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排序方式: 共有313条查询结果,搜索用时 15 毫秒
91.
Dean P.?AndersonEmail author James?D.?Forester Monica?G.?Turner Jacqui?L.?Frair Evelyn?H.?Merrill Daniel?Fortin Julie?S.?Mao Mark?S.?Boyce 《Landscape Ecology》2005,20(3):257-271
Home range size is a result of individual movements and the spatial distribution of a population. While body size, sex, and age are known to influence the area over which an animal ranges, it remains uncertain how landscape heterogeneity influences home range size. We examined elk (Cervus elaphus) seasonal home range sizes in relation to the quantity and spatial heterogeneity of forage biomass, forest cover, topography, snow–water equivalents, and landscape structure in three study landscapes: Yellowstone National Park, Wyoming, USA; eastern slopes of the Canadian Rockies, Alberta; and northern Wisconsin, USA. We used a 95% fixed kernel estimator to measure the home range size and location of all elk. To identify the scales at which important factors influenced home range sizes, we quantified environmental variables within the estimated home range polygon and within concentric circles with radii of 1000, 2000, 3000, 4000, and 5000 m from the home range center. Results indicate that there was an inverse relationship between forage biomass and summer and winter home range sizes in Alberta and Wisconsin, however the relationship was positive in Yellowstone. The size of summer and winter home ranges was positively related to percent forest cover; however this relationship was significant only when forest cover was quantified within the home range polygon or radii that were greater than or equal to 3000 m. Winter home ranges also had a positive relationship with snow–water equivalents. The predictive strength of summer home range models was greatest when landscape variables were quantified within the concentric circles with a radius of 3000 m or more, whereas the predictive strength of the winter models was greatest within the estimated home range polygon. Results suggest that elk ranging patterns reflected complex trade-offs that affect foraging, group dynamics, movement energetics, predation avoidance and thermal regulation. The multi-scale analysis indicates that elk based home ranging decisions on an area equal to their home range, but areas outside of the estimated home range were also important. 相似文献
92.
W M Boyce L W Woods M K Keel N J MacLachlan C O Porter H D Lehmkuhl 《Journal of zoo and wildlife medicine》2000,31(3):370-373
Ten fawns and four adult black-tailed deer (Odocoileus hemionus) in a captive herd died as a result of adenovirus-induced hemorrhagic disease. Acute, systemic infections were characterized by hemorrhagic enteropathy, pulmonary edema, and occasional ulceration of the upper alimentary tract. Localized infections were limited to the upper alimentary tract and included stomatitis, pharyngitis, mandibular osteomyelitis, and rumenitis. In deer with acute, systemic infections, a diagnosis was made by histopathology and immunohistochemistry. The serum neutralization test was useful for confirming a diagnosis in animals with prolonged, localized infections. Deer originating from herds with a history of adenovirus infection should not be transferred to other captive herds or released into free-ranging populations because they may serve as carriers of adenovirus. 相似文献
93.
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95.
AB Caselles A Miro‐Moran A Morillo Rodriguez JM Gallardo Bolaños C Ortega‐Ferrusola GM Salido FJ Peña JA Tapia IM Aparicio 《Reproduction in domestic animals》2014,49(2):254-262
Apoptosis in the testis is required to ensure an efficient spermatogenesis. However, sometimes, defective germ cells that are marked for elimination during this process escape elimination in the testes, giving rise to ejaculates with increased percentages of abnormal and apoptotic spermatozoa and a high percentage of apoptotic bodies. Apoptosis markers in the ejaculate have been associated with low fertility, either in animals or humans. Therefore, the goal of this study was to investigate whether fresh equine semen contains apoptotic bodies [initially named Merocyanine 540 (M540) bodies] and to study the relationship between the quantity of these bodies and cell concentration, the volume of ejaculate, viability and motility. Moreover, we also studied whether the presence apoptotic bodies in fresh semen was related to the resistance of the stallion spermatozoa to being incubated at 37°C or being frozen and thawed. Fresh equine semen was stained with fluorescent dyes such as M540 and Annexin‐V. Active Caspase 3 was studied in fresh semen through Western blotting and immunofluorescence with a specific antibody. Sperm kinematics was assessed in fresh, incubated and thawed samples using computer‐assisted semen analysis, and viability was evaluated with the LIVE/DEAD Sperm Viability Kit. Overall, our results demonstrate for the first time the presence of apoptotic bodies in equine semen. The quantity of apoptotic bodies was highly variable among stallions and was positively correlated with Caspase 3 activity in fresh samples and negatively correlated with the viability and motility of stallion spermatozoa after the cryopreservation process. 相似文献
96.
Semen from a Western Finncattle bull exhibiting a highly polymorphic spermiogram was processed by colloid centrifugation using Androcoll‐B, a species‐specific silane‐coated silica colloid. In the first experiment, Single Layer Centrifugation (SLC) was used to identify which density colloids were needed to separate different cell populations. Colloids of the two chosen densities were then used in a density gradient resulting in two sperm subpopulations, one containing nearly all normally sized spermatozoa and the other enriched for the macrocephalic spermatozoa. Microcephalic spermatozoa did not appear in either of the selected subpopulations. Using a combination of SLC and DGC with this species‐specific colloid, it was possible to separate the spermatozoa into different subpopulations, that is, a subpopulation containing nearly all normally sized spermatozoa, and another one enriched for the macrocephalic spermatozoa. Thus, colloid centrifugation could be used to select sufficient normal spermatozoa from a highly polymorphic ejaculate for AI, if desired. 相似文献
97.
