Effect Of Different Dietary Lipid Sources On Growth, Tissue Fatty Acid Composition And Muscles Quality Of African Catfish (Clarias Gariepinus)

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Date
2009-12
Authors
Ahmed Baghwetah, Ahmed Mohammed
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Publisher
Universiti Sains Malaysia
Abstract
This study was carried out to investigate the effects of total and partial replacement of fish oil (FO) with crude palm oil (CPO) and coconut oil (CNO) on growth performance, feed utilization, proximate composition and fatty acid composition of muscles and liver of African catfish (Clarias gariepinus). This was followed by an investigation on the effect of frozen storage on the muscle quality of fish raised on the respective test diets after 12 weeks. Five isonitrogenous (35% crude protein) and isoenergetic (19.73 kJ g-1) practical diets were formulated to contain 8% of fish oil (FO, Diet 1), crude palm oil (CPO, Diet 2), coconut oil (CNO, Diet 3), 1:1 fish oil to crude palm oil (FO/CPO, Diet 4) and 1:1 fish oil to coconut oil (FO/CNO, Diet 5). Each diet was given to duplicate groups of 90 fish with an initial weight of 6 ±0.05 gm in cement tanks until they reached the marketable size of  180 gm. Fish fed Diet 2 containing 100% CPO gave the best growth performance compared to the other treatments while those fed FO/CNO had the highest protein efficiency ratio (PER). There were no significant differences (P>0.05) for feed conversion ratio (FCR), survival rate, biological indices and yield production among all the fish fed the experimental diets. The plant based oil diets affected the muscle composition significantly at Weeks 4, 8 and 12 of the feeding trial, respectively. The muscles of fish fed CPO and CNO had the highest protein content while, the highest deposition of lipid was in fish fed FO diet. In general, the depositions of fatty acids in the muscles reflected the fatty acid composition of the experimental diets. In the fresh muscle, only post thaw drip was significantly lowest (P<0.05) for fish fed with FO while those on the FO/CPO diet had the highest amount of leaky liquid and those on the CNO Diet (Diet 5) had the softest muscles. Inclusion of dietary plant based oils reduced the lipid oxidation significantly. Only odour and chewiness attributes were affected by this replacement and all the colour values showed significant differences (P<0.05) except for the yellowness value. Frozen storage for 3 and 6 months showed, a parallel increase in post thaw drip with storage time. Increasing storage time, eliminated the differences in hardness and pH values. Lipid oxidation increased with storage time but, fish fed CPO and CNO had the lowest significant value. The sensory evaluation showed limited effect of this replacement, in odour, colour and juiciness attributes. The proximate composition was significantly affected by increase the storage time. Throughout storage time, only limited changes in fatty acids composition of the muscles were detected. This study demonstrated that, CPO and to a lesser extent CNO can be used as an alternative lipid source in African catfish diets to improve growth and feed utilization. In general both these lipid sources did not have a negative effect on muscle quality, since both of them decreased the muscles oxidation significantly.
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Keywords
Effect Of Different Dietary Lipid Sources , African Catfish
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