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41.
42.
Anders Jón Fjellheim Karina Jane Playfoot Jorunn Skjermo Olav Vadstein 《Aquaculture Research》2012,43(10):1499-1508
The diversity of the microbiota in 15 Atlantic cod (Gadus morhua L.) larvae from three different hatcheries with variable food type and water treatment was characterized with culture dependent and independent approaches. The culture‐dependent approach was phenotypic characterization of bacterial isolates based on 16 tests, and the culture‐independent approach was terminal restriction fragment length polymorphism (T‐RFLP) of PCR amplified 16S rRNA. Both approaches revealed large inter‐individual differences in the microbiota of cod larvae. Data from real time PCR indicate substantially lower variation in bacterial number larva?1 both within and between hatcheries than the data on colony forming units, resulting in an estimated four orders of magnitude variation in culturability between larvae. Considerably higher richness and diversity were observed with T‐RFLP than with phenotypic characterization, and no correlation between the two approaches was found for diversity indexes calculated at the individual level. Dissimilarity in the composition of the microbiota between individuals from the same rearing environment was comparable to the dissimilarities between hatcheries. The large inter‐individual variation is important to consider when designing experiments, as pooling of individuals will completely mask this variability. We conclude that colonization of individual cod larvae by bacteria seems to be a stochastic and not a deterministic process, which is not well understood. 相似文献
43.
Recent decline in cod stocks in the North Sea–Skagerrak–Kattegat shifts the sources of larval supply 下载免费PDF全文
Per R. Jonsson Hanna Corell Carl André Henrik Svedäng Per‐Olav Moksnes 《Fisheries Oceanography》2016,25(3):210-228
Cod stocks in the North Sea, including the Kattegat and the Skagerrak, have declined dramatically since the 1970s. Occasionally there is a high recruitment of juveniles in Kattegat/Skagerrak, without leading to the rebuilding of adult cod stocks despite reduced fishing mortality. In a biophysical model of egg and larval drift, we examined the potential importance of extant and historical spawning grounds for recruitment of cod in the Kattegat/Skagerrak seas using data of spawning stock biomass from the 1970s and from today's reduced stocks. The results suggest that Kattegat in the 1970s relied on largely locally retained (83%) larvae with little annual variation in recruitment. Kattegat also provided a substantial proportion of larvae recruiting in Swedish Skagerrak (72%). This is in contrast to present conditions where the Kattegat spawning stock has been reduced by 94%, and Kattegat only provides 34% of locally retained larvae and 30% to Swedish Skagerrak. Instead, the protected area in the Öresund and the Belt Sea are expected today to provide most larvae recruiting in Kattegat. Also, the inflow of larvae from the North Sea to Skagerrak and Kattegat can be significant although highly variable between years, with a positive correlation to the North‐Atlantic Oscillation index (NAO). The rebuilding of healthy spawning areas in the Kattegat may be key for restoring local cod stocks in both Kattegat and along the Skagerrak coast. This poses a management challenge if cod with local ‘Kattegat’ adaptations, e.g., in terms of egg density and migration patterns, are lost or reduced to non‐resilient densities. 相似文献
44.
Carolin Fischer Olav A. Høibø Geir I. Vestøl Marius Hauglin Endre H. Hansen Terje Gobakken 《Scandinavian Journal of Forest Research》2018,33(6):603-612
Norway spruce structural timber is one of the most important products of the Norwegian sawmilling industry, and a high grade-yield of structural timber is therefore important for the economic yield. Presorting of logs suited for production of structural timber might be one option to increase the grade yield. In this study, dynamic modulus of elasticity (Edyn) of structural timber was predicted based on forest inventory data at site level and single-tree data from airborne laser scanning (ALS) and harvester. The models were based on 611 boards from 4 sites in southeastern Norway. Important variables at site level were elevation, site index (SI), and mean stand age. However, when combining data from all information sources, mean stand age and site index were the only significant variables at site level. Tree height and variables describing the crown, like crown length and crown volume, were important vaiables extracted from ALS data. Stem diameter measures and tapering were important variables measured by the harvester. The combined model with variables from all three information sources reduced the variance the most, especially when using individual tree age instead of average stand age. However, combining all these data requires accurate positioning of the trees by the harvester. 相似文献
45.
