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排序方式: 共有347条查询结果,搜索用时 15 毫秒
1.
An experiment was conducted to examine the effect of progesterone prior to a GnRH‐PGF2α treatment on oestrus and pregnancy in seasonally anoestrous Awassi ewes. Twenty‐four ewes were randomly assigned to three groups to be pre‐treated with 60 mg medroxyprogesterone acetate sponges (group A), 600 mg progesterone sponges (group B) or blank sponges (group C) for 4 days. All ewes were injected with 100 μg of GnRH 24 h after sponge removal followed, 5 days later, by 20 mg PGF2α injection. Ewes were exposed to three fertile rams at the time of PGF2α injection (day 0, 0 h) and were checked for breeding marks at 6‐h intervals for 5 days. Blood samples were collected from all ewes 1 day (day ?10) prior to sponge insertion, at the time of sponge removal (day ?6), 1 day following sponge removal (day ?5, at the time of GnRH injection) and at the time of PGF2α injection (day 0) for analysis of progesterone. Progesterone concentrations on days ?10 and ?5 were basal and averaged 0.2 ± 0.04 and 0.2 ± 0.2 ng/ml, respectively. Progesterone concentrations on day ?6 were elevated only in group B ewes and were higher (p < 0.0001) than those of groups A and C. Progesterone concentrations on day 0 were higher (p = 0.002) in groups A and B than group C. Oestrous responses occurred only in ewes of groups A and B (p > 0.05). Induced oestrus conception rate was greater (p < 0.01) in group A than groups B and C. Ewes returned to oestrus 17–20 days following day 0 were two of eight, six of eight and three of eight of groups A, B and C, respectively, all of which eventually lambed. The overall lambing rate was 82% in progesterone‐primed ewes compared with only 38% non‐progesterone‐primed ewes (p < 0.05). Progesterone priming apparently sensitizes GnRH‐PGF2α‐treated seasonally anoestrous ewes and increases their response in oestrus and pregnancy rates. 相似文献
2.
Tommaso Gregori Richard Lam Simon L. Priestnall Christopher R. Lamb 《Veterinary radiology & ultrasound》2016,57(6):582-586
The truncation artifact in magnetic resonance (MR) images is a line of abnormal signal intensity that occurs parallel to an interface between tissues of markedly different signal intensity. In order to demonstrate the truncation artifact in sagittal images of the canine spinal cord and the effect of changing spatial resolution, we conducted an experimental in vitro study. A section of fixed canine spinal cord was imaged using a 1.5T magnet. Spatial resolution was increased by increasing the acquisition matrix and reconstruction matrix, producing series of T2‐weighted (T2w) images with the following pixel sizes: A, 1.6 (vertical) × 2.2 mm2 (horizontal); B, 1.2 × 1.7 mm2; C, 0.8 × 1.1 mm2; D, 0.4 × 0. 6 mm2. Plots of mean pixel value across the cord showed variations in signal intensity compatible with truncation artifact, which appeared as a single, wide central hyperintense zone in low‐resolution images and as multiple narrower zones in high spatial resolution images. Even in images obtained using the highest spatial resolution available for the MR system, the edge of the spinal cord was not accurately defined and the central canal was not visible. The experiment was repeated using an unfixed spinal cord specimen with focal compression applied to mimic a pathologic lesion. Slight hyperintensity was observed within the spinal cord at the site of compression although the cord was normal histologically. Results of this study suggest that caution should be applied when interpreting hyperintensity affecting the spinal cord in T2w sagittal images of clinical patients because of the possibility that the abnormal signal could represent a truncation artifact. 相似文献
3.
4.
