Rodrigue Yossa

Effects of dietary biotin and avidin on growth, survival, feed conversion, biotin status and gene expression of zebrafish Danio rerio.

A study was conducted to investigate the effects of dietary avidin on growth, survival, food conversion, biotin status and gene expression of zebrafish (Danio rerio Hamilton-Buchanan) juveniles (average wet mass 0.178 g) fed 7 purified diets for 12 weeks. Experimental diets were formulated to provide 0×, 1×, 15×, 30×, 60× and 120× excess avidin versus biotin kg(-1) diet, on a molar basis; a control diet contained neither supplemental biotin nor avidin. Fish fed the control diet had the lowest percentage weight gain and the highest mortality, while the highest percentage weight gain and the lowest mortality was observed with the 0× diet (P<0.05). A linear relationship was observed between feed conversion ratio (FCR) and dietary avidin (r=0.876; P<0.0001). Fish fed diets with 120× more avidin than biotin had the highest whole-body biotin content, while the lowest value was obtained with the control and avidin-free diets (P<0.05). Elevated levels of acetyl CoA carboxylase-A (acca), methylcrotonyl CoA carboxylase (mcc) and propionyl CoA carboxylase-A (pcca) transcripts were recorded in fish fed the control diet, in comparison to the other diets. A broken-line analysis indicated that feeding zebrafish a diet with 60 times more avidin than the dietary biotin requirement level will cause biotin deficiency signs.

Preliminary evidence of the contribution of the intestinal microflora to biotin supply in zebrafish Danio rerio (Hamilton-Buchanan).

A study was conducted to preliminarily assess the contribution of the intestinal microflora to biotin supply in zebrafish. Biotin and avidin were added to three isonitrogenous and isocaloric purified diets to provide molar avidin: biotin ratios of 0:0 (basal diet), 0:1 (biotin-supplemented diet), and 120:0. Another diet was made by supplementing the antibiotic succinylsulfathiazole (1%, wt/wt) to the basal diet. A fifth diet was the Zeigler commercial diet for zebrafish. Each diet was fed to a triplicate group of fish (mean initial mass 0.266 g) for 8 weeks. The condition factor, feed conversion ratio (FCR), percentage weight gain, and survival were similar in fish groups fed the commercial and the biotin-supplemented diets, but energy conversion efficiency and whole-body biotin content were highest in the fish fed the commercial diet (p<0.05). Reduced growth and survival, and increased FCR were noted in fish fed basal diet compared with those fed biotin-supplemented diet. The supplementation of avidin in diet led to lower survival and condition factor, and higher FCR than that observed with basal diet. Intestinal microbial synthesis is assumed to be a significant source of biotin to the zebrafish, as fish fed the antibiotic-supplemented diet showed the lowest growth, health condition, and feed utilization.

Combined effects of diets and temperature on mitochondrial function, growth and nutrient efficiency in rainbow trout (Oncorhynchus mykiss)

A 4×3 factorial experiment was conducted to evaluate the effects of two dietary protein sources (mixed fishmeal/plant protein-, and plant protein- based diet), two dietary lipid levels (10% and 20%) and three water temperatures (10°C, 14°C, and 18°C) on the growth performance, nutrient utilization efficiencies and mitochondrial enzyme complex activities in rainbow trout Oncorhynchus mykiss (average weight±SD, 39.5±5g) over a 180day rearing period. At the end of the experiment, weight gain (WG), condition factor (CF), and feed efficiency (FE) were significantly affected by diet×temperature interaction (P<0.05). Specific growth rate (SGR) was significantly affected by increasing temperature (P<0.05). The plant protein-based diets led to a higher CF than the mixed fishmeal/plant protein-based diets. The protein productive value (PPV), protein efficiency ratio (PER), lipid efficiency ratio, (LER) and lipid productive value (LPV) were all significantly affected by diet×temperature interaction (P<0.05). The diet×temperature interaction also had significant effects on mitochondrial enzyme complexes II, V and citrate synthase in the liver, complexes II and IV in the intestine, and complex IV in the muscle (P<0.05). Temperature had a significant main effect on the activity of the enzymatic complexes I and III in the liver, complex III and citrate synthase in the intestine, and complexes I, II, III, V and citrate synthase in the muscle (P<0.05). Diet had a significant main effect on complexes I and III in the liver, complexes II and III for the intestine and complexes I and II in the muscle (P<0.05). The significant temperature x diet interaction observed has practical ecological implications explicitly demonstrating how changes in temperature regimens as anticipated in the rising global temperature can influence organismal performance in relation to changes in dietary formulations (replacing fishmeal based diet with plant protein based ingredients). To illustrate the practical application of the observations from this study, the most economical and cost effective way to produce rainbow trout would be to use 40/10PP diet at 14°C because fish fed this treatment had a weight gain comparable to that of the fish fed the more expensive experimental diets (40/10 FM/PP, 40/20 FM/PP, and 40/20 PP).

