Ovarian Follicular Activity During Late Gestation and Postpartum in Guanaco (Lama guanicoe)          下载免费PDF全文

JL Riveros  G Schuler  B Urquieta  B Hoffmann  C Bonacic 《Reproduction in domestic animals》2015,50(1):129-134

This study evaluated ovarian activity in late gestation and post‐partum in guanacos in captivity. Follicular dynamics was monitored every second day from 40 days before and other 40 after delivery by transrectal sonography and by plasma steroids concentrations. Seven out of eight (87.5%) of gestating females presented ovarian follicular activity under progesterone levels >3 nmol/l with maximum follicular size of 8.42 ± 0.83 mm from days 23 to 1 before delivery. After delivery, all females have follicular wave development from day 0 to 38, with larger follicular size and longer follicular wave phases and interwave interval when compared with pre‐partum data. During post‐partum period, there was a close relationship between follicle size and estradiol‐17β concentration, with r = 0.69 at the beginning of growth phase and r = 0.86 in association with the largest dominant follicle. Plasma estradiol‐17β concentration varied from 11.92 to 198.55 pmol/l. Plasma estrone sulfate, free estrone and progesterone returned to baseline concentrations during peripartal period and remained basal thereafter. The results described follicular activity during late gestation and early post‐partum period. These findings provide relevant information to understand physiological changes occurring during this reproductive key period in seasonal breeders with long gestation duration as New and Old World camelids.  相似文献   

The conservation of threatened vascular plants and Europe     

S.M. Walters 《Biological conservation》1976,10(1):31-41

With the five-volume work Flora Europaea nearing completion, it has become possible to prepare a reasonably accurate list of threatened vascular plants for the whole European continent. This paper gives an account of this international conservation project, and considers the use of such data in formulating policies of nature conservation on a national, continental and world scale. Recommendations are made for future action.  相似文献   

A 0.5-million-year record of millennial-scale climate variability in the north atlantic   总被引：8，自引：0，他引：8  

JF McManus  DW Oppo  JL Cullen 《Science (New York, N.Y.)》1999,283(5404):971-975

Long, continuous, marine sediment records from the subpolar North Atlantic document the glacial modulation of regional climate instability throughout the past 0.5 million years. Whenever ice sheet size surpasses a critical threshold indicated by the benthic oxygen isotope (delta18O) value of 3.5 per mil during each of the past five glaciation cycles, indicators of iceberg discharge and sea-surface temperature display dramatically larger amplitudes of millennial-scale variability than when ice sheets are small. Sea-surface temperature oscillations of 1 degrees to 2 degreesC increase in size to approximately 4 degrees to 6 degreesC, and catastrophic iceberg discharges begin alternating repeatedly with brief quiescent intervals. The glacial growth associated with this amplification threshold represents a relatively small departure from the modern ice sheet configuration and sea level. Instability characterizes nearly all observed climate states, with the exception of a limited range of baseline conditions that includes the current Holocene interglacial.  相似文献   

Disc extrusion in a Rottweiler dog with caudal cervical spondylomyelopathy after failure of intervertebral distraction/stabilisation     

AM MARCHEVSKY  JL RICHARDSON 《Australian veterinary journal》1999,77(5):295-297

A Rottweiler dog was presented with an 8 week history of hindlimb ataxia. Neurological examination localised the lesion to the cervical spinal cord. Myelography demonstrated dynamic compressive lesions at C5-6 and C6-7 consistent with a diagnosis of caudal cervical spondylomyelopathy. Distraction/stabilisation of both discs was performed using interbody polymethyl methacrylate. Both implants subsequently failed leading to extrusion of the remaining dorsal annulus fibrosus of the C5-6 intervertebral disc and nonambulatory tetraparesis. A ventral slot combined with distraction/stabilisation using screws and polymethyl methacrylate was performed and resulted in nearly full neurological recovery.  相似文献   

Reproductive dominance of pasture trees in a fragmented tropical forest mosaic   总被引：1，自引：0，他引：1  

PR Aldrich  JL Hamrick 《Science (New York, N.Y.)》1998,281(5373):103-105

Tropical forest fragmentation threatens biodiversity, yet basic information on population responses for major groups such as plants is lacking. Hypervariable genetic markers were used to reconstruct a population-level pedigree in fragmented tropical forest for the tree Symphonia globulifera. Though seedlings occurred only in remnant forest, the pedigree showed that most seedlings had been produced by sequentially fewer adults in pasture, creating a genetic bottleneck. The pedigree also implicated shifts in the foraging of animals that disperse pollen and seed in a secondary constriction of the bottleneck. These results suggest that tropical conservation strategies should anticipate complex, cryptic responses to fragmentation.  相似文献   

