INFLUENCE OF TEMPERATURE AND DIETARY-PROTEIN SUPPLEMENTATION EITHER WITH FREE OR COATED LYSINE ON THE FRACTIONAL PROTEIN-TURNOVER RATES IN THE WHITE MUSCLE OF CARP
M. Delahiguera et al., INFLUENCE OF TEMPERATURE AND DIETARY-PROTEIN SUPPLEMENTATION EITHER WITH FREE OR COATED LYSINE ON THE FRACTIONAL PROTEIN-TURNOVER RATES IN THE WHITE MUSCLE OF CARP, Fish physiology and biochemistry, 18(1), 1998, pp. 85-95
The effect of protein quality and of supplementation of corn-gluten pr
otein with lysine on the growth, feed conversion and protein turnover
rates in white muscle was investigated in carp (Cyprinus carpio) accli
mated to either 18 or 25 degrees C. Fish fed the lysine-deficient diet
showed a significantly lower food intake, weight gain and feed-conver
sion efficiency than animals fed the lysine-sufficient diets, regardle
ss of environmental temperature. Coated lysine, compared with free lys
ine, proved to be a significantly better way of supplementing dietary
protein, as shown by feed-conversion indices at 18 and 25 degrees C. W
hite-muscle protein, RNA and DNA contents were not altered by dietary
treatment or water temperature. Supplementation with coated lysine, bu
t not with free lysine, significantly increased the protein-synthesis
rate (K-s) at 18 or 25 degrees C in comparison to lysine deficiency, a
lthough not to control values. The efficiency of protein synthesis (K-
RNA and retention (PRE) obtained for fish fed the coated-lysine diet,
at 18 degrees C, reached control values. At 25 degrees C PRE and prote
in accumulation rate (K-G) showed the following significant difference
s: lysine-deficient diet < free-lysine supplemented diet < coated-lysi
ne supplemented diet < control diet. Significant correlations were obs
erved for Ks in relation with K-D, K-RNA or protein-related growth, at
both temperatures.