Effects of dietary lipid levels on mitochondrial gene expression in low and high‐feed efficient families of rainbow trout Oncorhynchus mykiss

A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on mitochondrial gene expression in mixed sex rainbow trout Oncorhynchus mykiss. Practical diets with a fixed crude protein content of 42%, formulated to contain 10% (42/10), 20% (42/20) and 30% (42/30) dietary lipid, were fed to triplicate groups of either low-feed efficient (F129; mean ± s.d. = 105.67 ± 3.04 g initial average mass) or high-feed efficient (F134; mean ± s.d. = 97.86 ± 4.02 g) families of fish, to apparent satiety, twice per day, for 108 days. At the end of the experiment, diets 42/20 and 42/30 led to similar fish condition factors, which were higher than that observed with diet 42/10 (P < 0.05). F134 fish fed diet 42/10 showed the highest hepato-somatic index, while there was no significant difference among all the other treatments (P < 0.05). When the group of F134 fish fed diet 42/10 was used as the calibrator for gene expression analysis, the five genes selected for their involvement in lipid metabolism (complex I-nd1, complex III-cytb, complex IV-cox1, complex IV-cox2 and complex V-atp6) were up-regulated in the muscle and down-regulated in both the liver and the intestine. There was a significant family × diet interaction regarding nd1, cox2 and atp6 in the liver; nd1, cytb, cox1, cox2 and atp6 in the intestine, and nd1, cytb, cox1, cox2 and atp6 in the muscle (P < 0.05). The overall results of this study constitute basic information for the understanding of molecular mechanisms of lipid metabolism at the mitochondrial level in fishes.

A Practical Approach for Sexing Zebrafish, Danio rerio

This study aimed at a simple, rapid, reliable, practical, and non-destructive sexing technique for mature zebrafish (0.61 ± 0.011 g each). In the first experiment, 36 fish of each sex were selected on the basis of the presence of a prominent genital papilla on mature females and bred randomly. All the couples laid fertilized eggs with a mean fecundity of 304 eggs per female, for a 100% sexing accuracy. In the second experiment, 140 mature zebrafish were randomly selected and individually sexed like in the first experiment. Each fish was then dissected in order to confirm the reliability of this sexing technique through the observation of either the ovaries or the testes. Upon dissection, an accuracy of 100% was recorded. This study demonstrates that sexing mature zebrafish only on the basis of the presence of a prominent genital papilla on the mature female is a reliable technique.

Preliminary evaluation of purified lignin and hemicellulose as prebiotics candidates for Atlantic Salmon, Salmo salar L [Latest Articles]

ABSTRACT A study was conducted to investigate the potential of purified lignin and hemicellulose as prebiotics in diets for Atlantic salmon, Salmo salar L., postsmolt in seawater (30 ppt) at 14.9 ± 1.2°C. Triplicate groups of fish (initial individual body mass of 101.6 ± 1.2 g) were fed either the fishmeal-dense (32% of fishmeal) control diet (A) or one of the nine diets (15% fishmeal) supplemented with lignin:hemicellulose ratios (% diet:% diet) of 0.05:0 (B), 0.25:0 (C), 0.50:0 (D), 1.00:0 (E), 0:0.05 (F), 0:0.25 (G), 0:0.50 (H), 0.05:0.25 (I), and 0.25:0.50 (J) for 12 weeks in a complete randomized experimental design. At the end of the experiment, the thermal-unit growth coefficient (TGC) was significantly lower in salmon fed diets with 0.50% and 1.00% purified lignin than those fed the control diet, while there was no significant difference between the other treatments and the control diet (P < 0.05). The feed efficiency (FE) was significantly lower in salmon fed diets with 0.50% and 1.00% purified lignin and 0.05% hemicellulose than those fed the control diet, while there was no significant difference between the other treatments and the control diet (P < 0.05). The hepatosomatic index (HSI), intestinal villus length, and apparent digestibility coefficient (ADC) of nutrients in diets were similar (P > 0.05) among all the diets. This study demonstrated that inclusions of up to 0.25% of dietary purified lignin alone, and 0.25%–0.50% of dietary hemicellulose alone or in combination with dietary lignin can be considered as candidate prebiotics in Atlantic salmon nutrition.

