Ragnar Salte | Norwegian University of Life Sciences (original) (raw)

Papers by Ragnar Salte

Canadian Journal of Fisheries and Aquatic Sciences, 2010

We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris i... more We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris infection from survival records in a pedigreed family material of wild Atlantic salmon (Salmo salar) in a controlled challenge test. We used a statistical model that distinguishes between survival time for the fish that died and the ability to survive the entire test as two separate traits. Eleven of the 49 full-sib families suffered 100% mortality, 15 families had between 10% and 25% survival, and the four least affected families had survival rates between 36% and 48%. Estimated heritability of survival on the liability scale was 0.32 ± 0.10. Time until death for fish that died during the test and the ability to survive the entire test were not expressions of the same genetic trait. Simply selecting survivors as parents for the next generation is expected to more than double the overall survival rate in only one generation, given similar exposure to the parasite. Improving the genetic capacity to survive the infection will probably not eradicate the parasite, but when used as a disease control measure, such improvement may contain the infection at a level where the parasite ceases to be a major problem.

Journal of Fish Diseases, 2003

The present study demonstrates that farmed Atlantic salmon, Salmo salar, health is positively and... more The present study demonstrates that farmed Atlantic salmon, Salmo salar, health is positively and significantly affected by synergistic effects between very long-chain polyunsaturated fatty acids of the n-3 family eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) and iron, where positive effects of high dietary levels of EPA/DHA are enhanced when combined with low levels of iron. Based on cumulative mortalities in the different experimental groups, relative percentage of survival (RPS) for the high EPA/DHA-low iron group was 70% during an outbreak of furunculosis and 96% during an outbreak of cold water vibriosis compared with the controls. A non-additive effect between EPA/DHA and iron was confirmed by statistical analyses that revealed a significant effect of EPA/DHA alone and an interaction of iron with EPA/DHA. Liver cell cultures treated with EPA/DHA revealed that the synergistic effect could be related to an EPA/ DHA dependent regulation of mRNA for proteins important for transport (transferrin) and storage (ferritin) of iron in the salmon. In keeping with this finding, the transcriptional down-regulation of iron metabolism in vitro was reflected in decreased in vivo iron stores with increasing levels of dietary EPA/ DHA. Hence, to avoid overloading of the iron transport/storage-systems resulting in increased susceptibility to bacterial infections, high levels of dietary EPA/DHA should be accompanied by low levels of dietary iron.

Fish & Shellfish Immunology, 2008

Seven innate immune parameters were investigated in 64 full-sib families (the offspring of 64 sir... more Seven innate immune parameters were investigated in 64 full-sib families (the offspring of 64 sires and 45 dams) from two year-classes of farmed rohu carp (Labeo rohita). Survival rates were also available from Aeromonas hydrophila infection (aeromoniasis) recorded in controlled challenge tests on a different sample of individuals from the same families. Due to strong confounding between the animal additive genetic effect and the family effects (common environmental+non-additive genetic), reliable additive (co)variance components and hence heritabilities and genetic correlations could not be obtained for the investigated parameters. Therefore, estimates of the association of challenge test survival with the studied immune parameters were obtained as product moment correlations between family least square means. These correlations revealed statistically significant (p<0.05) negative correlations of survival with bacterial agglutination titre (-0.48), serum haemolysin titre (-0.29) and haemagglutination titre (-0.34); and significant positive correlation with ceruloplasmin level (0.51). The correlations of survival to aeromoniasis with myeloperoxidase activity, superoxide production and lysozyme activity were found to be not significantly different from zero (p>0.05). Assuming that the negatively correlated candidate traits are not favourable as indirect selection criteria, the results suggest that ceruloplasmin level could potentially be a marker for resistance to aeromoniasis in rohu. The use of this immune parameter as an indirect selection criterion for increased resistance to aeromoniasis in rohu will, however, require that the parameter shows significant additive genetic variation and a significant genetic correlation with survival. Further studies are therefore needed to obtain a reliable heritability estimate for ceruloplasmin and its genetic correlation with survival from aeromoniasis.

Environmental Biology of Fishes, 2007

Developmental stability reflects the degree to which phenotypic expression is unaffected by rando... more Developmental stability reflects the degree to which phenotypic expression is unaffected by random accidents or developmental noise. Developmental stability may be measured by phenodeviance or fluctuating asymmetry (FA), and estimation of developmental stability has attracted substantial interest because it appears to represent a relatively simple method to identify sub lethal stress exposure and to assess animal welfare. As a part of a long-term study, the work presented here primarily aimed to investigate impacts on developmental instability in farmed salmon offspring ten months post hatch attributable to maternal cortisol administration prior to spawning and mild hyperthermia exerted during incubation. Main results show that maternal cortisol enhancement increased the level of FA in pectoral and pelvic fins, but did not affect the frequency of malformations in offspring. Mild hyperthermia during incubation increased weight and fork length and also increased pelvic fin FA. Malformed fish were heavier and longer than the normal ones, and pelvic fin asymmetry was positively related to condition factor. These results illustrate plausible lasting impacts on offspring development due to the maternal endocrinological state at spawning and indicate that developmental instability in farmed salmon juveniles may mirror aspects of the broodstock's housing conditions.