Lam My Lan Jean-Claude Micha Duong Nhut Long Tran Thanh Hai 《Journal Of Applied Aquaculture》2013,25(3):168-183
ABSTRACT The on-farm trials of rotational rice-prawn farming in a semi-deep water area in the Mekong Delta of Vietnam was carried out in six rice fields (0.7–1.0 ha) to evaluate the production and economic efficiency of using low and high cost feed on prawn culture in paddies at different densities. Two stocking densities of 4 and 5 PL/m2 were investigated. Two treatments of feed types (pellets only or a combination of pellets, trash fish, and snail meat) were applied at stocking 4 PL/m2. At the treatment of 5 PL/m2, prawns were fed a combination of pellets, trash fish, and snail meat. Prawns were stocked in the mid-April and harvested in mid‐November before the next dry season rice crop. Rice farming was started 3 to 5 days after prawn harvesting. By cull harvesting during the culture period, final mean weights of prawn ranged from 47.2 to 57.2 g/prawn and the male:female ratio at harvesting was 2.5:1.0. The prawn yield of treatment 5 PL/m2 was highest (630 ± 22 kg/ha). Net profits in treatments using the combination of pellets, trash fish, and snail meat were 861 ± 193 US$/ha to 1,019 ± 25 US$/ha for the prawn crop and 1,393 ± 71 US$/ha to 1,576 ± 180 US$/ha for the whole system (prawn crop + dry rice crop) and significantly higher than in treatment using pellet only (P < 0.05). Prawns fed on pellets or a combination of pellets and snail meat both offer similar results in terms of production and economics. The dry rice crop offered high cost benefit ratio (2.29–2.33) with low operating cost (414–434 USD/ha) and it made a better use in sustainable rice fields through the rotational rice-prawn system. 相似文献
5.
Lam TJ Jansen J van den Borne BH Renes RJ Hogeveen H 《New Zealand veterinary journal》2011,59(1):8-15
The veterinary practitioner is one of the most important advisors for farmers in the field of udder health. He or she has the tools to improve udder health if farmers are motivated to do so. Many farmers think that udder health is important, but this does not always mean that management of mastitis is up to standard. Many veterinarians are of the opinion that they are unable to convince their clients of the possible profits to be gained from investing in management of mastitis. Something is required to bridge this gap. This article, based on data and experiences from The Netherlands, describes the communication issues that can be considered in order to improve the role of the veterinarian as advisor, to achieve better udder health. The outcome is beneficial for both farmers and veterinarians, the former for reasons of economics, welfare and ease of work; the latter because it creates extra, challenging work. It is concluded that the veterinary practitioner is in an ideal situation to advise and motivate farmers to improve udder health but, to do this, the means of communication need to take account of the different learning styles of farmers. The most important aspects of such communication are found to be a pro-active approach, personalisation of messages, providing a realistic frame of reference for the farmer, and use of the farmer's social environment. Importantly, all persons and organisations in a farmer's social environment should articulate the same message. 相似文献
6.
A serological follow-up study of 3.5 years duration was done of a dairy herd that had experienced a mass seroconversion to Neospora caninum following a point source exposure shortly before the 17th of January 2000. A total of 913 blood samples of 244 animals at seven sampling dates were used to investigate the seroprevalence dynamics in the herd. Most postnatally infected cattle remained seropositive during the period of investigation but 11 animals became seronegative after 6-27 months indicating transient infection. Six animals seroconverted later than the main group of 45 animals and 5 animals became seronegative after at least two seropositive records possibly due to a low infection dose or difference in the haplotypes of the infected animals. In total 58% (14/24) of the offspring of postnatally infected dams was seropositive. Nine of 16 (56%) daughters originating from inseminations after the postnatal infection of their dams were seropositive indicating endogenous transplacental infection. 相似文献
7.
ARB HIGGS RT NORRIS FC BALDOCK NJ CAMPBELL S. KOH RB RICHARDS 《Australian veterinary journal》1996,74(3):215-220
Objective: To investigate control options for contagious ecthyma (scabby mouth) in Australian sheep exported live to the Middle East.
Design: Prevalence, vaccination and modelling studies.
Procedure: One hundred and forty weaner sheep (less than 1 year old) on each of 106 farms in Western Australia (WA) and 18 farm groups of adult wethers received at a WA commercial feedlot were examined for lesions of scabby mouth. Sheep on a total of 26 farms in 3 States were divided into treatment and control groups for the vaccination study. A simple deterministic compartmental model was developed to establish which parameters had the greater effect on disease prevalence.
Results: The proportion of farms with evidence of scabby mouth in weaner sheep was 23.6% and, on those farms with the disease, the overall prevalence was 6.1%. At the feedlot, 4 out of 18 farm groups had 5 or more sheep with lesions on arrival. The overall prevalence in the 4 diseased groups was 5.2%. Sheep vaccinated on farm before trucking to the feed-lot had a lower prevalence of scabby mouth at the end of simulated shipping than controls. The main determinant of scabby mouth prevalence was the proportion of sheep immune to the disease.
