pastures at Glade Spring during each year. Grazing began in April and continued until September in 1995 and October in 1996. In 1994, steers that grazed E+ fescue exhibited lower (P < .05) phagocytic activity, major histocompatibility complex (MHC) class II expression, ceruloplasmin, and serum Cu than steers that grazed E- tall fescue. During 1995, steers grazing E+ fescue had lower (P < .05) phagocytic activity and MHC class II expression than steers that grazed E- fescue. In 1996, one-half of the steers within each paddock received a Cu oxide bolus at the beginning of the grazing season. During 1996, phagocytic activity was lower (P < .01) and MHC class II expression tended (P < .07) to be lower in steers that grazed E+ tall fescue than in steers that grazed E- tall fescue. Copper supplementation increased (P < .05) MHC class II expression in July regardless of endophyte status over nonsupplemented steers. Steers that grazed E- tall fescue had higher (P < .05) plasma or serum Cu concentrations than steers that grazed E+ tall fescue in each year of the study. These data indicate that the endophyte compromised the immune function of grazing steers, and the data suggest a relationship with depressed Cu status.