Effects of dietary lipid
level and source on growth and proximate composition of juvenile redclaw (Cherax
quadricarinatus) reared under semi-intensive culture conditions
M.P. Hernández-Vergara, D.B. Rouse, M.A.
Olvera-Novoa, D.A. Davis-2003
Aquaculture, 223(1-4): 107-115
Abstract:
The influence of dietary lipid level on growth,
survival, and proximate composition of juvenile redclaw crayfish was
evaluated during a 12-week growth trial utilizing semi-intensive culture
conditions. Four diets were formulated to be isoenergetic (17.58 kJ g-1)
and isonitrogenous (30% crude protein). Three of the diets were designed to
contain 4.2% (L4), 8.2% (L8) and 12.3% (L12) lipid in a 1:1 ratio of corn
oil/fish oil. A fourth diet was formulated to contain 8.7% (LC8) lipid, with
corn oil as lipid supplement. A fifth treatment (UF) was included in which
the redclaw were not fed in order to estimate the contribution of primary
production. Juvenile redclaw (4.08±0.2 g initial weights) were stocked at a
density of 10 per tank in 15, 2.5-m3 fiberglass tanks with three
replicates per treatment. The trial was conducted in an outdoor flow-through
water system. The redclaw in the unfed treatment gained 8.3 g whereas
redclaw that received a prepared ration gained an average of 31.9 g. Hence,
in this experiment natural productivity contributed about 26% of the weight
gain of the redclaw maintained in outdoor tanks. Among the fed treatments,
there were no significant differences in survival, final weight, growth, or
feed utilization. The hepatosomatic index (HI) generally increased with
lipid level and was influenced by the sex of the redclaw. Results indicated
that in similar culture conditions, diets containing 4% lipid are sufficient
for redclaw growth and survival when natural food is present.