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.     

Successful outcome after surgical correction of large colon atresia in a colt foal

This report describes successful surgical correction and long-term survival of a case of large colon atresia in a 24-h-old Warmblood colt, referred with signs of unrelenting abdominal pain and a suspicion of meconium impaction. Radiographic and ultrasonographic examination was indicative of large colon meconium impaction with secondary ileus. Due to deterioration of the foal, surgery was recommended. An atretic segment was found between the left ventral and dorsal large (ascending) colon. A band of fibrous tissue with no identifiable lumen connected the segments. Surgical correction was done by performing a stapled side-to-side anastomosis. Twelve days after surgery, the foal was discharged. Twenty-two months after discharge, the owner reported the foal developing as expected compared with its peers, but had a mild, self-limiting episode of colic at 20 months of age.     

A two-year comparison on nutritive value and yield of eight lucerne cultivars and one red clover cultivar

Red clover (Trifolium pratense) and lucerne (Medicago sativa) are among the most common legume species used for ruminant feeding systems. Besides the greater nutritive quality and first-year ley yield compared to lucerne, red clover decreases its yield over the years. However, under unfavourable soil conditions the persistency of lucerne can be compromised, not performing as expected. This study compared yield and chemical composition of eight lucerne cultivars and one tetraploid red clover cultivar, with similar growth capacity as lucerne, replicated over two years. In the second year, four lucerne cultivars and the red clover cultivar were analysed for crude protein (CP) fractions, dry matter and neutral detergent fibre (NDF) digestibility. A randomized block design was used with three field blocks per cultivar for the multiple comparisons within each year. There were differences in DM yield, concentrations of CP and NDF and CP fractions among the lucerne cultivars, but the differences were inconsistent between years and between growth cycles within year. The red clover cultivar had lower CP and NDF concentrations than a majority of the lucerne cultivars, and greater in vitro organic matter digestibility compared to all of the lucerne cultivars. Also, the red clover cultivar had greater rumen undegradable-to-degradable CP ratio but confirmed its lower yield persistency compared to the lucerne cultivars.     

Effects of starvation,subsequent feeding and photoperiod on flesh quality in farmed cod (Gadus morhua)

The study was designed to investigate the effect of four cycles of 5 weeks starvation followed by 10‐week refeeding compared with daily feeding under either natural photoperiod or continuous light (LL) regime on body composition and flesh quality in Atlantic cod in sea cages, northern Norway. The fish were sampled for body composition and flesh quality parameters at the start of the trial, twice at the end of a 10‐week feeding period and twice at the end of a 5‐week starvation period. There was effect of both feeding and light regime on growth, the two starving groups losing weight during starvation and regaining weight during refeeding, and the group under LL being heavier. But, the mean overall growth did not vary between groups. Starvation/refeeding regime resulted in higher slaughter yield, but no overall effect was seen on hepatosomatic index, water content, water holding capacity (WHC), muscle pH, hardness or flesh colour compared with control groups. Continuous light increased gutted weight and slaughter yield, lowered WHC and depressed maturation compared with fish under natural light regime. Increased growth rate resulted in softer fillets and lower muscle pH.     

Effect of cultivated copepods (Acartia tonsa) in first‐feeding of Atlantic cod (Gadus morhua) and ballan wrasse (Labrus bergylta) larvae

The aim of this study was to compare the nutritional composition and effects of short periods with cultivated copepod nauplii versus rotifers in first‐feeding. Atlantic cod (Gadus morhua) and ballan wrasse (Labrus bergylta) larvae were given four different dietary regimes in the earliest start‐feeding period. One group was fed the copepod Acartia tonsa nauplii (Cop), a second fed enriched rotifers (RotMG), a third fed unenriched rotifers (RotChl) and a fourth copepods for the seven first days of feeding and enriched rotifers the rest of the period (Cop7). Cod larvae were fed Artemia sp. between 20 and 40 dph (days posthatching), and ballan wrasse between 36 and 40 dph, with weaning to a formulated diet thereafter. In addition to assessing growth and survival, response to handling stress was measured. This study showed that even short periods of feeding with cultivated copepod nauplii (7 days) had positive long‐term effects on the growth and viability of the fish larvae. At the end of both studies (60 days posthatching), fish larvae fed copepods showed higher survival, better growth and viability than larvae fed rotifers. This underlines the importance of early larval nutrition.     

