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41.
The study is based on 141 pregnant Bos indicus cows, from days 20 to 70 post‐insemination. First, special attention was given to the macroscopically observable phenomena of attachment of the conceptus to the uterus, i.e. the implantation, from about days 20 to 30 post‐insemination up to day 70, and placentome development by growth, vascularization and increase in the number of cotyledons opposite to the endometrial caruncles. Secondly, as for the conceptuses, semiquantitative, statistical analyses were performed of the lengths of chorio‐allantois, amnion and yolk sac; and the different parts of the centre and two extremes of the yolk sacs were also analysed. Thirdly, the embryos/foetuses corresponding to their membranes were measured by their greatest length and by weight, and described by the appearance of external developmental phenomena during the investigated period like neurulation, somites, branchial arcs, brain vesicles, limb buds, C‐form, pigmented eye and facial grooves. In conclusion, all the data collected in this study from days 20 to 70 of bovine pregnancy were compared extensively with corresponding data of the literature. This resulted in an ‘embryo/foetal age‐scale’, which has extended the data in the literature by covering the first 8 to 70 days of pregnancy. This age‐scale of early bovine intrauterine development provides model for studies, even when using slaughtered cows without distinct knowledge of insemination or fertilization time, through macroscopic techniques. This distinctly facilitates research into the cow, which is now being widely used as ‘an experimental animal’ for testing new techniques of reproduction like in vitro fertilization, embryo transfer and cloning.  相似文献   
42.
A 5‐year‐old male Miniature Schnauzer was presented with unilateral cryptorchidism and signs of feminization. Abdominal ultrasonography revealed an enlarged right testis and a large, fluid‐filled cavity that appeared to arise from the prostate. Computed tomography revealed the cavity to be consistent with an enlarged uterine body, arising from the prostate, and showed two structures resembling uterine horns that terminated close to the adjacent testes. The dog had a normal male karyotype, 78 XY. Gonadohysterectomy was performed and both the surgical and the histological findings confirmed the presence of a uterus in this male animal, resulting in a diagnosis of persistent Mullerian duct syndrome (PMDS). The enlarged intra‐abdominal testis contained a Sertoli cell tumour. Computed tomography proved to be an excellent diagnostic tool for PMDS.  相似文献   
43.
1. Tropical aquatic ecosystems are species rich, with high numbers of endemics. Increasing pressure from human activities, including demands for food and energy, growing human population, and economic aspirations, highlights the need for a more concerted effort towards aquatic conservation. 2. Understanding of tropical aquatic ecosystems has developed largely from a northern temperate perspective that might not be always appropriate. Applying classic models of how water bodies function can hinder effective conservation strategies. This is coupled with very incomplete knowledge of species distributions and their ecology. 3. Better understanding of tropical aquatic ecology to guide conservation needs a research agenda that connects more strongly with the social‐ecological realities of tropical ecosystems. 4. Although approaches to conservation may be contested, a fundamental challenge to protection of aquatic habitats is a lack of capacity at the individual and institutional level. Without this, the development of improved techniques and approaches for tropical aquatic conservation will fail to reverse current trends of degradation. Research outputs on tropical aquatic ecosystems remain dominated by institutions based outside the tropics. 5. Building awareness and practice to conserve the aquatic ecosystems of the tropics can be supported through extending the dialogue across sectors and by connecting tiers of governance. An ecosystem services framework that identifies the benefits that humans derive from ecosystems provides a powerful tool, often linked with estimates of economic value. However, this can neglect important regulating services or distract from more fundamental existence value. 6. The preservation of tropical aquatic diversity will only be achieved if recognized as important at all levels, from local to global. Targeted external support can build awareness and capacity, but conserving aquatic ecosystems requires local commitment. Developing community monitoring that provides straightforward information on ecosystem health presents opportunities to connect citizens with the ecosystems that, ultimately, they depend on. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
44.
