Genetic relationships of body composition and feed utilization traits in European whitefish (Coregonus lavaretus L.) and implications for selective breeding in fishmeal- and soybean meal-based diet environments

Body composition traits have potential use in fish breeding programs as indicator traits for selective improvement of feed efficiency. Moreover, feed companies are increasingly replacing traditional fish meal (FM) based ingredients in feeds for carnivorous farmed fish with plant protein ingredients. Therefore, genetic relationships of composition and feed utilization traits need to be quantified for both current FM-based and future plant-based aquaculture feeds. Individual whole-body lipid% and protein%, daily gain (DG), ADFI, and G:F (daily gain/daily feed intake) were measured on 1,505 European whitefish (Coregonus lavaretus) from 70 half/full-sib families reared in a split-family design with either a typical FM or a novel soybean meal (SBM) based diet. Diet-specific genetic parameters were estimated with multiple-trait animal models. Lipid% was significantly greater in the FM diet group than in the SBM group, even independent of final BW or total feed intake. In both diets, lipid% showed moderate heritability (0.12 to 0.22) and had positive phenotypic and genetic correlations with DG (0.37 to 0.82) and ADFI (0.36 to 0.88). Therefore, selection against lipid% can be used to indirectly select for lower feed intake. Protein% showed low heritability (0.05 to 0.07), and generally very weak or zero correlations with DG and ADFI. In contrast to many previous studies on terrestrial livestock, lipid% showed zero or very weak phenotypic and genetic correlations with G:F. However, selection index calculations demonstrated that simultaneous selection for high DG and reduced lipid% could be used to indirectly increase G:F; this strategy increased absolute genetic response in G:F by a factor of 1.5 to 1.6 compared with selection on DG alone. Lipid% and protein% were not greatly affected by genotype-diet environment interactions, and therefore, selection strategies for improving body composition within current FM diets should also improve populations for future SBM diets.     

Spatial relationship between biodiversity and geodiversity across a gradient of land-use intensity in high-latitude landscapes

Context

‘Conserving Nature’s stage’ has been advanced as an important conservation principle because of known links between biodiversity and abiotic environmental diversity, especially in sensitive high-latitude environments and at the landscape scale. However these links have not been examined across gradients of human impact on the landscape.

Objectives

To (1) analyze the relationships between land-use intensity and both landscape-scale biodiversity and geodiversity, and (2) assess the contributions of geodiversity, climate and spatial variables to explaining vascular plant species richness in landscapes of low, moderate and high human impact.

Methods

We used generalized additive models (GAMs) to analyze relationships between land-use intensity and both geodiversity (geological, geomorphological and hydrological richness) and plant species richness in 6191 1-km² grid squares across Finland. We used linear regression-based variation partitioning (VP) to assess contributions of climate, geodiversity and spatial variable groups to accounting for spatial variation in species richness.

Results

In GAMs, geodiversity correlated negatively, and plant species richness positively, with land-use intensity. Both relationships were non-linear. In VP, geodiversity best accounted for species richness in areas of moderate to high human impact. These overall contributions were mainly due to variation explained jointly with climate, which dominated the models. Independent geodiversity contributions were highest in pristine environments, but low throughout.

Conclusions

Human action increases biodiversity but may reduce geodiversity, at landscape scale in high-latitude environments. Better understanding of the connections between biodiversity and abiotic environment along changing land-use gradients is essential in developing sustainable measures to conserve biodiversity under global change.

     

Biodiversity policies in commercial boreal forests: Optimal design of subsidy and tax combinations

This paper examines the first-best instruments for biodiversity maintenance in commercial boreal forests when landowners behave either in Faustmannian or Hartmanian way. Using an extended Hartman model, we show that biodiversity conservation requires both prolonged rotation age and leaving retention trees. While the former promotes some old growth species, the latter create new structural elements of decaying and dead wood, which can sustain a variety of saprolyxic species. A fully synchronized combination of retention tree subsidy and tax instrument is needed both to lengthen the privately optimal rotation period and to provide an incentive to leave retention trees. Using Finnish data we illustrate empirically the sizes of instruments. When combined with a harvest tax, the retention tree subsidy is 1000 and 750 € in the Faustmann and in the Hartman model, respectively. When used with a timber subsidy or a site value tax, the retention tree subsidy is 1700 €/ha in both models. The harvest tax rate varies over the range 40–65% in the Faustmann model and 20–40% in the Hartman model, while timber subsidy is between 0.5–1.0% and site value tax is about 1.75%.     

