Development of growth rate, body lipid,moisture,and energy models for white sturgeon (Acipenser transmontanus) fed at various feeding rates

The objectives were to develop and evaluate: 1) growth rate models, 2) body lipid, moisture, and energy models for white sturgeon fed at various feeding rates(FR; % body weight [BW] per day) and then evaluate responses at proportions of optimum feeding rate(OFR) across increasing BW(g). For objective1,19 datasets from the literature containing initial BW, FR and specific growth rate(SGR; % BW increase per day) were used. For objective 2.12 datasets from the literature(11 from objective 1) containing SGR,FR,final BW,body lipid(%),protein(%),ash(%),moisture(%),and energy(kJ/g) were used. The average rearing temperatures was 19.2 ± 1.5 ℃(mean ± SD). The average nutrient compositions and gross energy of the diets were 45.7 ± 4.3% protein,14.8 ± 3.2% lipid, and 20.4 ± 1.3 kJ/g,respectively. The logistic model was used for objectives 1 and 2 to develop a statistical relationship between SGR and FR, then an iterative technique was used to estimate OFR for each dataset. For objective 2, the statistical relationship between body lipid, energy, and moisture and FR was established. Using the OFR estimate, SGR, body lipid, energy and moisture were computed at various FR as a proportion of OFR, Finally, a nonparametric fitting procedure was used to establish relationships between SGR, body lipid, energy and moisture(responses)compared with BW(predictor) at various proportions of OFR. This allows visualization of the effect of under-or over-feeding on the various responses. When examining the differences between OFR at 100%and various proportions of OFR, SGR differences decrease and moisture differences increase as BW increases. Lipid and energy differences decrease as BW increases. To our knowledge, these are the first description of changes in nutrient compositions when white sturgeon are fed at various FR. Because physiological and behavioral properties that are unique to sturgeon, results from this study are specific to sturgeon under the conditions of this study and cannot be compared directly with salmonids even if some of the results are similar. This research provides insight to designing future nutritional studies in sturgeon.

SuperSAGE digital expression analysis of differential growth rate in a European sea bass population

One of the goals of the aquaculture industry is to understand and control growth associated traits through selective breeding.In the present study the molecular basis of growth heterogeneity in the European sea bass(Dicentrarchus labrax)was addressed.To establish growth heterogeneity in a group of hatchery bred sea bass individuals were tagged and their specific growth rates(SGR)determined at monthly intervals.Gene expression in the brain,liver and white muscle from fish with the most divergent sustained SGR(6 individuals of the first and last quartile)was assessed using SuperSAGE(Serial Analysis Gene Expression)combined with next generation SOLiD4 sequencing.A total of approx.11 million edited tags(26 bp),on average 2 million tags per SAGE library,that represented 47.071 unique transcripts were identified.Comparison of transcripts in fish with high and low SGR yielded 344,698 and 601 differently expressed tags(0.01%false discovery rate and 4-fold change)in brain,liver and muscle,respectively.The tags were mapped onto the sea bass genome and approximately one third of the tags could be assigned to annotated genes.Pathway enrichment analysis revealed in liver,muscle and brain intricate gene expression changes in endocrine regulatory pathways involved in growth,metabolic and the stress axis,underlying divergent SGR in sea bass.

Ascertaining the potential effects of temperature on growth,survival and feeding of different juvenile clown fish

Objective:To determine the physiological and ecological responses of marine ornamental fishes to the change of water temperature with its potential effects on the growth,survival and feeding in clown fish.Methods:Three different sea anemone fish(Premnas biaculeatus,Amphiprion clarkii,Amphiprion akallopisos)were reared in confinement at water temperatures of 26,28,30,32,and 34℃using thermostat and they were maintained up to the marketable size,and growth,survival and feeding were evaluated during the experimental period.Results:The results illustrated that water temperature influenced the physiological performance of juveniles of three different sea anemone fish significantly.The growth and survival rates of juveniles of three different clown fish significantly increased with the increase of water temperature from 26℃to 34℃(P<0.05).Water temperature also influenced the feeding of three different clown fish significantly with feed conversion ratio increased from(0.071±0.020),(0.075±0.030)and(0.079±0.028)to(0.057±0.040),(0.047±0.030)and(0.045±0.028)for Premnas biaculeatus,Amphiprion clarkii and Amphiprion akallopisos respectively with increase of water temperature from 26℃to 34℃(P<0.05).Specific growth rates(P<0.05)increased significantly with increase of water temperature and positively correlated with the feed conversion ratio,indicating that growth rates are significantly increased with increase of temperature.Conclusions:This study deliberately reveals that the physiological response of juveniles of clown fish as the change of water temperature and substantiated that water temperature influenced juvenile growth,survival and feeding significantly.This study also put forward that the reduced growth,survival and feeding of juveniles at lower temperature which have ecological impacts on clown fish juveniles in settlement and population replacement in the wild.