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排序方式: 共有107条查询结果,搜索用时 15 毫秒
41.
The effect of daily oral doses of 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3) on plasma mineral concentrations and incidence of milk fever was tested in 39 aged cows. Three dose levels of 1,25-(OH)2D3 (0, 100 and 200 µg/d) were compared in cows supplemented with 100 g Ca/d (250 g CaCO3) and in cows receiving no Ca supplement. 1,25-(OH)2D3 treatments were given from day 5 before expected calving (day –5) until the day after calving (Calving = day 0).Expected minima in Ca concentrations in plasma were seen on day 1 in placebo treated cows, while Ca concentrations in 1,25-(OH)2D3 treated cows were normal or increased in the period from start of treatment until day 3–5. In the parturient period (day –1 to +2) 1 of 21 treated cows developed milk fever, as compared to 4 of 18 untreated. A pronounced hypocalcaemia developed, however, in the 1,25-(OH)2D3 treated cows from day 3 to 5 onwards, culminating day 8–11 with 7 cases of milk fever. Ca supplements reduced the development of hypocalcaemia in the 1,25-(OH)2D3 treated cows, but could not completely prevent the occurrence of milk fever. 相似文献
42.
43.
Frode Guul-Simonsen Preben Stordal Christiansen Dan Edelsten Jørgen Ryhmer Kristiansen Niels Peder Madsen Egil Waagner Nielsen 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(2):105-110
Abstract Full-scale experiments with cooling of raw milk of good initial quality from a herd of 70 dairy cows have been performed under practical farm conditions, with different cooling and storage conditions, including instant cooling in a continuous process versus normal cooling in a batch process. During each milking, the milk was divided equally and successively for different cooling procedures. Quality evaluations (number of bacteria, acidity and oxidation of fat, sensoric quality) indicated that instant cooling/continuous process compared with normal cooling/batch process over 2.5 hours, both to 4°C, resulted in a slightly slower bacterial growth and a slightly slower hydrolysis and oxidation of milk fat. Instant raw milk cooled and stored at 2.5°C maintained a good quality for about one to two days more than when normal cooling over 1.5 hours and storing at 4°C was used. 相似文献
44.
Trond Bjørndal Kristin Aarland 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):238-253
Abstract Commercial salmon and trout farming has emerged as a major industry in Chile during the last two decades. Salmon is not a native species to Chile; however, excellent climatic conditions are provided for farming activities in the southern part of the country. After negligible production volumes during the early years, the harvest levels accelerated in the late 1980s, and since 1992 Chile has been the second largest producer of farmed salmon and trout in the world after Norway. This report reviews the development of the Chilean salmonid industry from its early stages until today with respect to production patterns, legislation and main markets. A cost comparison between Chilean and Norwegian farmed salmon is also provided. Finally, the international competitiveness and future challenges of the Chilean salmonid farming industry are analysed. 相似文献
45.
Andrew S. King Nicholas G. Elliott Mark A. James Catriona K. MacLeod Trond Bjorndal 《Aquaculture Economics & Management (Blackwell Science)》2013,17(4):383-409
ABSTRACTDeveloping an understanding of economic variance (risk) is critical when evaluating alternative aquaculture production technologies. This article assesses the efficacy of employing a quantitative stochastic analysis technique to support technology selection decision making by undertaking a case study investment assessment of three alternative production expansion strategies (offshore sea-pens, land-based RAS growout and larger post-smolt) for the Tasmanian salmon industry. Results demonstrate that salmon aquaculture is undertaken with considerable underlying levels of economic risk, expansion offshore probably represents the lowest initial capital investment and greatest economic return, and that levels of financial uncertainty increase with land-based RAS production. The study highlights stochastic modeling provides significant “added-value” over single-point deterministic analysis and that developing an appreciation of the input variability is a key component in critically evaluating alternative production technologies. 相似文献
46.
Trond Bjørndal Albert Imsland 《Aquaculture Economics & Management (Blackwell Science)》2016,20(1):109-129
Sole is a high-value flatfish species that is highly favored in many European markets. Nowadays most sole comes from capture fisheries; however, wild supply has been decreasing because of decreasing catches due to stocks overexploitation. Due to its high price and declining landings, as well as a desire by farmers to diversify their operations, there has been an expansion in sole aquaculture production in recent years and there are ambitious plans for further growth. In this paper we assess the potential for sole aquaculture in Europe using raceways. This is done by analyzing the production costs of sole farms and the price evolution in European sole markets. 相似文献
47.
Susanne Eich-Greatorex Vivekanand Vivekanand Maria M. Estevez Anna Schnürer Trond Børresen Trine A. Sogn 《Archives of Agronomy and Soil Science》2018,64(3):347-359
With advances in biogas technology, lignocellulosic material may be increasingly included in feedstock due to the abundance of raw materials. The main goal of this study was to evaluate fertilizing and soil amendment effects of digestates based on lignin-rich feedstock. The digestates originated from reactors fed with manure co-digested with Salix, wheat straw or sugarcane bagasse, respectively. In pot experiments with three different soils, Italian ryegrass and reed canary grass were grown with 120 kg ha?1 total nitrogen or 150 kg ha?1 available nitrogen, respectively, given as either mineral fertilizer or digestate. Soil chemical and physical characteristics were determined after ended experiments. Additionally, an incubation study was carried out to estimate N mineralization from one digestate over time. Digestate addition resulted in similar yields compared to mineral fertilizer, varying from 0.5 (loam) to 1 kg dry matter m?2 (silt) for Italian ryegrass and 1.2 (loam) to 2.3 kg m?2 (silt) for reed canary grass. Digestates contributed to a favourable pH for plant growth, reduced bulk density in the loam and improved water retention characteristics in the sand. Biogas digestates based on lignin-rich feedstock appear promising as fertilizers and for soil amelioration but results have to be verified in field experiments. 相似文献
48.
