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排序方式: 共有446条查询结果,搜索用时 15 毫秒
101.
102.
Gildas Tetaping Mbemya Naiza Arcngela Ribeiro de S Denise Damasceno Guerreiro Francisca Geovania Canafístula de Sousa Sylvain Njina Nguedia Benner Geraldo Alves Francielli Weber Santos Otília Deusdênia Loiola Pessoa Pierre Comizzoli Jos Ricardo Figueiredo Ana Paula Ribeiro Rodrigues 《Reproduction in domestic animals》2019,54(8):1121-1130
The objective of this study was to determine whether preantral follicles cultured in vitro for 7 days within ovine ovarian cortical strips could be isolated at the secondary follicles (SF) and grown until antral stage during an additional 6 days period of in vitro culture in the presence of aqueous extract of Justicia insularis. Fresh ovarian fragments from 16 adult sheep were fixed for histological analysis (Control 1) or in vitro cultured individually in α‐MEM+ supplemented with 0.3 mg/ml J. insularis (Step 1) for 7 days. Part of the fragments then were fixed for histological analysis (in vitro culture group). Remaining fragments were exposed stepwise to increasing trehalose concentrations before immediate isolation of SF and viability assessment (Control 2) or after 6 days of culture in α‐MEM++ supplemented with 0.3 mg/ml J. insularis (Step 2). In Step 1, percentage of follicular activation was 80%. In Step 2, a significant increase (p < 0.05) in follicular diameter and antrum formation within 6 days in vitro culture of isolated follicles was achieved. The total antioxidant capacity from both steps significantly increase (p < 0.05) from day 2 to day 6. Confocal analysis of oocytes showed 57.14% oocytes with homogeneous distribution and 42.86% with peri‐cortical distribution. In conclusion, SF can be successfully isolated from sheep ovarian cortex after 7 days of culture and are capable of surviving and forming an antral cavity if cultured in vitro for an additional 6 days in the presence of 0.3 mg/ml J. insularis. 相似文献
103.
Jessica Rae Marus Matthew James Magee Karunya Manikonda Megin C. Nichols 《Zoonoses and public health》2019,66(4):370-376
In the United States, multistate Salmonella outbreaks are most commonly linked to a food source; however, contact with live animals can also result in outbreaks of human illness. To characterize Salmonella outbreaks linked to animal contact and examine differences compared to foodborne outbreaks, we analysed data reported to the Centers for Disease Control and Prevention through the National Outbreak Reporting System (NORS) from 2009 to 2014 with a primary mode of transmission listed as “animal contact” or “food.” Four hundred and eighty‐four outbreaks with animal contact or foodborne transmission were reported through NORS; of these outbreaks, 99 (20.5%) resulted from Salmonella transmission through animal contact and 385 (79.5%) resulted from foodborne transmission, which resulted in 3,604 (19.8%) and 13,568 (80.2%) illnesses, respectively. A higher proportion of illnesses among children aged <1 year and children aged 1–4 years were linked to animal contact outbreaks compared to foodborne outbreaks (15.2% vs. 1.4%, p < 0.01 and 24.5% vs. 5.6%, p < 0.01, respectively). Illnesses resulting in hospitalizations (OR: 1.81, 95% CI: 1.62, 2.02) were more likely to be associated with animal contact compared to food. Animal contact outbreaks reported to NORS were more likely to be multistate compared to foodborne outbreaks (OR: 5.43, 95% CI: 3.37, 8.76) and had a longer median duration (99.0 days vs. 9.0 days, p < 0.01). Characterizing the differences between outbreaks of illness linked to animal contact and outbreaks linked to food provides useful information to investigators to improve public health response. 相似文献
104.
Castration of rabbits can be achieved with several surgical techniques. The choice of the technique currently depends on surgeon preference since objective comparison between techniques is lacking. The aim of the current study was to compare the scrotal and prescrotal approaches in pet rabbits. The surgery and anesthesia duration, the postoperative appetite and feces production, and the postoperative complications were compared. Thirteen rabbits were randomly assigned to the scrotal or prescrotal castration groups. Appetite, fecal output, surgical incisions, and scrotums were evaluated at 8 hourse, 24 hours, 32 hours, and 7 days after surgery. Scrotal edema at 8, 24, and 32 hours and anesthesia duration were significantly higher in the scrotal group compared to the prescrotal group (P = 0.008, P = 0.013, P = 0.021, and P = 0.034, respectively). A nonsignificant tendency toward a higher rate of licking and mutilation behaviors was observed in the scrotal group 24 hours postsurgery. No other complications were observed in either group. All rabbits quickly recovered a normal appetite and fecal output, and all surgical incisions healed without issue. Although the prescrotal technique was associated with less complications, both techniques were considered safe options for rabbits in this study. 相似文献
105.
106.
