Ethical question of the month — December 2002          下载免费PDF全文

Jessica Wolfe 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(3):189

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Feedback of 17 beta-estradiol on secretion of luteinizing hormone during different seasons of the year     

T T Stumpf  M L Day  P L Wolfe  M W Wolfe  A C Clutter  R J Kittok  J E Kinder 《Journal of animal science》1988,66(2):447-451

The working hypothesis was that the amount of increase in secretion of luteinizing hormone (LH) that results from positive feedback of 17 beta-estradiol (E2) is dependent on season of the year in mature bovine females. Seven beef cows, ovariectomized approximately 2 mo before the initiation of the experiment, were used in the initial year (1983) of the study. Three of the ovariectomized cows (OVX-E2) received an sc E2 implant, which provided low circulating levels of E2. The remaining four cows (OVX) were not implanted. Blood samples were collected serially (at 10-min intervals for 6 h) at each spring and fall equinox and at each summer and winter solstice. This protocol was replicated with a different group of cows in 1985 (OVX-E2, n = 4; OVX, n = 6). Concentration of LH in blood serum was quantified in all samples. Concentration of E2 in blood serum was measured in pools of samples from each serial blood collection. Concentrations of E2 were higher (P less than .05) in the implanted cows. Mean concentration of LH and amplitude of pulses of LH were higher (P less than .05) at each season of the year in cows that were ovariectomized and implanted with E2 than in cows that were ovariectomized and did not receive E2. An effect of season of the year on mean concentration of LH was detected (P less than .01). No influence of season or E2 was detected for frequency of pulses of LH. There was no significant treatment X season interaction.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Isolation, characterization, and molecular cloning of cryptic plasmids isolated from Edwardsiella ictaluri   总被引：1，自引：0，他引：1  

J C Newton  R C Bird  W T Blevins  G R Wilt  L G Wolfe 《American journal of veterinary research》1988,49(11):1856-1860

Fifty-five isolates of Edwardsiella ictaluri were examined for the presence of plasmid DNA by a rapid alkaline extraction procedure. All 49 isolates from channel catfish and a single isolate from Bengal danio carried 2 plasmids with molecular masses of approximately 3.2 and 3.7 megadaltons (Mdal). Five E ictaluri isolates from other fish contained 1 to 3 plasmids, which had molecular masses ranging from 2.5 to 45 Mdal. The 2 plasmids (3.2 and 3.7 Mdal) from the type strain of E ictaluri (ATCC 33202) were ligated into pUC19 cloning vectors, and restriction endonuclease maps of each insert were prepared.  相似文献   

Suckling behavior of calves with dams varying in milk production     

M L Day  K Imakawa  A C Clutter  P L Wolfe  D D Zalesky  M K Nielsen  J E Kinder 《Journal of animal science》1987,65(5):1207-1212

Two experiments were performed to test the hypothesis that suckling behavior of calves with similar growth potential varies depending on cows' level of estimated milk production and stage of lactation. Eleven mature cows, which varied in estimated 205-d milk production (996 to 2354 kg/205 d), nursing heifer calves of similar growth potential were used in Exp. 1. Suckling behavior of calves was observed for two 24-h periods at three stages of lactation (average of 52, 104 and 167 d postpartum). Suckling frequency (suckling bouts/24 h) declined as milk production increased at 52 d of lactation (-.00382 bouts/kg milk) but was unrelated to milk production at later stages. Duration of suckling (minutes/suckling bout) increased with estimated level of milk production at all stages of lactation (means = .001556 min/kg milk). Total time suckling tended to increase as estimated level of milk production decreased at 52 d of lactation, but this component of suckling behavior was unaffected by milk level at later stages. Suckling frequency declined from 8.6 bouts/24 h at 52 d of lactation to 4.5 bouts/24 h at 167 d of lactation when averaged across all cows. Total minutes nursed/24 h declined in a similar manner (64 min/24 h to 44 min/24 h) between 52 and 167 d of lactation. Duration of each suckling bout did not change with stage. In the second experiment the relationship of suckling behavior to estimated milk production was evaluated at four early stages (average of 17, 38, 59 and 80 d postpartum) of lactation using 20 mature cows.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Population dynamics of feral horses in Western North America     

Michael L. Wolfe PhD 《Journal of Equine Veterinary Science》1986,6(5)

A review of various studies on the population dynamics of feral horses (Equus caballus) in western North America reveals considerable variation both among and within individual herds, thereby rendering generalizations of questionable validity. In most populations, females commence reproduction at 3–4 years of age, with approximately one half of the mares in these age classses bearing foals in a given year. However, recent studies indicate that a modest but variable fraction (15–35%) of the 2-year olds in some populations may produces young. Among older age classes, fecundity rates generally range between 60% and 85%. Survival ratesamong foals and older animals probably average 90% and 95%, respectively, except in years of particularly adverse weather conditions (i.e. severe winters and drought). Although annual rates of increase of at least 20% have been documented in some herds, a more realistic average for most populations probably approximates 15%. Recent studies have demonstrated that population estimates based on aerial counts underestimate the actual number of animals present by a factor of 10–60%, depending upon the type of terrain and vegetation over which the census was flown.  相似文献   

APHIDS ON SUGAR BEET AND SOME WEEDS IN ENGLAND, AND NOTES ON WEEDS AS A SOURCE OF BEET VIRUSES   总被引：3，自引：3，他引：0  

G. D. Heathcote    R. A. Dunning  Marie D.  Wolfe 《Plant pathology》1965,14(1):1-10

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Effects of estradiol 17 beta implants on hematologic values and the chemiluminescence response of neutrophils of steers.     

