Feed consumption, growth and growth efficiency of rainbow trout (Oncorhynchus mykiss (Walbaum)) fed on diets containing a bacterial single-cell protein.
The aim of the present study was to compare the nutritive value of bacterial single-cell protein (BSCP) with that of fishmeal in rainbow trout (Oncorhynchus mykiss (Walbaum)). Four diets were formulated to contain a total of 458 g crude protein/kg of which 0% was from BSCP in diet 1 (BSCP-0), 25% in diet 2 (BSCP-25), 62.5% in diet 3 (BSCP-62.5) and 100% in diet 4 (BSCP-100); the remainder of the protein was from fishmeal. There were two studies: in study 1, duplicate groups of twenty-five fish were fed on one of the four experimental diets at the rate of 20 g/kg body weight per d for 132 d. Feed consumption rates of individual fish were measured using radiography and the overall apparent absorption efficiency for N in each group was measured over a 2-week period. In study 2, N intake, consumption, absorption and accretion were measured for each fish under controlled environmental conditions (12 h: 12 h light-dark regime; 14 degrees). Higher dietary levels of BSCP resulted in significantly higher feed consumption rates but reduced N absorption efficiency and growth rates. However, a diet containing 25% BSCP (75% fishmeal) did not significantly influence growth rates, feed consumption and absorption efficiency compared with a 100% fishmeal diet. The N growth efficiencies were highest in fish fed on the diet containing the highest level of fishmeal and significantly decreased with increasing BSCP content. Construction of N budgets demonstrated that the reduction in growth in fish eating an increasingly larger proportion of BSCP was due to a decrease in N absorption and an increase in the excretion of urea.
Perera
W M
WM
Department of Zoology, University of Aberdeen.
Carter
C G
CG
Houlihan
D F
DF
D000818:Animals; D001426:Bacterial Proteins / Q000008:administration & dosage*; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage*; D005396:Fish Products; D007408:Intestinal Absorption; D009584:Nitrogen / Q000378:metabolism; D009753:Nutritive Value; D017686:Oncorhynchus mykiss / Q000254:growth & development* / Q000378:metabolism
D001426:Bacterial Proteins; D004044:Dietary Proteins; C012551:single cell proteins; D009584:Nitrogen