Scots pine (Pinus sylvestris) sapwood was investigated for variation in treatability using the wood modifying agent, furfuryl alcohol (FA) in water. The
variation in treatability within trees, between trees and between different stands of Scots pine was studied. Investigated
variables that reduced the residual variance significantly were: site location, latitude of site, height of trees, annual
ring width, vertical and horizontal position in the tree and method of drying. Linear mixed model statistics were used and
tree number was handled as a random variable. The best model reduced the treatability residual variance by 67%. Location was
the single factor affecting treatability most. Differences in latitude between locations may be the reason for that. Latitude
correlated negatively with the treatability. Within the trees, the treatability of sapwood increased with distance from ground
and with distance from heartwood border. A small, but significantly better treatability was found for kiln dried wood (60°C)
compared to air dried wood (20°C). 相似文献
46.
Egil Simensen Olav ?ster?s Knut Egil B?e Camilla Kielland Lars Erik Ruud Geir N?ss 《Acta veterinaria Scandinavica》2010,52(1):14
Background
According to the Norwegian animal welfare regulations, it has been forbidden to build new tie-stall barns since the end of 2004. Previous studies have shown that cow performance and health differ between housing systems. The interaction between housing system and herd size with respect to performance and disease incidence has not been evaluated.Methods
Cow performance and health in 620 herds housed in free-stall barns were compared with in 192 herds housed in tie-stall barns based on a mail survey and data from the Norwegian Dairy Herd Recording and Cattle Health Systems. The housing systems herds were comparable with respect to herd size (15-55 cows). Associations between performance/disease incidence and housing system, herd size and year of building the cow barn were tested in general linear models, and values for fixed herd size of 20 and 50 cows were calculated. On the individual cow level mixed models were run to test the effect of among others housing system and herd size on test-day milk yield, and to evaluate lactation curves in different parities. All cows were of the Norwegian Red Breed.Results
Average milk production per cow-year was 134 kg lower in free-stall herd than in tie-stall herds, but in the range 27-45 cows there was no significant difference in yields between the herd categories. In herds with less than 27 cows there were increasingly lower yields in free-stalls, particularly in first parity, whereas the yields were increasingly higher in free-stalls with more than 45 cows.In free-stalls fertility was better, calving interval shorter, and the incidence rate of teat injuries, ketosis, indigestions, anoestrus and cystic ovaries was lower than in tie-stalls. All of these factors were more favourable in estimated 50-cow herds as compared to 20-cow herds. In the larger herd category, bulk milk somatic cell counts were higher, and the incidence rate of mastitis (all cases) and all diseases was lower.Conclusion
This study has shown that there is an interaction between housing system and herd size, and that performance and health is not universally better in small free-stalls than in tie-stalls. 相似文献47.
Adam D Martin Marit L Lystad Olav Reksen Erik Ropstad Andres Waldmann Ola Nafstad Knut Karlberg 《Acta veterinaria Scandinavica》2010,52(1):42
Background
Reproduction is the single greatest factor limiting beef cattle production. Previous research on beef suckler luteal activity has largely focused on the mechanisms, and duration, of postpartum anoestrus. However, the temporal pattern of luteal activity after resumption of post-partum ovarian activity, and the impact of pattern type on days open (DO) in purebred beef suckler cows, are unknown.Methods
Progesterone concentration was measured in milk samples taken thrice weekly from 120 lactations, in 87 animals, on 3 farms, over two years. Onset of luteal activity (OLA) was defined as the first day milk progesterone concentration exceeded 3 ng/ml for two successive measurements, or exceeded 5 ng/ml once. It was defined as delayed if it occurred more than 61 days postpartum. A short initial luteal phase consisted of progesterone concentrations which exceeded 3 ng/ml for fewer than 4 sequential measurements. Temporal progesterone patterns were classified as: 1) Normal cyclicity; 2) Cessation of luteal activity; 3) Prolonged luteal activity; 4) Erratic phase: failure to conform to 1, 2 or 3. Data concerning parity, previous calving interval, breeding values, calf birth and 200-d weight were obtained from the Norwegian Beef Cattle Recording System database.Results
The mean (SD) OLA was 41 d (20). Parity and calf birth weight were inversely correlated with OLA. Delayed OLA occurred in 14.4% of lactations. A short first luteal phase occurred in 61.5% of lactations, but this was unrelated to irregular luteal phase occurrence, pregnancy or DO. Irregular luteal phases occurred in 22% of lactations. The irregularities were: prolonged luteal phase (11%); cessation of luteal activity (5%); erratic luteal activity (6%). Early OLA was associated with prolonged luteal phases. DO was positively correlated with irregular luteal phases and negatively correlated with calf 200-d weight.Conclusions
This study demonstrates that irregular luteal phases negatively affect reproductive performance in purebred beef suckler cattle. A moderate incidence of irregular luteal phases was seen in the study population. Whilst a positive relationship was seen between OLA and DO, unfavourable associations between early OLA and incidence of irregular luteal phases should be considered when developing breeding programmes. 相似文献48.
