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Nitrate leaching losses and their control in a mixed farm system in the Cotswold Hills, England 总被引：3，自引：0，他引：3
K.D. Allingham R. Cartwright D. Donaghy J.S. Conway K.W.T. Goulding S.C. Jarvis 《Soil Use and Management》2002,18(4):421-427
Abstract. Nitrate leaching was measured for four years at the Royal Agricultural College 's Coates Farm in the Cotswolds, England. Coates is a typical Cotswold mixed farm with thin, well-drained calcareous soils especially prone to leaching. Over the duration of this study there were dairy, sheep and arable enterprises on the farm. A 'Farm Gate' nitrogen (N) budget was constructed. Small 120 m × 20 m 'farmlets' were sited in ten fields across the farm, covering all parts of the rotation, as the sites for detailed measurements. Each farmlet received the same management as the rest of the field in which they were situated. Using ceramic probes inserted to 60 cm, soil water was sampled every two weeks throughout the winter drainage season. The annual drainage varied from 135 mm under grassland in 1996/7 to 600 mm under cereals in 1998/9. Average N losses by leaching were determined mostly by rainfall and were 65 kg N ha–1 yr–1 , accounting for 25% of the N inputs. Especially leaky parts of the rotation were the ploughing out of a lucerne ley and the grazing of stubble turnips with sheep, both typical Cotswold farm practices. The research highlights some of the difficulties in developing practicable, profitable management practices to decrease nitrate losses. 相似文献
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J Wang Y Yoo C Gao I Takeuchi X Sun H Chang X Xiang PG Schultz 《Science (New York, N.Y.)》1998,279(5357):1712-1714
A quaternary combinatorial masking strategy was used in conjunction with photolithography to generate compositionally diverse thin-film phosphor libraries containing 1024 different compositions on substrates 2.5 centimeters square. A parallel imaging system and scanning spectrophotometer were used to identify and characterize compositions in the library with interesting luminescent behavior. Optimal compositions were identified with the use of gradient libraries, in which the stoichiometry of a material was varied continuously. This process led to the identification of an efficient blue photoluminescent composite material, Gd3Ga5O12/SiO2. Experimental evidence suggests that luminescence in this material may arise from interfacial effects between SiO2 and Gd3Ga5O12. 相似文献
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RC Elphic DJ Lawrence WC Feldman BL Barraclough S Maurice AB Binder PG Lucey 《Science (New York, N.Y.)》1998,281(5382):1493-1496
The Lunar Prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of Clementine spectral reflectance data. With the iron and titanium dependence removed, the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium, incompatible rare earth elements that are enriched in the final phases of magma crystallization. These regions are found mainly around the ramparts of the Imbrium impact basin but not around the other basins, including the much larger and deeper South Pole-Aitken basin. This result confirms the compositional uniqueness of the surface and interior of the Imbrium region. 相似文献
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Daub Matthias Hakl Ulrike Molendijk Leendert PG Schomaker Corrie Been Thomas H van Beers Thea G Jivishova Sevda Jivishov Emil Keusgen Michael Bluemel Roman Fischer Daniel Grundler Florian MW Reuther Marie Cappel Sabrina Bauer Harald Lang Christian Watrin Cliff den Nijs Loes JMF Van Bruggen Anne-Sophie Karssen Gerrit Kiewnick Sebastian Büchler Urs Roth Irma Frey Jürg 《植物病害和植物保护杂志》2015,122(4):189-193
Journal of Plant Diseases and Protection - 相似文献
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Naturally acquired immunity to buffalo fly (Haematobia irritans exigua) infestation was examined in cattle. Animals exposed to flies had serum antibodies to buffalo fly antigens at levels that correlated with the intensity of exposure. Two weeks of intense exposure to buffalo fly induced an increase in peripheral blood eosinophil numbers and a concomitant rise in serum antibody levels in exposed animals. Antigens specific for antibody induced by natural exposure were identified using antisera from exposed cattle to probe Western blots of whole fly homogenate separated using SDS-PAGE. Similar immunoreactive bands were found with buffalo fly saliva. Immunoreactive proteins were partially purified from whole fly homogenates by anion-exchange chromatography. Fractions eluted from columns were screened using Western blots probed with serum from exposed animals. Exposed animals showed immediate hypersensitivity to partially purified antigens and to buffalo fly saliva. Flies which fed on exposed animals with high serum levels of antibody to fly antigens did not show greater mortality than flies fed on unexposed animals. 相似文献
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C Valiente Y Corrada PE de la Sota PG Blanco D Arias C Gobello 《Reproduction in domestic animals》2009,44(S2):156-159
