Ebrahim Najdegerami, Mehran Javaheri,
Volume 12, Issue 3 (11-2012)
Abstract
Light is one of the most important environmental factors in fish life. The effect of photoperiod on the growth performances and survival of rainbow trout (Oncorhynchus mykiss) larvae and fingerlings was investigated in two consecutive experiments. In both experiments fishes were exposed to four treatments (24L/0D, 16L/8D, 8L/16D, 0L/24D) (light: dark, L: D) in three replicates. The results of first experiment indicated that photoperiod affected on the growth performances in larval stage of rainbow trout. The best weight gain and specific growth rate was observed in 24L: 0D and 16L: 8D without significant differences between them and the lowest rates was achieved in 0L: 24D. Also in second experiment, the effect of photoperiod on the growth performances was significant difference and the highest growth rate and specific growth rate was observed in 8L: 16D and the lowest in 24L: 0D and 0L: 24D. Our results showed that the effect of photoperiod in rainbow trout depends to developmental stage and larvae unlike fingerlings have better growth in long light phases.
Ebrahim Najdegerami,
Volume 15, Issue 2 (2-2015)
Abstract
Recently, concern over environmental and health effects of massive use of the antibiotics has let to growth of the bio-control agents application. Poly-&beta-hydroxybutyrate (PHB) is a natural polymer that can be depolymerized into water-soluble short-chain fatty acid monomers and acts as a microbial control agent. In this study, the effects of partially replacing the diet of Siberian sturgeon fingerlings with 2% and 5% PHB were investigated. Community level physiological profile (CLPP) was used to analyze anaerobic bacterial metabolic diversity in Siberian sturgeon fingerlings hindgut by using Biolog™ Ecoplate microplates. The results indicated that PHB increased metabolic activity in anaerobic bacteria in sturgeon hindgut. Also Lorenz curve and the Shannon index of Biolog™ Ecoplate data revealed that anaerobic metabolic potential of the bacterial community was different in the PHB-treated fishes as compared with the control situation.
