Selection experiments with salmon: IV. Growth of Atlantic salmon during two years in the sea     

Knut Gunnes  Trygve Gjedrem 《Aquaculture (Amsterdam, Netherlands)》1978,15(1):19-33

Brood stock of Atlantic salmon were sampled from 37 rivers or riversystems (strains) for three consecutive years. Each strain was represented by several full- and half-sib families. During the freshwater period each full-sib family was reared separately and each group was given as equal environmental conditions as possible. Fingerlings large enough to become 1-year-old smolt were freeze-branded and smolts from the different strains were sampled and transported to five salmon farms along the Norwegian coast. This paper deals with body weight and length of Atlantic salmon after a growth period of 2 years in the sea.Significant differences between strains were found for all three year classes. The interaction farm × strain was significant but accounted for only a small part of the total variation. It is concluded that genotype × environment interaction can be ignored when planning a selection programme for Altantic salmon for Norwegian farming conditions. A significant interaction sire × dam was found for the 1972 year-class, implying the presence of non-additive genetic variation. The heritabilities for body weight and length estimated from sire components (year-class 1973 and 1974) were quite high: 0.31 and 0.28, respectively. Genetic correlations between body weight and length were close to unity. The heritabilities for condition factor ($\text{K=}\text{weight in g}\text{(length in cm)}{}^3\text{·100}$ were small and none of the sire components were significant. It is concluded that the combination of weight and length used in calculating the K-factor has minor genetic basis.Genetic variation in body weight of Atlantic salmon is high, and about three times as high as for body length.  相似文献   

Monitoring fish stocks in relation to acidification in Norwegian watersheds     

T. Hesthagen  H. M. Berger  B. M. Larsen  R. Saksgård 《Water, air, and soil pollution》1995,85(2):641-646

The Norwegian Monitoring Programme for Long-Range Transported Air Pollutants started in 1980. The biological part of this programme includes besides invertebrate studies in streams, (i) fish community status in lakes by means of interviews, test-fishing in lakes by using standard gill-net series, recruitment studies of brown trout in inland streams, and juvenile stock assess and monitoring of fish kills in salmon rivers. Damaged fish stocks are recognized within a land area of 51,500 km² in southern Norway and 30 km² in northern Norway. At least 6,000 lake-dwelling fish stocks have either been lost or are at various stages of reduction. Brown trout (Salmo trutta) is the most widespread and abundant species of fish in Norwegian watersheds, and is also most severe affected by acidification. More recently, there are some indications of an increase in the abundance of brown trout in some areas. However, analysis of age structure in lakes, and fry densities in streams in such areas revealed large annual variations in recruitment rate, which indicates unstable water chemical conditions. Atlantic salmon (Salmo salar) is virtually extinct in 25 rivers in southernmost, southwestern and western Norway.  相似文献   

A simple in vitro test tube method for estimating the bioavailability of phosphorus in feed ingredients for swine     

Bollinger DW  Tsunoda A  Ledoux DR  Ellersieck MR  Veum TL 《Journal of agricultural and food chemistry》2004,52(7):1804-1809

A simplified in vitro test tube (TT) method was developed to estimate the percentage of available P in feed ingredients for swine. The entire digestion procedure with the TT method consists of three consecutive enzymatic digestions carried out in a 50-mL conical test tube: (1) Pre-digestion with endo-xylanase and beta-glucanase for 1 h, (2) peptic digestion for 2 h, and (3) pancreatic digestion for 2 or 4 h. The TT method is simpler and much easier to perform compared to the dialysis tubing (DT) method, because dialysis tubing is not used. Reducing sample size from 1.0 to 0.25 g for the TT method improved results. In conclusion, the accuracy and validity of the TT method is equal to that of our more complicated DT method (r = 0.97, P < 0.001), designed to mimic the digestive system of swine, for estimating the availability of P in plant-origin feed ingredients.  相似文献   

Repellency of insecticides and the effect of thiacloprid on bumble bee colony development in red clover (Trifolium pratense L.) seed crops     

Lars T. Havstad  John I. Øverland  Silja Valand  Trygve S. Aamlid 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2019,69(5):439-451

