Wild salmon should not be threatened by healthy and non-genetically manipulated escapees

Rungruangsak-Torrissen K. Cultured salmon as escapees should never threaten salmon stocks in the wild as long as they are healthy and are not genetically manipulated. By studying a key digestive protease, trypsin, which is sensitive to environmental changes and influences on food utilisation and growth during the whole life cycle of Atlantic salmon, it is indicated that changes in the phenotypic expression of trypsin can be induced by temperature during egg incubation and the start-feeding period of the alevins. In addition, Atlantic salmon with the same trypsin phenotype showed different feed conversion efficiency and growth rate at different temperatures. Trypsin genes seem to be stable, and although the pattern of expressed genes varies extensively, the expression of trypsinogen mRNA is quantitatively similar between individual salmon in line with the observation that the total trypsin specific activity was similar between the fish with different trypsin phenotypes. However the luminal secretion of the active enzyme, and probably the relative amounts of trypsin isozymes, could be modified by water temperature and food quality. These results indicate that changes in the environmental condition can influence gene expressions of the fish at DNA, RNA and protein levels, regardless of genetic expression of parents. This means that whether the escapees or wild fish is the spawning population, an incidence of the offsprings to have their gene expressions adapted to that environment will be similar. It is the environmental condition that has to be conserved in order to control the genetic structure of animals in the wild. It is naive to think that genetically manipulated escapees such as triploid salmon will not have any impact on wild population, as they are not fertile. Under a more favourable condition for growth, triploid escapees could compete with wild fish on food availability as they have higher consumption rates for higher growth rates, unlike ordinary diploid salmon that could have better food utilisation at a similar consumption rate. This may cause a higher survival rate in triploid escapees and if they spawn, hatching success and survival rate of the offsprings will be low due to low gamete quality for reproduction in triploid fish. This could result in a smaller population of the new generation in that environment in the wild.Wild salmon should not be threatened by healthy and non-genetically manipulated escapeesacceptedVersio

Forbedring av avlsstammer for Atlantisk laks ved bruk av gener som koder for trypsin-like isozymer

Sluttrapport NFR/NFFR- nr. 1402 - 701.30

Artificial hatching substrate and different time of transfer to startfeeding: Effect on growth and protease activities of the Atlantic salmon (Salmo salar).

Groups of Atlantic salmon (Salmo salar) eggs were hatched in a Californian hatching system with and without an astro-turf artificial substrate, and food was presented at four different points in development. Dry weight development and protease activities were studied. Irrespective of time of transfer the astro-turf reared fry were bigger than the flat screen reared fry at the termination of the experiment. In respect of growth the first and the fourth transfers were clearly suboptimal for the fry from both systems

Neural computational model GrowthEstimate: A model for studying living resources through digestive efficiency

Neural computational model GrowthEstimate: A model for studying living resources through digestive efficiencyThe neural computational model GrowthEstimate is introduced with focusing on new perspectives for the practical estimation of weight specific growth rate (SGR, % day–1). It is developed using recurrent neural networks of reservoir computing type, for estimating SGR based on the known data of three key biological factors relating to growth. These factors are: (1) weight (g) for specifying the age of the growth stage; (2) digestive efficiency through the pyloric caecal activity ratio of trypsin to chymotrypsin (T/C ratio) for specifying genetic differences in food utilization and growth potential, basically resulting from food consumption under variations in food quality and environmental conditions; and (3) protein growth efficiency through the condition factor (CF, 100 × g cm–3), as higher dietary protein level affecting higher skeletal growth (length) and resulting in lower CF. The computational model was trained using four datasets of different salmonids with size variations. It was evaluated with 15% of each dataset, resulting in an acceptable range of SGR outputs. Additional tests with different species indicated similarity between the estimated SGR outputs and the real SGR values, and the same ranking of wild population growth. The developed model GrowthEstimate is exceptionally useful for the precise and comparable growth estimation of living resources at individual levels, especially in natural ecosystems where the studied individuals, environmental conditions, food availability and consumption rates cannot be controlled. It is a revelation and will help to minimize uncertainty in wild stock assessment process. This will improve our knowledge in nutritional ecology, through the biochemical effects of climate change and environmental impact on the growth performance quality of aquatic living resources in the wild, as well as in aquaculture. The original GrowthEstimate software is available at GitHub repository (https://github.com/RungruangsakTorrissenManoonpong/GrowthEstimate). All other relevant data are within the paper. It will be improved for generality for future use, and required co-operations of the biodata collections of different species from different climate zones. Therefore, a co-operation will be available.publishedVersio

Causes of variation in carcass traits of Atlantic salmon (Salmo salar)

The aim of the present study was to reveal causes of variation in carcass traits of farmed Atlantic salmon (Salmo salar). During slaughtering of one year class Atlantic salmon, composed of half sib and full sib groups, samples for determination of carotenoid levels in flesh and ovaries were collected. Also the hepatosomatic and viscerosomatic indexes as well as relative visceral fat content were determined. As expected it was found that these traits were influenced by several factors. The material is too limited for firm conclusions, but evidently the carotenoid level depends largely on stage of maturity and possibly also on genetic factors. Genetic factors seem to influence the visceral fat content. In hepatosomatic and visceral indexes, and possibly in visceral fat content, a strange and still unexplained interaction between sex and stage of maturation was observed

Evaluation of growth performance and nutritional quality of diets using digestive enzyme markers and in vitro digestibility in Siamese fighting fish (Betta splendens Regan, 1910)

Digestive enzymes and their effects on in vitro digestibility of feeds and feedstuffs, as well as on growth performance quality were studied in Siamese fighting fish (Betta splendens Regan, 1910). The specific activities of total protease, amylase, trypsin and chymotrypsin increased during development and were higher in females than in males at maturation (P < 0.05). The activity ratio of trypsin to chymotrypsin corresponded to fish growth, and showed lower values in females than in males. White muscle levels of RNA decreased during development, with females having higher levels than males, while the protein levels increased with no difference between sexes. In the oocytes, trypsin-like and chymotrypsin-like specific activities were very low, and the concentrations of RNA, protein and protein/lipid ratio were higher than in the muscle. For in vitro digestibility, wheat gluten, soybean meal and fish meal were among good protein sources while the meals from peanut, fish and soybean were good carbohydrate sources. Golden apple snail meat was a good source for both protein and carbohydrate. The crude enzyme extracts from different growth stages and sexes had different abilities to digest the same feeds and feedstuffs. This will make it possible to preliminarily study the authenticated nutritional quality of raw materials for future feed formulations for B. splendens.Keywords: Betta splendens, digestive enzymes, feedstuff, in vitro digestibility, muscle quality, oocyte quality, Siamese fighting fishAfrican Journal of Biotechnology Vol. 12(14), pp. 1689-170