Effect of harvest date on onion yield in a northern climate

Summary

Timing of harvest is an essential factor affecting the quantity, quality and storability of onion yield. This study aimed to establish when no further yield increase is to be expected and to determine the relationship between maturity stage and yield development. Experiments on 4-6 harvests at 9-14 d intervals were conducted at several locations in southern Finland in 1996-1999. Generally little, if any, yield increase was recorded after plants had reached 100% maturity, but in some cases bulb growth continued after complete fall-down of leaves. On the other hand, harvesting before 100% maturity resulted in a yield loss of 0-45% of final yield. Weight loss, and thus energy consumption during drying, was still reduced after complete leaf fall-down. Therefore, it may be concluded that delaying harvest up to 100% maturity, or even longer, ensures that highest yield and lowest drying costs.     

Gelatinolytic matrix metalloproteinases-2 and -9 in tracheobronchial lavage fluid obtained from calves with concurrent infections of Pasteurella multocida and Mycoplasma bovirhinis

OBJECTIVE: To study gelatinolytic matrix metalloproteinases (MMPs) in tracheobronchial lavage fluid (TBLF) obtained from clinically normal calves and calves with Pasteurella multocida infection. SAMPLE POPULATION: Samples of TBLF obtained from 11 calves with clinical signs of respiratory tract disease and growth of P multocida and Mycoplasma spp during culture of TBLF and samples of TBLF from 6 clinically normal calves with no bacterial growth during culture of TBLF. PROCEDURE: MMPs in TBLF were analyzed by use of gelatin zymography. Gelatinases were identified on the basis of molecular weights and inhibition by EDTA. RESULTS: The main gelatinolytic MMPs detected were the proform (90 to 110 kd) and active form (75 to 85 kd) of MMP-9 (gelatinase B) and the proform (67 to 75 kd) and active form (< 65 kd) of MMP-2 (gelatinase A). Increased amounts of active MMP-2 and MMP-9 were detected in TBLF of calves with respiratory tract disease, compared with amounts of active MMP-2 and MMP-9 in TBLF of clinically normal calves. Concurrent infection with Mycoplasma bovirhinis in calves with pneumonia attributable to P multocida was associated with higher concentrations of MMP-9. CONCLUSIONS AND CLINICAL RELEVANCE: The host response to P multocida includes increases in MMP-2 and MMP-9 concentrations in TBLF. Greater amounts of MMPs detected in calves with concurrent M bovirhinis and P multocida infection indicates synergism between these organisms.     

Added value from an added chromosome: Potential of producing large fillet fish from autumn to spring with triploid rainbow trout,Oncorhynchus mykiss

Three‐summers‐old all‐female triploid and diploid rainbow trout were compared after one on‐growing season in sea net cages. Slaughter traits of round weight, gutted weight, fillet weight, carcass% and fillet% were measured at three times in November 2017, January and April 2018. The triploid group had lower daily growth coefficient mean (4.25) and higher feed conversion ratio (1.18) than diploids (4.48 and 1.05, respectively) during on‐growing (June–November). In November, no difference of means was found between mature or immature diploids and triploids for any of the weight traits when the effect of vertebrae defects was statistically removed. However, the triploids had attained higher means than mature or immature diploids in gutted and fillet weight by January, suggesting that the loss of muscle mass during early winter was lower in triploids. Sexually maturing diploids (46%) had lower slaughter yield means compared to triploids or immature diploids at each measurement time, and these differences also increased during overwintering. Instead, the means of yield traits remained similar between the triploid and immature diploid groups through the winter. Likewise, fillet redness remained at equally high level in triploids and immature diploids, whereas in maturing diploids this attribute decreased substantially during overwintering. The triploid group had a higher incidence of vertebral defects (12.0%) than diploids (5.3%). The present results demonstrate the potential of triploid trout in producing large‐sized (>2 kg) fillet fish until spring markets. However, more detailed investigations are needed, particularly regarding the animal health and growth efficiency in triploids, relative to their diploid counterparts.     