水稻株型育种生理生态特性的研究现状与展望   总被引：21，自引：0，他引：21  

王建林  徐正进  魏树和 《辽宁农业科学》2000,(4):23-27

阐述了株型育种发展的阶段及各阶段的特点,从茎、叶、穗、分蘖、根５个方面与水稻株型育各种有关的各种形态、生理、生态特性的研究现状进行了综合评述。认为株高增加、叶片直立、分蘖力适中、根系发达不早衰是株型育种目标的共同点,而北方粳稻区穗子直立更有利于提高光能利用率。认为通过籼粳稻杂交、水陆稻杂交,并进行多次人回交或复交,将非Ｆ１优势固定或通过籼粳杂交转能广亲和材料采用“架桥”的方法,是实现优化性状组配的  相似文献   

The prevalence of Echinococcus granulosus in farm dogs in mid-Wales     

T.M.H. Walters  M.J. Clarkson 《Veterinary parasitology》1980,7(3):185-190

One hundred and fourteen farms in Powys, mid-Wales, were visited on two occasions approximately 8 months apart during 1975. All the farm dogs were dosed with arecoline acetarsol and the faecal purges were examined for the presence of Echinococcus granulosus.Sixty-seven farms (58.8%) contained at least one infected dog on at least one of the visits but only 36 farms and 43 farms had infected dog at the first and second visits, respectively.Four hundred and twenty-nine dogs provided at least one sample and 108 (25.2%) of these samples contained E. granulosus. Only seven dogs were infected at both visits.The mean numbers of worms found in the samples were 241.6 and 156.4 at the first and second visits, respectively, but almost 50% of the positive samples contained fewer than 26 worms. The worms were identified as the sheep strain, the known cause of hydatid disease in man in Wales.  相似文献   

Monitoring and surveillance in abattoirs of residues of antibacterial substances – a description of programs in Australia and the USA     

JL CUPIT  NL BLACKMAN†  TJ NICHOLLS†  IB STEPHENS†  RJ WILD 《Australian veterinary journal》1994,71(12):400-403

SUMMARY Australia and the USA are major international meat exporting countries. Both countries conduct programs to monitor and survey for antibacterial residues. Australian programs use a urine screening test, whereas the US programs use tissue fluids as the test medium. The development of surveillance programs to provide rapid feedback to producers is a feature of the Australian programs. The programs in each country compare favourably with regard to numbers of animals tested, results and action taken to prevent residues. The results of the Australian programs justify the promotion of a ‘clean food’ image for Australian meat products with respect to antibacterial drugs.  相似文献   

Importance of different levels of potassium in the diet on whole-body 40 K count and muscle and blood potassium     

R K Johnson  L E Walters  J V Whiteman 《Journal of animal science》1972,35(5):931-936

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Recent Developments in Oestrous Synchronization of Postpartum Dairy Cows with and without Ovarian Disorders   总被引：1，自引：0，他引：1  

JL Yániz  K Murugavel  F López-Gatius 《Reproduction in domestic animals》2004,39(2):86-93

This report reviews the most recent developments in prostaglandin‐based oestrous synchronization programmes for postpartum dairy cows and addresses the efficiency of controlled breeding protocols based on such developments for cows with abnormal ovarian conditions. A double prostaglandin protocol applied 11–14 days apart seems to be capable of bringing most cows to oestrus. Because of varying oestrus onset times, improved conception rates are obtained following artificial insemination (AI) at detected oestrus rather than fixed‐time AI in prostaglandin‐treated cows. The administration of oestradiol or human chorionic gonadotrophin, or both these hormones, after prostaglandin treatment, improves the synchrony of oestrus yet does not enhance the conception rate. Progesterone‐based treatments for oestrous synchronization are considered the most appropriate for non‐cyclic or anoestrous postpartum dairy cows; prostaglandin alone being ineffective because of the absence of a mature corpus luteum in these cows. Improved oestrus synchrony and fertility rate have been reported using short‐term progesterone treatment regimes (7–9 days) with or without oestradiol benzoate combined with the use of a luteolytic agent given 1 day before, or at the time of, progesterone withdrawal. The ovulation synchronization (Ovsynch) protocol, based on the use of gonadotrophin releasing hormone and prostaglandin, was developed to coordinate follicular recruitment, CL regression and the time of ovulation. This protocol allows fixed time insemination and has proved effective in improving reproductive management in postpartum dairy cows. However, timed AI following Ovsynch seems to have no beneficial effects in heifers, because of an inconsistent follicle wave pattern, and in anoestrous cows, given their lack of prostaglandin responsive CL. To date, there are several prostaglandin based, fixed‐time insemination oestrous synchronization protocols for use in early postpartum dairy cows with ovarian disorders such as ovarian cysts and acyclicity.  相似文献