Effects of experimentally generated bull antisperm antibodies on in vitro fertilization.
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To test the hypothesis that bull antisperm antibodies have the capacity to interfere with fertilization, antisperm antibodies were generated in three 13-mo-old Holstein bulls by auto-immunizing each bull with sperm three times. All bulls produced serum antisperm IgG1 and IgG2 antibodies. No serum antisperm IgA nor seminal plasma antisperm antibodies of any isotype could be detected by ELISA. Western blots were performed with immunopurified IgG1 and IgG2 from pre- and post-immunization sera from one test bull. Both post-immunization IgG1 and IgG2 recognized a 45-kDa sperm antigen. Serum samples from a normal bull stud population tested by ELISA had significantly higher levels of antisperm antibodies than did heifers. The bull stud serum samples giving the highest ELISA values differed from those of the immunized bulls in that their antisperm antibodies were of the IgM isotype only. Bull sperm were incubated with serum from the immunized and control bulls, then added to bovine oocytes in vitro. Incubation of sperm with post-immunization serum reduced in vitro fertilization rates (p < 0.01). This study demonstrated that antisperm IgG1 and IgG2 generated by sperm auto-immunizations reduced fertility in vitro, and therefore naturally occurring antisperm antibodies may affect fertility in bulls. (+info)
Chemical control of Haematobia irritans with 0.5% topical ivermectin solution in cattle.
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A field trial was conducted to evaluate the efficacy of a topical formulation of ivermectin administered at the dose of 500 micrograms/kg against horn flies (Haematobia irritans) in cattle. Eighty-eight cattle in four herds naturally exposed to horn flies were used in the trial. Replicates were formed of two herds. Within replicates, one herd was randomly allocated to the untreated control and the other to the ivermectin treatment group. Horn fly counts were taken on the treatment day (Day 0) and on Days 7, 14, 21, 28, and 35 post-treatment. There were no horn flies on any cattle in the treatment group, whereas all the control cattle were continuously infested by horn flies on each examination day. (+info)
Experimental infection of pregnant cows with Bacillus licheniformis bacteria.
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To study the abortifacient potential and fetoplacental tropism of Bacillus licheniformis bacteria, eight cows in the sixth to eighth month of gestation were inoculated intravenously either once (n = 4) or on four successive days (n = 4) with B. licheniformis at doses ranging from 10(9) to 10(12) colony-forming units. Cows were euthanatized and necropsied prior to abortion (n = 2), at the time of abortion (n = 2), or at calving (n = 4). Live-born calves (n = 5) were euthanatized immediately after delivery and necropsied. B. licheniformis was reisolated from placentomes/endometrium in six of eight (75%) cows and from one fetus aborted 43 days after inoculation. Lesions associated with B. licheniformis were restricted to the pregnant uterus, with the exception of one cow, which developed pneumonia. Necrosis in the fetal compartment of the placenta were present in three of four (75%) cows of both inoculation groups. Lesions were mainly restricted to fetal membranes and especially to the fetal side of the placentomes. Necrosis and diffuse neutrophil infiltrations of both villi and intervillous areas occurred in the fetal part of the placenta, and the placentomal interface was distended by bacteria, neutrophils, erythrocytes, and debris. Within trophoblasts, bacteria were located both free in the cytoplasm and in cytoplasmatic vesicles. Inflammation was present in three of eight (38%) calves. Placental and fetal lesions were similar to those found in cases of spontaneous abortions associated with B. licheniformis. The abortifacient potential of B. licheniformis and the tropism for the bovine placenta is demonstrated here for the first time. (+info)
Naturally occurring Tyzzer's disease in a calf.
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Naturally occurring Clostridium piliforme infection (Tyzzer's disease) was found in a calf. Light microscopic examination revealed multifocal coagulative necrosis in the liver, catarrhal gastroenteritis, tracheitis and pneumonia, and thymic atrophy. Warthin-Starry staining clearly showed large filamentous bacilli in bundles or criss-cross patterns within the hepatocytes and epithelium and smooth muscle cells of the ileum and cecum. Immunohistochemistry using anti-C. piliforme RT and MSK strain antisera showed positive reaction against the bacilli. Electron microscopic examination revealed bacilli within the hepatocytes that demonstrated a characteristic vegetative form, with peritrichous flagella, and spores. The polymerase chain reaction (PCR) study using the paraffin-embedded liver sections, the 196-bp DNA fragment specific to 16S ribosomal RNA of C. piliforme was amplified. The characteristics of these bacilli are consistent with those of of C. piliforme. The PCR technique using paraffin-embedded sections should be useful for confirming C. piliforme infection in spontaneous cases. (+info)
Genomic DNA restriction site heterogeneity in bovine Pasteurella multocida serogroup A isolates detected with an rRNA probe.
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A total of 81 Pasteurella multocida isolates from healthy and diseased dairy and beef cattle originating from various geographical locations was examined by rRNA gene restriction site polymorphism analysis (ribotyping), restriction endonuclease analysis (REA), SDS-PAGE analysis of whole-cell (WCP) and outer-membrane (OMP) proteins, and capsule and somatic serotyping. Bacterial strains were isolated from nose, lung and in one case testicle, of Holstein and cross-bred beef cattle. The isolates represented for the most part serogroup A3 (88%). Ribotyping was performed on DNA digested with HaeII, electrophoresed and then hybridised with 32P-labelled 16S-23S rRNA from Escherichia coli. Six ribotypes (R1-R6) and 10 REA types were found among the 81 isolates with similar discrimination index (DI) of c. 0.60. Protein profiles revealed reproducibility and high levels of polymorphisms among lung isolates. Isolates were compared according to their geographical habitat, their isolation from dairy or from beef cattle and from nasal cavities or lungs. No correlation was apparent between geographical locations and ribotypes. Overall, isolates obtained from dairy cattle were predominantly R1, whereas those obtained from beef cattle were equally distributed between R1 and R2. R1 was more representative of lung isolates. For some strains, particularly the single isolate ribotypes, good correlation was achieved between WCP analysis, REA types and ribotypes. For others, REA to some extent and WCP profiles were able to discriminate among isolates within ribotypes. The data suggest that a combination of ribotyping, REA and WCP analysis is useful for investigating the epidemiology of bovine P. multocida serogroup A. (+info)
The prevalence of verotoxins, Escherichia coli O157:H7, and Salmonella in the feces and rumen of cattle at processing.
