Growth Hormone Transgenic Atlantic Salmon Research Articles

Influence of feeding a high plant protein diet on growth and nutrient utilization to combined ‘all-fish’ growth-hormone transgenic diploid and triploid Atlantic salmon (Salmo salar L.)

Abstract 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.

Ecological risk analysis and genetically modified salmon: management in the face of uncertainty.

The commercialization of growth hormone transgenic Atlantic salmon for aquaculture has become a controversial public policy issue. Concerns exist over the potential ecological effects of this biotechnology should animals escape captivity. From within an ecological risk-analysis framework, science has been sought to provide decision makers with evidence upon which to base regulatory decisions pertaining to genetically modified salmon. Here I review the available empirical information on the potential ecological and genetic effects of transgenic salmon and discuss the underlying eco-evolutionary science behind the topic. I conclude that data gaps and irreducible epistemic uncertainties limit the role of scientific inference in support of ecological risk management for transgenic salmon. I argue that predictive uncertainties are pervasive in complex eco-evolutionary systems and that it behooves those involved in the risk-analysis process to accept and communicate these limitations in the interest of timely, clear, and cautious risk-management options.

Reproductive performance of alternative male phenotypes of growth hormone transgenic Atlantic salmon (Salmo salar).

Growth hormone (GH) transgenic Atlantic salmon (Salmo salar) is one of the first transgenic animals being considered for commercial farming, yet ecological and genetic concerns remain should they enter the wild and interact reproductively with wild fish. Here, we provide the first empirical data reporting on the breeding performance of GH transgenic Atlantic salmon males, including that of an alternative male reproductive phenotype (i.e. small, precocially mature parr), in pair-wise competitive trials within a naturalised stream mesocosm. Wild anadromous (i.e. large, migratory) males outperformed captively reared transgenic counterparts in terms of nest fidelity, quivering frequency and spawn participation. Similarly, despite displaying less aggression, captively reared nontransgenic mature parr were superior competitors to their transgenic counterparts in terms of nest fidelity and spawn participation. Moreover, nontransgenic parr had higher overall fertilisation success than transgenic parr, and their offspring were represented in more spawning trials. Although transgenic males displayed reduced breeding performance relative to nontransgenics, both male reproductive phenotypes demonstrated the ability to participate in natural spawning events and thus have the potential to contribute genes to subsequent generations.

Gill Morphometry in Growth Hormone Transgenic Pacific Coho Salmon, Onchorhynchus kisutch, Differs Markedly from that in GH Transgenic Atlantic Salmon

In a previous study we showed that many of the morphological features of the respiratory system of GH (growth hormone) transgenic Atlantic salmon are greater than similarly sized control salmon. Here we show that the manifestation of GH transgene is similar in two different lines of GH transgenic Pacific coho salmon, but that it is very different from that in the GH transgenic Atlantic salmon. The GH transgenic Pacific coho salmon do not have a larger gill surface area than similarly sized control fish.

Gut morphology in growth hormone transgenic Atlantic salmon

Growth hormone transgenic Atlantic salmon Salmo salar reared at 12–13°C were F2 generation derived, using eggs from a transgenic F1 female and fertilized with milt from a non‐transgenic male. At the time of tissue sampling the transgenic salmon were growing 1·6 times faster than control salmon. Transgenic salmon tended to have more intestinal folds that were longer than those of control salmon. Consequently, the transgenic salmon had a larger digestive surface area both in the anterior intestine (surface area 1·5 times control) and in the pyloric caeca (surface area 1·2 times control). Most morphological features of the intestine and of the pyloric caeca of transgenic salmon were larger than those of control salmon; in particular, the surface area of the anterior intestine was concordant with the growth rate difference.

Gill Morphometry in Growth Hormone Transgenic Atlantic Salmon

We show that many of the morphological features of the respiratory system of growth enhanced transgenic salmon are greater than those of similarly sized control salmon. Growth hormone transgenic Atlantic salmon, Salmo salar were the F2 generation produced using eggs from a transgenic F1 female and milt from a nontransgenic male. At the time the gill tissues were sampled, the transgenic salmon were growing 2.1 times more rapidly than the nontransgenic control salmon, and they had oxygen uptake rates that were about 1.6 times greater than control salmon. In the present study we show that the gill surface area available for respiratory exchange in the transgenic salmon is about 1.24 times that in control salmon which does not parallel the 1.6 elevation in oxygen uptake. The increase in gill exchange area was due largely to a relatively uniform increase in length of each gill filament.