Gonadotropin-releasing hormone (GnRH) antagonists are particularly useful when a rapid inhibitory effect on the gonadal axis is required. The aim of this study was to test the efficacy and clinical safety of a low and high dose of the third generation GnRH antagonist, acyline, on pregnancy termination in female dogs. The effect of the antagonist on the progesterone (P4 ) serum concentration was also described. Twenty-one mid-pregnant bitches were randomly assigned to a single subcutaneous (SC) dose of a placebo (PLACE; n = 7), a low (ACY-L; 110 μg/kg; n = 6) or high (ACY-H; 330 μg/kg; n = 8) dose of acyline. The animals were followed up for 15 days. All ACY treated but no placebo-treated animals terminated their pregnancy by abortion (p < 0.01). The ACY-L and ACY-H groups interrupted their pregnancy 7 ± 1.9 and 6.4 ± 1.3 days after treatment, respectively (p = 0.7). A significant interaction between treatment and day was found (p < 0.01) for P4 serum concentrations when PLACE was compared with both ACY groups. No difference was found for this hormone between both ACY groups (p > 0.05) where P4 diminished throughout the study. The decreasing rate varied among animals and was closely related to the time of abortion when P4 reached basal concentrations. In PLACE animals, gestation progressed normally and P4 did not change throughout the study (p > 0.05). None of the bitches presented side effects. It was concluded that acyline safely terminated mid-pregnancy by permanently decreasing P4 serum concentrations. 相似文献
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LA Quintela AI Peña MD Vega J Gullón C Prieto M Barrio JJ Becerra PG Herradón 《Reproduction in domestic animals》2009,44(5):829-833
This study was aimed to evaluate the reproductive performance of rabbit does artificially inseminated (AI) with a GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH. ethylamide to induce ovulation by intravaginal administration, delivered in the seminal dose. In a preliminary experiment, 39 does were divided into three groups (n = 13) that, at the time of AI, received the following ovulation induction treatments: (i) control group: 20 μg of gonadorelin administered intramuscularly; (ii) 25 μg of the GnRH analogue added to the seminal dose; (iii) 30 μg of the GnRH analogue added to the seminal dose. Fertility did not differ between the three groups (control: 80.6%, group 2: 82.8%, group 3: 73.3%). In a second experiment, a large‐scale field trial was conducted to test the use of 25 μg of the GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH ethylamide delivered in the seminal dose (n = 270) against 20 μg of gonadorelin administered intramuscularly. Fertility was higher (p < 0.05) when ovulation was induced by intravaginal administration of the GnRH agonist (91.1% vs 85.6%). Prolificacy or mortality at birth was never affected by the ovulation induction treatments. In a third experiment, two groups of does [control group (n = 39): ovulation was induced using 20 μg of gonadorelin administered intramuscularly; treatment group (n = 40): ovulation was induced using 25 μg of [(des‐Gly10, d ‐Ala6)‐LHRH ethylamide added to the seminal dose] were inseminated at 42‐day intervals for five successive AI cycles, to test the response to the GnRH agonist after repeated intravaginal administration to the same animals. Fertility and prolificacy were not influenced by the ovulation induction treatment neither there was an interaction between treatment and parity. The last experiment was aimed to determine whether it could be possible to add the GnRH agonist to the semen in the AI Center, just after semen collection and dilution, or it would have to be added in the farm, immediately before AI. Kindling rates did not significantly differ when ovulation was induced by intramuscular injection of gonadorelin (84.5%) or when the GnRH agonist was added to the seminal dose just at the moment (93.8 %) or 24 h before AI (90.4 %), but it was significantly lower when the hormone was added to the semen 32 h before AI (76.3 %). Prolificacy, however, was not influenced by the ovulation induction treatment. 相似文献
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RR Oliveira DM Rates G Pugliesi PG Ker RP Arruda EA Moraes GR Carvalho 《Reproduction in domestic animals》2014,49(5):845-850
The use of cholesterol‐loaded cyclodextrin (CLC) on semen cryopreservation has been related with better sperm viability in several species; however, the effect on fertility is not known in donkey semen. Ejaculates (n = 25) from five donkeys were diluted in S‐MEDIUM with 0, 1, 2 or 3 mg of CLC/120 × 106 spermatozoa. Semen was frozen, and thawed samples were evaluated by computer‐assisted sperm analyser system (CASA), supravital test, hyposmotic swelling test and fluorescent dyes to assess the integrity of sperm membranes. Mares (n = 60) were inseminated with frozen‐thawed semen treated with the doses of 0 or 1 mg CLC. Percentages of sperm with progressive motility and with functional plasma membrane were greater (p < 0.05) in the CLC‐treated groups than in the control. Percentages of intact plasma membrane and intact plasma membrane and acrosome detected by fluorescent dyes were also greater (p < 0.05) in CLC‐treated groups. Although no difference (p > 0.05) in conception rates was detected between groups (control, 3/30, 10%; CLC‐treated, 1/30, 3.3%), fertility was low for artificial insemination programs in mares. Therefore, we firstly demonstrated that frozen semen treated with CLC in S‐MEDIA extender before freezing improves the in vitro sperm viability, but semen treated or not with CLC in S‐MEDIUM extender results in a very low conception rate in mares inseminated with thawed donkey semen. 相似文献