EFFECTS OF DIFFERENT LEVELS OF COMMERCIAL PRODUCT OF PROBIOTIC AND STOCKING DENSITY ON GROWTH PERFORMANCE, SURVIVABILITY AND FEED UTILIZATION OF MONOSEX NILE TILAPIA (OREOCHROMIS NILOTICUS L.) FRY DURING THE REARING PERIOD
Ramadan A. Abou-Seif
Department of Aquaculture, Central Laboratory for Aquaculture Research, Agriculture Research Center, Egypt.
Received 2/ 8/ 2011
Accepted 18/ 9/ 2011
Abstract
This study was carried out to investigate the effects of different levels of probiotic (Super biobuds) supplemented to the diet as a natural growth promoter and either under low or high density on growth performance, survival rate, feed utilization, total fingerlings production and economical efficiency for Nile tilapia Oreochromis niloticus during a single-stage nursery-rearing system. Four experimental diets were formulated to contain 0.0 (control), 1.0, 1.5 and 2.0 g probiotic per kg diet. The basal diet contained 35% crude protein. Monosex Nile tilapia fry averaging 0.18 g in weight were stocked at a rate of 20 and 30 fish/m3, within each density, 0.0, 1.0, 1.5 and 2.0g probiotic/kg diet were applied. Sixteen concrete ponds with 10 cm clayey loam each of 5×2.5×1.0 m were used to represent the two stocking density and the four doses of probiotic. The administration of feed was provided at a rate of 5% of live body weight of experimental fish, twice/day, 6 days a week, for 120 day. Each treatment was performed in duplicate. The obtained results revealed that diets supplemented with probiotic and maintain under low density showed significantly (P<0.05) better results of growth performance than those with the basal diet (control). Also, diet containing probiotic and fish group reared under low density resulted in significantly (P<0.05) a better productive performance as reflected in gain %, specific growth rate (SGR), relative growth rate (RGR) and feed conversion ratio (FCR), protein efficiency ratio (PER). The survival rate was enhanced due to the inclusion of probiotic in fish diets. On the other hand no significant differences (P>0.05) were observed in groups fed with probiotic supplemented diet and either under high density or low density. Moreover, using probiotic (Super biobuds) improved also the economical efficiency. Our results indicated that administration of probiotic (Super biobuds) in the diet promoted growth, enhanced survivability , decreased (improved) FCR and improved stress tolerance under high stocking density conditions suggesting its use will be beneficial for the aquaculture industry of monosex Nile tilapia fry during a single-stage nursery rearing system, that produce an adequate quantity of healthy fingerlings with lowest mortality at the beginning of the culture season for fish farmer.
Key wards: Nile tilapia, probiotic-super biobuds, stocking density, growth performance, feed utilization and survival rate.