Jelly S. Chang’a Robinson H. Mdegela Ruth Ryoba Torleiv Løken Olav Reksen 《Tropical animal health and production》2010,42(8):1669-1676
Smallholder farmers’ knowledge and practice of dairy calf management on 129 farms with calves less than 10 months of age in
Southeastern and Southern Highland areas of Tanzania was assessed. The method of study included both a farm visit and completion
of a questionnaire. Most of the farmers were female, with a primary level of education, and majority kept 1–3 milking cows
that yielded 6–10 l milk/cow/day. Most of the calves were fed milk using a residual calf suckling system. Weaning age was
3–8 months. Overall, the body condition of the calves was poor, ranged from 1 to 2.5 with a mode of 2. The majority of the
farmers believed that helminthosis was the most common disease condition affecting the calves; diarrhea was ranked as the
second. Calf death was reported by 20% of the farmers to have occurred in their herd lasting the 2 years prior to the study.
Calf body condition score was related to body weight for calves younger than 9 weeks, and older than 23 weeks of age, whereas
no such relationship existed in the age group 9 to 23 weeks. The sex distribution was skewed with less male calves being older
than 23 weeks. We hypothesize that male calves experience inferior management compared with female calves. This study demonstrates
a low level of knowledge on, and poor practices of calf management among the surveyed farmers that suggest the need for educational
intervention. 相似文献
49.
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
50.
Erik Vikingstad Eva Andersson Tom Johnny Hansen Birgitta Norberg Ian Mayer Sigurd Olav Stefansson Per Gunnar Fjelldal Geir Lasse Taranger 《Fish physiology and biochemistry》2016,42(3):895-907
Maturing male and female Atlantic salmon (Salmo salar L.) were held under three temperature regimes for 10 weeks between September and December: warm (constant 14–16 °C), ambient (decreasing from 11 to 5 °C), and cold (decreasing from 7 to 3 °C). Blood samples were analyzed for plasma steroid levels, and the fish were inspected for the presence of expressible milt (total volume and spermatocrit) and ovulation weekly. Samples of eggs were dry-fertilized with milt stripped from three males held at the same temperatures and incubated until the eyed stage. In females, levels of plasma testosterone (T) and 17β-oestradiol (E2) dropped as ovulation approached, concurrent with a rapid increase in levels of plasma 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P). In males, levels of T and 11-ketotestosterone (11-KT) peaked 2–3 weeks after the first appearance of expressible milt, while levels of 17,20β-P increased steadily and did not exhibit a definite peak. Exposure of females to cold water amplified and advanced the profiles of all three steroids compared with the ambient group, and increased the survival rates to the eyed egg stage. Cold water had no immediate effect on the male steroid profiles, but later, higher levels of 17,20β-P were evident compared with both the ambient controls and the warm water group, while the effects on 11-KT and T were more variable. Exposure to warm water completely inhibited both milt production and ovulation. Moreover, warm water modulated the steroid profiles of the males with lower 11-KT levels compared with ambient controls and lower 17,20β-P level compared with cold-water-treated males. In females, warm water resulted in total inhibition of the peri-ovulatory peak in 17,20β-P and prevented the normal decline of T and E2 levels associated with ovulation. The findings of the present study are highly relevant for broodstock management in aquaculture, as well in understanding the impact of climate change/temperature variability on wild salmon spawning. 相似文献