Cyclic variation in cattle feed intake data: characterization and implications for experimental design

Feed intake data were collected every 6 h in a 140-d feeding trial involving two pens of 15 bull calves, each using one Pinpointer single-animal feeding stall per pen. Spectral analysis of these data revealed strong cyclic patterns of feed intake. These patterns were unique to each animal and consisted of two or more cycle lengths, some up to 28 d, for each animal. Feed intake behavior is an important factor in many forms of animal experimentation. Animal researchers frequently use row-column designs, where columns represent animals and rows represent periods. Latin squares and crossover designs are common examples. Standard analysis of variance procedures are appropriate for these experiments only if certain assumptions are met; one is that if cyclic variation is present, it is identical for all animals, i.e., there is no row X column interaction. If this assumption is not satisfied, standard analysis of variance procedures will result in upward bias of the mean square error and may result in serious distortion of treatment effect estimates. This occurred using the data from the feeding trial reported in this paper. Time-series analysis of covariance greatly improved the accuracy and efficiency of estimates of treatment effects. Consideration of variations in cyclic behavior should be part of the design process in experiments using feed intake data. Guidelines for the design of experiments to take advantage of time-series methodology are given.     

A haptoglobin-hemoglobin receptor conveys innate immunity to Trypanosoma brucei in humans

The protozoan parasite Trypanosoma brucei is lysed by apolipoprotein L-I, a component of human high-density lipoprotein (HDL) particles that are also characterized by the presence of haptoglobin-related protein. We report that this process is mediated by a parasite glycoprotein receptor, which binds the haptoglobin-hemoglobin complex with high affinity for the uptake and incorporation of heme into intracellular hemoproteins. In mice, this receptor was required for optimal parasite growth and the resistance of parasites to the oxidative burst by host macrophages. In humans, the trypanosome receptor also recognized the complex between hemoglobin and haptoglobin-related protein, which explains its ability to capture trypanolytic HDLs. Thus, in humans the presence of haptoglobin-related protein has diverted the function of the trypanosome haptoglobin-hemoglobin receptor to elicit innate host immunity against the parasite.     

Unitary control in quantum ensembles: maximizing signal intensity in coherent spectroscopy

Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.     

Growth characteristics of the endangered thick‐shelled river mussel (Unio crassus) near the northern limit of its natural range

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The effect of cell density on biomass and fatty acid productivity during cultivation of Rhodomonas salina in a tubular photobioreactor

The microalga Rhodomonas salina is widely used in aquaculture. There is a need for optimization of the growth of the microalgae and its content of essential fatty acids. Here, the fatty acid profile of Rhodomonas in relation to cell density during cultivation in a tubular PBR is investigated. It is expected that cell density is an important factor in controlling productivity and fatty acid content of the microalgae because cell density is important in determining light availability due to the self‐shading of the algae. The carbon productivity as a function of cell density is described by a saturation curve. The carbon productivity and the productivity of total fatty acids are lowest at the lowest cell density, and independent of cell density at higher cell densities. The relative contribution of the two poly‐unsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increases with increasing cell density and saturates at 1 × 10⁶ cells/ml. We conclude that large‐scale production of Rhodomonas in this tubular PBR should take place at cell densities of 1 × 10⁶ cells/ml, while there are indications for increasing difficulties in maintaining steady‐state production in this PBR at higher cell densities.     

A cost‐effectiveness analysis of live feeds in juvenile turbot Scophthalmus maximus (Linnaeus, 1758) farming: copepods versus Artemia

The biological benefits of copepods as live feed for marine finfish larvae have already been well established in the literature. Copepods have better biochemical compositions that improve growth, reduce malpigmentations and allow successful farming of ‘new’ marine finfish species. However, their current usage is quite limited. One of the reasons has been lack of economic knowledge concerning the cost‐effectiveness of copepod application compared to other commonly used feed items such as the brine shrimp Artemia. In this study, a cost‐effectiveness analysis is made on two alternative live feed items (copepods and Artemia) in juvenile turbot farming. Unit cost of production and profit are compared between the two feeding regimes using a unique data set from an existing turbot fry production facility in Denmark. The result reveals that copepods are not only biochemically superior but they are also economically a cost‐effective alternative. Thus, a commercial use of copepods will significantly reduce the production costs for turbot. Furthermore, the unexploited economic potential can be utilized for the successful farming of other high‐valued marine finfish species such as tuna, flounders, cod, sole and halibut. Generally, the biochemical superiority coupled with economic benefits can lead to the commercial utilization of copepods as complementary live feed in the short run and in some situations as a substitute in the long run.     

