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排序方式: 共有354条查询结果,搜索用时 15 毫秒
71.
The DB2 calf strain of bovine coronavirus (BCV) was used to inoculate 1-day-old specific-pathogen-free (SPF) turkey poults in three trials. In all trials, the birds developed clinical signs of enteritis at 48-72 hr postinoculation. Birds euthanatized at 3, 5, and 7 days postinoculation (DPI) had flaccid, pale intestines with watery contents, and the ceca were markedly enlarged with frothy contents. Coronavirus particles were detected by immune electron microscopy with BCV antibodies from the intestinal contents of birds killed at 3, 5, 7, and 12 DPI. Body weights of inoculated poults killed at 3, 5, and 7 DPI were significantly reduced as compared with controls. Hemagglutinating antibodies were detected in sera of convalescent birds at 12 DPI. However, experimental inoculation of 1-day-old SPF chicks in two trials with the same virus resulted in no clinical signs or macroscopic or microscopic lesions. No coronaviruses were detected from intestinal contents, and there were no significant differences in body weights of inoculated and noninoculated control chicks. 相似文献
72.
Behrooz Hassanpour Mohd Mansor Ismail Zainalabidin Mohamed Nitty Hirawaty Kamarulzaman 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):218-234
This study investigates the sources of total factor productivity (TFP) growth in rainbow trout production in Iran using data envelopment analysis (DEA). The Malmquist index is then employed to decompose the TFP growth into technical efficiency change and technological progress. We utilized panel data of 207 trout farms in the country over a 5-year period from 2003 to 2007. The results of this study revealed that TFP growth of rainbow trout farming has an increasing trend over the period at an average annual rate of 3.7%. The trend of cumulative technological change is negative and tends to be contrary to cumulative technical efficiency change. Although there is no technological change or innovation on trout farming, the technical efficiency change was found to be the sole source for TFP change, whereas the mean of technical efficiency was estimated to be about 66%. Therefore, there is still a great relative potential for increasing trout production through improvement in managerial efficiency as well as technological progress. The study suggests that Iran also has considerable room to enhance trout aquaculture's TFP growth by shifting the production frontier with adoption of new technologies and improving innovation. 相似文献
73.
Siti Hazirah Zolkafli Maizura Ithnin Kuang-Lim Chan Mohd Isa Zainol Abidin Ismanizan Ismail Ngoot Chin Ting Leslie Cheng-Li Ooi Rajinder Singh 《Breeding Science》2021,71(2):253
Oil palm is continually being improved via controlled crossing of selected palms to ensure sustainable yields and productivity. As such, correct parental assignment is important as the presence of illegitimates will compromise the progress of improvement. In the present study, we determined the optimal number of microsatellite (SSR) markers for detection of illegitimates in selected oil palm crosses with high confidence. Determining the optimal number of markers to assign parentage will ensure that the DNA fingerprinting will be cost effective for routine use as a quality control tool in oil palm improvement programs. Here, we evaluated a wide range of crosses that included a cross derived from wild germplasm palm. The results revealed that markers with high PIC are informative and detect most of the alleles present in a cross, including those exhibited by the illegitimates. A larger number of optimum sets of markers are needed to detect all illegitimates for crosses with higher levels of genetic diversity. The optimal number of polymorphic SSR markers determined in the present study can ensure that appropriate quality control is implemented for oil palm improvement programs. 相似文献
74.
