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排序方式: 共有85条查询结果,搜索用时 31 毫秒
1.
AR RABIEE KL MACMILLAN F SCHWARZENBERGER D THALLER MJ RATHBONE TE TRIGG 《Australian veterinary journal》2001,79(10):690-694
OBJECTIVE: To evaluate the potential of an implant of a GnRH-agonist (deslorelin) to create a progesterone free animal suitable for studying progesterone (P4) metabolism in intact cows by measuring blood P4 and faecal P4 metabolites. METHODS: Experiment 1: Eighteen non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to one of three groups to study plasma P4 concentrations preceding an intravaginal insert. These groups comprised: i) a deslorelin group (GnRH-agonist implanted); ii) a PGF group receiving two injections of prostaglandin (PGF2alpha) 12 days apart; and, iii) an ovariectomised (OVX) group. An intravaginal device (CIDR) was inserted into the vagina of each animal and left in place for 11 days. Plasma P4 concentrations were measured during the study period. Experiment 2: Twelve non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to two groups: i) a deslorelin group (GnRH-agonist implanted); and ii) an ovariectomised group. Plasma P4 and faecal P4 metabolites (20-oxo-pregnanes, 20alpha-OH and 20beta-OH) were monitored for a period of 5 weeks. RESULTS: Experiment 1: Average plasma P4 concentration did not differ between the three groups (1.28, 1.43 and 1.55 ng/mL for deslorelin, OVX and PGF cows, respectively, P = 0.8) during the period of supplementation. Experiment 2: There was no difference in plasma P4 (mean plasma P4 < 0.02 ng/mL, P = 0.9) and faecal P4 metabolites between deslorelin and OVX cows 2 weeks after the implantation (P = 0.7). CONCLUSIONS: These data showed that a GnRH-agonist (deslorelin) implant may be used as an alternative to ovariectomy to create a progesterone free animal suitable for studying the metabolism of administered P4. 相似文献
2.
Wyatt CR Barrett WJ Brackett EJ Davis WC Besser TE 《Veterinary immunology and immunopathology》1999,67(3):213-222
Ileal intraepithelial lymphocyte (IEL) suspensions from suckling calves (1-3 weeks old) and weaned calves (3-6 months old) were phenotyped to determine whether there were differences in the lymphocyte populations consistent with postnatal maturation of the mucosal immune system. Flow cytometric comparisons of IEL from the two age groups revealed the presence of significantly larger proportions of CD4+ T lymphocytes and CD8+ T cells in the weaned animals. In contrast, there was a significantly larger proportion of B-B2+ IEL in the suckling calves. Freshly isolated IEL from both groups of calves expressed mRNA for TNF-alpha and IFN-gamma, but not IL-4 or IL-10. The B-B2+ IEL population was more closely examined by flow cytometry. These cells co-expressed IgM and CD21. However, they did not express IgA, IgG1, nor any of several additional leukocyte differentiation molecules. Immunohistochemical data confirmed the presence of IgM+ lymphocytes, and the paucity of IgA+ and IgG1+ lymphocytes in suckling calf ileum. However, substantial numbers of IgA+ and IgG1+ cells were observed in weaned calf ileum. Together, the data are consistent with ongoing postnatal maturation of the gut mucosal immune system. 相似文献
3.
