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SUMMARY

On the basis of the hypothesis that the peak numbers of infective nematode third-stage larvae (L3) on herbage in winter months results from fall contamination of pastures, 2 methods to reduce fall contamination were tested. In trial 1, morantal sustained-release boluses were administered to 15 fall-calving cows on Sept 7, 1982. Fifteen untreated cows (controls) were placed on separate pastures. Numbers of L3 on herbage during the winter and spring were assessed by use of worm-free tracer calves.

In trial 2, 19 cattle due to calve in the fall were administered 200 μg of invermectin/kg of body weight, sc, on Sept 2, 1983. Also, 17 cattle similarly were given a placebo injection and served as control animals. Treated cattle were placed on the pasture used by control cattle in trial 1 and control cattle on the pasture used by treated cattle in trial 1. Worm-free tracer calves were again used to assess numbers of L3 on herbage.

In trial 1, tracer calves grazing the control animal pasture from January 14 to 28 acquired 37 times as many nematodes as did those grazing the treated animal pasture. In trial 2, the greatest difference observed was a 10- fold increase of nematodes in calves grazing control animal pastures, compared with worm numbers in tracer calves grazing the treated animal pasture.

Free access
in American Journal of Veterinary Research

SUMMARY

Flow cytometric and conventional fluorescence microscopic methods were compared to detect heterologous (rabbit) neutrophil antibody bound to equine neutrophils. Unfixed and paraformaldehyde-fixed neutrophils were treated with normal rabbit serum or various dilutions of an antineutrophil serum. The cells were then reacted with fluorescein conjugates of goat anti-rabbit IgG, staphylococcal protein A, and streptococcal protein G. Antibody binding was evaluated by use of fluorescence microscopy and flow cytometry. Unfixed neutrophils treated with normal rabbit serum did not fluoresce, whereas many of the fixed neutrophils had distinct cytoplasmic and some membranous (nonspecific) fluorescence. Unfixed cells treated with the antiserum had localized areas (capping) of intense membrane fluorescence, whereas fixed cells had bright uniform membranous fluorescence. The intensity of specific fluorescence varied with the antiserum dilution and the conjugate. On flow cytometry, over 80% of unfixed cells treated with antiserum dilutions up to 1:1,024, 1:2,048, and 1:256 fluoresced, respectively, with anti-IgG, protein-G, and protein-A conjugates. Fixed cells generally had similar percentages of fluorescent cells, but at a higher (1-step) antiserum dilution. It was concluded that flow cytometry is more sensitive than conventional fluorescence microscopy to detect antibodies associated with equine neutrophils.

Free access
in American Journal of Veterinary Research

SUMMARY

Total protein concentration was determined in serum, bronchoalveolar lavage (bal) fluid, and nasal flush fluid obtained from specific-pathogen-free cats from birth to maturity and from adult conventionally raised cats. Protein components were analyzed by Immunoelectrophoresis and isoelectric focusing. Albumin, and α-, β-, and γ-globulins were among the proteins identified in bal fluid, and their isoelectric point ranged from 3.1 to 5.1. γ-Globulin was not detected in serum or bal fluid of newborn kittens before they had ingested colostrum. By day 3 after ingestion of colostrum, IgG was detected in high concentration in serum and was the predominant immunoglobulin in serum and bal fluid of older cats. Nasal flush fluid from cats > 6 months old contained albumin, and α-, β-, and γ-globulins, with IgA being the predominant immunoglobulin. Total protein concentration in nasal flush fluid increased progressively with increasing age, and albumin was the predominant protein. Protein concentration was significantly (P < 0.01) higher in bal fluid from conventionally raised adult cats than in that from specific-pathogen-free cats.

