Changes in growth, nutrient utilization, intestine and liver among tinfoil barb (Barbonymus schwanenfeldii, Bleeker ۱۸۵۳) fry fed varying dietary fiber level

An ۸-week feeding trial was conducted to assess the effects of dietary fiber on growth, feed efficiency, nutrient utilization, intestinal α-amylase activity and liver and intestinal histology of Barbonymus schwanenfeldii fry. Five isonitrogenous and isocaloric diets were prepared using ۰, ۳, ۶, ۹ and ۱۲% α-cellulose as fiber source at the expense of tapioca starch. Each diet was randomly assigned to triplicate groups of ۲۰ fish (۰.۵۶±۰.۰۰ g). Results revealed that tinfoil barb fry tolerated up to ۱۲% dietary fiber without compromising their growth. Average daily feed intake and feed conversion ratio showed a decreasing trend with increasing fiber levels despite insignificant differences among the dietary groups. Meanwhile, protein efficiency ratio had a positive association with dietary fiber levels. Compared to control group, whole body proximate composition and protein and lipid retention of dietary fiber groups were not significantly different. However, fish fed ۹ and ۱۲ % fiber retained higher (p<۰.۰۵) carbohydrate than those fed the control diet. None of the diets significantly altered whole body gross energy and its retention. Analysis of intestinal α-amylase showed higher activity (p<۰.۰۵) in the midgut of fish except a higher activity in the hindgut of those fed ۹% fiber. Besides, there were not any histopathological signs on the gut and liver of fish fed ۰–۱۲ % dietary fiber. While the villus area remained uniform across the dietary groups, fish fed ۹% fiber had smaller (p<۰.۰۵) hepatocytes and nuclei compared to control group. Compared with the control group, condition factor of fish fed dietary fiber was not significantly different, but those fed ۶% fiber had a higher (p<۰.۰۵) viscerosomatic index among the dietary groups. In conclusion, tinfoil barb fry could tolerate up to ۱۲% dietary fiber with ۷.۲۵% starch.

کلیدواژه ها:

Barbonymus schwanenfeldii ، Fiber ، Starch ، Specific growth rate ، Nutrient retention