Antimicrobial substances and chick growth promotion: The growth‐promoting activities of antimicrobial substances,including fifty‐two used either in therapy or as dietary additives     

J. Bunyan  L. Jeffries  Jessica R. Sayers  A. L. Gulliver  K. Coleman 《British poultry science》1977,18(3):283-294

1. Fifty‐five antimicrobial substances were tested for their ability to promote growth when added to the diet of chicks.

2. Both cephalosporins and all the nine penicillins tested were active.

3. Of six aminoglycosides, streptomycin and gentamicin had the greatest activity and neomycin had none.

4. Growth rate was significantly improved by clindamycin, lincomycin, vancomycin, spectinomycin, rifampicin, oxytetracycline, chlortetracycline, erythromycin, tylosin, flavomycin, virginiamycin and zinc bacitracin. Chloramphenicol and nalidixic acid were inactive. Polymixin B, novo‐biocin, cycloserine, phosphonomycin, and sodium fusidate had little activity. Fusidic acid promoted growth at 250 mg/kg diet.

5. Trimethoprim was inactive alone and in combination with sulpha‐diazine. Of seven 5‐nitroimidazoles, only dimetridazole and metronidazole showed slight activity. Of the six 5‐nitrofurans, only nitrovin, the standard reference substance used, promoted growth.

6. Caprylohydroxamic acid, a urease inhibitor, had no beneficial effect on growth rate or on the efficiency of food conversion.

7. The growth‐promoting properties of the various substances could not be related with their known antimicrobial and absorption characteristics in mammals.  相似文献   

Biochemical,physiological and production indices related to fat metabolism in the laying fowl at various stages of physiological development     

A. R. Neill  K. G. Reichmann  J. K. Connor 《British poultry science》1977,18(3):315-324

1. The significance of fat accumulation during physiological development of layers was studied using White Leghorn x Australorp pullets from 12 weeks of age.

2. Liver fat, carcass fat, liver weight and body weight increased markedly at the onset of sexual maturity.

3. Within the liver, the protein to DNA ratio did not alter significantly during development; glycogen was not consistently depleted by egg production.

4. Liver fat content was significantly correlated with carcass fat, liver weight and DNA concentration, and plasma total lipid and cholesterol, independent of stage of development; with body weight, liver protein, moisture, and protein to DNA ratio, excluding the period prior to commencement of sexual maturation; and with plasma phospholipid during lay.

5. Obesity was a feature of faster growing fowls which matured earlier, consumed more, utilised food less efficiently for egg production and produced fewer saleable eggs.  相似文献   

Ecology since colonial times     

Cook RE 《Science (New York, N.Y.)》1979,203(4379):429

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The dynamics of estuaries     

Cheng RT 《Science (New York, N.Y.)》1979,203(4377):260

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Mantle Geochemistry: Probing the Source of the Earth's Crust     

Kerr RA 《Science (New York, N.Y.)》1979,203(4380):530-532

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A figure in psychology     

Herrnstein RJ 《Science (New York, N.Y.)》1979,206(4421):921-922

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Surgeons observed     

Wilson RN 《Science (New York, N.Y.)》1979,206(4421):923-924

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Measurement of fluctuating magnetic gradients originating from oceanic internal waves     

Podney W  Sager R 《Science (New York, N.Y.)》1979,205(4413):1381-1382

Fluctuating magnetic gradients over oceans come from electric currents flowing in seawater arising from its motions across the earth's magnetic field. Gradients of 0.3 to 0.6 picoteslas per meter for each meter of internal wave displacement have been measured at frequencies of 2 to 5 millihertz with a superconductive magnetic gradiometer supported 7 meters above the surface of water 18 meters deep about 1.5 kilometers offshore from San Diego, California.  相似文献   

Vapor phase explosions: elementary detonations?     

Fowles GR 《Science (New York, N.Y.)》1979,204(4389):168-169

Although liquid-vapor explosions are widely observed, there is no established explanation for their initiation and propagation. Thermodynamics admits the possibility that superheated liquids can support detonations analogous to those that occur in chemical explosives. For liquid methane superheated 50 K above its boiling point at 1 atmosphere, the energy of explosion is 2 to 3 percent of that of TNT.  相似文献   

Marine life histories     

Scheltema RS 《Science (New York, N.Y.)》1979,205(4402):181-182

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