Haemato-immunological and serum biochemical parameters, intestinal histomorphology and growth performance of rainbow trout (Oncorhynchus mykiss) fed dietary fermentable fibre (Vitacel®)

The aim of this study was to investigate the effects of dietary fermentable fibre (Vitacel (R)) on haemato-immunological and serum biochemical parameters, intestinal histomorphology, growth performance and proximate body composition of rainbow trout (Oncorhynchus mykiss). One hundred and twenty fish (81.65 +/- 1.49 g) were fed diets containing 0 and 10 g kg(-1) fermentable fibre (Vitacel (R)) for 50 days. At the end of feeding trial, growth performance parameters were significantly improved in fermentable fibre (Vitacel (R))-fed fish. Although feeding on fermentable fibre (Vitacel (R))-supplemented diet had no remarkable effect on haematological parameters (RBC, Htc and Hb) (P > 0.05), white blood cell (WBC) count and monocyte level were significantly affected (P = 0.040 and P = 0.020, respectively). In case of serum biochemical parameters, a significant increase and decrease were observed in serum total protein (P = 0.040) and cholesterol level (P = 0.000), respectively. Also, lysozyme level was significantly increased following administration of Vitacel (R) in diet (P = 0.006). Histomorphological evaluations revealed that villus length (P = 0.004) and tunica muscularis thickness (P = 0.000) were significantly higher in fermentable fibre (Vitacel (R))-fed fish. These results indicate that fermentable fibre can be considered as a dietary supplement for improving the health status and performance of rainbow trout.