The Expanding Role of Recombinant Gonadotropins in Assisted Reproduction     

TE Adams  I Boime 《Reproduction in domestic animals》2008,43(S2):186-192

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   

Resistance to macrocyclic lactone anthelmintics and associated risk factors on sheep farms in the lower North Island of New Zealand     

Hughes PL  Dowling AF  Callinan AP 《New Zealand veterinary journal》2007,55(4):177-183

AIM: To estimate the prevalence of resistance to macrocyclic lactone (ML) anthelmintics over a 3-year period on sheep farms in the Taihape area, and to determine associations between the presence of ML resistance and farm management practices. METHODS: All farmers with >1,000 lambing ewes served by one veterinary practice in the Taihape area of the central North Island of New Zealand were invited to take part in the study (n=157); respondents were selected on their willingness to participate. Resistance to ML was measured during 2004-2006, using a standard faecal egg count reduction test (FECRT) and a half dose of oral ivermectin (IVM; 0.1 mg/kg; n=84). Additional FECRTs were conducted separately on some farms, using full doses of IVM (n=47), levamisole (LEV; n=49), a benzimidazole (BZ; n=76), and a BZ/LEV combination (n=42). Resistance was defined as <95% faecal nematode egg count reduction (FECR) 7-10 days post-treatment. Larval cultures were performed on pooled faecal samples from all pre- and post-treatment groups for which any positive faecal nematode egg counts (FEC) were recorded. To ascertain whether particular management or drenching strategies were associated with the presence of resistance, a questionnaire comprising 50 questions was developed, and each farmer interviewed individually. RESULTS: Of all farmers invited, 84/157 (54%) participated in this study. Based on undifferentiated FEC, ML resistance to the half-dose IVM was evident on 46/84 (55%) participating farms. The majority of these cases (71%) involved Ostertagia (Teladorsagia) circumcincta. Resistance was also evident to full doses of IVM on 22/47 (47%), BZ on 41/76 (54%), LEV on 18/49 (37%), and BZ/LEV on 2/42 (5%) farms. Positive associations (p<0.05) were evident between the presence of ML resistance and management practices, such as: weaning over half of the lambs onto paddocks not grazed by lambing ewes since June; not always returning lambs to the same paddock after drenching; and the use of visual signs to assess 'worminess'. Measuring drench efficacy in January to March rather than later in the year, and presence of resistance to BZ or LEV were associated with a higher apparent prevalence of ML resistance (p<0.05). CONCLUSIONS: Anthelmintic resistance, and particularly ML resistance, was widespread on sheep farms in the Taihape area, and mostly involved O. circumcincta. The prevalence of resistance was lower on farms on which management practices, particularly those involving lambs, maintained refugia of unselected nematodes. Further investigation is required to develop control strategies which minimise selection for resistant worms, and how these may vary with climate.  相似文献   

Vetbase 3.1 (software)          下载免费PDF全文

Patricia M. Dowling 《The Canadian veterinary journal. La revue veterinaire canadienne》1999,40(11):811

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Equine protozoal myeloencephalitis caused by Neospora hughesi in an adult horse in Saskatchewan     

Bruce K. Wobeser  Dale L. Godson  Daniel Rejmanek  Patricia Dowling 《The Canadian veterinary journal. La revue veterinaire canadienne》2009,50(8):851-853

A protozoal parasite identified as Neospora hughesi was found in inflammatory lesions in the central nervous system of a Canadian-born adult horse presented with neurological signs. This is believed to be the first case of equine protozoal myeloencephalitis (EPM) caused by Neospora hughesi in a horse outside of the United States.  相似文献   

Assessing opportunity and relocation costs of marine protected areas using a behavioural model of longline fleet dynamics     

Natalie A Dowling  Chris Wilcox  Marc Mangel  Sean Pascoe 《Fish and Fisheries》2012,13(2):139-157

