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101.
The prevalence of bovine respiratory disease (BRD) was assessed in a population of 10,142 beef calves representing nine pure breeds and three composite populations born in 1983 through 1988. Twenty-four percent of the calves experienced at least one episode of respiratory disease during the 1st yr of life; frequencies over the six birth years ranged from 14 to 38%. The timing of respiratory disease outbreaks differed among birth years; in 4 of the 6 yr, more illness occurred in the pasture before weaning than in the feedlot after weaning. Frequencies of BRD during preweaning and postweaning periods were analyzed separately. Pure breeds and composite populations within a single preweaning location differed in frequency of illness during the preweaning period. However, not all possible breed comparisons could be made because preweaning location differed for the breed groups, and preweaning location had a significant effect on the frequency of respiratory disease in the preweaning period. The preweaning location effect did not carry through to the postweaning period. Pinzgauers had the highest BRD frequency within the feedlot (24.6%). The heritability estimates of BRD during the preweaning and postweaning periods did not differ significantly from 0 (.10 +/- .02 and .06 +/- .07, respectively). Although it is likely that response to selection for resistance to BRD would be slight using the animal's history of BRD as the selection criterion, including information on relatives or additional immune traits may improve the accuracy of an estimated breeding value for BRD resistance. 相似文献
102.
T R Kasari T S Taylor A N Baird E L Morris 《Journal of the American Veterinary Medical Association》1992,201(7):1053-1057
Osteolytic defects were detected radiographically in the distal sesamoid bone of a 16-month-old Bralers heifer, in the middle phalanx of a 14-month-old American Gray Brahman bull, and in the distal phalanx of a 3-year-old American Gray Brahman bull. The articular cartilage was damaged in each animal because of osteolysis or pathologic fracture. After each animal was anesthetized and positioned in lateral recumbency, the lesions were curetted and packed with cancellous bone harvested from the same animal's tuber coxae. Basic postoperative management involved stall rest and immobilization of the graft site with a fiberglass cast (42 to 79 days), after which a support bandage was used for approximately 2 weeks. Recurrence of lameness has not been observed in these animals for 60 months, 58 months, and 21 months, respectively. These cases exemplify the benefit of using an autogenous cancellous bone graft for treatment of severe osteolysis of a digit in cattle. 相似文献
103.
W. E. HAWKINS J. W. FOURNIE R. M. OVERSTREET W. W. WALKER 《Journal of fish diseases》1988,11(3):259-266
Abstract. Three cases of skeletal muscle neoplasms occurring in two small fish species used in carcinogen tests are reported. The cases illustrated a wide range of histologic patterns, and consisted of a well-differentiated juvenile type, a well-differentiated pleomorphic type and a poorly differentiated pleomorphic type. A rhabdomyosarcoma with juvenile type features developed in the Japanese medaka, Oryzias latipes , exposed to 0·5 ml/1 of the solvent dimethylformamide. A pleomorphic type rhabdomyosarcoma occurred in one medaka and in one guppy, Poecilia reticulata , exposed to the carcinogen methylazoxymethanol acetate. These cases indicate the potential for skeletal muscle cells in medaka and guppy to become neoplastic but, because the tumours occurred at a low frequency, there may not necessarily be a chemical aetiology. 相似文献
104.
With the help of a new synthetic material follicles and corpora lutea from the ovaries of 80 cows in different stages of the sexual cycle were examined for modifications of their blood vessel architecture. In the theca externa the main artery which runs towards the follicle, separates into arterioles of which capillaries derive in the theca interna, building a basket-like network around the zona granulosa. After ovulation the follicle wall forms characteristic fields. Capillaries grow into the zona granulosa and thus the folds form the lobular structure of the corpus luteum. Capillaries which rise from the ruptured part of the follicle, spread centripetally and together with lutein cells they build up the not lobulated cupola of the corpus luteum. The regression of the corpus luteum starts around the 16th day of the cycle, beginning at the capillary network of the cupola. A contraction of the vessels and a quick decrease of the volume follow. 相似文献
105.
An ultrasonic linear array scanner with a transrectal probe was used to observe ovarian and uterine changes associated with the reproductive cycle in llamas. 'Waves' of follicular development and regression occurred in unstimulated females, during which the dominant follicle reached a maximum size of 9 to 13 mm; both ovaries were equally active. Ovulation was induced by mating in 80 per cent of cases, and when mating was accompanied by the administration of human chorionic gonadotrophin the ovulation rate increased to 90 per cent and the time to ovulation decreased from two to three days to one to two days. Some spontaneous ovulations occurred. Corpora lutea reached a maximum size of 12 mm (non-pregnant) or 14 mm (pregnant) after seven or 16 days, respectively. The lifespan of the corpus luteum was approximately 11 days in non-pregnant llamas and the regression time was advanced by the administration of prostaglandin or embryo recovery. Pregnancy could be diagnosed as early as 19 days after mating. 相似文献
106.
107.