S. V. K. Jagadish E. M. Septiningsih A. Kohli M. J. Thomson C. Ye E. Redoña A. Kumar G. B. Gregorio R. Wassmann A. M. Ismail R. K. Singh 《Journal of Agronomy and Crop Science》2012,198(5):360-373
Rice, with its wide geographic distribution extending from 50°N to 35°S, is expected to be the most vulnerable cultivated crop to future changing climates. Among the different abiotic stresses, extreme temperatures coinciding with critical developmental stages, increasingly frequent floods and drought spells, and worsening sea water inundation are some of the major threats to sustainable rice productivity. Following the successful implementation of molecular marker‐assisted backcrossing to introgress large‐effect QTL for submergence tolerance in rice mega varieties, rice breeding for drought, salinity and, recently, heat tolerance is employing the same approach. Although tolerance for combined submergence and salinity has been achieved, developing rice varieties with multiple tolerance for other abiotic and biotic stresses and finding the appropriate agronomic package to exploit their performance remain a challenge. The major bottleneck is the lack of unidentified large‐effect QTL for other abiotic stresses that are strongly influenced by genotype × environment (G × E) interaction. Rapid advances in the use of molecular tools, including a plethora of SNP markers, are expected to facilitate the development of major abiotic stress‐tolerant rice. In response to the actual farmer field situation, progress achieved in understanding and developing independent abiotic stress tolerance is being exploited to combine tolerances (for example, heat and drought; salinity and submergence) to address emerging environmental problems across a wide range of rice ecosystems. 相似文献
75.
76.
Francisco Gomez‐Coronado Ana S. Almeida Oscar Santamaria Ismail Cakmak Maria J. Poblaciones 《Journal of Agronomy and Crop Science》2019,205(3):341-352
About 3 billion people may suffer from micronutrient deficiency such as Ca, Fe, Mg or Zn, caused not only by a mineral deficiency in staple food but also by a high content of phytates which bind those minerals and inhibit their absorption. With the aim of evaluating the potential of new cultivars of bread‐making wheat to accumulate those minerals and low phytates, nine advanced breeding lines from an ongoing Portuguese breeding program were studied during 2 years in a field experiment. A wide genetic variability was found between the studied genotypes in all the parameters studied, especially grain yield (ranging on average between 2,027 and 3,209 kg/ha) and grain Mg and Zn concentrations (ranging on average between 1,070 and 1,336 mg/kg, and 23.4 and 30.7 mg/kg, respectively). In global terms, the cultivars with best performance, and therefore, the most potentially suitable to be used in a breeding program, were the Cultivars 3 and 4. However, such a potential varied depending on the analysed trait, and it was clearly influenced by the climatic conditions. The consumption of 100 g of Cultivar‐4 produced under the most favourable conditions might provide a 5.2% of Ca, 26.4% of Fe, 38.9% of Mg and 31.9% of Zn of the recommended daily intakes, with a very good bioavailability for Fe and Ca, but low for Mg and Zn. 相似文献
77.
Hasan M. Khan Zahid S. Chaudhry Muhammad Ismail Khalid Khan 《Water, air, and soil pollution》2010,213(1-4):353-362
The gamma spectrometric analysis of soil and essential foodstuffs, e.g., wheat, millet, potato, lentils and cauliflower, which form the main component of the daily diet of the local public, was carried out using high purity germanium (HpGe) detector coupled with a computer based high-resolution multi-channel analyzer. The activity concentration in soil samples for 226Ra, 232Th and 40K ranged from 30.0 Bq kg?1 to 81.2 Bq kg?1, 31.4 Bq kg?1 to 78.25 Bq kg?1 and 308.8 Bq kg?1 to 2177.6 Bq kg?1, with mean values of 56.2, 58.5 and 851.9 Bq kg?1, respectively. The average activity measured for 226Ra, 232Th and 40K in soil samples was found higher than the world average. The major radionuclide found in the food items studied was 40K, while 226Ra, 232Th and 137Cs were detected in very nominal amounts. The results clearly indicate that these radionuclides have no health hazard to human beings, as they are well below the annual limit of intake (ALI) for these radionuclides. The transfer factors of these radionuclides from soil to food were also studied. The mean transfer factors of 40K, 226Ra, 232Th and 137Cs from soil to food were estimated to be about 0.17, 0.07, 0.16 and 0.23, respectively. An artificial radionuclide, 137Cs, was also present in detectable amount in all samples. The internal and external hazard indices were measured and had mean values of 0.70 and 0.55, respectively. Absorbed dose rates and effective dose have been determined in the present study. Concentration of trace metals, such as Cr, Pb, Ni and Zn, was also determined in the soil samples. The concentrations of radionuclides and trace metals found in these samples during the present study were nominal and do not pose any potential health hazard to the general public. 相似文献
78.
