Aeromonas hydrophila infection variably affects the survival of tinfoil barb (Barbonymus schwanenfeldii, Bleeker ۱۸۵۳) fry fed dietary sugars and starch

A ۵۶-day feeding trial was conducted to evaluate the effects of carbohydrate types on growth, feed efficiency, nutrient utilization, intestinal α-amylase activity, and liver and intestinal histology of Barbonymus schwanenfeldii fry and their resistance to Aeromonas hydrophila. Five isonitrogenous and isocaloric diets were prepared using glucose, maltose, sucrose, and dextrin and tapioca starch. Each diet was randomly assigned to triplicate groups of ۲۰ fish (۱.۵۰±۰.۰۱ g). Diets prepared using dextrin and tapioca starch had higher (p<۰.۰۵) water stability than other diets. Fish fed dietary glucose had lower (p<۰.۰۵) growth and protein efficiency ratio and higher (p<۰.۰۵) feed conversion ratio than those fed other diets. Dietary tapioca starch increased (p<۰.۰۵) the whole-body gross energy, lipid, and lipid retention while reduced (p<۰.۰۵) the body ash. Dietary glucose reduced (p<۰.۰۵) the body protein and energy retentions than other carbohydrates. A significantly higher (p<۰.۰۵) α-amylase activity was observed in the midgut of fish fed sucrose, dextrin and tapioca, hindgut of those fed glucose and hindgut and midgut of those fed maltose. When compared with tapioca, other dietary groups had comparable villus dimensions. However, compared to tapioca, other dietary groups had smaller (p<۰.۰۵) hepatocytes whereas glucose group had smaller (p<۰.۰۵) hepatocyte nucleus. Condition factor of fish fed dietary glucose was significantly lower (p<۰.۰۵) than those fed other types of carbohydrate. Post-challenge fish fed maltose and glucose groups expressed comparable survival with tapioca groups. In conclusion, this study revealed that ۱۹.۲۵% dietary maltose or tapioca starch could be most suitable to promote growth and nutrient utilization in B. schwanenfeldii fry and to protect against A. hydrophila infection.

Keywords:

Barbonymus schwanenfeldii , Aeromonas hydrophila , Sugars , Starch