THE USE OF SPIRULINA PLATENSIS (MICROALGAE) AS FOOD ADDITIVES TO STIMULATE GROWTH AND IMMUNITYMODULATION FOR NILE TILAPIA (OREOCHROMUS NILOTICUS) CHALLENGED WITH PATHOGENIC BACTERIA (PSEUDOMONAS FLUORSCENCE)
Mostafa A. E. El Gammal, 1 Adel M. Shalaby 2
and Ashraf A. E. Ramadan 3
1- Fish Limnology Department,
2- Fish physiology Department
3-Fish Genetics Department, Central Laboratory for Aquaculture Research, Abbassa, Abo-Hammad, Sharqia, Egypt.
Received 8/ 2/ 2010 Accepted 24/ 3/ 2010
Abstract
This study was carried out to evaluate the effect of using Spirulina platensis as growth and immunity modulator for Nile tilapia (Oreochromus niloticus). Fingerlings of O. niloticus of weight (3.3 ± 0.2 g) were randomly distributed into 4 groups, five replicates each group at a rate 20 fish per 100L aquarium and fed by 7 % of their body weight on a diet containing either (0.0, 5, 10,15 gm of Spirulina platensis powder/kg basal diet) for 90 days. After the feeding trial, fish of each treatment were challenged by pathogenic bacteria (Pseudomonas fluorscence) which was injected Intra-peritoneal (IP) and they were kept under observation for 14 days to record any abnormal clinical signs and daily mortality rate. Final fish weight, weight gain, and specific growth rate (SGR) which increased significantly (p<0.05) with the increase of Spirulina addition in fish diets. The highest growth rate was obtained at 15g Spirulina /kg diet and the control diet produced the lowest. The fish groups fed on diet of 15g/kg diet showed the lowest feed conversation ratio (FCR ,1.03) but the control gave the highest FCR (1.45). fish fed Spirulina diet produced increased Protein efficiency ratio (PER) with when Spirulina additive increased in diet. No regular adverse effects was found in present study neither mortality nor condition factor K (p<0.05). The highest values of Hepatosomatic indices (HIS) were significantly recorded in the diet control. Carcass composition of fish fed diets supplemented th Spirulina platensis gave higher quality with less fat than control and high protein content and ash content. However, the highest red blood cells count (RBCs), haemoglobin content(HB), haematocrite value (Hct), white blood cells count (WBCs) and Nitro-Blue Tetrazolium (NBT) values were obtained at Spirulina diet, meanwhile, the lowest values were obtained in control fishes. Also, the total plasma protein and globulin values were increased by the increasing of Spirulina additives in diet before and after infection and significantly differences occurred between the treatments than that of the control. Glucose, uric acid, creatinine, Aspartate amino transeferase (AST) and alanine amino transeferase (ALT) were decreased significantly at (p<0.05) by increasing the level of spirulina in diet after infection. Total fish mortality 14 days after (IP) injection with Pseudomonas fluorscence decreased with the increased Spirulina level in fish diets. These results indicate that Spirulina supplementation is promising for disease prevention in tilapia culture and improved the growth rate and carcass quality.
Key words: Spirulina, Nile tilapia, growth performance, feed utilization, haematology,biochemical parameters, NBT, non-specific immunity, Pseudomonas fluorescence.