JM Baldrighi MF Sá Filho EOS Batista RNVR Lopes JA Visintin PS Baruselli MEOA Assumpção 《Reproduction in domestic animals》2014,49(6):1015-1020
This study was performed to evaluate plasma concentrations of anti‐Mullerian hormone (AMH) and the ovarian antral follicle population (AFP) in different genetic groups. Cyclic heifers (13 Bubalus bubalis [Murrah]; 15 Bos taurus [Holstein] and 10 Bos indicus [Gyr]) were maintained under the same management and were synchronized with two doses of 150 μg IM d‐cloprostenol administered 14 days apart. After the second d‐cloprostenol treatment, heifers had their ovaries scanned daily by ultrasound to define the day of ovulation. On the same day, the AFP was determined and a plasma sample was collected to measure AMH. Murrah heifers had less AFP (25.6 ± 2.1 follicles; p = 0.01) and plasma AMH concentration (0.18 ± 0.03 ng/ml; p < 0.001) than Gyr (60.0 ± 12.2 follicles and 0.60 ± 0.12 ng/ml of AMH); however, data were similar when compared to Holstein (35.9 ± 6.8 follicles and 0.24 ± 0.06 ng/ml of AMH) heifers. Regardless of genetic background, there was a positive relationship between the AFP and plasmatic AMH concentration (Murrah [r = 0.62; p < 0.01], Holstein [r = 0.66; p < 0.001] and Gyr [r = 0.88; p < 0.001]). Also, when heifers were classified according to high‐ or low‐AMH concentration based on the average within each genetic group, high‐AMH heifers had greater (p < 0.0001) AFP than low‐AMH heifers. In conclusion, both Murrah and Holstein heifers presented lower plasma AMH concentration and AFP when compared to Gyr. 相似文献
98.
CM Balao da Silva C Ortega Ferrusola JM Gallardo Bolaños M Plaza Dávila P Martín‐Muñoz JM Morrell H Rodriguez Martínez FJ Peña 《Reproduction in domestic animals》2014,49(6):1021-1027
Flow cytometry is considered the only reliable method for the separation of X and Y chromosome bearing spermatozoa in equines. The MoFlo SX DP sorter is highly efficient, allowing the production of foals of the desired sex. However, to achieve acceptable pregnancy rates the currently used protocol requires working with fresh semen obtained close to, or at, the sorting facility. An alternative protocol was tested during two consecutive breeding seasons. Fresh stallion semen was cooled for 20 h, during which staining with Hoechst 33342 took place. On the following day, this sample was flow sorted and compared with spermatozoa from the same ejaculate that had been sexed on the previous day. All sperm parameters evaluated remained unchanged when fresh sorted and refrigerated sorted semen were compared. Pre‐sorting storage at 5°C did not alter sperm velocities nor kinetics, viability or membrane permeability, production of reactive oxygen species, mitochondrial membrane potential or DNA fragmentation index of the sorted sample. The findings open for the possibility of using semen from stallions housed far from the sorting facilities. Processed and stained sperm could be shipped refrigerated on the previous day, sorted and inseminated on the next day. 相似文献
99.
LA Gracia‐Calvo LJ Ezquerra M Martín‐Cuervo ME Durán H Tapio JM Gallardo FJ Peña C Ortega‐Ferrusola 《Reproduction in domestic animals》2014,49(6):1043-1048
Laparoscopic hernioplasty techniques have been developed in the recent years to avoid the recurrence of inguinal hernias and to spare the testicles for breeding purposes in stallions. However, there have been no previous comprehensive and systematic studies of the reproductive outcomes and prognoses for stallions after inguinal hernioplasty. Therefore, the objective of this study was to assess the possible effects of one of these techniques (standing laparoscopic peritoneal flap hernioplasty) on the sperm production and motility characteristics of six healthy stallions that received this procedure based on 1‐year follow‐ups. There were no significant differences in the measured sperm variables (assessments based on the DSO, MOT, PMOT, VSL, VCL and VAP) during 1‐year follow‐ups. 相似文献
100.
Y Yulnawati MC Abraham D Laskowski A Johannisson JM Morrell 《Reproduction in domestic animals》2014,49(6):954-956
The objective of this study was to evaluate bull sperm kinematics after centrifugation through a single layer of a colloid [Single Layer Centrifugation (SLC)]. Ejaculates from 20 bulls were extended and stored at 4–6°C for 24 h during transport to the laboratory for SLC through Androcoll‐B, followed by measurement of sperm kinematics in all samples. Total motility (86% and 88% for uncentrifuged and SLC samples, respectively) and progressive motility (84% for both the groups) were similar (p > 0.05). In contrast, straightness (STR) (0.65 vs 0.69), linearity (LIN) (0.32 vs 0.35) and beat cross frequency (BCF) (22.3 vs 23.6 Hz) were significantly higher in the SLC‐selected samples than in the uncentrifuged samples, whereas velocity of the average path (VAP) (95 vs 90 μm/s), curvilinear velocity (VCL) (192 vs 180 μm/s), amplitude of lateral head deviation (ALH) (7 μm vs 6.5 μm) and hypermotility (49% vs 38%) were significantly decreased. The kinematics of the samples with the poorest motility was improved most by SLC. In conclusion, even though SLC had no direct effect on total and progressive motility, it appeared to have a positive influence on several other kinematic parameters that may be important for fertilization after artificial insemination. 相似文献