Inactivation of Piscine orthoreovirus

Piscine orthoreovirus infects various salmonid fish species, and the infection is associated with diseases such as heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar). There are no vaccines available or genetically selected resistant hosts that can efficiently control piscine orthoreovirus (PRV) infection. Currently, the only prophylactic measure against PRV is general biosecurity measures aiming to break the transmission cycle. Methods to eradicate infectious virus from contaminated facilities are desirable, but the knowledge on how to inactivate PRV is lacking. A major bottleneck for inactivation studies is the lack of ability to propagate PRV in cell culture. Therefore, in this study we developed an in vivo model for detection of infectious PRV particles after treatment of the virus with inactivation tools such as heat, pH, iodine, UV and commercially available disinfectants. The results show that standard iodine treatment is efficient in inactivation of the virus, and similarly are high and low pH extremes and treatment with Virocid, a commercially available disinfectant. A UV dose of at least 50 mJ/cm² is required for inactivation, and the virus has high resistance against heat treatment.     

INTER‐ AND INTRAFRACTION MOTION FOR STEREOTACTIC RADIOSURGERY IN DOGS AND CATS USING A MODIFIED BRAINLAB FRAMELESS STEREOTACTIC MASK SYSTEM

Precise and accurate patient positioning is necessary when doing stereotactic radiosurgery (SRS) to ensure adequate dosing to the tumor and sparing of normal tissues. This prospective cross‐sectional study aimed to assess feasibility of a commercially available modified frameless SRS positioning system for use in veterinary radiotherapy patients with brain tumors. Fifty‐one dogs and 12 cats were enrolled. Baseline and verification CT images were acquired. The verification CT images from 32 dogs and five cats had sufficient images for fusion to baseline CT images. A rigid box‐based fusion was performed to determine interfraction motion. Forty‐eight dogs and 11 cats were assessed for intrafraction motion by cine CT. Seventy percent of dogs and 60% of cats had interfraction 3D vector translational shifts >1 mm, with mean values of 1.9 mm in dogs, and 1.8 mm in cats. In dogs muscle wasting was weakly correlated with translational shifts. The maximum angular interfraction motion observed was 6.3° (roll), 3.5° (pitch), and 3.3° (yaw). There was no correlation between angular interfraction motion and weight, brachycephaly, or muscle wasting. Fifty‐seven percent of dogs and 50% of cats had respiration‐related intrafraction motion. Of these, 4.5% of dogs and 10% of cats had intrafraction motion >1 mm. This study demonstrates the modified Brainlab system is feasible for SRS in dogs and cats. The smaller cranial size and difference in anatomy increases setup uncertainty in some animals beyond limits usually accepted in SRS. Image‐guided positioning is recommended to achieve clinically acceptable setup accuracy (<1 mm) for SRS.     

Genetic variation in dieback resistance in Fraxinus excelsior confirmed by progeny inoculation assay

Ash dieback caused by the pathogenic fungus Hymenoscyphus fraxineus [previously known as H. pseudoalbidus (sexual stage) and Chalara fraxinea (asexual stage)] is a widespread problem in Europe. Here, we assess crown damage from natural infection and necrosis development following artificial controlled inoculations on full‐sib and half‐sib progeny from Danish Fraxinus excelsior clones with contrasting and well‐characterized levels of susceptibility to the disease. The inoculation assay was performed on a total of 123 offspring, and necrosis development monitored over two years. The offspring from low susceptible mother clones developed smaller necroses when compared to offspring from susceptible clones. Their crown damage due to natural infections was also significantly less. The correlation coefficient between average crown damages of mother clones and the average of their progeny was 0.85 (natural infections), while the correlation between crown damage of mother clones and the average necrosis development in their progeny after controlled inoculation was 0.73. The correlation between resistance of parent trees and crown damage/necrosis development on their offspring confirms the presence of heritable resistance and indicates that a bioassay based on controlled inoculations has the potential of becoming a fast and cost‐effective tool for estimation of dieback susceptibility in breeding programmes for resistance in ash trees.     

Effects of Salinity,Commercial Salts,and Water Type on Cultivation of the Cryptophyte Microalgae Rhodomonas salina and the Calanoid Copepod Acartia tonsa

Marine aquaculture facilities positioned far from the sea need access to seawater (SW); hence, commercial salts are often the chosen solution. In marine hatcheries, most fish larvae require live feed (zooplankton) that are in turn fed with microalgae. The objective of this research was to investigate the applicability of commercial salts and clarify the potential effects on the cultivation of the microalga Rhodomonas salina and the copepod Acartia tonsa. Three commercial salts were tested, Red Sea Salt (RS), Red Sea – Coral Pro Salt (CP), and Blue Treasure Salt. R. salina was cultured at salinities of 10, 20, and 30 psu resulting in equal growth rates at salinities 20 and 30 in SW and RS mixed with deionized (DI) water. The optimum salinity for R. salina was 29 psu. For A. tonsa eggs, we observed highest hatching success in 30 psu with CP or RS mixed with DI water. The egg hatching success was not affected by salinities 15–40 and optimal hatching was obtained at 27 psu. Results confirm it was possible to use commercial salts for rearing of both R. salina and A. tonsa, widening the application of these species for aquaculture facilities without access to SW.