Mechanics of standing in birds: Functional explanation of lameness problems in giant Turkeys     

A. Abourachid 《British poultry science》1993,34(5):887-898

1. The parameters used for the mechanics of standing in birds are defined and compared for two strains of turkeys, a giant, broad‐breasted strain (up to 40 kg), the result of artificial selection, and a traditional, smaller bird (9 kg), in order to show whether the mechanics of standing are modified by selection.

2. Using a geometrical similarity hypothesis, it was found that, although the locomotor apparatus of both strains are similar, the stresses on the pelvic muscles of broad‐breasted turkeys are increased. This is induced by the anterior position of the centres of gravity of their trunks, the result of selected pectoral hypertrophy.

3. The modification to the mechanics of standing may be related to the increase in locomotor disease in strains of giant turkeys.  相似文献   

Food intake adjustments of chicks: Short term reactions of genetic stocks to deficiencies in lysine,methionine or tryptophan     

D. O. Noble  M. L. Picard  E. A. Dunnington  G. Uzu  A. S. Larsen  P. B. Siegel 《British poultry science》1993,34(4):725-735

1. Growth, food intake, and food preference were measured in two experimental lines (White Rocks and White Leghorns) of chickens fed diets varying in content of lysine, methionine, or tryptophan. Diet A was balanced in all amino acids, while the remaining 6 diets were moderately ( ～ 30%) or slightly ( ～ 15%) deficient in either lysine, methionine, or tryptophan relative to NRC recommendations for broiler diets.

2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks.

3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks.

4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet.

5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid.  相似文献   

Response     

Kamb A 《Science (New York, N.Y.)》1995,267(5194):16

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Electrochemical detection of single molecules     

Fan FR  Bard AJ 《Science (New York, N.Y.)》1995,267(5199):871-874

The electrochemical behavior of a single molecule can be observed by trapping a small volume of a dilute solution of the electroactive species between an ultramicroelectrode tip with a diameter of approximately 15 nanometers and a conductive substrate. A scanning electrochemical microscope was used to adjust the tip-substrate distance ( approximately 10 nanometers), and the oxidation of [(trimethylammonio)methyl] ferrocene (Cp(2)FeTMA(+)) to Cp(2)FeTMA(2+) was carried out. The response was stochastic, and anodic current peaks were observed as the molecule moved into and out of the electrode-substrate gap. Similar experiments were performed with a solution containing two redox species, ferrocene carboxylate (Cp(2)FeCOO(-)) and Os(bpy)(3)(2+) (bpy is 2,2'-bipyridyl).  相似文献   

Report backs science, chides politicians     

Lawler A 《Science (New York, N.Y.)》1995,269(5231):1665

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Listen Up! The World's Oceans May Be Starting to Warm     

Regalado A 《Science (New York, N.Y.)》1995,268(5216):1436-1437

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Agency chiefs seek help with budgets     

Lawler A 《Science (New York, N.Y.)》1995,267(5195):165

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Italian academic life     

Gavezzotti A 《Science (New York, N.Y.)》1995,267(5200):949

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Self-Assembled Metal Colloid Monolayers: An Approach to SERS Substrates     

Freeman RG  Grabar KC  Allison KJ  Bright RM  Davis JA  Guthrie AP  Hommer MB  Jackson MA  Smith PC  Walter DG  Natan MJ 《Science (New York, N.Y.)》1995,267(5204):1629-1632

The self-assembly of monodisperse gold and silver colloid particles into monolayers on polymer-coated substrates yields macroscopic surfaces that are highly active for surface-enhanced Raman scattering (SERS). Particles are bound to the substrate through multiple bonds between the colloidal metal and functional groups on the polymer such as cyanide (CN), amine (NH(2)), and thiol (SH). Surface evolution, which can be followed in real time by ultraviolet-visible spectroscopy and SERS, can be controlled to yield high reproducibility on both the nanometer and the centimeter scales. On conducting substrates, colloid monolayers are electrochemically addressable and behave like a collection of closely spaced microelectrodes. These favorable properties and the ease of monolayer construction suggest a widespread use for metal colloid-based substrates.  相似文献   

Through the glass lightly     

Bard AJ 《Science (New York, N.Y.)》1995,267(5204):1618-1618

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