Enhancing performance and fatty acids composition of nile tilapia (Oreochromis niloticus) through housefly maggots (musca domestica) meal cultured on aquatic macrophytes
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Date
2019
Authors
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Publisher
Sokoine University of Agriculture
Abstract
Fish forms an integral part of human diet in Tanzania being rich in protein and Omega 3
fatty acids (ω-3FAs) which are important for growth and proper functioning of human
body. The amount of ω-3FAs and performance of tilapia (O. niloticus), the most cultured
and consumed fish in Tanzania reported to be low due to inadequate of quality feeds. This
study was conducted to compare the effect of three substrates on yield and composition of
housefly maggots (HFM); assessed growth performance of O. niloticus fed HFM were
mixed with other ingridients and investigated the enhancement of omega 3 fatty acids
composition in the produced O. niloticus. The used substrates for HFM production were
poultry manure (HFMChick), Lemna species of freshwater macrophytes (HFMLemn) and
Eucheuma species of marine macrophytes (HFMEuch). The produced housefly maggots
were then used to formulate nine isonitrogenous diets with 35% crude protein and two
diets; one contained 5% of fish meal and the other diet containing soybean meal as
protein sources. Diets were named as SBM, FM, HFMChick, HFMLemn and HFMEuch,
denoting soybean meal, fish meal, and housefly maggots cultured on poultry manure,
housefly maggots cultured on Lemna species of freshwater macrophyte and housefly
maggots cultured on Eucheuma species of marine macrophyte, respectively. Eight weeks
feeding trial was carried out on triplicate groups of ten fish (1.9–2.2 g) in recirculation
aquaculture systems (RAS). Fingerlings were randomly allocated to the treatments. The
fish were fed up to 5% of their body weights twice daily from 09:30 to 09:45hours in the
morning and 16:30 to 16:45 hours evening throughout the experimental period. Effect of
inclusion levels of HFM and other diets on fish growth, feed utilization and ω-3FAs were
determined. Gas chromatography mass spectrometer (GC-MS) was used to analyze the
composition of Omega 3 fatty acids. Results showed that the yields of HFM from poultry manure and Eucheuma species of marine macrophytes (HFMEuch) substrates were
significantly higher (P<0.05) than those from Lemna species of freshwater macrophyte.
The protein content of HFM from Eucheuma species of macrophyte was significantly
higher (P<0.05) than those from poultry manure and Lemna species of freshwater
macrophyte. Fish fed on diets containing HFMEuch and FM had significantly higher
(P<0.05) growth performance compared to fish fed on HFMChick, HFMLemn and SBM
diets. Thirty two (32) types of FAs with different saturation levels were detected. The fish
fed HFM cultured on Eucheuma species had the highest composition of FAs (32)
compared to others. In conclusion, poultry manure substrates showed good result for
culturing HFM in terms of yield than other substrates.
HFMEuch achieved high
performance of O. niloticus with higher amount of ω-3FAs levels. Eucheuma species can
be used to culture HFM as alternative feed ingredient to improve performance and composition of ω-3FAs in cultured O. niloticus.
Description
M. Sc. Dissertation
Keywords
Fatty acids composition, Nile tilapia, Oreochromis niloticus, Housefly maggots, Musca domestica, Meal cultured, Aquatic macrophytes, Nile tilapia performance