【目的】 研究催乳素(PRL)对内蒙古绒山羊初级毛囊和次级毛囊体外生长及形态变化的影响。【方法】 机械法结合切割法分离内蒙古绒山羊的初级毛囊和次级毛囊,在初级毛囊培养液中分别添加0、5、10、50、100 ng/mL催乳素进行体外培养,每组24根,共培养5 d,每天在显微镜下观察其形态并拍照,统计其生长长度、生长速度和存活率,筛选出最适催乳素处理浓度。然后将初级毛囊与次级毛囊分别分为初级毛囊对照组(PF-K)、初级毛囊试验组(PF-PRL)、次级毛囊对照组(SF-K)、次级毛囊试验组(SF-PRL),每组24根,对照组用基础培养液培养,试验组在基础培养液中添加最适浓度的催乳素,培养5 d,每天观察毛囊的形态并拍照,同时测量各组毛囊的生长长度。【结果】 10 ng/mL催乳素组毛囊的平均日生长长度均极显著高于其他浓度组(P<0.01),最终生长长度和存活率均最高,因此,后续试验选择10 ng/mL催乳素处理毛囊。试验组和对照组初/次级毛囊的毛干与根鞘部位同时伸长,随着培养时间的增加均出现不同程度的弯曲。PF-PRL、SF-PRL组毛囊在2~5 d的总长度分别极显著高于PF-K、SF-K组(P<0.01)。PF-K组除第1天与第0天差异不显著外,1~5 d毛囊的总长度依次显著增加(P<0.05);PF-PRL组0~5 d毛囊的总长度依次显著增加(P<0.05)。SF-K组毛囊第5天的总长度显著高于0~4 d (P<0.05);SF-PRL组第4、5天毛囊的总长度均显著高于0~3 d (P<0.05),第3天毛囊的总长度显著高于0~2 d (P<0.05)。PF-PRL、SF-PRL组毛囊在2~5 d的平均日生长长度分别极显著高于PF-K、SF-K组(P<0.01)。【结论】 10 ng/mL催乳素是体外促进毛囊生长的最适浓度,10 ng/mL催乳素对体外培养的内蒙古绒山羊的初级毛囊和次级毛囊均有极显著的促生长作用。 相似文献
4.
Comparison of three methods of feeding colostrum to dairy calves 总被引:4,自引:0,他引:4
T E Besser C C Gay L Pritchett 《Journal of the American Veterinary Medical Association》1991,198(3):419-422
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 less than 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 greater than or equal to 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. 相似文献
5.
Long-term persistence of multi-drug-resistant Salmonella enterica serovar Newport in two dairy herds
Cobbold RN Rice DH Davis MA Besser TE Hancock DD 《Journal of the American Veterinary Medical Association》2006,228(4):585-591
OBJECTIVE: To evaluate the association between maintaining joint hospital and maternity pens and persistence of multi-drug-resistant (MDR) Salmonella enterica serovar Newport on 2 dairy farms. DESIGN: Observational study. SAMPLE POPULATION: Feces and environmental samples from 2 dairy herds. PROCEDURE: Herds were monitored for fecal shedding of S enterica Newport after outbreaks of clinical disease. Fecal and environmental samples were collected approximately monthly from pens housing sick cows and calving cows and from pens containing lactating cows. Cattle shedding the organism were tested serially on subsequent visits to determine carrier status. One farm was resampled after initiation of interventional procedures, including separation of hospital and maternity pens. Isolates were characterized via serotyping, determination of antimicrobial resistance phenotype, detection of the CMY-2 gene, and DNA fingerprinting. RESULTS: The prevalence (32.4% and 33.3% on farms A and B, respectively) of isolating Salmonella from samples from joint hospital-maternity pens was significantly higher than the prevalence in samples from pens housing preparturient cows (0.8%, both farms) and postparturient cows on Farm B (8.8%). Multi-drug-resistant Salmonella Newport was isolated in high numbers from bedding material, feed refusals, lagoon slurry, and milk filters. One cow excreted the organism for 190 days. Interventional procedures yielded significant reductions in the prevalences of isolating the organism from fecal and environmental samples. Most isolates were of the C2 serogroup and were resistant to third-generation cephalosporins. CONCLUSIONS AND CLINICAL RELEVANCE: Management practices may be effective at reducing the persistence of MDR Salmonella spp in dairy herds, thus mitigating animal and public health risk. 相似文献
6.
绵羊在发情周期中各生殖激素浓度变化与卵泡发育、成熟和排卵有着密切的关系。为了研究巴美肉羊血清生殖激素的动态变化及其与排卵数关系,试验采用电化学法,测定了12只成年母羊发情期血清中2种类固醇激素(E2和P4)的浓度水平,分析其动态变化规律,并用SAS 9.0的方差分析程序分析激素浓度与排卵数的关系。结果表明,两种激素在排单卵组和排双卵组绵羊间变化规律不同,E2在排单卵组表现为先下降后升高的变化趋势,在排双卵组表现为持续下降趋势;P4在排单卵组表现为持续上升的趋势,在排双卵组为先上升后下降的变化趋势。排单卵和排双卵组绵羊在各时间点的E2和P4激素浓度差异均不显著(P>0.05)。 相似文献
7.
