Dietary lipid and gross energy affect protein utilization in the rare minnow Gobiocypris rarus

Abstract

A bstractAn 8-week feeding trial was conducted to detect the optimal dietary protein and energy, as well as the eff ects of protein to energy ratio on growth, for the rare minnow ( Gobiocypris rarus ), which are critical to nutrition standardization for model fi sh. Twenty-four diets were formulated to contain three gross energy (10, 12.5, 15 kJ/g), four protein (20%, 25%, 30%, 35%), and two lipid levels (3%, 6%). The results showed that optimal dietary E/P was 41.7-50 kJ/g for maximum growth in juvenile rare minnows at 6% dietary crude lipid. At 3% dietary lipid, specifi c growth rate (SGR) increased markedly when E/P decreased from 62.5 kJ/g to 35.7 kJ/g and gross energy was 12.5 kJ/g, and from 75 kJ/g to 42.9 kJ/g when gross energy was 15.0 kJ/g. The optimal gross energy was estimated at 12.5 kJ/g and excess energy decreased food intake and growth. Dietary lipid exhibited an apparent protein-sparing eff ect. Optimal protein decreased from 35% to 25%-30% with an increase in dietary lipid from 3% to 6% without adversely eff ecting growth. Dietary lipid level aff ects the optimal dietary E/P ratio. In conclusion, recommended dietary protein and energy for rare minnow are 20%-35% and 10-12.5 kJ/g, respectively.

The Effect of Environmental Enrichment on Laboratory Rare Minnows (Gobiocypris rarus): Growth, Physiology, and Behavior

“…If an animal’s growth is significantly affected by adverse conditions, then its welfare could deteriorate significantly [ 40 ]. Previous studies have shown that the factors affecting the growth of rare minnows include nutrients [ 41 , 42 ], water temperature [ 43 ] and other physical and chemical characteristics of their water environment, feeding, and other culturing strategies [ 43 , 44 , 45 ]. Therefore, these impact factors are restricted or controlled in the standard drafts of rare minnows to ensure their basic welfare.…”