The effect of a novel bovine mastitis trivalent vaccine, containing Staphylococcus aureus capsular polysaccharide type 5 (T5), 8 (T8), and 336 (T336), on lymphocyte subpopulations, antibody production, and neutrophil phagocytosis was evaluated. Twenty pregnant heifers were immunized with either the trivalent alone, trivalent emulsified in Freund's incomplete adjuvant (FICA), trivalent in aluminum hydroxide, or adjuvant only (FICA). Immunization was done 30 d before the expected calving date followed by 2 boosts in a 2-week interval. Compared to FICA, serum antigen-specific immunoglobulin (Ig)G1 and IgG2 were significantly increased in all the vaccinated groups before parturition and sustained until 3 wk postpartum. In comparison with the trivalent alone, formulation with either adjuvant enhanced production of IgG2, but not IgG1. Immune sera, which contained the highest amount of antibodies, slightly increased neutrophil phagocytosis to the 3 serotypes of killed S. aureus, but most of the differences were not significant due to large variation between the cows. The percentage of CD4+ lymphocyte was significantly higher in vaccinated groups than that of FICA 4 wk after the primary immunization. In comparison with FICA, cows inoculated with trivalent vaccine and adjuvants had an increased percentage of CD8+ lymphocytes at 2 time points, 2 wk before and after calving. Our results indicated that the whole cell trivalent vaccine, with or without adjuvants, is able to elicit antibody responses specific to the 3 capsular polysaccharide antigens. The increase of T8-specific IgG2 was more noticeable when the vaccine was emulsified with adjuvants.

Objective--To evaluate the immunologic response of a killed tachyzoite vaccine against Neospora caninum and its effectiveness in preventing fetal loss associated with experimentally induced neosporosis in sheep. Animals--30 Dorset ewes. Procedure--Ewes were randomly allocated to receive vaccination on days 1 and 60 of the study with a killed N caninum tachyzoite preparation in a commercially available adjuvant or a saline-adjuvant mixture. A ram was placed on pasture with the ewes from days 15 to 60. Blood was collected from ewes before primary and booster vaccinations and prior to experimental challenge with N caninum tachyzoite performed on day 90; sera were assessed via Neospora agglutination (NA) and immunofluorescence antibody (IFA) assays. Blood was collected from lambs before they suckled, and sera were tested for antibodies against N caninum. Results--Of the 14 vaccinated ewes that became pregnant, 12 gave birth to live-born lambs; in contrast, 5 of 11 pregnant control ewes gave birth to live-born lambs. Whereas vaccination improved fetal survival in pregnant ewes challenged with N caninum tachyzoites, it did not appear to have any appreciable effect on transmission of N caninum to offspring, as indicated by results of NA and IFA assays. Conclusions and Clinical Relevance--The N caninum tachyzoite vaccine used in this study appeared to provide protection against fetal loss associated with experimentally induced neosporosis in a high proportion of pregnant ewes.

Objective: To evaluate the genetic relatedness and antibiotic sensitivity profiles of Campylobacter coli isolates from sows and piglets housed in an integrated swine production facility. Sample Population: Ninety-nine isolates of Campylobacter coli were collected from 3 sows (Yorkshire-Landrace) and 18 piglets (Yorkshire-Landrace X Duroc or Hampshire) housed in a common farrowing barn. Procedure: When piglets were weaned (21 day of age) fecal samples were collected for the sows and rectal samples were collected from the piglets. Isolation of Campylobacter coli was performed using an enrichment broth and restrictive media under microaerophilic conditions. Results: The Campylobacter coli isolates segregated into 20 ribogroups and exhibited 32 antibiotic susceptibility profiles. The Ribogroup (224-373-S-5) contained 35 isolates from eleven animals. Thirty-eight percent of the animals exhibited a single ribogroup, while 10% of the animals exhibited four ribogroups. No discernible pattern of ribogroup relatedness was observed among the sows and piglets or among littermates. Conclusion: The data suggests a high level of diversity in both ribotypic patterns and antibiotic sensitivity profiles among the Campylobacter coli isolated from related pigs housed in a single facility. Further, no evidence was found for a direct transfer of specific Campylobacter coli ribotypes from a sow to her piglets.

