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Tibbetts S.M.,National Research Council Canada | Wall C.L.,Center for Aquaculture Technologies Canada | Barbosa-Solomieu V.,AquaBounty Canada | Barbosa-Solomieu V.,French Research Institute for Exploitation of the Sea | And 4 more authors.
Aquaculture | Year: 2013

Full-sibling, size-matched 'all-fish' growth hormone transgenic (TG; gene construct EO-1α) and non-transgenic (NTG) Atlantic salmon (Salmo salar L.) comprised of conventional diploid (DIP) and reproductively-sterile triploid (TRIP) fish were fed the same experimental grower diet in freshwater until they tripled their weight. The study was conducted to provide baseline data on growth performance, feed efficiency, nutrient digestibility, skeletal disorders, bone ash content and bone mineral composition of NTG/DIP, NTG/TRIP, TG/DIP and TG/TRIP fish and to determine if a practical grower diet for conventional NTG/DIP Atlantic salmon requires modification for TG/TRIP fish. TG fish consumed a significantly higher amount of feed on a daily basis but due to enhanced growth rates, better feed conversion ratios and higher nitrogen retention efficiency they achieved target weight gain in a considerably shorter period (40%) than NTG fish. Total feed required to produce the same fish biomass was reduced by 25%; representative of a significant reduction in overall feed intake. Of TG fish, TRIP had some significant effects on production traits primarily due to lower feed intake relative to DIP fish. Although feed intake was lower in TG/TRIP fish, feed efficiency, digestibility and nutrient retention efficiencies were equal to those of TG/DIP fish and, without exception; TG/TRIP fish out-performed their conventional NTG counterparts, regardless of ploidy. TG/DIP and TG/TRIP fish demonstrated a higher cellular capacity to direct dietary non-protein energy towards satisfying their daily metabolic energy requirements, allowing for a higher proportion of dietary amino acids to be directed towards protein biosynthesis; rather than catabolised as a dietary energy source. Since dietary protein is the largest and most expensive component of salmon feeds and also the major source of nitrogenous pollution from salmon farming, this could represent a highly beneficial alteration of energy metabolism which could result in more economical and ecologically-sustainable Atlantic salmon aquaculture, especially when conducted in closed-containment land-based systems. Although bone ash content of TG fish was slightly lower than NTG fish, no significant differences in key bone mineral composition were observed and the occurrence of skeletal disorders was low (<. 4%), regardless of transgenics or ploidy. © 2013.

Ganga R.,Center for Aquaculture Technologies Canada | Tibbetts S.M.,National Research Council Canada | Wall C.L.,Center for Aquaculture Technologies Canada | Wall C.L.,National Research Council Canada | And 6 more authors.
Aquaculture | Year: 2015

This study assessed the capacity of non-transgenic (NTG) and growth-hormone transgenic (TG; gene construct EO-1α) Atlantic salmon (. Salmo salar L.), comprised of conventional diploid (DIP) and reproductively-sterile triploid (TRIP) fish, to utilize a diet containing relatively high amounts of plant protein (PP) concomitant with lower levels of fish meal (FM) protein. Triplicate groups of full-sibling NTG/DIP, NTG/TRIP, TG/DIP and TG/TRIP salmon (initial weight, 27-35. g) were held in freshwater and fed two experimental diets until they exceeded 400% growth. Two isonitrogenous (50% crude protein), isolipidic (21% lipid) and isoenergetic (22. MJ/kg gross energy) experimental diets were tested. The control diet (FM) contained 64 and 36%, while PP diet contained 32 and 68% of total dietary protein from FM and PP, respectively. TG and NTG fish achieved the target (>. 150. g) weight in 89 and 206. days, respectively. TG fish exhibited significantly higher specific growth rates (SGR) (2.48 vs 0.7%/day) and thermal growth coefficient (TGC) (3.04 vs 0.79) than NTG, regardless of ploidy or diet. TG/TRIP fish had significantly lower growth rates than DIP due to lower feed intake, while no ploidy effect was observed within the NTG group. Feed conversion ratio (FCR) was significantly better in TG/DIP and TG/TRIP fish having achieved the same target weight with 20-25% less feed due to improved protein utilization and retention efficiency compared to NTG fish. NTG fish had higher digestibility of protein (93% vs 89%), lipid (95% vs 94%) and energy (89% vs 85%) relative to their TG siblings, and was similar between DIP and TRIP fish. Nutrients' digestibility was significantly lower in TG fish fed PP diet than those fed FM diet, regardless of ploidy. At the end of the study, TG fish had significantly lower whole-body protein (56% vs 59%) and higher lipid (36% vs 34%) and energy (2746 vs 2694. kJ/100. g) content than NTG fish. However, as a result of the rapid growth rate and efficient feed utilization, nutrient gain and retention efficiencies were significantly higher in TG than NTG fish. DIP and TRIP TG Atlantic salmon have the ability to maintain accelerated growth even when fed a high PP diet (68% of dietary protein), which may have important benefits for the production of growth hormone transgenic Atlantic salmon. Statement of relevance: The results from the present study are innovative and may have important benefits for the optimization and production of growth hormone transgenic Atlantic salmon using sustainable feed ingredients. © 2015.