Longer wavelengths of light improve the growth, intake and feed efficiency of individually reared juvenile pikeperch Sander lucioperca (L.)

We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n =5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P <0.05) while blue was comparable to white light in terms of the measured parameters. After the growth trial, the spectral sensitivity of photoreceptor cells in the retina was tested using microspectrophotometry, which revealed the presence of rods with λ_max at ca. 530 nm and two cone classes, absorbing maximally at ca. 535 and 603 nm, all containing a porphyropsin-based pigment. These results suggest that the presence of mid and long wavelength-sensitive cones enhances visual sensitivity under mid-wavelength and long-wavelength environments, and thus supports the finding that longer wavelengths of incoming light can improve FE and SGR of the cultivated pikeperch.     

Biosecurity on Finnish cattle,pig and sheep farms – results from a questionnaire

Biosecurity is important in order to prevent disease transmission between animals on farms as well as from farm to farm. Personal biosecurity routines such as hand washing and the use of protective clothing and footwear are measures that should be used at all farms. Other measures are for example related to purchasing new animals to the farm.     

Negative frequency-dependent selection of sexually antagonistic alleles in Myodes glareolus

Sexually antagonistic genetic variation, where optimal values of traits are sex-dependent, is known to slow the loss of genetic variance associated with directional selection on fitness-related traits. However, sexual antagonism alone is not sufficient to maintain variation indefinitely. Selection of rare forms within the sexes can help to conserve genotypic diversity. We combined theoretical models and a field experiment with Myodes glareolus to show that negative frequency-dependent selection on male dominance maintains variation in sexually antagonistic alleles. In our experiment, high-dominance male bank voles were found to have low-fecundity sisters, and vice versa. These results show that investigations of sexually antagonistic traits should take into account the effects of social interactions on the interplay between ecology and evolution, and that investigations of genetic variation should not be conducted solely under laboratory conditions.     

Protection, immune response and side-effects in European whitefish (Coregonus lavaretus L.) vaccinated against vibriosis and furunculosis

As indicated by market demand and cultivation prospects, the whitefish (Coregonus lavaretus L.) has the potential to become an important alternative to rainbow trout in fish farming in Finland. The fish processing industry has called for a fish species having non-pigmented flesh, and there is a long tradition of whitefish farming for stocking purposes in Finland. However, cultivation in net cages in the brackish water of the coastal area exposes fish to vibriosis (Listonella (Vibrio) anguillarum) and furunculosis (Aeromonas salmonicida salmonicida). Hence, profitable whitefish farming requires the efficient control of both of these diseases. The efficacy of vaccination (Apoject 1800®) was studied in the laboratory using challenge tests and by monitoring specific antibody production (ELISA) and the blood leucocyte pattern. The fish (22 g) were vaccinated at 15°C and the immunity developed during 8 weeks prior to challenge with vibriosis (1.8×10⁵ cfu) and 12 weeks prior to challenge with furunculosis (4.9×10² cfu). The challenge was performed by i.p. injection. Side-effects around the injection site were studied 16 weeks post-vaccination. The immune system of the whitefish responded well and vaccination gave good protection against vibriosis and furunculosis. The RPS was 100% following the Vibrio challenge and 99% following the Aeromonas challenge. The antibody levels continued increasing in the vaccinated group throughout the study period. Lymphocyte and neutrophil counts were elevated in vaccinated compared to non-vaccinated fish at 8 weeks post-vaccination, but not after 16 weeks. Vaccination produced weak adhesions around the injection site in 42% and minor pigmentation in 9% of the 65 fish examined.