Free access
in American Journal of Veterinary Research

SUMMARY

To examine the influence of allergen-induced type-1 hypersensitivity on the pathogenesis of bovine respiratory syncytial virus (brsv) infection, we sensitized calves by aerosol to Micropolyspora faeni (mf) and challenge exposed them during infection with brsv. The development of mf-specific IgE serum concentrations was confirmed by elisa. The dynamics of arachidonic acid metabolism and histamine release during a type-1 hypersensitivity reaction in the bovine lung were studied by quantitating the concentrations of prostaglandin (pg)e2, pgf , pgi 2 as 6-keto-pgf , thromboxane (tx) A2 as txb 2, and histamine in plasma of brsv-infected and/or mf-sensitized/challenge-exposed calves. Four treatment groups were established: (1) brsv infection only, (2) aerosol sensitization to mf followed by brsv infection and aerosol challenge exposure to mf, (3) mf aerosol sensitization and challenge exposure without brsv infection, and (4) aerosol sensitization to mf followed by brsv infection without mf challenge exposure. Significantly increased concentrations of pgi 2 were associated with mf aerosol exposure, particularly when combined with brsv infection in group 2. After mf challenge exposure, txb 2 concentrations were significantly greater in the virus and mf challenge-exposed group 2. Individual calf data for the change in mf-specific IgE concentration between the first and second mf challenge exposures and the change in pg e2 concentration 30 minutes after the second mf challenge exposure had a highly significant direct correlation. Histamine concentrations were significantly greater in calves infected with brsv than in uninfected controls regardless of mf exposure. These data further substantiate the thesis that implicates type-1 hypersensitivity as a pathogenic mechanism in brsv-related disease.

Free access
in American Journal of Veterinary Research

Summary

Swab specimens for fungal isolation were collected from the healthy conjunctival sacs of 3 species of captive camelids (Lama glama, L guanicoe, L pacos) and llamaguanaco hybrids. Fungi were collected from over half the animals in winter (53%) and summer (56%). Fungal species of 10 genera were isolated. In both seasons, Aspergillus was the most commonly isolated genus; at least 9 species of Aspergillus were found. The fungal organisms isolated were similar to those found in healthy eyes of other domestic animals and may represent a random seeding from the environment where they are ubiquitous.

Free access
in American Journal of Veterinary Research

Summary

An efficient, single-step method for purification of the 110-kilodalton (kDa) hemolysin of Actmobacillus pleuropneumoniae was developed. An immunoaffinity column was made by cross-linking murine monoclonal antibody 8C2 to the 110-kDa hemolysin of A pleuropneumoniae strain J45 serotype 5 to protein A-agarose beads. Purified hemolysin with high hemolytic activity was obtained after washing the column with phosphate-buffered saline solution, and eluting the hemolysin with 50 mM diethylamine, pH 11.0. The same column was also used to purify the hemolysin from A pleuropneumoniae strain 4074 serotype 1. The purification procedure could be completed within 5 hours, and almost 50% of the total hemolytic activity and hemolysin protein was recovered in pure form.

Free access
in American Journal of Veterinary Research

SUMMARY

It has been shown that zearalenone disrupts early pregnancy in swine without altering intrauterine content of estradiol 17β or progesterone, embryo migration, or estradiol-17β synthesis by blastocysts. However, serum concentrations of progesterone were reduced 2 to 3 weeks after mating in gilts that ingested zearalenone. Therefore, progesterone was administered to gilts during early pregnancy to determine whether it could counteract the detrimental actions of zearalenone on embryonic development. Thirty-two crossbred gilts (Hampshire × Chester White × Yorkshire × Duroc) were assigned randomly to a 2 × 2 factorial arrangement of treatments: zearalenone (z); zearalenone plus progesterone (zp); progesterone (p); or control (c). From postmating days 4 to 15, z- and zp-treated gilts were fed 1 mg of z/kg of body weight, and p-treated and c gilts were fed ethanol as vehicle in a cornsoybean diet. On postmating days 3 to 15, p- and zp-treated gilts were injected im with 100 mg of progesterone, and c and z-treated gilts were injected with progesterone carrier (15% ethanol, 15% benzyl alcohol, 70% propylene glycol). Blood was collected from gilts by puncture of the jugular vein daily from days 3 to 15, on alternate days from days 17 to 31, and then twice weekly until the end of the experiment. Fetal development was assessed in z- and zp-treated gilts on postmating day 47.6 ± 2.9 by cesarean section and in p-treated and c gilts at slaughter on postmating days 51.2 ± 3.2. Serum concentrations of progesterone in p-treated gilts were greater on days 7 to 8, 10 to 15, 17, and 19 than in c gilts. Serum concentrations of progesterone were greater on days 8, 10, and 12 in zp-treated than in c gilts. However, serum concentrations of progesterone were lower in zp-treated gilts than in c gilts on postmating days 19 to 31. Serum concentrations of progesterone were lower in z-treated gilts than c gilts on postmating days 15, 17, and 19. At slaughter or cesarean section, viable fetuses were not found in z-treated gilts, but 80% of the c and p-treated gilts had viable fetuses. All z-treated gilts were classified as pseudopregnant because uteri were turgid and the ovaries had functional corpora lutea. Uteri of zp-treated gilts appeared normal. Corpora lutea of pregnancy had regressed by postmating day 35 in 7 of 8 zp-treated gilts. Crown-to-rump length was similar between p-treated and c gilts (94 vs 92 mm). Fetal weight was similar between p-treated and c gilts (70 vs 62 g). These data demonstrate that 100 mg of progesterone/d failed to counteract the adverse effects of 1 mg of z/kg of body weight on early pregnancy in primiparous gilts.

