Effect of Dietary Cod Liver Oil on Growth and Fatty Acids of Juvenile Hybrid Tilapia

Abstract

An 8‐week growth trial was conducted to determine the effects of different levels of cod liver oil (CLO) on growth and tissue fatty acids of male hybrid tilapia (Nile tilapia Oreochromis niloticus × blue tilapia O. aureus). Eight isonitrogenous and isoenergetic diets containing various percentages of dodecanoic acid and CLO (5.0:0, 4.5:0.5, 4.0:1.0, 3.5:1.5, 3.0:2.0, 2.0:3.0, 1.0:4.0, 0:5.0) were fed to triplicate groups of tilapia with an initial body weight of 0.83 g (SD = ±0.03). The fish were kept at 26 ± 1°C in aquaria connected to a freshwater water‐recirculating system. Tilapia fed diets with 2.0% or more CLO had a significantly (α = 0.05) higher specific growth rate, feed efficiency, and protein deposition than those fed diets with lower CLO. Percent muscle and liver fatty acid 18:3, n‐3 (where the ratio is the number of carbon atoms to the number of double bonds, and n designates the position of the first double bond); 20:5, n‐3; 22:5, n‐3; and 22:6, n‐3 increased with increasing CLO, but 20:3, n‐9 decreased significantly. Tilapia fed a diet without any CLO had significantly lower growth performances and showed a typical n‐3 deficiency, with the ratio of liver (20:3, n‐9) and muscle (22:6, n‐3) fatty acids greater than 0.4. This study lends more support to our previous report that besides n‐6, hybrid tilapia may also require n‐3 fatty acids for maximum growth.

Effect of dietary n-3 HUFA on growth performance and tissue fatty acid composition of gibel carp Carassius auratus gibelio

“…2006). However, many other studies reported that substitution of FO with other lipid sources would decrease flesh n‐3 HUFA (Chou et al. 2001; Bell et al.…”

“…1983). There are two possible reasons accounting for this: (i) the higher n‐3 HUFA in the diets was highly susceptible to oxidation and might led to poor palatability or digestibility (Chou et al. 2001; Du et al.…”

Effect of altering linoleic acid and linolenic acid dietary levels and ratios on the performance and tissue fatty acid profiles of Nile tilapia Oreochromis niloticus fry

“…Hybrid tilapia fed a CLO diet showed a slight depression in growth and feed efficiency ratio that might be associated with the higher n-3 PUFA concentrations found in CLO (Ng et al 2001). Chou et al (2001) reported no growth depression in hybrid tilapia fed semi-purified Experimental conditions: water changed three times weekly, temperature was maintained at 28-32°C by using heater, and ammonia concentration was maintained at less than 0.3 mg/l with pH of 8.00. The fish were fed to apparent satiation diets with graded levels of CLO for up to 5% and suggested that hybrid tilapia may also require n-3 FAs for maximum growth.…”

“…Huang et al (1998) found that growth rates of hybrid tilapia fed soybean oil and fish oil were similar and both were better than that of fish fed lard or HUFA. In contrast, studies by Chou and Shiau (1999) and Chou et al (2001) demonstrated that hybrid tilapia, in addition to their requirement for n-6 FAs, required EPA and/or DHA. To evaluate the requirements of FAs, several different means of altering the LA/LNA ratios have been developed in human and animal models (Blank et al 2002).…”

“…Selection of the three types of oil was based on the fact that both n-6 and n-3 series of FAs are dietary essential for tilapia Shiau 1999 andChou et al 2001). Therefore, linseed oil (L) is rich in n-3 acids, while soybean oil (S) and corn oil (C) are rich in n-6 acids.…”