Background, aim and scope  Street sediment samples were collected at 50 locations in a mixed land use area of Hamilton, Ontario, Canada, and metal levels were analyzed using a sequential extraction procedure for different particle size classes to provide an estimate of potential toxicity as well as the potential for treatment through best management practices (BMPs). Methodology  The street sediment samples were dry sieved into four different particle size categories and a sequential extraction procedure was done on each size category following the methodology proposed by Tessier et al. 1979 using a Hitachi 180-80 Polarized Zeeman Atomic Absorption Spectrophotometer. Results and discussion  Analysis of variance, post hoc least-significant difference tests, and kriging analysis showed that spatially Mn and Fe levels were associated with a well-defined heavy industrial area that includes large iron- and steel-making operations; Cu and Pb were associated with both the industrial and high-volume traffic areas, while Zn tended to be more associated with high-volume traffic areas. The potential bioavailability of the metals, based on the sum of chemical fractions 1 (exchangeable) and 2 (carbonate-bound), decreased in order: Zn > Cd > Mn > Pb > Cu > Fe. Based on aquatic sediment quality guidelines, there is some concern regarding the potential impact of the street sediment when runoff reaches receiving waters. Conclusions  It is possible that a combination of BMPs, including street sweeping and constructed wetlands, could help to reduce street sediment impact on environmental quality in the Hamilton region. The data presented here would be important in developing and optimizing the design of these BMPs.  相似文献   
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Douglas-fir (Pseudotusga menziesii (Mirb.) Franco), a native to the Pacific Coast Range in North America, is recognized as a tree that is long-lived and can grow rapidly to standing volumes that approach the highest recorded for temperate conifers. Managed plantations in western Oregon register maximum periodic annual increments (PAI) at ages between 20 and 40 years of ∼30 m3 ha−1 year−1. The same seed source, when planted in New Zealand and elsewhere in the Southern Hemisphere, may attain a PAI of ∼50 m3 ha−1 year−1. Is this higher productivity mainly related to climate or to isolation from native pests? To evaluate the role of climate, we obtained meteorological data from plantation sites in New Zealand and Oregon, from which we established relationships between mean monthly temperature extremes and solar irradiance, air humidity deficits, and frost frequency. Using these empirical relationships, long-term weather records were converted to the meteorological variables required to drive a process-based forest growth model, 3-PG, for sites approaching the most productive in New Zealand and in Oregon. Annual precipitation is similar in both areas, but sites in Oregon receive only 10% during the growing season, resulting in humidity deficits 30% larger than those recorded in New Zealand. According to sensitivity analyses and direct measurements, the more productive Douglas-fir forests in Oregon avoid the limiting effects of summer drought by obtaining water from the subsoil and fractured bedrock. If such forests were under a reduced evaporative demand similar to that in New Zealand, we show that they would exhibit comparable productivity.  相似文献   
47.
Spawning runs of brown trout Salmo trutta L., and rainbow trout, Oncorhynchus mykiss Walbaum, were compared in three tributaries of two lakes for timing, numbers and redd characteristics. Redd characteristics for the two species in four other streams were examined. No significant differences in redd characteristics between the two species were observed, but in all lake tributaries the possibilities of superimposition of spring spawning rainbow trout on redds of brown trout were examined. A common feature was the high ratio of numbers of spawners to the area of preferred spawning gravel, and it was concluded that in the lake tributaries, superimposition resulted in increased mortality of brown trout eggs, and in one case elimination of the brown trout population. Management possibilities for control of the species proportions in comparable situations are discussed.  相似文献   
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The aim of this work was to evaluate the effects of the supplementation of two extra‐virgin olive oils (EVOO) having different polyphenols content, on canine spermatozoa kinetic parameters and seminal plasma oxidative status. The study was conducted on 12 clinically healthy dogs of different breeds (2–7 years, 5–48 kg of body weight) divided into two groups: an experimental group supplemented with EVOO (Coratina cultivar) high in polyphenols (H‐P) and a control group fed EVOO (Cima di Bitonto cultivar) low in polyphenols (L‐P). The oil was daily administered per os (1 ml/3 kg BW) before meal. Semen collection was made twice at 15 days distance (D01 and D02) and then at 30 (D30), 60 (D60) and 90 (D90) days. Semen concentration and kinetic parameters were measured using computer‐assisted sperm analysis (CASA) system to evaluate: sperm total count, sperm motile (MOT%), progressive motility (PROGR%) and its fractions, straight‐line velocity (VSL, μm/s), curvilinear velocity (VCL, μm/s), average path velocity (VAP, μm/s), amplitude of lateral head displacement (ALH, μm), beat cross frequency (BCF, Hz), straightness (STR%) and linearity (LIN%). On seminal plasma, reactive oxygen species (ROS) and biological antioxidant potential (BAP) were tested. From findings, no differences were found for sperm MOT, VSL, VCL, VAP, ALH, BCF, STR, LIN and BAP. A gradual enhancement of PROGR% was observed in H‐P group (< .01). The ROS levels were higher in dogs H‐P compared to the other group (< .05). In conclusion, our results highlight the positive effects of EVOO polyphenols on sperm PROGR% in healthy dogs.  相似文献   
50.
This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used.  相似文献   
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