Mahmoud Nafisi Bahabadi

The objectives of the present study were to evaluate some factors such as growth performance, survival rates, food conversion ratio (FCR), protein efficiency ratio (PER), specific growth rate (SGR), net protein utilization (NPU) and nutritional values of rainbow trout (Oncorhynchus mykiss) larvae, fed on pellets incorporated with a commercial probiotic “BioPlus 2B”. This product contains two stains of bacteria viz., Bacilus subtilis and Bacillus licheniformis. For experimental feeding, 12,000 numbers of rainbow trout larvae having mean weight of 400 mg were held in 12 Californian troughs as six treatments with two replications at a density of 1000 nos. per trough. Fish were fed with probiotic supplemented (at 0, 0.1, 0.2, 0.5 0.75 and 1% levels) pellet diets for a period of 36 days. The results showed that there was significant correlation between increasing rate of probiotics fed and some parameters like weight gain (WG), growth rate (GR), SGR and NPU in the experimental treatments. On termination of the experimental feeding, it was observed that increasing level of probiotics in the diet had a direct relation with protein content of the larvae and inverse relationship with lipid value.