Objective - To evaluate the effectiveness of various sampling techniques for determining antimicrobial resistance patterns in Escherichia coli isolated from feces of feedlot cattle. Sample Population - Fecal samples obtained from 328 beef steers and 6 feedlot pens in which the cattle resided. Procedure - Single fecal samples were collected from the rectum of each steer and from floors of pens in which the cattle resided. Fecal material from each single sample was combined into pools containing 5 and 10 samples. Five isolates of Escherichia coli from each single sample and each pooled sample were tested for susceptibility to 17 antimicrobials. Results - Patterns of antimicrobial resistance for fecal samples obtained from the rectum of cattle did not differ from fecal samples obtained from pen floors. Resistance patterns from pooled samples differed from patterns observed for single fecal samples. Little pen-to-pen variation in resistance prevalence was observed. Clustering of resistance phenotypes within samples was detected. Conclusions and Clinical Relevance - Studies of antimicrobial resistance in feedlot cattle can rely on fecal samples obtained from pen floors, thus avoiding the cost and effort of obtaining fecal samples from the rectum of cattle. Pooled fecal samples yielded resistance patterns that were consistent with those of single fecal samples when the prevalence of resistance to an antimicrobial was > 2%. Pooling may be a practical alternative when investigating patterns of resistance that are not rare. Apparent clustering of resistance phenotypes within samples argues for examining fewer isolates per fecal sample and more fecal samples per pen.

Effects of 2 drugs commonly used for chemical restraint of cattle were evaluated for their effect on laryngeal and pharyngeal anatomy, function, and response to stimuli. Eighteen adult Jersey cows, free of respiratory tract disease, were studied. Cows were assigned at random to 1 of 3 treatment groups. Endoscopic evaluations were performed before and at a predetermined time interval after administration of each drug. Responses to stimuli were evaluated by stimulating 7 preselected sites (epiglottis, left and right arytenoid cartilages, left and right vocal folds, and left and right dorsolateral pharyngeal walls) with a closed, transendoscopic biopsy probe. Xylazine HCl (0.05 mg/kg of body weight, IV) was administered to group-1 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Xylazine (0.07 mg/kg, IV) was administered to group-2 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Acepromazine maleate (0.035 mg/kg, iv) was administered to group-3 cows (n = 6), and endoscopy was repeated 10 minutes after administration of the drug. Responses to stimuli were scored as brisk (0), moderate (1), slow (2), and absent (3). Scores for responses to stimuli were compared, using the Wilcoxon signed-rank test for data within groups, and a general linear models procedure, using the Kruskal-Wallis test between groups. Interobserver agreement rates were generated for each group. A value of P<0.05 was considered significant. Xylazine profoundly changed laryngeal sensitivity and function at both dosages. The corniculate processes of the arytenoid cartilages were observed to be in a markedly adducted position after sedation. Response to stimuli was significantly (P = 0.03) slower than normal after sedation, using both dosages. Displacement of the soft palate dorsal to the epiglottis was persistent in 50% of the cows after stimulation tests subsequent to sedation with xylazine. Acepromazine had a mild effect on laryngeal sensitivity and function. The corniculate processes of the arytenoid cartilages were observed in paramedian position after sedation. Acepromazine did not significantly affect responses to stimuli. Effects of sedation on responses to stimuli were not significantly different for groups 1 and 2. However, effects for group 3 were significantly different from those for groups 1 and 2 (P = 0.006 and 0.004, respectively). Endoscopic evaluation of the proximal portion of the respiratory tract of cattle should be performed without sedation, when possible. If sedation is required to facilitate restraint for endoscopy, acepromazine maleate is recommended over xylazine on the basis of results of this study.

