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Marine‐derived fish meal (FM) is a traditional component of commercial aquaculture feeds for many farmed fish species. Modern bioprocessing technologies have been developed to produce high‐protein plant‐based ingredients for aquafeeds to further reduce FM and other conventional animal protein sources. A 90‐day feeding trial using juvenile rainbow trout (Oncorhynchus mykiss) (27.9 ± 1.4 g; mean ± SE) was completed to evaluate growth, feed efficiency, general health and immunological responses to diets containing experimental plant‐based protein sources and reduced FM. Trout were fed one of four dietary treatments: experimental bioprocessed soy protein concentrate (BSPC), commercially available enzymatically hydrolysed soy protein concentrate (CSPC), experimental bioprocessed barley protein concentrate (BBPC) and a FM control (FMC). At trial termination, there were no significant differences in relative growth (RG) or specific growth rate (SGR) between fish fed either FMC or BSPC (p > .05). Fish fed either CSPC or BBPC resulted in significantly lower RG and SGR than the FMC (p < .05). Significant respiratory burst analysis differences were observed among treatments at day 90 (p < .01), for fish fed either FMC or CSPC diets. This assessment of bioprocessed plant‐based protein ingredients facilitates the characterization and incorporation of bioprocessed soy and barley protein as the industry continues to evaluate FM replacements in rainbow trout feeds.  相似文献   
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3预防沙门氏菌传播的措施 3.1卫生和消毒 在引进新一批鸡群前,所有鸡舍和器具必须进行清洁消毒,特别是在前一批鸡群为沙门氏菌阳性的情况下,清洁消毒就更有必要.卫生措施的有效性可通过严格的细菌学定量检测验证,要求肠道细菌计数小于103个/25 m2.  相似文献   
3.
A risk programming method that evaluates production plans based on expected income and risk was demonstrated using representative data from Panama. Results illustrate the usefulness of the program in presenting production choices to decision makers and evaluating those choices under changing conditions.
Less experienced or less financially secure farmers may select farm plans that differ quite importantly from those chosen by more experienced or more financially secure farmers. If farm survival is in doubt, more conservative farm plans will generally be adopted. Without consideration of the potential losses, it will often appear that all farmers should pursue the most intensive farm plan within their farming capabilities. However, many farmers will employ less intensive management strategies if the potential for losses associated with more intensive strategies is perceived to be excessive.
The model indicated that management strategies were sensitive to changes in shrimp price and feed cost, but less sensitive to the costs of post larvae or energy. Also, shrimp farm managers should give serious consideration to not producing in the dry season due to relatively high risk and low expected returns. Farmers should be most concerned with quality and availability of post larvae, not price. If hatcheries can address these concerns, the higher price of hatchery post larvae will be justified.  相似文献   
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A survey of 451 Countryside Stewardship Scheme (CSS) agreements was carried out across England in 1998-1999 to characterise the ecological quality of the land. The land within the agreements was mapped using the UK Biodiversity Action Plan Broad and Priority Habitats and the vegetation of the agreements was sampled using random quadrats. By far the most widespread Broad Habitat was Improved Grassland, accounting for around 50% of all agreement land. Of this, the majority was semi-improved. Priority Habitats accounted for 15% of all agreement land (equivalent to around 18,500 ha). In addition to the 15%, there was also land within habitat mosaics containing one or more Priority Habitat. The analysis of vegetation revealed that 53% of all randomly-placed quadrats were categorised as Infertile Grassland and 24% as Fertile Grassland. Survey data were compared with results from the Countryside Survey 2000, a national assessment of vegetation undertaken in 1998. In the lowland areas of England, CSS land had a much higher proportion of grassland habitats and was much more likely to be typical of low fertility situations than the countryside as a whole. In the marginal uplands and uplands, CSS agreement land contained a greater proportion of grassland, but with a reduced proportion of important upland Broad Habitats, such as Dwarf Shrub Heath and Bog, although these do tend to be found more in the Environmentally Sensitive Areas. The differences between the CSS and the countryside as a whole clearly reflect the priorities of the CSS, especially the high proportion of grassland. The CSS has targeted Broad and Priority Habitats and in this respect has been successful.  相似文献   
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