The use of antimicrobial drugs in livestock is suspected to contribute to bacterial antimicrobial resistance (AR) development. Dairy farms experiencing recent outbreaks of salmonellosis involving multi-resistant (MR) Salmonella strains were compared to control farms with respect to AR among bovine commensal E. coli isolates. For most antimicrobials tested, the percentage of AR E. coli isolated from salmonellosis-affected farms was significantly higher than that from control farms. Calf E. coli from both case and control farms had greater levels of AR than cow isolates. Commensal E. coli isolates from case farms and calves tended to more frequently be MR. These data are consistent with the existence of higher antimicrobial selection pressure on farms with recent salmonellosis outbreaks, however, the directionality of the relationship remains to be elucidated. An improved understanding of the epidemiology of AR bacteria in livestock production, both at the herd and molecular level, is essential to mitigate risk to public health and food safety. 相似文献
8.
Using recombinant gonadotropins for assisted reproduction of domestic species is still in its infancy. Yet, the purity, potency and pathogen-free nature of recombinant gonadotropins make them attractive alternatives to tissue-derived gonadotropic agents. In this study, the authors summarize the work to date using recombinant gonadotropins to enhance the - fertility of domestic animals and they discussed their recent studies examining the biopotency of single chain analogues of human gonadotropins. In these studies, single chain analogues of follicle stimulating hormone (Fcα), chorionic gonadotropin (CGβα) or a gonadotropin construct with dual activity (FcCGβα) were administered to sheep pre-treated with antisera directed against GnRH. Ovulation was induced 3 days after analogue administration using hCG (1000 IU, iv). Although Fcα or CGβα alone induced only modest oestradiol production during the pre-hCG period, serum concentrations of oestradiol were markedly increased (p < 0.05) 3 days after administration of FcCGβα or the Fcα + CGβα combination. Final ovarian weight was significantly increased (p < 0.05) in animals receiving Fcα, Fcα + CGβα or FcCGβα. Collectively, these observations demonstrate that the single chain analogues of the human gonadotropins are active in sheep. 相似文献
9.
10.
Evaluation of 3 Assays for Failure of Passive Transfer in Calves 总被引:2,自引:1,他引:1
Jeff W. Tyler Dale D. Hancock Steven M. Parish Douglas E. Rea Thomas E. Besser Sean G. Sanders Leilani K. Wilson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1996,10(5):304-307
This study examined the sensitivity, specificity, predictive values, and classification accuracy of 3 commonly used screening tests for failure of passive transfer: the sodium sulfite turbidity test, the zinc sulfate turbidity test, and re-fractometry relative to serum immunoglobulin G1, (IgG1) concentrations determined by radial immunodiffusion. Serum samples were obtained from 242 calves ranging from 1 to 8 days of age. Using a serum concentration of 1,000 mg/dL IgG1 to define adequate passive transfer, the zinc sulfate test had a sensitivity of 1.00 and a specificity of 0.52 in the detection of inadequate passive transfer. The endpoint of the test appeared to be higher than desired; calves testing negative had mean serum IgG1 concentration of 955 mg/dL and a large proportion of calves with adequate passive transfer were misclassified as positive for failure of passive transfer. Using the qualitative zinc sulfate test, the percentage of calves correctly classified with regard to passive transfer status was less than that observed with either the sodium sulfite test or refractometry. The sensitivity of the sodium sulfite assay was 0.85 at a 1+ endpoint and 1.00 at a 2 or 3+ endpoint. The specificity of the sodium sulfite assay varied from 0.87 at a 1+ endpoint and 0.56 at a 2+ endpoint. The sensitivity and specificity of refractometry varied from 0.01 to 1.00 depending on the choice of endpoint. Refractometry correctly classified the largest proportion of calves with regard to their passive transfer status at test endpoints of 5.0 and 5.5 g/dL, 83% and 82% respectively. The highest percentages of calves correctly classified occurred with the sodium sulfite test using a 1+ endpoint (86.30%) and refractometry using a 5.0 g/dL endpoint (83.00%). A regression equation was developed that permitted calculation of an optimal endpoint for refractometric determinations of total serum protein concentration. A serum protein concentration of 5.2 g/dL was equivalent to 1,000 mg/dL serum IgG1. Optimal selection of tests for passive transfer status in calves will be governed by the prevalence of failure of passive transfer, test performance, and the anticipated costs of classification errors. 相似文献