Effects of total replacement of fish oil by pork lard or rapeseed oil and recovery by a fish oil finishing diet on growth, health and fish quality of gibel carp (Carassius auratus gibelio)

An 84-day growth trial was designed to investigate effects of dietary replacements fish oil with pork lard (PL) or rapeseed oil (RO) on growth and quality of gibel carp (Carassius auratus gibelio var. CAS III) (initial body weight: 158.2 ± 0.2 g), and responses of the fish refed fish oil (FO) diet. Three isonitrogenous (crude protein: 30%) and isolipid (crude lipid: 10%) diets were formulated containing 7.73% FO, PL or RO. Five experimental treatments including FO group (FO), PL group (PL), RO group (RO), group fed PL for 42 days and refed FO for 42 days (PL+rFO), RO and refed FO group (RO+rFO) was tested. At the end of first 42 days, the fish fed PL and RO had higher mortality than that of the control (P > 0.05). At the end of whole experiment, fish fed PL and RO showed higher plasma cortisol than FO fish (P 0.05). PL and RO diet decreased muscle EPA, DHA and n-3/n-6 ratio (P