Effects of Crude Extract of Azadirachta indica Leaves at Controlling Prolific Breeding in Oreochromis niloticus (Linnaeus, 1758)
Tilapias are yet to reach their full aquaculture potential because of the problem of prolific breeding which usually results in overpopulation thus leading to stunted growth. The potential use of Azadirachta indica leafs as an antifertility substance in controlling prolific breeding in Oreochromis niloticus was investigated. Crude extract of Azadirachta indica leaves were added to a basal diet (35% crude protein) at 0.0, 0.5. 1.0, 2.0, 4.0 and 8.0 g kg-1 diet, respectively (D1, D2, D3, D4, D5 and D6) and fed to 180 Oreochromis niloticus (90 males and 90 females) Mean±SD weight of 29.30±2.02-31.79±3.11 g twice daily (0900-0930, 1700-1730) at 3% of their body weight for 56 days to evaluate the effects on growth and reproduction. There was variation (p<0.05) in growth parameters with fish fed 1.0 g kg-1 diet showing best Mean±SD weight gain of 19.68±3.22 g. A total of 63-89 hatchlings were counted in the control tank in the 3rd week and 35-51 hatchlings from fish fed with 0.5 g kg-1 diet in the 5th week, there was no breeding in the groups; D3, D4, D5 and D6 during the course of this study. This study infers that Azadirachta indica leafs extract could be used in controlling prolific breeding in Oreochromis niloticus for efficient and sustainable development of tilapia farming.
Received: August 15, 2011;
Accepted: November 02, 2011;
Published: December 16, 2011
Tilapia constitutes one of the most productive and internationally traded food
fish in the world (Modadugu and Belen, 2004). They serve
as a major source of animal proteins especially in the developing countries.
Tilapias are however yet to reach their full aquaculture potential because of
the problem of prolific breeding which usually results in overpopulation thus
leading to stunted growth, this uncontrolled reproduction have also be observed
to lead to the production of fish with low nutritional and commercial values
(Beardmore, 1996). This fish has been observed to reach
sexual maturity at about 20 g of body weight (Mairs and Little,
1991), the female have also been observed to spawn every 4 to 6 weeks (Balarin
and Hatton, 1979). For efficient and sustainable development of tilapia
farming there is need to control its prolific breeding. Mairs
and Little (1991) and Guerrero (1982) reviewed population
control methods in cultured tilapia, such control methods include; manual sexing,
cage culture, high density stocking, use of predators, intermittent/selective
harvesting, among others. However, these methods have their limitations for
example in manual sexing it has been observed that it is difficult for even
the most skilled workers to achieve greater than 90% accuracy in sexing and
so breeding and reproduction is rarely completely controlled, use of hormones,
irradiation and chemosterilant; these have been observed to be expensive and
to cause apprehension among consumer as to their safety and cage culture have
been observed to prevent recruitment rather than stopping breeding so losses
to reproduction effort will still exert a negative influence on growth.
In the recent years, there has been a gradual revival of interest in the use
of medicinal plants especially in developing countries because herbal medicines
had been reported to be safe, biodegradable and environmentally friendly especially
when compared with synthetic drugs. Many plants have been found to possess the
property of preventing conception orally. Meymand et
al. (2002) observed delay in the reproduction of rats that were administered
with Azadirachta indica seed extract, Nusier et
al. (2007) observed a decrease in the number of spermatocytes and spermatids
in the group of rats that receive higher dose of Rosmarinus officinalis leaves
extracts. Jegede (2010) observed that Hibiscus Rosa-sinensis
(Linn) leaf meal could be used in controlling reproduction in Oreochromis
niloticus. Azadirachta indica is a fast-growing tree that can reach
a height of 15-20 m, usually evergreen tree, with a fairly dense crown and a
globrous leafs divided into leaflets. The bark is fairly thick, furrowed longitudinally
or obliquely and it is dark grey outside and reddish brown inside, the opposite
pinnate leaves are 20-40 cm long, the terminal leaflet is often missing, the
petioles are short. The aim of this study was to evaluate the effects of Azadirachta
indica leaves extract at controlling prolific breeding in Oreochromis
MATERIALS AND METHODS
Experimental site: This study was carried at Kwara state Ministry of Agriculture and natural Resources hatchery farm Ilorin, Kwara state, Nigeria. Ilorin is the state capital of Kwara state located in north western Nigeria on latitude 08°l30N and longitude 04°35E.
Identification and preparation of plant materials: Azadirachta indica
fresh leaves were collected within University of Ilorin campus, Ilorin, they
were authenticated at the herbarium section of Department of Plant Biology University
of Ilorin, Nigeria. The fresh leafs were shade-dried between 2-3 weeks. The
dried leaves were ground into fine powder using a blender and then sieved. The
crude ethanol extract was prepared as described by Musa
et al. (2000) with little modification, 100 g of the dried powdered
leaves was soaked in 250 mL of ethanol for 24 h and the filtrate was concentrated
into jelly-like semi solid substance in an oven at a temperature of 40°C
between 3-4 h and then stored in the refrigerator till when needed.
Preparation of experimental diets: The feedstuffs were obtained locally
from the market. Basal feed was formulated to provide 35% crude protein as shown
in Table 1. Azadirachta indica leaves extracts were
added to the basal diet at 0.5, 1.0, 2.0, 4.0 and 8.0 g kg-1 diet,
respectively. The feedstuff were thoroughly mixed in a pelleting/mixing machine,
hot water was added at intervals to gelatinized the starch, feeds were pelletized
using 2 mm diameter die, air dried and each packed in a labeled polythene bag
and stored in the refrigerator till when needed. The proximate compositions
of the experimental diets were analyzed using AOAC (1990)
method of analysis.
