Performance evaluation of blended virgin coconut oil on growth, feed utilization, body composition, body fatty acids, plasma metabolites of Nile tilapia (Oreochromis niloticus) and resistance to Streptococcus iniae challenge

Liping Liu*, Andrews Apraku, Xiangjun Leng, Emmanuel J. Rupia, Christian Larbi Ayisi
College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
 
E-mail: lp-liu@shou.edu.cn  

The use of alternative lipids as a means to spare protein activity in Nile tilapia (O. niloticus) feeds is becoming increasingly expensive due to the inadequacy and overexploitation and rising cost of fish oil (FO). However, the effect of coconut oil (CO) as alternative to FO on growth performance, feed utilization efficiency, plasma metabolites, and lipids in O. niloticus remain poorly understood.

In the present study, five isolipidic experimental diets (32% crude protein) were formulated to contain fish oil (A) and virgin coconut oil (E) as sole lipids or blends of FO+VCO in ratio of 75:25% (B), 50:50% (C) and 25:75% (D) respectively. Triplicate groups of fish were fed one of five diets to apparent satiation, twice daily for 8 weeks. No significant differences (P<0.05) were observed in growth performance, protein efficiency ratio and weight gain. However, it was observed that, fish fed diet C (FO 50:50 VCO) exhibited the best performance among all parameters measured, while feed intake and final weight was the highest in fish fed diet E. No significance (P≥0.05) was observed among biochemical parameters. Significant effects of dietary fatty acid profile reflected in those fed the diets in whole body, muscle and liver C12:0 and C14:0. However, eiccosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) were significantly different (P≥0.05) compared to their respective diets while liver n-3:n-6 ratio significantly increased and recording low levels in whole body and muscle. Plasma metabolites indicators and bacteria challenge among treatments were not altered by the inclusion of the alternative lipid. These results suggest that the inclusion of elevated levels of VCO in diets enhance growth and are viable for feeding O. niloticus.