Journal of Applied Aquaculture: 25 years of disseminating applied aquaculture research

The Journal of Applied Aquaculture (JAA) was founded by Dr. Douglas Tave in 1991. In those days, the first publisher of JAA, Haworth Press, recognized the necessity to establish an academic platform that would specifically focus on sharing practically, financially, and logistically viable solutions to the observable aquaculture problems. Since 2008, JAA has been published by Taylor & Francis Group, LLC. Dr. Douglas Tave served as the first Editor-in-chief of JAA from 1991 to 2010; thereafter, Dr. Randall Brummett occupied this position from 2010 to 2011 and from 2012 to 2015, while Dr. Yolanda J. Brady held this position from 2011 to 2012. Since the publication of its first issue in 1991, JAA has received thousands of manuscripts dealing with practical aspects of aquatic plant and animal productions, as well as findings related to the use of aquaculture development strategies to achieve economic and food security objectives throughout the world. Thanks to the generous contributions of its authors, reviewers, and Associate Editors, as well as the support of the publisher, JAA is currently one of the leading peer-reviewed journal for disseminating practical information generated through applied research, which supports the sustainable growth of the global aquaculture. Over the last 25 years, JAA has undergone several technology milestones, in accordance with the advances in information technology. Between 1991 and 2010, JAA was published in printed only; since 2010, the journal is published both in print and online. In addition, between 1991 and 2011, manuscript packages were submitted directly via emails or mails to the Editor-in-Chief; since 2011, JAA uses ScholarOne Manuscripts to manage all the manuscripts from submission to production. Moreover, since 2008, the authors have the option to publish their articles Open Access in JAA, for a fee. With the growing reputation of JAA, the publisher (Taylor & Francis Group, LLC) keeps on improving the journal’s features, in order to make the interactions between the authors, reviewers, and editors of JAA more ethical and efficient. Among the most relevant features implemented by the publisher in 2016 only, there are:

Approaches for controlling sea lice infestation in global salmon farming: What is applicable in Canadian aquaculture industry

ABSTRACT This article describes the sea lice control methods that are currently applicable to salmon farming in Canada. Three commercial chemical products are approved for use against sea lice in Canada: Slice®, Interox® Paramove® 50, and Calicide®. Physical control methods include photoperiod and cage-depth manipulations, desiccation of farm equipment, and the use of electric fences. Biological control measures include the polyculture of salmon with wrasse or mussel. Nutraceuticals and immunostimulants shown to reduce sea lice infestations in salmon include unmethylated DNA, yeast fermentation extract-Brewer’s yeast compound, AllBrew and NuPro, MacroGard®, and Optimûn®. Salmon farmers are recommended to use site-specific integrated approaches, by properly adapting a combination of chemical, physical, biological, and nutritional measures to the environmental and financial characteristics of their farm. In the future, development of vaccines against sea lice and of salmon lines resistant to sea lice will play a pivotal role in fighting against this parasite.

Writing a Scientific Manuscript from Original Aquaculture Research

Good presentation of a manuscript is essential for its fast and successful editorial review. A well-written and thoroughly organized manuscript is easy to read and presents data in a manner easy to understand without a lot of repetition. Editors and reviewers are more inclined to engage with authors to improve scientific quality of well-presented manuscripts, further increasing the chances of publication. Although general approaches to scientific writing have been published, little attention has been focused on scientific writing in aquaculture research. Here, we provide students and less-experienced aquaculture researchers with some insights on research organization and manuscript presentation in order to improve their chances of getting their research into print.