Effects of neem (Azadirachta Indica) leaf powder on intestinal hstomorphology and growth performance in Nile Tilapia (Oreochromis niloticus) fingerlings
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
The application of leaves from neem tree (Azadirachta indica) as dietary
feed additive in Nile tilapia (Oreochromis niloticus) fish is gaining
attention worldwide due to its effectiveness and minimal side effects on
the aquatic environment. As a phytomedicine has been included in
juvenile Nile tilapia diets at inclusion levels of 2–8 g/kg feed to control
reproduction, by exerting degenerative histological changes on gonadal
tissues of Nile tilapia fish. However, a slow growth rate and lowered
feed utilization were reported in juvenile Nile tilapia post-exposure to
neem compounded feeds. Therefore, this study aimed to evaluate the
effects of neem leaf powder (NLP) on intestinal histomorphology in
tilapia fish and its association with growth performance. A total of 180
Nile tilapia fingerlings were randomly distributed in four groups
(n = 30 for growth performance, n = 15 for intestinal histomorphology)
and kept in a clear-water recirculation aquaculture system (RAS). A
total of 45 fingerlings used in control groups, while 135 used in treated
groups. The fish received NLP at concentrations of 0 g, 1 g, 4 g, and 8 g
for each kilogram of Nile tilapia commercial feed and the experiment
was conducted for 90 days. Results showed that the inclusion of NLP at
4 g/Kg feed significantly (P < 0.05) enhanced weight gain (WG), percent
weight gain (PWG), daily weight gain (DWG), and specific growth rate
(SGR) in comparison to treated groups given NLP 1 g and 8 g/kg feed
and the control group. A higher survival rate (P < 0.05) was recorded in
the group fed NLP at 8 g/Kg feed. Values for intestinal
histomorphometry (villous height) in the middle/spiral intestine in the
group fed 8 g/Kg feed were significantly lower (p < 0.05) than in the
control group. Moreover, compared to the control group, the treated
group on early exposure to NLP (Days 0–3) had increased TNF-α and
single-stranded DNA (ssDNA) expression. The TNF-α was associated
with significant (p < 0.05) increased expression of TNF-α in all portions
of the intestines and pancreatic regions compared. This was reflected by the inflammatory effect in the proximal, middle, and distal intestines.
But on long-term exposure (Day 30–90), all treated groups and all three
intestinal portions experienced epithelial recovery associated with
decreased expression of TNF-α and ssDNA. In conclusion, there was
an adaptation in long-term exposure to the used NLP doses on Nile
tilapia fingerlings, and the inclusion from one up to 4 g of NLP per Kg
feed has no detrimental effect on intestinal morphology and promotes
growth and feed utilization.
Description
Dissertation
Keywords
Nile tilapia, Neem plant, Intestine, Histomorphology, TNF-α, ssDNA, Growth performance, Histomorphometry