Browell EV Butler CF Fenn MA Grant WB Ismail S Schoeberl MR Toon OB Loewenstein M Podolske JR 《Science (New York, N.Y.)》1993,261(5125):1155-1158
Stratospheric ozone and aerosol distributions were measured across the wintertime Arctic vortex from January to March 1992 with an airborne lidar system as part of the 1992 Airborne Arctic Stratospheric Expedition (AASE II). Aerosols from the Mount Pinatubo eruption were found outside and inside the vortex with distinctly different distributions that clearly identified the dynamics of the vortex. Changes in aerosols inside the vortex indicated advection of air from outside to inside the vortex below 16 kilometers. No polar stratospheric clouds were observed and no evidence was found for frozen volcanic aerosols inside the vortex. Between January and March, ozone depletion was observed inside the vortex from 14 to 20 kilometers with a maximum average loss of about 23 percent near 18 kilometers. 相似文献
79.
This study evaluated the effect of two bacteria, Bacillus amyloliquefaciens and the dairy yogurt (DY) Lactobacillus sp., on improving the growth performance, feed conversion ratio (FCR) and some immunological and haematological parameters. Nile tilapia (19.1 g) were stocked in 0.42 m3 tanks at 67 fish m?3 and fed with two probiotic‐incorporated diets and a control diet for 99 days, followed by a normal diet for another 61 days. At the end of the probiotic feeding, the mean weight, FCR and production rate showed no significant difference among the treatments. However, after 61 days of feeding of the normal diet, the B. amyloliquefaciens fish showed significantly superior growth and better FCR than the control. The DY group had the lowest growth and the poorest FCR. Significantly higher serum lysozyme activity, head‐kidney superoxide dismutase, total immunoglobulin and serum bacterial agglutination titres were recorded in the probiotic groups than the control. Haematological parameters showed no difference between treatments. The B. amyloliquefaciens fed fish showed that the gut microflora was dominated by B. amyloliquefaciens even after the withdrawal of the probiotic. On the contrary, the probiotic bacterial species isolated from the dairy yoghurt did not persist longer in the gut. These results indicate the beneficial effect of administering the bacteria isolated from fish gut microflora, B. amyloliquefaciens, in improving growth, FCR and immunological parameters. The high persistence of B. amyloliquefaciens indicates that the probiotic colonization in the gut is essential for the best responses and economics. 相似文献
80.
The study was conducted for the determination of the main nerves of the lumbosacral plexus in the helmeted guineafowl. Five helmeted guineafowls were used. Fowls were anaesthetised and the a. carotis communis was cut for blood drainage. Body cavities were revealed and were fixated with 10% formaldehyde. Nerves forming the lumbosacral plexus were dissected and photographed. Results were named according to the Nomina Anatomica Avium. It was determined that the lumbosacral plexus forms by 8 synsacral ventral rami from the ventrolateral side of synsacrum which include (2–9) synsacral spinal nerves. It was seen that the lumbar plexus was formed by the ventral rami of the 2nd, 3rd and 4th spinal nerves, and the sacral plexus was formed by the ventral rami of the 5th, 6th, 7th, 8th and 9th synsacral spinal nerves. It was observed that following nerves of n. pubicus (ilioinguinalis), r. cutaneous femoris lateralis, r. cutaneous femoris medialis (n. saphenus), n. femoralis and n. obturatorius originate from the lumbar plexus, and following nerves of n. ischiadicus, the common branch of n. fibularis and n. tibialis originate from the sacral plexus. It was determined that the n. ischiadicus was formed by the truncus cranialis, medianus and caudalis. In conclusion, it was determined that there are macro anatomical differences between different avian species in the quantity, thickness and distribution of the spinal nerves that form the lumbosacral plexus, and in formations of the plexus, and in separations of nerve branches. 相似文献