Krisna Rungruangsak Torrissen

Changes in plasma and muscle free amino acids in atlantic salmon (Salmo salar) during absorption of diets containing different amounts of hydrolysed cod muscle protein

1. 1. Atlantic salmon (Salmo salar) were fed three diets of increasingly pre-digested protein for 4 weeks. They were then starved for 2 days, then fed to satiation. 2. 2. Plasma and muscle samples were collected before feeding and 0, 6, 12, 24, 48 and 72 hr after feeding and analysed for free amino acids. 3. 3. Plasma essential free amino acids were significantly higher (P < 0.05) at 6 and 12 hr post-prandial, while the non-essential amino acids were hardly affected. 4. 4. Minor differences were obtained in muscle free amino acids. Maximum concentration was obtained at 24 hr post-prandial in fish fed the control, and at 12 hr post-prandial for both the pre-digested feeds. 5. 5. In both plasma and muscle, total free amino acids were higher in those fed the proteolysed feeds than in those fed the non-proteolysed feed.

Genetic variation in growth rate of Atlantic salmon with different trypsin-like isozyme patterns

Abstract The growth rates of three different year-classes (1984, 1985 and 1987) of Atlantic salmon ( Salmo salar ) were studied using trypsin-like isozyme pattern in the pyloric caeca as a biological genetic marker. The fish with the homozygote variant TRP-2(92/92) and with the heterozygote variant TRP-2(92/100) had higher average weight than those with the genotypes which did not possess the variant TRP-2(92) . The difference in weight between the two groups (with and without TRP-2(92) variant) was significant from smolt until the end of the experiment in autumn of the first sea-year (1984 year-class) and until spring in the second sea-year (1985 year-class). The difference was about 30%, and decreased to 10% at maturation. The specific growth rate was critical during the first sea-year. The fish with the allele TRP-2(92) showed the advantage of faster growth in the first sea-year, especially during winter time. With the covariation of significant difference in weight (until the autumn in the second sea-year) among different families, higher production of food fish of at least 20% could be possible at the time of slaughter during the second sea-year with the use of a selective breeding programme based either on trypsin-like isozyme pattern and family or on the isozyme pattern of individuals. The effects of selection by using the variant TRP-2(92) could be observed within the period of the generation selected.

Genetic variation of trypsin-like isozymes correlated to fish size of Atlantic salmon (Salmo salar)

Abstract Trypsin-like isozyme patterns of 580 Atlantic salmon fry were studied by isoelectrofocussing. Three common isozymes designated TRP-1, TRP-2 and TRP-3 were observed, with the variant TRP-2 (92), and two variants possibly of the TRP-1 system. The distributions of genotype variants of the TRP-2 system within families seemed to be in accordance with a model assuming Mendelian inheritance. Clear association between fish size and genotypes was observed, and the fish of designated genotype TRP-2 ( 92 92 ) had an average weight significantly higher than those of the other genotypes. This covariation indicates a usefulness of the variants for improving genetic resources for future breeding programmes.

Protease activities and carotenoid levels during the sexual maturation of Atlantic salmon (Salmo salar)

Abstract Protease activities in the digestive tract and carotenoid levels in flesh, ovaries and plasma were determined in Atlantic salmon (Salmo salar) in their third sea year during the period from early March until December. Protease activities in the digestive tissues changed significantly during the maturation process: the fish have higher enzyme activities in early maturation and lower in the later stages until maturity. The trypsin-like isozymes were studied by IEF electrophoresis during maturation, and variations observed were possibly genetic. The level of astaxanthin in flesh and ovaries decreased significantly during sexual maturation, but the total amount in the ovaries continued to increase. The covariance between astaxanthin in the plasma and trypsin-like activities in the digestive tissues was significant, and the level of astaxanthin in the plasma was also influenced by time and stage of sexual maturation.

Artificial hatching substrate and different times of transfer to first feeding: Effect on growth and protease activities of the Atlantic salmon (Salmo salar)

Abstract Groups of Atlantic salmon ( Salmo salar ) eggs were hatched in a Californian incubation system with and without an astro-turf artificial substrate. Food was first 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 heavier than flat-screenreared fry at the termination of the experiment. With respect to growth, the first and the fourth transfers were clearly suboptimal for the fry from both systems.

Growth depression and acclimatization of protease activity in Atlantic salmon first-feeding fry responding to a diet supplemented with zooplankton

Abstract Groups of Atlantic salmon fry were given dry feed supplemented with frozen zooplankton, or dry feed only. A tendency toward decreased endogenous digestive protease activity and a highly significant depression in growth rate were observed in groups given supplemental feed.