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661.
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663.
An experiment was conducted to test the hypothesis that the requirement for Ca expressed as a ratio between standardized total tract digestible (STTD) Ca and STTD P obtained in short-term experiments may be applied to pigs fed diets without or with microbial phytase from 11 to 130 kg. In a 5-phase program, 160 pigs (body weight: 11.2 ± 1.8 kg) were randomly allotted to 32 pens and 4 corn–soybean meal-based diets in a 2 × 2 factorial design with 2 diet formulation principles (total Ca or STTD Ca), and 2 phytase inclusion levels (0 or 500 units/kg of feed) assuming phytase released 0.11% STTD P and 0.16% total Ca. The STTD Ca:STTD P ratios were 1.40:1, 1.35:1, 1.25:1, 1.18:1, and 1.10:1 for phases 1 to 5, and STTD P was at the requirement. Weights of pigs and feed left in feeders were recorded at the end of each phase. At the conclusion of phase 1 (day 24), 1 pig per pen was euthanized and a blood sample and the right femur were collected. At the end of phases 2 to 5, a blood sample was collected from the same pig in each pen. At the conclusion of the experiment (day 126), the right femur of 1 pig per pen was collected and carcass characteristics from this pig were measured. No interactions were observed between diet formulation principle and phytase inclusion for growth performance in any phase and no differences among treatments were observed for overall growth performance. Plasma Ca and P and bone ash at the end of phase 1 were also not influenced by dietary treatments. However, on day 126, pigs fed nonphytase diets formulated based on total Ca had greater bone ash than pigs fed STTD Ca-based diets, but if phytase was used, no differences were observed between the 2 formulation principles (interaction P < 0.05). At the end of phases 2 and 3, pigs fed diets without phytase had greater (P < 0.05) plasma P than pigs fed diets with phytase, but no differences were observed at the end of phases 4 and 5. A negative quadratic effect (P < 0.05) of phase (2 to 5) on the concentration of plasma Ca was observed, whereas plasma P increased (quadratic; P < 0.05) from phases 2 to 5. However, there was no interaction or effect of diet formulation principle or phytase inclusion on any carcass characteristics measured. In conclusion, STTD Ca to STTD P ratios can be used in diet formulation for growing-finishing pigs without affecting growth performance or carcass characteristics and phytase inclusion ameliorates bone resorption caused by low dietary Ca and P. 相似文献
664.
Hua-Feng Wang María Vanessa Lencinas Cynthia Ross Friedman Xiao-Ke Wang Jiang-Xiao Qiu 《New Forests》2011,42(1):101-116
Biodiversity in managed plantations has become an important issue for long-term sustainability of ecosystems. The environmental
effects of plantations comprised of fast-growing introduced trees have been vigorously debated. On one hand, monocultures
have been said to exhaust resources, resulting in decreased biodiversity. Conversely, it has been stated that monocultures
may favor regeneration of undergrowth plants from surrounding forests, increasing biodiversity. In order to clarify the effects
of planting Eucalyptus trees on species composition, diversity, and functional type of understory vegetation in Yunnan province, a field trial was
implemented to compare Eucalyptus plantations (EPs) with two other local current vegetation types (secondary evergreen forests (SEs), and abandoned farmlands
(AFs)). Each vegetation type was sampled in each of three elevational ranges (low = 1,000–1,400 meters above sea level (masl),
medium = 1,400–1,800 masl, and high = 1,800–2,200 masl). Sample sites within each elevational range had similar environmental
characteristics (slope, aspect, etc.). Thus, we sampled three vegetation types at each of three sites at each of three elevations
for a total of 27 plots. We calculated relative abundance and importance value of species and diversity indexes to evaluate
differences among local current vegetation types and elevational ranges, employing multivariate ordination analyses and other
methods such as Analyses of Variance (ANOVA) and Indicator Species Analysis. We found that fast growing introduced Eucalyptus plantations led to reduced plant diversity in the study area, and that rare or threatened species were recorded almost exclusively
in the SE plots, being essentially absent from the EP and AF plots. The understory plant diversity did not correlate with
the altitude gradient significantly. Eucalyptus plantations (EPs) have a simpler community structure than that of either secondary evergreen forests (SEs; similar to natural
state) or abandoned farmlands (AFs). No variable significantly explained variation of the understory shrub layer, but soil
moisture-holding capacity and overstory coverage were significant in explaining variation of the understory herb layer, suggesting
that the study of soil physical properties is necessary for better understanding of their importance in Eucalyptus plantations and other local current vegetation types. 相似文献
665.
Intensively managed loblolly pine (Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations (n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (?4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives. 相似文献
666.
Enhancement of conditioned arterial pressure responses in cats after brainstem lesions 总被引:1,自引:0,他引:1
Cats were classically conditioned after the baroreceptor reflexes were abolished by bilateral placement of electrolytic lesions in the nucleus tractus solitarii. The conditioned increases in arterial pressure were more than five times larger than the responses obtained in similarly trained controls. This finding suggests that the baroreceptor reflexes actively inhibit conditioned increases of arterial pressure. 相似文献
667.
Gobert V Gottar M Matskevich AA Rutschmann S Royet J Belvin M Hoffmann JA Ferrandon D 《Science (New York, N.Y.)》2003,302(5653):2126-2130
The Toll-dependent defense against Gram-positive bacterial infections in Drosophila is mediated through the peptidoglycan recognition protein SA (PGRP-SA). A mutation termed osiris disrupts the Gram-negative binding protein 1 (GNBP1) gene and leads to compromised survival of mutant flies after Gram-positive infections, but not after fungal or Gram-negative bacterial challenge. Our results demonstrate that GNBP1 and PGRP-SA can jointly activate the Toll pathway. The potential for a combination of distinct proteins to mediate detection of infectious nonself in the fly will refine the concept of pattern recognition in insects. 相似文献
668.
Gonçalves Mariana Gabriele Marcolino Avalos Fabio Arnaldo Pomar dos Reis Josimar Vieira Costa Milton Verdade Silva Sérgio Henrique Godinho Poggere Giovana Clarice Curi Nilton de Menezes Michele Duarte 《Precision Agriculture》2022,23(3):1027-1050
Precision Agriculture - This work proposes an approach for establishing coffee management classes mainly supported by pedological information (soil survey) and land parcels, taking into account... 相似文献
669.
Bin Wu Vanessa Oesker Jutta Wiese Rolf Schmaljohann Johannes F. Imhoff 《Marine drugs》2014,12(3):1208-1219
Two unusual pyridones, trichodin A (1) and trichodin B (2), together with the known compound, pyridoxatin (3), were extracted from mycelia and culture broth of the marine fungus, Trichoderma sp. strain MF106 isolated from the Greenland Seas. The structures of the new compounds were characterized as an intramolecular cyclization of a pyridine basic backbone with a phenyl group. The structure and relative configuration of the new compounds were established by spectroscopic means. The new compound 1 and the known compound 3 showed antibiotic activities against the clinically relevant microorganism, Staphylococcus epidermidis, with IC50 values of 24 μM and 4 μM, respectively. 相似文献
670.