Abstract. Experiments were conducted for one year on two different soil types. On a clay soil straw was either (a) burnt, (b) baled leaving the stubble, or (c) chopped and spread. The soil was tine cultivated to depths of 5, 10 or 15 cm or ploughed to 20 or 30 cm before winter wheat was sown conventionally. In addition, a direct-drilled crop was sown after each straw treatment. On a silt loam soil the direct-drilled, tine cultivated to 15 cm and ploughed to 30 cm treatments following burning or chopping and spreading straw were repeated.
Tine cultivation incorporated less straw than ploughing, decreased plant establishment and early growth but did not decrease yield. Direct-drilling through chopped straw decreased yield on the silt loam but not on the clay soil. Short straw (< 5 cm) was easier to incorporate than longer straw. Ploughing was the most efficient method of straw incorporation because it inverts soil. Early effects on crop growth and nutrient uptake following straw incorporation were transient and associated with large amounts of straw in the seeded layer of soil. 相似文献
Tine cultivation incorporated less straw than ploughing, decreased plant establishment and early growth but did not decrease yield. Direct-drilling through chopped straw decreased yield on the silt loam but not on the clay soil. Short straw (< 5 cm) was easier to incorporate than longer straw. Ploughing was the most efficient method of straw incorporation because it inverts soil. Early effects on crop growth and nutrient uptake following straw incorporation were transient and associated with large amounts of straw in the seeded layer of soil. 相似文献
108.
The sera of 188 lambs from seven breed groups were analyzed for the concentrations of IgG1, IgG2, IgM and IgA by radial immunodiffusion using monospecific antibodies. From each lamb, 14 blood samples were drawn before and 5 samples after weaning. The following results were obtained: 1. Immunoglobulins could not be detected in sera drawn before the first intake of colostrum. 2. In normally suckling lambs, the peak concentrations of maternal immunoglobulins are attained at 0-18 hrs after birth. They can be assessed in a single blood sample drawn between 18 and 24 hrs. 3. The half-life times of maternal immunoglobulin in lamb sera are 11 days for IgG1, 7 days for IgG2, 6 days for IgM and 18 hours for IgA. 4. The absolute peak heights relate to the amounts of colostrum ingested before 12-18 hrs after birth. 5. The decline of maternal immunoglobulins in lamb sera over-laps with the onset of lamb immunoglobulin synthesis. Renewed rises of concentrations are observed for IgG2 after week 2, for IgM after week 3 and for IgG1 after week 7. The concentrations of IgA remain at the low levels characteristic for the serum of grown sheep. 6. The role of immunoglobulin synthesis in suckling lambs is only briefly and to a small extent reduced after weaning. 相似文献
109.
Effect of a new pelleting process on the level of contamination of poultry mash by Escherichia coli and Salmonella 总被引:2,自引:0,他引:2
R H McCapes H E Ekperigin W J Cameron W L Ritchie J Slagter V Stangeland K V Nagaraja 《Avian diseases》1989,33(1):103-111
The efficacy of a new pelleting process in eliminating naturally occurring Escherichia coli and salmonella from poultry mash was assessed by comparing the microbial load in raw and processed mash. Instead of using steam produced in a boiler, the new process conditioned mash in an Original Vertical Conditioner with steam and other hot gases generated by direct combustion in a Vaporator. E. coli was isolated from 72-100% of samples of raw mash in all trials, and the mean number of colony-forming units of E. coli/g of samples was 6.8 +/- 4.0 X 10(4). Salmonellae (S. senftenberg, S. bredeney, and S. mbandaka) were isolated from 5-10% of samples of raw mash utilized in three of the seven trials. Within limitations of the sampling and analytical tests utilized, the new pelleting process eliminated salmonella from all mash in which the organism was known to be present but eliminated E. coli in only three trials. The process appeared to be 100% effective against both organisms when mash entering the pellet mill from the conditioner had a temperature of 85.7 C and a moisture content of 14.5% and had been retained and treated with steam and hot gases for 4.1 minutes. 相似文献
110.
Characterization of Brucella canis protein antigens and polypeptide antibody responses of infected dogs 总被引:1,自引:0,他引:1
The cytoplasmic protein antigens (CPAg) of Brucella canis were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analysis of 35S-labeled polypeptides. Approximate molecular weights of the immunoreactive polypeptides were determined by migration patterns of the immunoprecipitated polypeptides after SDS-PAGE or Western immunoblotting of sera collected at various times after experimental infection of dogs. Polypeptides were specifically precipitated by sera of infected dogs, but not from the sera of normal or false-positive (seropositive, non-infected) animals. During the initial month after infection, proteins with molecular weight masses (MW) of approximately 18, 22, 31, 42 and 54 kDa were commonly recognized. A 20-kDa polypeptide was first recognized at 8-10 weeks after infection, but it was detected inconsistently after 6 months. Additional polypeptides detected from 2 to 12 months post-infection had MW of 22, 66-68 and, less regularly, 42, 60, 82, 100 and greater than 200 kDa. The polypeptides most consistently recognized in sera from B. canis-infected dogs had MW of 18, 22 and 68 kDa. 相似文献