This study was conducted to evaluate the suitability of dried mallow plant,
Malva parviflora L., as an alternative protein source for Nile tilapia. Three
experimental diets were formulated to contain this plant meal at levels of 10, 20 and
30% of the total dietary protein (diets 2, 3 and 4, respectively) and one diet acting as a
control (diet 1) which included only fish meal, and soybean meal as protein sources.
The four diets were isonitrogenous (26%) and isocaloric (4400 kcal GE/kg dry matter
of feed). The feeding experiment extended for 10 weeks. The results of this experiment showed that the best growth rate and FCR
(1.8S) were observed by fish group fed the control diet, while the poorest FCR (2.0S)
was observed by fish group fed diet 4, where 30% of its soybean protein was replaced
by mallow meal protein. Slight decrease in protein efficiency ratio (PER) and protein
productive value (PPV) was reported when the soybean protein was replaced by the
mallow protein. The control group showed slightly higher protein and fat contents than
the tested groups. The differences in PER were not significant (P>O.OS) among
groups fed diets No.1, 2 and 3. While differences were significant (P diets No. 1 and 3 on one side and diet No. 4 on the other side. Diets with higher
inclusion levels of mallow (diets 3 and 4) significantly depressed growth performance
of the fish (SGR 1.S2%/day) in both groups compared to diets 1 and 2 (SGR: 1.74%
and 1.68%/day, respectively). There were differences in muscular area among diet 1
and other treated groups showed larger muscular area for the control and those fed
on 10% mallow than for those fed on 20 and 30% mallow. There were also differences
in organs weight among fish groups, where higher indices were calculated for groups
fed diets 1 and 2 than for diets 3 and 4. The 20% inclusion level of mallow realized the
lowest feed cost/kg fish gain. These results suggest that mallow can be used to
substitute up to 10% of dietary protein in Nile tilapia diets without significant reduction
in growth.