Free access
in American Journal of Veterinary Research

SUMMARY

Previous studies of the amino acid analogue, α-ketoisocaproate (kjc), indicate that it can stimulate lymphocyte blastogenesis and antibody responses of sheep. To determine whether kic could overcome the effects of adrenocorticotropic hormone (acth)-induced lymphocyte suppression, 24 lambs were fed a control diet, a diet supplemented with 0.05% kic, or a diet supplemented with 0.05% of the parent amino acid leucine. Immune status was monitored by determining lymphocyte blastogenic responsiveness to phytohemagglutinin-P (pha), concanavalin A (conA), and pokeweed mitogen (pwm) and percentages of T-cell subsets in the blood, using monoclonal antibodies and a flow cytometer. Serum Cortisol, insulin, and glucagon concentrations also were determined. After 60 days of consuming the respective diet, lambs were administered either saline solution or acth (100 IU) twice daily for 3 consecutive days. Administration of acth increased serum cortisol and insulin concentrations; however, no effects were seen for serum glucagon concentration. Compared with saline administration, acth administration significantly (P < 0.05) suppressed mitogen-stimulated lymphocyte blastogenesis by approximately 50%, regardless of the mitogen used, and significantly (P < 0.01) decreased the percentage of circulating T lymphocytes and decreased (P < 0.01) the ratio of T4 to T8 cells. Lambs fed kic had greater pha- and conA-stimulated blastogenic responses and significantly (P < 0.05) increased ratio of T4 to T8 cells in the blood, compared with lambs fed the leucine-supplemented diet or the control diet and given corresponding injections. These data indicate that acth decreased in vitro lymphocyte blastogenesis and altered the subset ratios of blood lymphocytes in sheep. These changes were partially prevented by feeding kic.

Free access
in American Journal of Veterinary Research

Summary

Absorption of colostral immunoglobulins by Holstein calves was studied in 3 herds in which 3 methods of colostrum feeding were used. Failure of passive transfer, as determined by calf serum immunoglobulin G1 (IgG1) concentration < 10 mg/ml at 48 hours of age, was diagnosed in 61.4% of calves from a dairy in which calves were nursed by their dams, 19.3% of calves from a dairy using nipple-bottle feeding, and 10.8% of calves from a dairy using tube feeding.

The management factor determined to have the greatest influence on the probability of failure of passive transfer in the herds using artificial methods of colostrum feeding (bottle feeding or tube feeding) was the volume of colostrum fed as it affected the amount of IgG1 received by the calf. In dairies that used artificial feeding methods, failure of passive transfer was infrequent in calves fed ≥ 100 g IgG1 in the first colostrum feeding. In the dairy that allowed calves to suckle, prevalence of failure of passive transfer was greater than 50% even among calves nursed by cows with above-average colostral IgG1 concentration. Analysis of the effect of other management factors on calf immunoglobulin absorption revealed small negative effects associated with the use of previously frozen colostrum and the use of colostrum from cows with long nonlactating intervals.

Free access
in Journal of the American Veterinary Medical Association