Growth of the conceptus in alpacas     

Bravo PW  Mayta MM  Ordoñez CA 《American journal of veterinary research》2000,61(12):1508-1511

OBJECTIVE: To determine growth of the alpaca conceptus during early gestation, using ultrasonography. ANIMALS: 40 pregnant alpacas (20 multiparous, 20 nulliparous). PROCEDURE: Transrectal ultrasonography with a 5-MHz probe was performed 3 times weekly from days 7 through 45 after copulation (day of copulation = day 0). Blood samples were collected for progesterone assay on days of ultrasonography. RESULTS: Forty embryonic vesicles and embryos were identified and measured. Embryonic vesicles were first detected on day 12 after copulation and appeared spherical. Cumulative percentage of embryonic vesicles detected was 50, 82.5, and 100% on days 12, 14, and 16, respectively. Embryos were first detected by day 22 and heartbeats by day 24. Similarly, cumulative percentage of embryos detected was 17.5, 82.5 and 100% for 22, 24, and 26 days after copulation, respectively. Embryonic vesicles occupied both uterine horns beginning on day 19. A positive correlation existed between length and width of embryonic vesicles. Size of embryonic vesicles and embryos and progesterone concentrations did not differ between multiparous and nulliparous females. Five sets of twins were detected from days 21 through 33 after copulation, but the conceptus identified in the right uterine horn became nondetectable between days 28 and 33. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonography was useful in detecting the earliest appearance of alpaca embryonic vesicles and determining the changes in growth from days 12 through 45 after copulation. Embryos were first detected by day 22. Transrectal ultrasonography was not harmful to animals and did not provoke embryonic death in this study.  相似文献   

Simultaneous identification of plant stresses and diseases in arable crops using proximal optical sensing and self-organising maps     

D. Moshou  C. Bravo  S. Wahlen  J. West  A. McCartney  J. De Baerdemaeker  H. Ramon 《Precision Agriculture》2006,7(3):149-164

The objective of this research was to detect plant stress caused by disease infestation and to discriminate this type of stress from nutrient deficiency stress in field conditions using spectral reflectance information. Yellow Rust infected winter wheat plants were compared to nutrient stressed and healthy plants. In-field hyperspectral reflectance images were taken with an imaging spectrograph. A normalisation method based on reflectance and light intensity adjustments was applied. For achieving high performance stress identification, Self-Organising Maps (SOMs) and Quadratic Discriminant Analysis (QDA) were introduced. Winter wheat infected with Yellow Rust was successfully recognised from nutrient stressed and healthy plants. Overall performance using five wavebands was more than 99%.  相似文献   

Exploring overlooked components of remote South-east Pacific oceanic islands: Larval and macrobenthic assemblages in reef habitats with distinct underwater soundscapes     

Sergio A. Carrasco  Macarena Bravo  Elba Avilés  Paula Ruíz  Alfio Yori  Iván A. Hinojosa 《水产资源保护:海洋与淡水生态系统》2021,31(2):273-289

1. Identifying the diverse assemblage of species inhabiting rocky and coral reef habitats in isolated oceanic environments, and the important sound cues emitted from the reef, are crucial components to understand how species locate suitable habitats for the completion of their life-cycle and, thus, the functioning of these vulnerable ecosystems.
2. Recent field information suggests that the majority of reef biodiversity comprises small cryptic invertebrates; however, knowledge on these small components is extremely scarce.
3. The present study used light attraction methods to explore the diversity of larval, post-larval and macrobenthic cryptic fauna, and hydrophones to characterize the natural soundscape of rocky and coral reef habitats at the Robinson Crusoe island (Juan Fernandez Archipelago; 33°38′S, 78°50′W), and Rapa Nui (Easter Island; 27°7′S, 109°21′W), respectively.
4. Pelagic collections found important site-specific patterns and identified two main species assemblages: early-life stages (e.g. eggs, larval and juvenile stages of crustaceans, molluscs, and fishes) and emerging macrobenthos (e.g. demersal zooplankton such as peracarid crustaceans, ostracods, copepods, and polychaetes), with the latter contributing between 73 and 98% to the total catches.
5. The soundscape records showed marked differences among sites and seasons at Robinson Crusoe island, with variable differences found between day and night. However, at Rapa Nui, there were no differences between sites, but the ambient sound was higher at night possibly due to higher snapping shrimp activity.
6. This information highlights the importance of considering small-scale (site-to-site) patterns when evaluating overlooked components of diversity (i.e. biological or acoustic) in oceanic habitats, and provides the basis for understanding the importance of natural noise in the settlement of most reef-associated species, crucial features for the conservation of these remote and vulnerable ecosystems.

