Enhanced growth and decreased mortality in Atlantic salmon (Salmo salar) after probiotic bath.

AIMS: Disease in farmed Atlantic salmon occurs in all its life stages. Salmon are particularly vulnerable to infectious diseases at transition from the freshwater stage to the saltwater stage. Our aim in these studies reported was to investigate the possibility that waterborne delivery of a probiotic comprised of naturally occurring marine bacterial species would reduce the mortality and improve the health and growth of farmed Atlantic salmon. METHODS AND RESULTS: In three trials at two aquaculture production sites in Norway, isolates of Aliivibrio bacteria were added to the rearing water of Atlantic salmon. The fish were followed in 4-6 months after one single bath with observations and samplings. Growth, ulcers and survival were recorded. At the end of the studies growth was up to 31% larger in the probiotic enhanced groups and in trial 1 both mortality and prevalence of ulcer were significantly lower in the probiotic enhanced group compared to the control. Feed conversion rates were recorded in trial 1 and 2 and were from 9 to 28 % better for the probiotic enhanced groups compared to the control groups. CONCLUSION: Bathing of Atlantic salmon with probiotic Aliivibrio strains increased growth, reduced mortality and improved FCR in the postsmolt period. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates the potential to enhance growth, prevent ulcers and decrease mortality in Atlantic salmon after adding probiotic strains of Aliivibrio spp. into the rearing water. The study can have impact on animal welfare, economy and sustainability in the aquaculture industry.

Use of Arthrobacter davidanieli as a live vaccine against Renibacterium salmoninarum and Piscirickettsia salmonis in salmonids.

Arthrobacter davidanieli (proposed species nomenclature) is a non-pathogenic Gram-variable bacterium related to, but taxonomically distinct from, Renibacterium salmoninarum, the aetiological agent of bacterial kidney disease (BKD). We have demonstrated that vaccination with live A. davidanieli is effective against BKD in Atlantic salmon (Salmo salar) showing above 80 relative percent survival in experimental challenge trials. Good protection was also demonstrated in long-term field trials where Atlantic salmon were naturally exposed to R. salmoninarum challenge until 23 months after vaccination. The same vaccine, which is licensed in Canada against BKD has also proved effective in reducing mortality from experimental challenge of coho salmon (Oncorhynchus kisutch) with Piscirickettsia salmonis, the causative agent of piscirickettsiosis. Under field conditions in Chile, use of the vaccine led to a significant reduction in piscirickettsiosis mortality in coho salmon over 10 months following sea transfer. The vaccine strain is unique in that it is the first live organism to be licensed as a vaccine for use in aquaculture. Potential mechanisms of protection against the two taxonomically disparate pathogens are discussed.

Relationship between ossification of the cartilages of the foot and conformation and radiographic measurements of the front feet in Finnhorses.

One hundred Finnhorse cadaver front feet were measured and examined both radiographically and visually to report the incidence of various foot problems and their relationship to ossification of the cartilages of the foot. Ossification extending above the proximal border of the navicular bone and/or separate centres of ossification were found in 36 feet, and the lateral cartilages showed more ossification than the medial cartilages. The feet were generally broad with well developed frogs, but the long toe-low heel syndrome was a relatively common finding. Ossification of the cartilages correlated with the length of the heels but was not related to any clinically significant foot abnormalities such as contracted or under-run heels or signs of unequal weightbearing. Ossification of the cartilages did not seem to be either the cause or the result of general conformational adaptations of the front feet.