The study of using herb extracts supplemented feed to increase yield of Nile tilapia with
0.5% (w/w) of garlic and garlic-mix extract for 16 weeks. There were 3 experimental groups; control
that fed with normal organic feed (C), group that fed with garlic extract added organic feed (T1), and
group that fed with garlic-mix extract added organic feed (T2). Sampling fishes were separated to be
2 sizes; Large and Small.
For growth parameters at the end of the experiment (16 weeks), it was found that the mean
of body weight (weight, g) of the T2-Large group was larger than the others statistically (p <0.05).
The weight gain (%) was significantly high in T1-Small and T2-Small (p <0.05). For specific growth
rate (SGR), groups that fed with herb extracts (T1-Large, T1-Small, T2-Large and T2-Small) were
significantly higher than the control group (p <0.05). For average daily gain (ADG), T2-Large group
was significantly higher than the others (p <0.05)
For efficiency of blood system, it was found that the means of haematocrit at 16 weeks of
large fish groups (C-Large T1-Large and T2-Large) were significantly higher than all groups of small
fish (C-Small T1-Small and T2-Small) (p <0.05). For lysozyme activity at 16 week, it was found that
value of T2-Large had higher than other groups. For SOD enzymes at 16 weeks, these values of herb
extracts fed fishes (T1-Large and T2-Large) were significantly higher than the other fish groups (p
<0.05).
For efficiency of digestive system, digestive enzyme activities (amylase, lipase, trypsin and
chymotrypsin) and intestinal histology was measured. For amylase activity, it was found that these
values of large fish groups (C-Large, T1-Large and T2-Large) in each week were significantly higher
than those of the small fish groups (C-Small, T1-Small and T2-Small) (p <0.05). Moreover in herb
extract fed group (T1-Large, T1-Small, T2-Large and T2-Small) was significantly lower than control
group (p <0.05).
For lipase activity in the initial week, there was no significant difference (p> 0.05). During
supplemented herbal extracts, it was found that the garlic-mix fed group (T2-Large and T-Small) had
high values. At the end of experiment, these values of T2-Large was significantly highest (p <0.05).For trypsin activity, at the initial week, the values of large fish groups (C-Large, T1-Large
and T2-Large) were significantly higher than those of the small fish groups (C-Small, T1-Small and
T2-Small) (p <0.05). When fishes were fed with herb extracts, it was found that groups of T1-Small
and T2-Small had higher values than the other groups (p <0.05). At the end of experiment, C-Large
had significantly the lowest value (p <0.05).
For Chymotrypsin activity, it was noticed that these values of each week were different. At
initial week, there was no significant difference (p> 0.05). During supplemented herbal extracts, it
was found that C-Large, C-Small and T1-Large had high values than other groups (p <0.05). At the
end of experiment, C-Large had significantly highest (p <0.05).
For trypsin activity / chymotrypsin activity (T / C ratio), it was found that the low values
were small fish group (C-Small, T1 -Small and T2-Small). At the end of experiment, T2-Small had
significantly the highest value (p <0.05). In each period, the herb extract fed group (T1-Large, T1-
Small, T2-Large, and T2-Small) was significantly higher than the control group (C-Large and CSmall)
(p <0.05).
For histology of intestine, it was found that these of both large and small groups fed with
herb extracts (T2-Large and T2-Small) showed obviously change with complete tissue structure than
the other groups.
For histological changes in intestinal region, T2-Large group showed the maximum villi
length at week-12 of 236.03 ? 64.47 mm, but no significant different from other large groups (p>0.05).
In C-Small group, it showed significantly from the other small fish group with the highest villi length
at week-12 of 203.47 ? 15.99 mm (p <0.05).
For final harvest, the control group (C) had the final harvest of 51.6 kg. The garlic extract
group (T1) had the final harvest of 52.1 kg. Whereas the garlic-mix extract group (T2) had the final
harvest of 62.3 kg. It showed that T2 increase the total harvest of 20.7% from the control group.
In conclusion, formula of garlic with other herb extract showed significantly increasing the
yield of Nile tilapia that fed with organic food (P <0.05). This extract was able to accelerate growth
in small fish during culture.