Morphological diversity of Paramoeba perurans trophozoites and their interaction with Atlantic salmon,Salmo salar L., gills

Amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans affects several cultured marine fish species worldwide. In this study, the morphology and ultrastructure of P. perurans in vitro and in vivo was investigated using scanning and transmission electron microscopy (SEM and TEM, respectively). Amoebae cultures contained several different morphologies ranging from a distinct rounded cell structure and polymorphic cells with pseudopodia of different lengths and shapes. SEM studies of the gills of AGD‐affected Atlantic salmon, Salmo salar L., revealed the presence of enlarged swellings in affected gill filaments and fusion of adjacent lamellae. Spherical amoebae appeared to embed within the epithelium, and subsequently leave hemispherical indentations with visible fenestrations in the basolateral surface following their departure. These fenestrated structures corresponded to the presence of pseudopodia which could be seen by TEM to penetrate into the epithelium. The membrane–membrane interface contained an amorphous and slightly fibrous matrix. This suggests the existence of cellular glycocalyces and a role for extracellular products in mediating pathological changes in amoebic gill disease.     

Viral co‐infections in farmed Atlantic salmon,Salmo salar L., displaying myocarditis

Several different viruses have been associated with myocarditis‐related diseases in the Atlantic salmon aquaculture industry. In this study, we investigated the presence of PMCV, SAV, PRV and the recently identified Atlantic salmon calicivirus (ASCV), alone and as co‐infections in farmed Atlantic salmon displaying myocarditis. The analyses were performed at the individual level and comprised qPCR and histopathological examination of 397 salmon from 25 farms along the Norwegian coast. The samples were collected in 2009 and 2010, 5–22 months post‐sea transfer. The study documented multiple causes of myocarditis and revealed co‐infections including individual fish infected with all four viruses. There was an overall correlation between lesions characteristic of CMS and PD and the presence of PMCV and SAV, respectively. Although PRV was ubiquitously present, high viral loads were with a few exceptions, correlated with lesions characteristic of HSMI. ASCV did not seem to have any impact on myocardial infection by PMCV, SAV or PRV. qPCR indicated a negative correlation between PMCV and SAV viral loads. Co‐infections result in mixed and atypical pathological changes which pose a challenge for disease diagnostic work.     

Use of flubendazole as a therapeutic agent against rotifers (Brachionus plicatilis) in intensive cultures of the harpacticoid copepod Tisbe holothuriae

Copepods are well known to be the optimal live feed for most species of marine fish larvae. Still copepods are rarely used in marine hatcheries worldwide. Lack of efficient production techniques are among the reasons for this. Consequently, Artemia and rotifers are utilized in commercial settings. One problem in intensive production of copepods is contamination with rotifers. Rotifers have higher growth rates than copepods and consequently will compete out the copepods when accidentally introduced to the copepod production systems. Once contamination has occurred, the only cure has been to shut down production and subsequently use a therapeutic agent to eliminate all zooplankton in the system before restart with a stock culture free of rotifers. We tested flubendazole as a mean of controlling rotifers (Brachionus plicatilis) in intensive laboratory cultures of the harpacticoid copepod (Tisbe holothuria). Flubendazole was lethal to rotifers in concentrations as low as 0.05 mg L^?1. There was no significant effect on the concentration of copepods, even at the highest concentration tested, i.e. 5.0 mg L^?1 flubendazole. We conclude that flubendazole is an effective drug for control of B. plicatilis in T. holothuriae batch cultures.     

Spatial integration of freshwater fish markets in the Northern Baltic Sea area

Freshwater fish species and Baltic salmon (Salmo salar) are important to small-scale fisheries in Finland and Sweden. The formerly local markets for these species have expanded as trade has been opened up to international competition. In this study we use cointegration analysis to test the spatial integration of freshwater fish markets in Finland and between Finland and Sweden. The analysed fish species are salmon, perch (Perca fluviatilis), pikeperch (Sander lucioperca), European whitefish (Goregonus lavaretus) and pike (Exos lucius), and the data covers ex-vessel prices from 1993 or 1995 to 2004. We found that the regional prices in Finland were cointegrated. This indicates that the prices are determined on a single market in Finland. Moreover, the study suggests that Finnish and Swedish markets in Baltic salmon, whitefish, pikeperch and perch were partially integrated, while integration of pike markets could not be found. The political implication is that an essential part of the local small-scale fisheries’ operational environment is determined outside the national borders.