Hanne Hjorth Tønnesen Ivar Mysterud Jan Karlsen Olav M. Skulberg Carl M. M. Laane Trond Schumacher 《Veterinary research communications》2010,34(4):347-357
Alveld is a disease in lambs of domestic sheep (Ovis aries L.), characterized by a combination of photosensitivity and liver damage. Generation of singlet oxygen play a major role
in phototoxicity reactions. The compound phylloerythrin (phytoporphyrin) is so far assumed to be the main photodynamic agent
in hepatogenous photosensitivity diseases in sheep. Phylloerythrin is a potent photosensitizer and an efficient source of
singlet oxygen. The compound accumulates in the peripheral circualtion upon liver damage. Liver dysfunction is also likely
to cause an increase in the blood level of bilirubin. Formation of singlet oxygen by bilirubin is reported. In the present
work the photosensitizing potential of serum has been measured and related to the bilirubin- and phylloerythrin levels in
lambs suffering from alveld and in clinically healthy controls. The singlet oxygen level of the serum was taken as a measure
of the photosensitizing potential. The observed singlet oxygen values in serum from alveld lambs were significantly higher
than the corresponding values observed in clinically healthy control lambs. This indicates that the serum of the alveld lambs
contains an elevated concentration of photosensitizer. The singlet oxygen level was not correlated to the concentration of
bilirubin or phylloerythrin. The results indicate that the photosensitizing mechanism is quite complex and may involve other
sensitizer(s) than phylloerythrin. 相似文献
49.
A. Datta B. M. Sindel P. Kristiansen R. S. Jessop & W. L. Felton 《Journal of Agronomy and Crop Science》2009,195(3):178-185
Isoxaflutole at 75 g ai ha?1 is registered in Australia for the control of several broadleaf weeds in chickpea (Cicer arietinum L.). Although isoxaflutole provides satisfactory control of problematic weeds, under certain conditions crop injury can occur. Higher air temperature and moisture content of soil are reported to affect the metabolism of soil applied herbicide. Controlled environment experiments were used to determine the tolerance of chickpea to isoxaflutole under a range of temperature and soil moisture levels. For the soil moisture study, the variables examined were two desi chickpea genotypes (Kyabra as a tolerant cultivar and Yorker as a sensitive cultivar), three soil moisture levels [50 % field capacity (FC), 75 % FC and FC] with three herbicide rates [0, 75 (recommended rate) and 300 g ai ha?1]. For the temperature by soil moisture study, the variables examined were two other desi chickpea genotypes (97039‐1275 as a tolerant line and 91025‐3021 as a sensitive line), three temperature regimes (20/5, 30/15 and 35/25 °C), two soil moisture conditions (50 % FC and FC) with the same three herbicide rates. The results demonstrated that the chickpea genotypes exhibited differential tolerance to isoxaflutole, but that differences in response were affected by rate, temperature and soil moisture. Increasing temperature and soil moisture content made the susceptible chickpea genotype more vulnerable to isoxaflutole damage. Injury to the susceptible genotype in terms of increased leaf chlorosis and reduction in shoot height and dry matter production increased as soil moisture increased from 50 % FC to FC and temperature increased from 20/5 to 35/25 °C. Overall damage of the sensitive genotype from increasing rates of isoxaflutole also increased when soil moisture content increased from 50 % FC to FC within the fixed temperature regime of 30/15 °C. The sensitivity of chickpea to isoxaflutole depends on existing temperature and moisture content and the chances of crop damage were enhanced with increasing temperature and moisture levels. 相似文献
50.
Y. Bajgai N. Hulugalle P. Kristiansen M. McHenry A. Cowie 《Soil Use and Management》2014,30(3):328-336
Annual horticultural systems rely on frequent and intensive tillage to prepare beds, manage weeds and control insects. But this practice reduces soil organic carbon (SOC) through accelerated CO2 emission. Crop residue incorporation could counteract this loss. We investigated whether vegetable systems could be made more resilient by including a high‐residue grain crop such as sweet corn (Zea mays L. var. rugosa), in the rotation through the use of conventional (no residue, no soil sieving) and organic (residue incorporated and soil sieved) soil management scenarios. We evaluated short‐term emission of CO2‐C and soil C content in incubated Chromosol and Vertosol soils (Australian Classification) with and without sieving (simulated tillage) or the incorporation of ground sweet corn residue. Residue treatment emitted 2.3 times more CO2‐C compared to the no‐residue treatment, and furthermore, sieved soil emitted 1.5 times more CO2‐C than the unsieved across the two soil types. The residue incorporation had a greater effect on CO2‐C flux than simulated tillage, suggesting that C availability and form can be more important than physical disturbance in cropping soils. The organic scenario (with residue and sieved) emitted more CO2‐C, but had 13% more SOC compared with the conventional scenario (without residue and unsieved), indicating that organic systems may retain more SOC than a conventional system. The SOC lost by soil disturbance was more than offset by the incorporation of residue in the laboratory conditions. Therefore, the possible SOC loss by tillage for weed control under organic management may be offset by organic residue input. 相似文献