K L Angel  J Schumacher  D F Wolfe  P H Klesius  J W Tyler  R L Carson 《American journal of veterinary research》1992,53(1):78-82

The effects of subcutaneous administration of a commercially available estradiol 17 beta implant on hematologic values and the chemiluminescence response of neutrophils were evaluated in 14 steers. Chemiluminescence and hematologic values were measured in treated (n = 8) and nontreated (n = 6) steers on days -14, -7, and -1 prior to implantation. Estradiol 17B was implanted into the treated group of steers on day 0, and blood samples were obtained from all steers on days 1, 2, 3, 4, 8, 15, 22, 29, 36, 43, and 50. The concentration of estrogen in serum was significantly (P = 0.0120) higher following implantation. Chemiluminescence and hematologic indices were not significantly affected by either implant status or serum concentrations of estrogen. The results of this study suggested that the use of implants containing estradiol 17 beta for promotion of weight gain in steers will not result in alterations of hematologic values or the neutrophil respiratory burst.  相似文献   

Bone marrow hypoplasia secondary to florfenicol toxicity in a Thomson's gazelle (Gazella thomsonii)   总被引：1，自引：0，他引：1  

Tuttle AD  Papich MG  Wolfe BA 《Journal of veterinary pharmacology and therapeutics》2006,29(4):317-319

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Concepts of plant health – reviewing and challenging the foundations of plant protection     

T. F. Döring  M. Pautasso  M. R. Finckh  M. S. Wolfe 《Plant pathology》2012,61(1):1-15

Plant health is a frequently used but ill‐defined term. However, there is an extensive literature on general health definitions and health criteria in human medicine. Taking up ideas from these philosophical debates, concepts of plant health are reviewed and a framework developed to locate these concepts according to their position in several philosophical controversies. In particular, (i) the role of values in defining plant health in a naturalist versus a normativist approach; (ii) negative and positive definitions of plant health; (iii) reductionist versus holistic perspectives; (iv) the focus on functionality versus resilience, i.e. the ability of the plant to perform under stress with or without human interference; (v) materialist versus vitalist approaches; and (vi) biocentric versus anthropocentric views, are surveyed. The ways in which these perspectives relate to mainstream and alternative approaches to plant protection are explored and we suggest how the contradicting views might be reconciled. It is argued that none of these perspectives is without inherent contradictions, but that by combining contrasting approaches it is possible to provide a comprehensive though fuzzy concept. Rather than giving a new definition of plant health, a conceptual framework is developed that suggests what questions may be answered in debates on plant health issues and how such debates could be organized.  相似文献   

Impact of two types of complete pelleted,wild ungulate feeds and two pelleted feed to hay ratios on the development of urolithogenic compounds in meat goats as a model for giraffes     

K. Sullivan  S. Freeman  E. van Heugten  K. Ange‐van Heugten  B. Wolfe  M. H. Poore 《Journal of animal physiology and animal nutrition》2013,97(3):566-576

Urolith formation has been documented in giraffes and goats. As research in giraffes poses logistical challenges, 16 buck goats were used as a model. The impact of two commercially available, pelleted feeds used for giraffes, ADF‐16 and Wild Herbivore (WH), as well as the impact of alfalfa hay and pellet proportions (20% hay:80% pellets, 80P or 80% hay:20% pellet, 20P) on the formation of urolithogenic precursors in goat urine was accomplished in a 2 × 2 factorial balance study. Complete diets contained 0.60, 0.32, 0.35 and 0.26% phosphorus (P) with calcium:P ratios of 1.60, 4.16, 3.06 and 5.23, for 80P‐ADF‐16, 20P‐ADF‐16, 80P‐WH and 20P‐WH respectively. Total faeces and urine were collected over two 5‐day periods to assess N and mineral balance. Fresh urine samples were collected and evaluated microscopically for urolithic crystal content. Urinary nitrogen (N) was lower and N retention was higher in goats fed 80P diets (p < 0.05). Intake of P was greatest for goats fed 80P‐ADF‐16; however, urinary P excretion and P retention were not affected by treatment. Crystal scores were higher in animals receiving 80P diets (p = 0.08), with crystals being composed predominantly of calcium phosphate. Urine pH was alkaline (>8) for all treatments. Urinary P concentration, a risk factor for urolithiasis, was highest (p ≤ 0.06) in the 80P‐ADF‐16 treatment (0.38 vs. 0.01, 0.02 and 0.04 mg/dl for 20P‐ADF‐16, 80P‐WH and 20P‐WH respectively), reflecting its highest dietary P level. Further investigation is recommended to determine the long‐term effects of these diets on urolithogenic compound formation.  相似文献