Increasing use of spatial management tools in fisheries requires an understanding of fleet response, and in particular to where displaced fishing effort is likely to move. We develop a state‐dependent decision‐making model to address the spatial allocation of effort in an Australian tuna longline fishery. We assume that fishers have an economic objective in deciding where to fish, but that decisions in any period are also influenced by the remaining quota held at the time of the decision. Key features of the model include endogenous price dynamics, a moving stock and a competitive pool of different vessel types operating from different port locations. We utilize this model to illustrate fleet responses to marine reserves and limits on fishing effort. The results illustrate that the model framework provides advantages over statistically based models in that decisions made in response to the imposition of a reserve are not consistent with a proportional reallocation of effort. Rather, the stochastic dynamic model yielded an overall profit level of ～4% higher relative to scenarios with no reserve. Incorporating the opportunity cost of a quota into the model resulted in an optimal utilization of effort, in which effort was concentrated in time periods and locations yielding maximized profit. Under a low level of effort relative to the season length, the model indicated an overall profit level 43% greater than the highest obtained when the same level of effort was applied solely within any given quarter of the season.  相似文献   

蓟马取食对苜蓿氨基酸组成及含量的影响     

武杰瑞  刘秉毅  特木尔布和  爽爽  代蕊  张志强 《草地学报》2022,30(1):62-68

为了探究蓟马取食对苜蓿(Medicago sativa L.)氨基酸组成及含量的影响,本研究以'草原2号'(Medicago varia Martin.'Caoyuan No.2')感蓟马品种和'草原4号'(Medicago sativa L.'Caoyuan No.4')抗蓟马品种为材料,分别进行牛角花齿蓟马(Odo...  相似文献   

Is risk consistent across tier‐based harvest control rule management systems? A comparison of four case‐studies          下载免费PDF全文

Catherine M Dichmont  André E Punt  Natalie Dowling  José A A De Oliveira  Lorne R Little  Miriana Sporcic  Elizabeth Fulton  Rebecca Gorton  Neil Klaer  Malcolm Haddon  David C Smith 《Fish and Fisheries》2016,17(3):731-747

There can be substantial differences in data quality and quantity among fished species. Consequently, the quality and type of assessments can also vary substantially. However, all species, especially those that are targeted, need to be managed. Several jurisdictions have developed hierarchical tier systems that categorize stocks based on, for example, the data available for assessment purposes and/or the extent to which quantities on which management advice is based can be estimated. Four case‐studies (Australia's Southern and Eastern Scalefish and Shark Fishery, the USA west coast groundfishery, the USA Alaskan crab fishery and EU fisheries) are used to contrast the types of hierarchical tier systems available, and to assess the extent to which each system constrains risk to be equivalent among the tiers (termed risk equivalency). Only the Australian system explicitly aims to achieve risk equivalency. However, this intent has not been fully operationalized. Our review reveals that best practice is not to define tiers simply on data availability, but also on what the assessments based on those data are capable of estimating. In addition, clearly differentiating the quantification of uncertainty from how decision‐makers wish to address that uncertainty would simplify justification of buffers (the gap between the assessment‐produced target catch or effort and the final management decision that accounts for uncertainty and risk). Risk equivalency can be achieved using management strategy evaluation to select the values for control variables, which determine the buffer given the uncertainty associated with the assessment.  相似文献   

Oxytetracycline residues in tissue, organs, and eggs of poultry fed supplemented rations     

S E Katz  C A Fassbender  J J Dowling 《Journal of the Association of Official Analytical Chemists》1973,56(1):77-81

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A meta-analysis review of the effects of recombinant bovine somatotropin: 1. Methodology and effects on production   总被引：1，自引：0，他引：1       下载免费PDF全文

I. R. Dohoo  K. Leslie  L. DesCteaux  A. Fredeen  P. Dowling  A. Preston    W. Shewfelt 《Canadian journal of veterinary research》2003,67(4):241-251

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Treatment of subclinical mastitis.     

J W Tyler  R C Wilson  P Dowling 《Veterinary Clinics of North America: Food Animal Practice》1992,8(1):17-28

Topics addressed in this article include applied pharmacology of the bovine mammary gland, principles of antibiotic sensitivity testing, mechanisms of antimicrobial resistance, causes of treatment failures, diagnostic considerations, and therapy of specific subclinical mastitis syndromes. Recent research concerning systemic therapy of subclinical mastitis is highlighted and critically reviewed. Limitations of antibiotic sensitivity testing are discussed. The lack of proven, efficacious therapy for many subclinical mastitis syndromes is emphasized.  相似文献