Alternatives lipid ingredients can impact the growth performance and disease resistance in farmed
fish. Vegetable oils and terrestrial animal fats have been commonly used to manufacture aquafeeds
and they can heavily impact the physiological and immune responses of farmed fish. On the other
hand, single cell ingredient, Schizochytrium sp. meal can be a sustainable alternative to fish oil
due to its high content of docosahexaenoic acid.
Five experimental diets (catfish oil, soybean oil, lard, menhaden oil, and Schizochytrium sp. meal) were formulated to be isonitrogenous
(36%) and isolipidic (7.8%). Six hundred channel catfish (initial weight ~5 g) were randomly distributed across 20 aquaria (110 L,
30 fish/tank, n=4) and fed the experimental
diets to apparent satiation for 10 weeks. The
tanks operated as a recirculating aquaculture
system and the dietary treatments were
assigned in a completely randomized design.
On the last day of the feeding trial, fish were
weighed to calculate production performance
and sampled for condition indices and
hematology. For the bacterial challenge, the
remaining fish were transferred to and
acclimated in fiber glass tanks (22 L) operating
as a flow through system and challenged with
an LD50 of Edwardsiella ictaluri through
immersion (6.2×106 CFU/mL). Data were
subjected to analysis of variance in one-way
ANOVA, post-hoc testing was performed
using Tukey’s test. Fish grew on average
832.6% when compared to the initial weight.
There were no significant differences in the
production performance variables, except for
feed efficiency (P = 0.023), in which the
menhaden treatment was more efficient
compared to the lard treatment. However, fish
fed diets containing lard had significantly
higher survival after the bacterial challenge
when compared to the fish fed diets
supplemented with soybean oil (Figure 1). It
can be concluded that terrestrial animal fat
reduced channel catfish feed efficiency;
however, it did increase their resistance against
Edwardsiella ictaluri.