  相似文献   

Tree size and light availability increase photochemical instead of non-photochemical capacities of Nothofagus nitida trees growing in an evergreen temperate rain forest     

Coopman RE  Briceño VF  Corcuera LJ  Reyes-Díaz M  Alvarez D  Sáez K  García-Plazaola JI  Alberdi M  Bravo LA 《Tree physiology》2011,31(10):1128-1141

Nothofagus nitida (Phil.) Krasser (Nothofagaceae) regenerates under the canopy in microsites protected from high light. Nonetheless, it is common to find older saplings in clear areas and adults as emergent trees of the Chilean evergreen forest. We hypothesized that this shade to sun transition in N. nitida is supported by an increase in photochemical and non-photochemical energy dissipation capacities of both photosystems in parallel with the increase in plant size and light availability. To dissect the relative contribution of light environment and plant developmental stage to these physiological responses, the photosynthetic performance of both photosystems was studied from the morpho-anatomical to the biochemical level in current-year leaves of N. nitida plants of different heights (ranging from 0.1 to 7 m) growing under contrasting light environments (integrated quantum flux (IQF) 5-40 mol m(-2). Tree height (TH) and light environment (IQF) independently increased the saturated electron transport rates of both photosystems, as well as leaf and palisade thickness, but non-photochemical energy flux, photoinhibition susceptibility, state transition capacity, and the contents of D1 and PsbS proteins were not affected by IQF and TH. Spongy mesophyll thickness and palisade cell diameter decreased with IQF and TH. A(max), light compensation and saturation points, Rubisco and nitrogen content (area basis) only increased with light environment (IQF), whereas dark respiration (R(d)) decreased slightly and relative chlorophyll content was higher in taller trees. Overall, the independent effects of more illuminated environment and tree height mainly increased the photochemical instead of the non-photochemical energy flux. Regardless of the photochemical increase with TH, carbon assimilation only significantly improved with higher IQF. Therefore it seems that mainly acclimation to the light environment supports the phenotypic transition of N. nitida from shade to sun.  相似文献   

Climatic variability and other site factor influences on natural regeneration of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. in Mediterranean forests     

Encarna Rodriguez-Garcia  Georg Gratzer  Felipe Bravo 《Annals of Forest Science》2011,68(4):811-823

Background  

How environmental factors affect forest regeneration is relevant for systems that depend partially or fully on natural regeneration.  相似文献   

Multinomial logit estimation of a diameter growth matrix model of two Mediterranean pine species in Spain     

Ernesto Escalante  Valentín Pando  Cristóbal Ordoñez  Felipe Bravo 《Annals of Forest Science》2011,68(4):715-726

• Introduction   

Understanding diameter growth of the Mediterranean pine species is fundamental for evaluating and making appropriate strategic decisions in forest management. A matrix diameter growth model for two Mediterranean pine forest ecosystems in Spain has been developed.  相似文献   

Effects of shrub and canopy cover on the relative growth rate of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. seedlings of different sizes     

Encarna Rodríguez-García  Cristóbal Ordóñez  Felipe Bravo 《Annals of Forest Science》2011,68(2):337-346

