Bile components and lecithin supplemented to plant based diets do not diminish diet related intestinal inflammation in Atlantic salmon.
BACKGROUND
The present study was undertaken to gain knowledge on the role of bile components and lecithin on development of aberrations in digestive functions which seemingly have increased in Atlantic salmon in parallel with the increased use of plant ingredients in fish feed. Post smolt Atlantic salmon were fed for 77 days one of three basal diets: a high fish meal diet (HFM), a low fishmeal diet (LFM), or a diet with high protein soybean meal (HPS). Five additional diets were made from the LFM diet by supplementing with: purified taurocholate (1.8 %), bovine bile salt (1.8 %), taurine (0.4 %), lecithin (1.5 %), or a mix of supplements (suppl mix) containing taurocholate (1.8 %), cholesterol (1.5 %) and lecithin (0.4 %). Two additional diets were made from the HPS diet by supplementing with: bovine bile salt (1.8 %) or the suppl mix. Body and intestinal weights were recorded, and blood, bile, intestinal tissues and digesta were sampled for evaluation of growth, nutrient metabolism and intestinal structure and function.


RESULTS
In comparison with fish fed the HFM diet fish fed the LFM and HPS diets grew less and showed reduced plasma bile salt and cholesterol levels. Histological examination of the distal intestine showed signs of enteritis in both LFM and HPS diet groups, though more pronounced in the HPS diet group. The HPS diet reduced digesta dry matter and capacity of leucine amino peptidase in the distal intestine. None of the dietary supplements improved endpoints regarding fish performance, gut function or inflammation in the distal intestine. Some endpoints rather indicated negative effects.


CONCLUSIONS
Dietary supplementation with bile components or lecithin in general did not improve endpoints regarding performance or gut health in Atlantic salmon, in clear contrast to what has been previously reported for rainbow trout. Follow-up studies are needed to clarify if lower levels of bile salts and cholesterol may give different and beneficial effects, or if other supplements, and other combinations of supplements might prevent or ameliorate inflammation in the distal intestine.
Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway. trond.kortner@nmbu.no.
Trond M
TM
Kortner
Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.|Present Address: US Fish & Wildlife Service, Lamar, PA, 16848, USA.
Michael H
MH
Penn
Department of Laboratory Medicine, Division for Clinical Chemistry, Karolinska University Hospital, Huddinge, Sweden.
Ingemar
I
Bjӧrkhem
Biomar AS, Nordre gate 11, 7011, Trondheim, Norway.
Kjell
K
Måsøval
Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
Åshild
Å
Krogdahl
D000821:Animal Feed; D000818:Animals; D001646:Bile / Q000737:chemistry / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000032:analysis; D002784:Cholesterol / Q000032:analysis; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D005393:Fish Diseases / Q000178:diet therapy*; D007249:Inflammation / Q000178:diet therapy / Q000662:veterinary*; D007422:Intestines / Q000473:pathology; D054709:Lecithins / Q000378:metabolism*; D020317:Salmo salar / Q000502:physiology*
D001647:Bile Acids and Salts; D054709:Lecithins; D002784:Cholesterol
Bile; Cholesterol; Fish feed; Gut health; Intestinal inflammation; Plant ingredients