The study intended to compare repellency of three insecticides on bumble bees and honey bees in Norwegian red clover (Trifolium pratense L.) seed crops, and to examine effects of thiacloprid on bumble bee colony development in the field. The repellency study was carried out in a large-scale field trial in SE Norway in 2013. On average for observations during the first week after spraying, 17 and 40% less honey bees (P?=?.03) and 26 and 20% less bumble bees (P?=?.36) were observed on plots sprayed with the pyrethroids lambda-cyhalothrin and alpha-cypermethrin, respectively, than on unsprayed control plots. No pollinator repellency was found on plots sprayed with the neonicotinoid thiacloprid. Compared with unsprayed control the seed yield increases were 22% on plots sprayed with thiacloprid vs. 12–13% on plots sprayed with pyrethroids (P?=?.10). Follow-up studies in 2014–2016 focused on the effect of thiacloprid on bumble bee colony development in commercially reared nests of Bombus terrestris placed into red clover seed crops at the start of flowering. Unsprayed control crops were compared with crops sprayed either at the bud stage or when 18–44% of flower heads were in full bloom. Chemical analyses of adult bumble bees showed that thiacloprid was taken up in bees when crops were sprayed during flowering, but not detected when crops were sprayed at the bud stage. The bumble bees in late-sprayed crops also developed weaker colonies than in unsprayed crops. Dead bees with a high internal concentration of thiacloprid were found in one crop sprayed during the night at 35% flowering. This shows that thiacloprid is not bee-safe if sprayed after anthesis and that spraying has to be conducted at the bud stage to reduce its contamination of nectar and pollen.  相似文献   

Comparative life-history characteristics of native and hatchery-reared brown trout, Salmo trutta L., in a sub-Alpine reservoir     

T. Hesthagen  & L. Flòystad  O. Hegge  M. Staurnes  J. Skurdal 《Fisheries Management and Ecology》1999,6(1):47-61

Wild and non-native hatchery-reared brown trout, Salmo trutta L., released when 2 summers old, were caught in the littoral habitat of Vinstervatna Reservoir, southern Norway. Hatchery-reared brown trout grew more slowly and had a smaller asymptotic length (293 ± 71 mm CL) than native fish (391 ± 56 mm CL). Hatchery-reared brown trout also exhibited significantly shorter life spans than native fish. This category consisted mainly of individuals aged 2+ and 3+ years, and only 1.5% of the specimens were aged ≥5 years. The ages of the native fish in the sample were between 2 and 8 years, and the most abundant age groups of trout were 4+ and 5+ years. It is suggested that the differences in life-history characteristics are related to adaptations by the native trout to the local environmental conditions. In this reservoir, which has a limited food supply as a result of water level fluctuations and a high level of inter- and intraspecific competition, environmental effects might be significant.  相似文献   

Production of fish protein hydrolysates step by step: technological aspects,equipment used,major energy costs and methods of their minimizing     

Inna Petrova  Ignat Tolstorebrov  Trygve Magne Eikevik 《International Aquatic Research》2018,10(3):223-241

Nowadays, there is a growing interest on how to utilize fish materials remaining from the main production and considered as unappropriated for a direct human consumption. There are numbers of possible solutions to recover valuable nutrients from that matter and one of the most efficient is the production of fish protein hydrolysate. This article is devoted to overview existing information about the production of dried fish protein hydrolysates with a focus on dehydration process during production and equipment used for moisture removal. Drying step of the production is considered as the most energy demanding and, therefore, described in detail. Questions considering energy demands of the drying are highlighted in the article together with the proposals for the improvement of energy efficiency. This work also describes source of the raw material, the main steps of the technological scheme with the equipment used and valuable information on the intermediate state of fish protein hydrolysate between the process operations.  相似文献   

Yield and Quality of Mixed Seed Crops of Timothy ( Phleum pratense ) and Clovers ( Trifolium spp.) in an Organic Cropping System     

Trygve S. Aamlid 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):18-24

Seed production of timothy ( Phleum pratense L.) in mixed crops with alsike ( Trifolium hybridum L.), white ( T. repens L.) or red ( T. pratense L.) clover was evaluated in an organic cash crop system. No fertilizer was applied except for household compost in the sowing year. While the first year crops of the alsike clover/timothy and red clover/timothy leys were harvested for clover seed, the first year crop of the white clover/timothy ley and all second year crops were harvested for timothy seed. The botanical composition of the alsike clover/timothy crop averaged 89/11 in the first ley year, and 8/92 in the second year. The corresponding yields averaged 443 kg ha -1 clover seed and 849 kg ha -1 timothy seed, respectively. Second year seed yields of timothy from mixtures with red and white clover were, in turn, 7% higher and 44% lower than from the corresponding mixture with alsike clover. First year seed yields of alsike clover from the alsike clover/timothy combination, and first year yields of timothy from the timothy/white clover combination were mostly rejected because of insufficient purity. In contrast, first year seed yields of red clover from the red clover/ timothy combination, and second year yields of timothy from all combinations, never failed to met the international requirement of maximum 1% contamination of one particular species in certified seed.  相似文献   

Soil fertility in three cropping systems after conversion from conventional to organic farming     

