Abstract
Normal Protein (NP) and High Protein (HP) diets were provided to rainbow trout families from juvenile to maturity. Muscle protein concentration increased during growth and the protein to lipid (P/L) ratio was doubled at late stage with respect to the dietary P/L ratio. The HP-diet fish showed higher protein deposition in body and white muscle, and had lower condition factor due to protein deposition associated more with body length than body weight. Fish growth rates were decreased at maturation, and the HP-diet fish showed lower growth rate including the activity ratio of trypsin to chymotrypsin (T/C ratio) and feed efficiency. Trypsin and chymotrypsin specific activities were related to dietary protein levels, and the T/C ratio was related to intestinal weight and growth rate independent of the enzymes specific activity levels. The families with high growth capacity could double increase white muscle P/L ratio levels, compared to low and medium growth families, if they were fed on HP-diet. The digestive enzyme extracts from high growth families resulted in higher in vitro protein digestibility for all diets. The effect of dietary P/L ratio on digestion, skeletal growth (length) and the white muscle P/L ratio in fish with different growth capacities is illustrated.
Highlights
One of the principal goals in contemporary aquaculture is the dual optimisation of growth efficiency and protein content through a process of selective culture
There were no significant differences in body weight between the two dietary groups the High Protein (HP)-diet fish seemed to have a relatively higher body weight than the Normal Protein (NP)-diet fish before maturation (P > .05)
During maturation in the last two months, fish growth rates were reduced in both dietary groups, and the high protein (HP-)diet fish showed a higher decrease in specific growth rate (SGR) (P < .001) with the body weight changed (P > .05) from a relatively higher in September 2003 to a relatively lower in November 2003, compared to the normal protein (NP-)diet fish (Figure 1 and Table 2)
Summary
One of the principal goals in contemporary aquaculture is the dual optimisation of growth efficiency and protein content through a process of selective culture. In aquaculture, dietary protein and lipid are varied throughout the life cycle to optimise the economic return. We aim to understand a basic knowledge on long-term protein growth by investigating the effects of maintaining dietary protein and lipid concentrations throughout the fish life cycle on digestive efficiency and protein growth using a unique combination of techniques recently described by Rungruangsak-Torrissen’s research team [11, 12, 14]. We aim to study the potential for maximising protein growth efficiency in rainbow trout (Oncorhynchus mykiss Walbaum) families with differences in growth capacity by varying the concentrations of dietary protein and lipid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
