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ABSTRACT: The depletion of ascorbic acid derivatives in fish feed during the feed processing (extrusion cooking and drying) was studied at five extrusion cooking temperatures and at 85°C for 2 h dryer processing temperature. Three ascorbic acid derivatives were used: L-ascorbyl-2-mono-phosphate Mg (APM), L-ascorbic acid sodium (AAS) and L-ascorbic acid palmitic acid ester (AAP). Samples were collected after drying and ascorbic acid derivatives losses evaluated. APM was found to be quiet stable with an average retention of 88%, but AAS and AAP were unstable and the depletion was very high. 相似文献
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ABSTRACT: The microstructure of extruded pellets (EP) for fish under various extrusion cooking temperatures was studied by using a twin-shaft extruder. As the extrusion cooking temperature increased, the expansion rate increased and the bulk density of EP decreased. The liquefaction of the material started because of the increase in inner material temperature, the decrease in inner material pressure, and the decrease in main motor amperage. Thus, the microstructure of EP changed depending on the extrusion cooking conditions, that is, the extrusion cooking temperature effected greatly the liquefaction of the material. Generally, when the extrusion cooking temperature increased, the expansion rate increased, but a suitable temperature was found for a maximum expansion rate. The microstructure of the EP was caused by the liquefaction of the material and the microstructure effects on the function of EP. For example, the water holding capacity was affected by the inner bubble structure of an EP. These functions affect the character of the feed. EP produced under suitable conditions can have additional functions for feed. 相似文献
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NAOTAKA OMOTO MAMORU MAEBAYASHI ERI MITSUHASHI KOJI YOSHITOMI SHINJI ADACHI KOHEI YAMAUCHI 《Fisheries Science》2002,68(5):1047-1054
The effects of giving oral estradiol-17β (E2 ) and 17α-methyltestosterone (MT) on gonadal sex differentiation in the F2 hybrid sturgeon, the bester ( Huso huso female × Acipenser ruthenus male), are investigated. Giving E2 at 10 μg/g diet to fish from 14 months until 31 months of age induced incomplete feminization and resulted in approximately 40% abnormal ovary development in which oocytes were observed without ovarian lamellar structures and gonadal shape was similar to normal testis. Giving MT at 25 μg/g diet for the same duration failed to induce masculinization, and resulted in approximately 30% undeveloped gonads even at 30–37 months of age. In contrast, E2 and MT at only 1 μg/g diet given from 3 to 18 months of age was sufficient to induce feminization and masculinization, respectively. In these fish, feminization and masculinization were observed at 9 months, when most putative ovaries and testes were histologically distinguishable by the shape of the gonadal surface. These results indicate that sex reversal can be induced in these fish by hormone treatment that is started at 3 months age, before morphological differentiation occurs on the stroma of the gonads. 相似文献
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