The Langendorff isolated heart preparation was adapted to determine the effect of furazolidone (0.5 and 2 migrogram/ml of perfusate) on hearts of 3-week-old broiler chickens. Following 115 minutes of perfusion, both concentrations of furazolidone caused approximately a two-fold increase in myocardial vascular resistance and a six-fold increase in myocardial vascular resistance and a six-fold increase in lactate dehydrogenase release into the effluent fluid, compared with a control perfused group of isolated hearts (P less than 0.01). Ultrastructural alteration differences were not found between the drug-treated and control groups. It was concluded that: (i) furazolidone, at concentrations only moderately above therapeutic plasma concentrations, caused detrimental changes in myocardial vascular resistance and lactate dehydrogenase release and (ii) the isolated chicken heart preparation is an example of a cost-effective, reliable laboratory tool for screening potential cardiotoxins.

A study was conducted to determine aflatoxins in tissues and non-tissues of 2 Holstein cows given oral doses of 0.35 mg of purified aflatoxin B1/kg of body weight/day for 3 consecutive days. Cow 1 was slaughtered 24 hours after the 3rd dose, and cow 2, after day 3, was fed aflatoxin-free rations for 7 additional days before slaughter. Tissue samples of brain, gallbladder and bile, heart, intestine, kidney, liver, lung, mammary gland, skeletal muscle, spleen, supramammary lymph nodes, thymus, and tongue, and nontissue samples of blood, feces, milk, rumen content, and urine were examined. Aflatoxins B1 and M1 were found in all samples of cow 1, except the thymus. Kidney, liver, and mammary gland had the highest concentrations of total aflatoxins (57.9, 13.2, and 25.1 ng/g, respectively), with the aflatoxin M1 concentration 40 times more than the aflatoxin B1 level in kidney. Aflatoxin residues were present (0.02 to 0.11 ng/g) only in kidney, liver, and intestine of the tissues from cow 2 (fed aflatoxin-free feed for 7 additional days). Aflatoxin B1 was not present in nontissue samples, but aflatoxin M1 (0.10 and 1.5 ng/ml) was found in the last milk and urine samples from the same cow. Urine assays are a possible way to monitor the presence of aflatoxin residues in meat tissues.

Two of 3 groups of Holstein-Friesian steers (groups II and III; n = 5 each) were fed a ration containing corn naturally contaminated with 800 ng of aflatoxin/g. The other group of steers (group I; n = 5) was fed a ration containing noncontaminated corn. The respective rations were fed for 17.5 weeks, except the ration given to group III; the latter's first diet (contaminated with aflatoxin) was changed to a noncontaminated diet after 15 weeks, continuing for the remaining 2.5 weeks. All steers were killed and tissues and fluids were obtained for aflatoxin analysis. Although aflatoxin B1 and M1 could be detected in blood and urine at several sampling times during the experimental period in groups II and III steers (given the diets containing aflatoxin), there appeared to be no effects on body weight gains and immune phenomena, such as lymphoblastogenesis and antibody production, but there was a waning of the delayed cutaneous hypersensitivity in steers given aflatoxin-contaminated diets. In group III animals (diet was changed to noncontaminated ration at 15 weeks), aflatoxin B1 and M1 disappeared from urine before they were slaughtered. All tissues and fluids, except the rumen contents from these group III steers, were void of detectable aflatoxins B1 and M1 at necropsy. The concentrations of aflatoxin B1 in the rumen content of the latter steers were low. All tissues collected at necropsy from the group II steers fed the aflatoxin diet throughout the 17.5 weeks had detectable aflatoxins B1 or M1 present.

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.

An experimental chlorate product (ECP) developed by the United States Department of Agriculture has been shown to have bactericidal effects against enteropathogens such as Escherichia coli. In studies with broilers and pigs, the bactericidal activity of ECP was enhanced by prior adaptation of gastrointestinal microflora to nitrate. The objective of this study was to examine the effects of nitrate adaptation on the bactericidal activity of ECP against E. coli in Holstein steers. Results indicate that ECP was effective at reducing E. coli. However, ECP did not reduce E. coli in a dose-dependent manner, indicating that the highest ECP dose provided in this study exceeded that needed to be efficacious. Adapting gastrointestinal microflora with nitrate prior to feeding ECP did not improve efficacy of ECP against E. coli. Rapid reduction of nitrate in the rumen is implicated as a possible explanation for why adaptation to nitrate did not enhance the bactericidal effects of ECP in cattle.