The effect of dietary immunostimulants on digestive tract physiology and morphology of river trout (Salmo trutta m. fario)
Teresa
Ostaszewska1,
Maciej
Kamaszewski1,
Hubert
Szudrowicz1,
Robert
Kasprzak1,
Zdzisław
Zakęś2,
Maciej
Rożyński2,
Sławomir
Krejszeff2,
Stefan
Dobosz2,
Romuald
Rożyński2,
Krzysztof
Formicki3*,
Agata
Korzelecka-Orkisz3,
Adam
Tański3,
Piotr
Gomułka4,
Krystyna
Demska-Zakęś4 and
Elżbieta
Ziomek4
-
1
Warsaw University of Life Sciences, Poland
-
2
Stanisław Sakowicz Inland Fisheries Institute, Poland
-
3
West Pomeranian University of Technology, Poland
-
4
University of Warmia and Mazury in Olsztyn, Poland
The study aimed to assess the effects of natural dietary immunostimulant addition on survival, growth, digestive enzyme activity and immune system response of river trout (Salmo trutta m. fario). The experimental rearing lasted 28 days and it took place in The Stanisław Sakowicz Inland Fisheries Institute, in the research facility in Rutki, Poland.
Fish (initial TL = 17.2 cm, BM = 75 g) were placed in 12 tanks, at a density of 40 fish per tank. The tanks were supplied with water stemming from the Radunia river (10.1-13.3 ˚C, 8.5-9.7 mg O2/l). A natural fotoperiod (September-October) was applied. Fish were divided into 4 feeding groups (a triplicate of tanks in each) and fed manually for 28 days. Group A was fed with an experimental diet (University of Warmia and Mazury in Olsztyn), while fish from group B were fed the same diet, but enriched in the immunostimulant Bioimmuno II (Inland Fisheries Institute in Olsztyn). Similarly, group C was fed the commercial diet EFICO E (Biomar, Denmark), while group D was given the same EFICO E diet, but enriched in the immunostimulator Focus Plus (Biomar).
After the rearing period, fish were anaesthetized (1 ml/l of etomidate, Propiscin, Inland Fisheries Institute in Olsztyn), weighed and measured, then their digestive tracts and spleens were isolated and fixed for further analyses. Digestive enzyme activity was measured in the stomach (pepsin) and sections of the anterior and posterior intestine (amylase, lipase, trypsin, chymotrypsin, alkaline and acidic phosphatases, leucine aminopeptidase and γ-glutamylotransferase) using nitrogen snap-frozen samples. The enzymatic activities were measured with spectrophotometric biochemical methods and were presented as U/mg of total protein content. Meanwhile, tissue samples fixed in Bouin solution were used for histological analysis. Melano-macrophage centres were in the spleen were analyzed on slides stained with H&E, while immunohistochemical methods were used to detect CD3-positive T-cells in mucosal folds in the anterior intestine.
Fish survival in all groups was 100% and no statistically significant differences in body growth were obtained. The addition of immunostimulants resulted in lowered amylase and leucine aminopeptidase activity in the anterior intestine of fish from groups B and D (when compared to groups A and C, respectively), but no differences were recorded for the other measured enzymes. In the posterior intestine, only the chymotrypsin activity was lower in fish from groups B and D. Histological analysis revealed that the sizes of melano-macrophage centres and the number of CD3-positive T-cells were both statistically significantly larger in groups B and D.
The obtained results indicate that dietary additions of immunostimulants activate the immune system but do not impede the digestive physiology in river trout.
Acknowledgements
The study was done within the project no 00001-6521.1-OR1600002/17/18 financed by Sectoral Operational Programme "Fisheries and See 2014-2020"
Keywords:
Digestive enzyme activity,
Immune System,
immunostimulants,
Melano-macrophage centres,
River trout
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Poster
Topic:
ECOLOGY AND LIFE CYCLES
Citation:
Ostaszewska
T,
Kamaszewski
M,
Szudrowicz
H,
Kasprzak
R,
Zakęś
Z,
Rożyński
M,
Krejszeff
S,
Dobosz
S,
Rożyński
R,
Formicki
K,
Korzelecka-Orkisz
A,
Tański
A,
Gomułka
P,
Demska-Zakęś
K and
Ziomek
E
(2019). The effect of dietary immunostimulants on digestive tract physiology and morphology of river trout (Salmo trutta m. fario).
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00020
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Received:
30 May 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Prof. Krzysztof Formicki, West Pomeranian University of Technology, Szczecin, Poland, Krzysztof.Formicki@zut.edu.pl