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Fecal samples collected from cattle at processing during a 1-year period were tested for verotoxins (VT1, VT2), Escherichia coli O157:H7, and Salmonella. Verotoxins were detected in 42.6% (95% CI, 39.8% to 45.4%), E. coli O157:H7 in 7.5% (95% CI, 6.1% to 9.1%), and Salmonella in 0.08% (95% CI, 0.004% to 0.5%) of the fecal samples. In yearling cattle, the median within-lot prevalence (percentage of positive samples within a lot) was 40% (range, 0% to 100%) for verotoxins and 0% for E. coli O157:H7 (range, 0% to 100%) and Salmonella (range, 0% to 17%). One or more fecal samples were positive for verotoxins in 80.4% (95% CI, 72.8% to 86.4%) of the lots of yearling cattle, whereas E. coli O157:H7 were detected in 33.6% (95% CI, 26.0% to 42.0%) of the lots. In cull cows, the median within-lot prevalence was 50% (range, 0% to 100%) for verotoxins and 0% (range, 0% to 100%) for E. coli O157:H7 and Salmonella (range, 0% to 0%). Verotoxins were detected in one or more fecal samples from 78.0% (95% CI, 70.4% to 84.2%) of the lots of cull cows, whereas E. coli O157:H7 were detected in only 6.0% (95% CI, 3.0% to 11.4%) of the lots of cull cows. The prevalence of verotoxins in fecal samples was lower in yearling cattle than in cull cows, whereas the prevalence of E. coli O157:H7 in fecal samples was higher in yearling cattle than in cull cows. The prevalence of E. coli O157:H7 in fecal samples was highest in the summer months. Rumen fill, body condition score, sex, type of cattle (dairy, beef), and distance travelled to the plant were not associated with the fecal prevalence of verotoxins or E. coli O157:H7. The prevalence of verotoxins in fecal samples of cull cows was associated with the source of the cattle. It was highest in cows from the auction market (52%) and farm/ranch (47%) and lowest in cows from the feedlot (31%). In rumen samples, the prevalence of verotoxins was 6.4% (95% CI, 4.2% to 9.4%), and it was 0.8% (95% CI, 0.2% to 2.3%) for E. coli O157:H7, and 0.3% (95% CI, 0.007% to 1.5%) for Salmonella. (+info)
Feeding and watering behavior of healthy and morbid steers in a commercial feedlot.
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Our objective was to determine whether there were differences in feeding and watering behavior of newly received healthy and morbid feedlot steers. Two separate 32-d feeding trials were conducted in Wellton, Arizona, in July and November 1996. Radio frequency technology was used to record individual animal behaviors from 108 (average weight 139 kg) and 143 (average weight 160 kg) steers in each respective trial. Steers that were subsequently identified as morbid were present at the feed bunk in greater percentages than reported in previous studies. In Trial 1, healthy steers spent more (P < .001) time at the feed bunk and had more (P < .009) feeding bouts than morbid steers. In Trial 2, healthy steers did not spend more time at the feed bunk, but they had more (P < .02) daily feeding bouts than morbid steers. There were no differences in daily time spent at the water trough by healthy or morbid steers in either trial. The greatest proportion of feeding and watering behavior occurred during the daylight hours in response to feed delivery. The pattern of time spent at the feed bunk throughout the 32-d feeding period was similar for healthy and subsequently morbid steers, but healthy steers had more feeding bouts per day. (+info)
Physiological changes and digestive capabilities of newly received feedlot cattle.
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Newly arrived feedlot calves undergo numerous stressors that result in 1) transient endocrine responses, 2) altered products of energy and protein metabolism, 3) changes in appetite and growth rate, 4) possible limited compromise of digestive and rumen function, and 5) a challenged immune system. The most consistent endocrine and metabolic responses to marketing, transport, and feedlot adaptation are seen with cortisol and epinephrine. In contrast to earlier work done with indirect in vitro gas production measurements, recent research has shown that the ruminal microbial population is able to effectively digest available substrate immediately following a calfs weaning, trucking, and 24 h of feed and water deprivation. Additionally, a period of feed and water deprivation up to 72 h coupled with 8 h of trucking does not reduce the concentration or total numbers of either the viable cellulolytic or total bacteria present in the rumen of newly weaned or feedlot-adapted calves. However, ruminal volume, DM, total weight of ruminal contents, and total protozoal numbers decrease as duration of feed deprivation increases. To compensate for the reduced DMI that occurs in the first 2 wk after arrival at the feedlot, increased nutrient density is needed to meet an animal's requirements for nutrients. Limited data suggest that newly arrived calves prefer a diet that is similar in moisture and texture to feeds with which they are familiar. Additionally, modification of the stress-associated behavior using trainer animals may improve the feed intake of newly received calves and may reduce calf morbidity. (+info)