Anne Kjersti Bakken  Tor Arvid Breland  Trond K. Haraldsen  Trygve S. Aamlid  Tore E. Sveistrup 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):81-90

Abstract

Temporal changes in the scores of selected soil fertility indices were studied over six years in three different cases of organic crop rotation located in southern, eastern and central Norway. The cropping history and the initial scores of fertility indices prior to conversion to organic cropping differed between the sites. Crop yields, regarded as an overall, integrating fertility indicator, were in all rotations highly variable with few consistent temporal trends following the first year after conversion. On the site in eastern Norway, where conversion followed several years of all-arable crop rotations, earthworm number and biomass and soil physical properties improved, whereas the system was apparently degrading with regard to P and K trade balances and contents in soil. On the other two sites, the picture was less clear. On the southern site, which had a relatively fertile soil before conversion, the contents of soil organic matter and K decreased during the six-year period, but the scores of other fertility indices showed no trends. On the site in central Norway, there were positive trends for earthworm-related indices such as worm biomass and tubular biopores, and negative trends for soil porosity. The results, especially those from the eastern site, illustrate the general difficulty in drawing conclusions about overall fertility or sustainability when partial indicators show divergent trends. Consequently, the study gave no unambiguous support to the initial working hypothesis that organic farming increases inherent overall soil fertility, but rather showed that the effect varied among indicators and depended on status of the cases at conversion. It is concluded that indicators are probably better used as tools to learn about and improve system components than as absolute measures of sustainability.  相似文献   

Osteochondrosis and Arthrosis in Pigs: VI. Relationship to Feed Level and Calcium,Phosphorus and Protein Levels in The Ration     

Trygve Grndalen 《Acta veterinaria Scandinavica》1974,15(2):147

Eight feeding experiments, each comprising 48 boars or gilts, were carried out. The factors feed level, Ca, P and protein levels were varied within practical physiological limits. The animals were slaughtered at close to 100 kg live weight. Lesions in joints and bones were of a noninfectious, non-rachitic nature and of the osteochondrosis and arthrosis type. Ten to 12 g Ca and approx. 10 g P/kg ration gave histomorphologically seemingly more optimum structure of the spongious bone tissue and a higher ash percentage in bones than 7 g Ca and 6 g P, or unbalanced mineral levels in the ration. However, there was no significant difference in degree or incidence of joint and bone lesions between mineral groups. Neither were there such differences present between feed level groups or protein level groups. This may for the feed level groups be partly due to the low feed level pigs having a longer period of time during which they were highly susceptible to the development of lesions. The low feed level animals had longer long bones at 100 kg live weight than the high feed level animals. The length of the vertebral column was, however, approximately similar in the 2 feed level groups. The angles of the condyles and head of the femur according to the length axis were influenced by feed level or growth rate, most probably by an effect on the endochondral ossification.  相似文献   

Utilization of durum wheat landraces in East Shewa,central Ethiopia: Are home uses an incentive for on-farm conservation?     

Bayush Tsegaye  Trygve Berg 《Agriculture and Human Values》2007,24(2):219-230

The study was conducted in East Shewa, central Ethiopia, where durum wheat landraces were once popular, but were displaced and re-introduced. Combinations of survey techniques are employed to document the different home uses of durum wheat landraces and to assess whether these serve as an incentive to on-farm conservation. The findings reveal that wheat landraces have multiple dietary and sociocultural uses that contribute to the maintenance of landraces on-farm. Temporal analysis of historical information showed that (1) richness in food traditions is associated with a high level of landrace diversity on-farm; (2) food traditions in East Shewa did not change radically as a result of the integration of farmers into the market economy; and (3) farm households still have an appreciation of, and a preference for, the home-use related qualities of the landraces, this despite their long term disappearance and the subsequent availability of several improved wheat varieties. The study illustrates the relationship between the local availability of landrace wheats and their on-farm survival. The home uses of landraces plays an instrumental role in the promotion of on-farm (in situ) conservation. Augmenting conservation activities with non-breeding approaches (e.g., awareness-creation) would support the survival of wheat landraces for the foreseeable future. Bayush Tsegaye (PhD) is a graduate from Noragric – the Department of International Environment and Development Studies, of the Norwegian University of Life Sciences. Prior to joining the University, she was engaged in various development programs in Ethiopia affiliated with government institutions as well as national and international non-governmental organizations. Her research interests include community management of plant genetic resources, food security, and gender issues. Trygve Berg is an Associate Professor at Noragric – the Department of International Environment and Development Studies, of the Norwegian University of Life Sciences. His research interests focus on the management of plant genetic resources and participatory plant breeding.  相似文献