• Introduction   

Shrubs are recognized as important tree regeneration niches. In this study, we experimentally analysed the effects of shrub presence, canopy cover (closed cover and open cover-gaps), and seedling size on Pinus pinaster growth.  相似文献   

Montezuma pine nutrient status as affected by alder densities nitrogen fertilization     

Miguel&#x;A. Lpez‐Lpez  Celedonio Aguirre‐Bravo  Robin Reich 《植物养料与土壤学杂志》2006,169(6):833-840

Literature reports both positive and negative effects of N‐fixing alders on conifer growth in alder‐conifer stands. Such divergent effects probably result from poorly understood species interactions. The aim of this work was to examine how varying alder‐to‐pine ratios (APRs) and N fertilization affect pine nutrient status. A pseudo‐experiment was installed in each of two areas of regeneration (AR) with different amounts of radiation reaching alder. The experimental approach consisted of a series of pseudoreplicated plots with five APRs within each AR. Half of each plot received 200 kg N ha^–1. Data were interpreted by vector analysis. Alders in the AR 1987 induced needle‐biomass reductions, K deficiency, and P accumulation in pine needles. However, nutrient availability increased with the proportion of alders in the AR 1989, where alders received high sunlight due to a less dense pine stand. Nitrogen fertilization increased needle biomass and N in three out of five alder proportions where alders were sunlight‐limited. In the other stand, with the exception of the no‐alder and A4 plots, positive effects of N fertilization increased with decreasing alder density. We conclude that sunlight‐limited alders may not positively affect associated‐species growth even in N‐limited sites.  相似文献   

Changes in water retention properties due to the application of sugar foam in red soils     

C. Pérez-de-los-Reyes  J.A. Amorós Ortíz-VillajosF.J. García Navarro  S. Bravo Martín-ConsuegraC. Sánchez Jiménez  D. Chocano EtesonR. Jiménez-Ballesta 《Agricultural Water Management》2011,98(12):1834-1839

This work describes the influence of the application of sugar foam (an organic residue from sugar beet industry) on water retention properties, over an extended period of time (>25 years), in two red soils in the La Mancha region of Spain. The properties of gravimetric moisture at field capacity, gravimetric moisture in the permanent wilting point and available water retention capacity both in the original soil - without the addition of sugar foam - and in the soil affected by the addition of sugar foam are compared. For this purpose, the profiles are characterised macro morphologically. Chemical, physical-chemical and mineralogical parameters are determined, in addition to determining the water retention curves of each soil with tensiometers and Richards pressure plates.The sugar foam applied to the soil altered its physical and chemical properties. An increase in contents of organic matter (3.5% versus 1.4%), calcium carbonate (40.8% versus 0%) and pH (8.2 versus 6.3) are observed in the superficial horizon of the studied soils, although there is no such significant increase in electrical conductivity (0.33 dS/m versus 0.25 dS/m). With regard to the physical properties, the depth of horizon A increases (32 cm versus 12 cm), the stoniness reduces (5% versus 25%), the structure is well developed, due to the texture becomes finer (silty versus sandy clay loam), and, finally, the bulk density reduces (0.79 g cm⁻³ versus 1.19 g cm⁻³).The gravimetric moisture at field capacity was 49% in the soil altered with sugar foam, versus 12% in the non-altered soil; the gravimetric moisture in the permanent wilting point was 14.5% versus 8% and the available water retention capacity was 34.5% and 4%, respectively. It can be concluded that the increase of calcium carbonate, organic matter and the reduction of bulk density are the most influential factors in this process. The scientific novelty of this work is that the hydro-behaviour of the soil due to the addition of sugar foam improves the characteristic values of moisture and, therefore, the agronomical qualities of the soil.  相似文献   

Effects of dietary supplementation with phytonutrients on vaccine-stimulated immunity against infection with Eimeria tenella     

Lee SH  Lillehoj HS  Jang SI  Lee KW  Bravo D  Lillehoj EP 《Veterinary parasitology》2011,181(2-4):97-105

  相似文献