Experimental design: One hundred and eighty Oreochromis niloticus
of Mean±SD weight 29.30±2.02-31.79±3.11 g were obtained
from Kwara state Ministry of Agriculture and Natural Resources Hatchery Farm
Ilorin, Kwara state, Nigeria. Fishes were acclimatized for one week, after acclimatization
they were divided into six groups D1, D2, D3, D4, D5 and D6, respectively (also
representing the six experimental diets with D1, serving as the control group)
each group was replicated three times, each replicate consist of 10 fishes,
these were stocked in out door concrete tanks (2x2x1.25 m) supplied with 450
L of water. Fish were fed 3% of their body weight/day with the diets at two
installments between 0900-0930 and 1700-1730 for 56 days. Tanks were drained
and washed twice a week and replenished with fresh water. Water parameter which
include dissolved oxygen, pH and temperature were monitored biweekly.
Hatchling count: Total count of the hatchlings was done in each of the tanks that breeding occurred.
Data analysis: All data were analyzed using one-way ANOVA and students t-test as contained in the SPSS 16.
Table 1 shows that inclusion of crude extract of Azadirachta
indica leaves at different level did not significantly alter the proximate
composition of the experimental feeds. In Table 2 there was
variation in the growth parameters (p<0.05), with the group fed 1.0 g kg-1
diet having the best Mean±SD weight of 21.63±3.21 g, while the
Lowest±SD weight gain of 13.48±2.51 g was observed in the group
that received the highest level of inclusion of the plant extract (8.0 g kg-1
of diet), the food conversion ratio of groups D2 and D3 showed no significant
difference. The crude extract was also observed to reduces the number of hatchlings
in Oreochromis niloticus as shown Table 3, fish from
the control group spawned twice with hatchling counts of 69.75±15.44
while fish that received the lowest inclusion level of 0.5 g kg-1
diet spawned once with fewer numbers of hatchlings (42.75±7.14) statistical
analysis showed a significant difference between them (p<0.05), there was
no spawning observed in the groups; D3, D4, D5 and D6, respectively during the
course of the study.
|| Ingredients and proximate composition of experimental diets
|Vitamin/mineral premix: Vitamin A, I.U.; Vitamin D, 11252U;
Vitamin E, 71 U; Vitamin K3, 2 mg; Vitamin B12, 0.015 mg; Panthothenic acid
5 mg; Nicotinic acid 14 mg; Folic acid, 0.4 mg; Biotin, 0.04 mg; Choline,
150 mg; Cobalt 0.2 mg; Copper, 4.5 mg; Iron, 21 mg; Manganese, 20 mg; Iodine,
0.6 mg; Selenium, 2.2 mg; Zinc, 20 mg; Antioxidant, 2 mg
|| Growth Performance and Feed Utilization by Oreochromis
niloticus fed with Azadirachta indica leaves extract
|aPercentage weight gain = (final wt./-initial wt.)x100,
bAverage Daily Growth (g) = (final wt.-initial wt.)/No. of days,
cSpecific growth rate (% day-1) = (In final wt.-In
initial wt./No. of days)x100, dFood conversion ratio = feed intake/body
weight gain, eProtein efficiency ratio = wt gain of fish/*protein
consumed, *Protein consumed was calculated as the difference between the
quantity of feed fed and the left over on dry matter basis. Different letters
with in the same row show significant different at p≤0.05
|| Number of hatchlings
||Water parameter of Oreochromis niloticus fed with crude
extract of Azadirachta indica
|Different letters show with in same row significant difference
The Mean±SD of the temperature, pH and dissolved oxygen were 27.9±0.7°C-28.9±0.12°C,
7.49±0.03-7.69±07°C and 4.9±0.08-5.6±0.2°C,
respectively, there was no significant difference (p>0.05) between the temperature
and dissolved oxygen across the group but the pH was observed to slightly increase
in the groups that received the crude plant extracts (p<0.05) as shown in
Negative effects on growth was also observed at a higher level of inclusion
similar results was also obtained by Ibraheem et al.
(2007) when Mangifera indica leaves extract was fed to rats. The
phytochemical screening of these leafs by Biu et al.
(2009) showed a high concentration of saponin, moderate concentration of
tannin and glycosides while alkaloids, terpenes, flavonoids reducing sugar and
pentoses showed low concentration. Saponin from other plant source had been
reported to have negative effect on reproduction (Benie
et al., 1990; Chen et al., 1998; Francisa
et al., 2005; Luckstadt and Primavera-Tirol,
2006) thus the saponin content of this leafs could have been responsible
for the effect observed on the reproduction. Several plant extracts had also
been reported to either suppresses or promote growth in some experimental animals,
however the result showed an increase in weight gain with increase in inclusion
level up to 1.0 g kg-1 and a decrease in weight gain as the inclusion
level increased to 8.0 g kg-1 this conform with the work of Wankar
et al. (2009), who observed higher body weight gain in broilers fed
with Azadirachta indica leaves as compared with the control. The water
quality parameters during this study were within the acceptable range for tilapia
culture (Ross, 2000).
This study infers that for a sustainable development in tilapia culture crude extract of Azadirachta indica leaves could be use to control prolific breeding in Oreochromis niloticus with little of no negative effect on growth.
The authors sincerely thank the management of Kebbi State University of Science and technology for the sponsor.
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