Conclusion: A program of vaccination for scabby mouth will reduce the prevalence of disease during live export. However, using current technology it is not possible to deliver shipments of sheep to the Middle East that are guaranteed completely free of scabby mouth. 相似文献
Design: Prevalence, vaccination and modelling studies.
Procedure: One hundred and forty weaner sheep (less than 1 year old) on each of 106 farms in Western Australia (WA) and 18 farm groups of adult wethers received at a WA commercial feedlot were examined for lesions of scabby mouth. Sheep on a total of 26 farms in 3 States were divided into treatment and control groups for the vaccination study. A simple deterministic compartmental model was developed to establish which parameters had the greater effect on disease prevalence.
Results: The proportion of farms with evidence of scabby mouth in weaner sheep was 23.6% and, on those farms with the disease, the overall prevalence was 6.1%. At the feedlot, 4 out of 18 farm groups had 5 or more sheep with lesions on arrival. The overall prevalence in the 4 diseased groups was 5.2%. Sheep vaccinated on farm before trucking to the feed-lot had a lower prevalence of scabby mouth at the end of simulated shipping than controls. The main determinant of scabby mouth prevalence was the proportion of sheep immune to the disease.
Conclusion: A program of vaccination for scabby mouth will reduce the prevalence of disease during live export. However, using current technology it is not possible to deliver shipments of sheep to the Middle East that are guaranteed completely free of scabby mouth. 相似文献
8.
Clinical application of multidetector computed tomography and magnetic resonance imaging for evaluation of cranial nerves in horses in comparison with high resolution imaging standards 下载免费PDF全文
J. Dixon R. Lam R. Weller G. Manso‐Díaz M. Smith R. J. Piercy 《Equine Veterinary Education》2017,29(7):376-384
Although horses are affected by cranial nerve disease, our understanding of these structures' imaging anatomy is limited, and the optimal modality for imaging of each of these nerves is unclear. The aim of this study was to describe the imaging appearance of the equine cranial nerves on high‐resolution 1.5T magnetic resonance imaging (MRI) and computed tomography (CT) scans of a cadaver head, and with these as standards, examine the utility of MRI and CT performed in clinical cases. High‐resolution MRI and CT images were prospectively acquired of the head of a normal Thoroughbred gelding following euthanasia. Ten clinical cases undergoing high‐field MRI under general anaesthesia and 10 clinical cases undergoing CT in the standing horse under sedation were retrospectively evaluated by three reviewers to assess cranial nerve visibility. On high‐resolution, thin‐slice, MRI scans of the normal cadaver head, each of the 12 cranial nerves and their topographic location could be appreciated. On high‐resolution cadaver CT, cranial nerves II, V and VII were clearly visible, but others were less easily identified; osseous structures were clearly visualised. Clinical MRI and CT allowed for variable visualisation of the cranial nerves, dependent on the sequence and the orientation of scan planes. High‐field MRI allowed excellent visualisation of equine cranial nerves, whereas CT allowed for more detailed visualisation of the osseous canals and foramina. In live horses, the ability to identify all 12 nerves is challenging with either MRI or CT; however, high‐field MRI enables better visualisation of the nerve bundles than CT. 相似文献
9.
Development and characterization of a technique for percutaneous radiologic gastrojejunostomy tube placement in the dog 下载免费PDF全文
10.
F. Lam Prof. Dr. R. O. Foschi Prof. Dr. J. D. Barrett Technician Q. Y. He 《Wood Science and Technology》1993,27(2):81-94
Summary A procedure has been developed to determine the cut-off frequency in an algorithm to evaluate the localized modulus of elasticity (MOE) in lumber. MOE profiles have been artificially generated to serve as input for evaluation of the procedure. A noise component has also been added to the input record to test the robustness and accuracy of the procedure. Good agreement between program predictions and the known localized MOE values has been obtained. The efficiency of the procedure has also been tested using MOE profiles collected from experiments. The program performed efficiently and program predictions seemed reasonable. 相似文献