Smolt development in growth hormone transgenic Atlantic salmon

Growth hormone transgenic Atlantic salmon ( Salmo salar) produced using a gene construct comprised of an antifreeze protein (AFP) gene promoter from ocean pout ( Macrozoarces americanus) and the growth hormone (GH) gene from chinook salmon ( Oncorhynchus tshawytscha) were used for this study of smolt development. An F 2 generation of these transgenic salmon was initiated in November 1995 using milt from a transgenic F 1 male and eggs from a normal female, hatching in January and first feeding in February 1996. With elevated temperature (16°C) initially and various combinations of temperature–photoperiod manipulation, the transgenic individuals approached smolt size (16 cm) in June; their normal siblings were <10 cm. Most transgenic individuals survived >96 h following direct transfer to 35‰ seawater in June. Normal individuals survived less than 24 h. Transgenic individuals had high gill Na +–K + ATPase activity levels and declining condition factor in late June, indicative of smolt status. Following transfer to seawater in early July, transgenic fish from the various temperature–photoperiod treatments grew rapidly, with few mortalities, until observations were discontinued in October 1996. High temperature (16°C) in one treatment, which inhibits development or maintenance of elevated gill Na +–K + ATPase activity in non-transgenic Atlantic salmon, resulted in only slightly lower gill ATPase levels in transgenic individuals. These survived and grew well during 4 months in seawater. Similarly, constant light (LD:24) in another treatment, which inhibits normal smolt development in non-transgenic salmon, did not prevent smolt development or adversely affect post-smolt survival and growth in seawater. It is concluded that transgenic salmon from all treatments completed smolting at age 6 months with satisfactory survival and growth in seawater. It appears that GH transgenic Atlantic salmon can be reared under temperature and photoperiod regimes which optimize growth, but which would inhibit normal smolt development and post-smolt performance of non-transgenic salmon.

Respiratory metabolism and swimming performance in growth hormone transgenic Atlantic salmon

We show that growth hormone enhanced transgenic salmon have a higher oxygen uptake during routine culture conditions and during forced swimming activity relative to similarly sized control fish. They also have a slightly higher critical oxygen level that limits oxygen uptake. However, they do not differ in regards to critical swimming speed. Growth hormone transgenic Atlantic salmon, Salmo salar, at 12-13°C were an F2 generation using eggs from a transgenic F1 female and milt from a nontransgenic male. They grew two to three times faster than control fish throughout the study period. Under routine culture conditions, both transgenic and control fish exhibited a diurnal cycle in oxygen uptake. However, oxygen uptake of transgenic fish was 1.7 times that of control fish at all times of the day. Oxygen uptake was independent of oxygen concentration above 10 mg/L in both groups of fish; critical oxygen uptake level was 6 mg/L in transgenic fish and 4 mg/L in control fish. During the oxygen decrease, transgenic fish and control fish lost equilibrium at the same low oxygen concentration levels. In the swim tunnel, oxygen uptake of transgenic fish was 1.6 times that of control fish at all swimming speeds. Critical swimming speeds did not differ between transgenic and control fish and were similar to literature values for salmonids.

Respiratory metabolism and swimming performance in growth hormone transgenic Atlantic salmon

Respiratory metabolism and swimming performance in growth hormone transgenic Atlantic salmon

Alternative reproductive tactics in atlantic salmon: factors affecting mature parr success

In Atlantic salmon, as in most salmonids, males can mature early in the life cycle, as small freshwater fish, termed parr, and/or undergo a sea migration before maturing as full–size adults. The alternative life histories are contingent on environmental and social circumstances, such as growth rate, territory quality or any other factor that affects the individual9s state. In order to model the choice of life history in this group of commercially valuable species, it is necessary to understand not only the relative contribution of the different male types to subsequent generations, but also to know the factors that affect reproductive success in each type. In this paper we present the results of a study designed to investigate the factors that affect the reproductive success of mature parr. We used highly polymorphic minisatellite DNA markers to analyse paternity in a series of mating experiments where the number and body size of parr were manipulated. The fraction of eggs fertilized by mature parr ranged from 26 to 40 per cent, with individual parr fertilizing up to 26 per cent of the eggs. A strong positive correlation was found between parr size and reproductive success. The relative success of parr decreased with increasing parr number. Data from this and other studies on variation in the timing and degree of parr reproductive success are discussed in relation to the evolution of male mating strategies and life history in salmonids.