Jerry Penha Karlo Y. P. Hakamada James E. Hines James D. Nichols 《Ecology of Freshwater Fish》2019,28(2):274-284
The metapopulation paradigm has been central to improve the conservation and management of natural populations. However, despite the large number of studies on metapopulation dynamics, the overall support for the relationships on which the paradigm is based has not been strong. Here, we studied the occupancy dynamics of two Neotropical fishes (i.e., Pimelodella gracilis and Leporinus friderici) to investigate two fundamental premises of the metapopulation paradigm, that is, that isolation and area/habitat quality affect colonisation and extinction probabilities in predictable ways. In order to do this, we used a modification of occupancy models that allows modelling the probability of a site's occupancy as a function of the occupancy of its neighbourhood. We found a weak positive effect of neighbourhood occupancy on P. gracilis colonisation, which is consistent with the propagule rain metapopulation, that is, colonists arriving from outside the studied system. However, we found a strong negative neighbourhood effect on extinction probability, suggesting that declining populations from stream sections are rescued from extinction by neighbouring patches. In contrast, the effect of neighbourhood occupancy on the metapopulation dynamics of L. friderici was in the opposite direction, affecting positively colonisation but not affecting extinction rates, which is consistent with the classical metapopulation model. In addition, the occupancy dynamics of both species were affected by water velocity. To our knowledge, this is the first study to link directly dispersal to local population dynamics in Neotropical fishes, and one of the few studies doing inferences on spatial population dynamics based on direct estimates of neighbourhood occupancy. 相似文献
107.
J. Doland Nichols 《Small-Scale Forestry》2007,6(2):127-140
Until recently the focus of forestry regulations in New South Wales (NSW) was on public rather than private lands. This paper
describes the process of developing legislation to control where and how private native forestry takes place. To date, the
lead agency in attempting to formulate a clear policy has been the Department of Natural Resources. First, through a series
of committee meetings of representatives of key stakeholder groups, a draft private native forestry code was devised and was
released for public comment. After a period of intense negative reaction from both those in favour of continuing timber production
in native forests and those in favour of requiring that private lands be managed as nature reserves, the draft code was withdrawn
and a government-appointed committee then began again the process of drawing up a code acceptable to most stakeholders. 相似文献
108.
More than 20% of Kenya’s population lives on rangelands, which account for over 80% of the total landmass and support more
than 50% of the national livestock herd. As these areas have experienced a major livestock (cattle) productivity decline due
to encroachment on pastures by woody weeds, government efforts are targeted at increasing palatable grass cover. Paradoxically,
these efforts have been less than successful, as some communities do not identify some weeds as a nuisance, in fact ascribing
value to them. To identify specifically what such values are, as well as perceived problems with woody weeds, interviews were
conducted with 165 respondents in two distinct ethnic groups (Maasai and Kamba) practising different production systems within
the Kenyan rangelands. We found that the groups had complex attitudes toward “woody weeds”, seeing both negative and positive
aspects to them. Both groups thought predominately that woody weeds lowered grass quantity and quality. Both communities appreciated
some weeds as forage for livestock and sources of firewood, while variations existed between the two communities in their
use of woody weeds for construction, bee forage and soil conservation. It is concluded that woody plants on these rangelands
cannot be exclusively be classified as weeds, but rather need to be included in systems of rangeland management. 相似文献
109.
Lluis Coll Christian Messier Sylvain Delagrange Frank Berninger 《Annals of Forest Science》2007,64(3):275-285
The effect of different vegetation control methods (mowing and cultivation between plantation rows, herbicide application and cover plant sowing) on hybrid poplar (P. maximowiczii × balsamifera) growth, biomass allocation and leaf carbon assimilation was investigated in two plantations (1- and 2-year-old) established in previously forested sites of south-eastern Québec. Any vegetation control treatment applied the same year in which the plantation was established did not have an effect on hybrid poplar aboveground growth. However significant differences among treatments were observed belowground, where the removal of the competing vegetation at the tree base increased the fine root:leaf biomass ratio of plants, thus probably facilitating their establishment. In contrast, 2-year-old plants grew better when treated with herbicides, but no positive effect of the mechanical treatments was detected. In both sites, trees growing on herbicide-treated plots showed considerably higher leaf carbon assimilation and leaf N concentration which were both strongly correlated. We conclude that a strong vegetation competition for nutrients takes effect on hybrid poplar plantations on previously forested sites since there was no water shortage for any treatment during the study period. 相似文献
110.
We investigated the radial variation of sap flow within sapwood below the live crown in relation to tree size in 10-, 32-, 54- and 91-year-old maritime pine stands (Pinus pinaster Ait.). Radial variations were determined with two thermal dissipation sensors; one measured sap flux in the outer 20 mm of the xylem (Jref), whereas the other was moved radially across the sapwood in 20-mm increments to measure sap flux at multiple depths (Jref). For all tree sizes, sap flow ratios (Ri = JiJref (-1)) declined with increasing sapwood depth, but the decrease was steeper in trees with large diameters. Correction factors (C) were calculated to extrapolate Jref for an estimate of whole-tree sap flux. A negative linear relationship was established between stem diameter and C, the latter ranging from 0.6 to 1.0. We found that neglecting these radial corrections in 10-, 32-, 54- and 91-year-old trees would lead to overestimation of stand transpiration by 4, 14, 26 and 47%, respectively. Therefore, it is necessary to account for the differential radial profiles of sap flow in relation to tree size when comparing tree transpiration and hydraulic properties among trees differing in size. 相似文献