Xu Q.,Memorial University of Newfoundland | Feng C.Y.,Memorial University of Newfoundland | Hori T.S.,Memorial University of Newfoundland | Plouffe D.A.,Center for Aquaculture Technologies Canada | And 2 more authors.
Comparative Biochemistry and Physiology - Part D: Genomics and Proteomics | Year: 2013

Growth hormone transgenic (GHTg) Atlantic salmon (Salmo salar) have enhanced growth when compared to their non-transgenic counterparts, and this trait can be beneficial for aquaculture production. Biological confinement of GHTg Atlantic salmon may be achieved through the induction of triploidy (3N). The growth rates of triploid GH transgenic (3NGHTg) Atlantic salmon juveniles were found to significantly vary between families in the AquaBounty breeding program. In order to characterize gene expression associated with enhanced growth in juvenile 3NGHTg Atlantic salmon, a functional genomics approach (32K cDNA microarray hybridizations followed by QPCR) was used to identify and validate liver transcripts that were differentially expressed between two fast-growing 3NGHTg Atlantic salmon families (AS11, AS26) and a slow-growing 3NGHTg Atlantic salmon family (AS25); juvenile growth rate was evaluated over a 45-day period. Of 687 microarray-identified differentially expressed features, 143 (116 more highly expressed in fast-growing and 27 more highly expressed in slow-growing juveniles) were identified in the AS11 vs. AS25 microarray study, while 544 (442 more highly expressed in fast-growing and 102 more highly expressed in slow-growing juveniles) were identified in the AS26 vs. AS25 microarray study. Forty microarray features (39 putatively associated with fast growth and 1 putatively associated with slow growth) were present in both microarray experiment gene lists. The expression levels of 15 microarray-identified transcripts were studied using QPCR with individual RNA samples to validate microarray results and to study biological variability of transcript expression. The QPCR results agreed with the microarray results for 12 of 13 putative fast-growth associated transcripts, but QPCR did not validate the microarray results for 2 putative slow-growth associated transcripts. Many of the 39 microarray-identified genes putatively associated at the transcript expression level with fast-growing 3NGHTg salmon juveniles (including APOA1, APOA4, B2M, FADSDS6, FTM, and GAPDH) are involved in metabolism, iron homeostasis and oxygen transport, and immune- or stress-related responses. The results of this study increase our knowledge of family-specific impacts on growth rate and hepatic gene expression in juvenile 3NGHTg Atlantic salmon. In addition, this study provides a suite of putative rapid growth rate-associated transcripts that may contribute to the development of molecular markers [e.g. intronic, exonic or regulatory region single nucleotide polymorphisms (SNPs)] for the selection of GHTg Atlantic salmon broodstock that can be utilized to produce sterile triploids of desired growth performance for future commercial applications. © 2013 Elsevier Inc.

Evans M.L.,Oregon State University | Hori T.S.,Center for Aquaculture Technologies Canada | Rise M.L.,Memorial University of Newfoundland | Fleming I.A.,Memorial University of Newfoundland
PLoS ONE | Year: 2015

Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/ or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs; in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing on the transcriptome of Atlantic salmon (Salmo salar). Full siblings were reared in either a hatchery environment devoid of structure or an environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcript abundance in head tissues using the cGRASP-designed Agilent 4×44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between the rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented in this gene list, several associated with mitosis/cell cycle and muscle and heart development. There were also pronounced differences among families in the degree of transcriptional response to rearing environment enrichment, suggesting that gene-by-environment effects, possibly related to parental origin, could influence the efficacy of enrichment interventions. © 2015 Evans et al.

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