Canadian Journal of Fisheries and Aquatic Sciences, 2010

We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris i... more We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris infection from survival records in a pedigreed family material of wild Atlantic salmon (Salmo salar) in a controlled challenge test. We used a statistical model that distinguishes between survival time for the fish that died and the ability to survive the entire test as two separate traits. Eleven of the 49 full-sib families suffered 100% mortality, 15 families had between 10% and 25% survival, and the four least affected families had survival rates between 36% and 48%. Estimated heritability of survival on the liability scale was 0.32 ± 0.10. Time until death for fish that died during the test and the ability to survive the entire test were not expressions of the same genetic trait. Simply selecting survivors as parents for the next generation is expected to more than double the overall survival rate in only one generation, given similar exposure to the parasite. Improving the genetic capacity to survive the infection will probably not eradicate the parasite, but when used as a disease control measure, such improvement may contain the infection at a level where the parasite ceases to be a major problem.

Aquaculture, 2005

Susceptibility to the salmon louse Lepeophtheirus salmonis was recorded in three year-classes of ... more Susceptibility to the salmon louse Lepeophtheirus salmonis was recorded in three year-classes of Atlantic salmon with 300 (year-classes 2000 and 2001) and 50 (year-class 2001) full-sib families. The number of lice during natural infections was recorded on individual ...

Aquaculture, 2005

A total of 339 full-sib families (representing 143 paternal half-sib families) and 337 full-sib f... more A total of 339 full-sib families (representing 143 paternal half-sib families) and 337 full-sib families (representing 145 paternal half-sib families) were respectively challenged with White Spot Syndrome Virus (WSSV) in a controlled environment and tested for growth performance under ...

Aquaculture, 1992

... INTRODUCTION Oxolinic acid (OA) has proved its value as an antimicrobial agent under fish far... more ... INTRODUCTION Oxolinic acid (OA) has proved its value as an antimicrobial agent under fish farming conditions (Austin et al., 1983; Austin and Austin, 1987; Ar-chimbault et al., 1988). ... Vet., 19: 39-43. Austin, B. and Austin, DA (Editors), 1987. Control of bacterial fish diseases. ...

Aquaculture, 2005

In 1997, CENIACUA (Centro de Investigaciones para la Acuicultura en Colombia) in collaboration wi... more In 1997, CENIACUA (Centro de Investigaciones para la Acuicultura en Colombia) in collaboration with AKVAFORSK (Institute of Aquaculture Research, Norway) initiated a family-based selection scheme in Penaeus (Litopenaeus) vannamei to improve growth rate and survival in ...

Aquaculture, 1988

Aquaculture, 68 (1988) 299-304 299 Elsevier Science Publishers BV, Amsterdam - Printed in The Net... more Aquaculture, 68 (1988) 299-304 299 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands Species and Individual Variation in Lysozyme Activity in Fish of Interest in Aquaculture BJORN GRINDE'*, OYSTEIN LIE', TRYGVE POPPE' and RAGNAR SALTE' 'Department of ...

Aquaculture, 2006

Two infection protocols, individual oral (IO) and waterborne infection (WB), were evaluated to ch... more Two infection protocols, individual oral (IO) and waterborne infection (WB), were evaluated to challenge Penaeus (Litopenaeus) vannamei with White Spot Syndrome Virus (WSSV). Five different batches of full and half-sib families were infected experimentally and tested for growth performance under commercial growth conditions. The genetic variance for WSSV resistance was estimated using a linear sire-dam repeatability model that considers test-day survival as the dependent variable. The heritability estimates using the IO protocol ranged from 0.01 ± 0.00 to 0.02 ± 0.01, whereas the heritability estimates using the WB infection protocol were not significantly different from zero. The genetic correlations measured as the product moment correlation between full-sib family breeding values for resistance to WSSVand harvest body weight in ponds were unfavourable in three of the five batches and favourable in one of them. The dosage of WSSV was better controlled with IO oral infection than with other methods, with all animals being exposed to approximately the same risk of infection at the same time. This should improve the accuracy of the genetic parameters and hence improve the accuracy of the breeding values. It should, however, be noted that once the outbreak was established and the mortalities began, the shape and the magnitude of the slope of the mortality curves showed little difference in the infection pattern between batches irrespective of the dosage and infection protocol, and in most of the cases the cumulative mortality was greater than 80%. The main reason for this is probably the high densities of animals in the tanks needed for the genetic evaluations.

Aquaculture, 2006

Genetic parameters for resistance to White Spot Syndrome Virus (WSSV) in the shrimp species Penae... more Genetic parameters for resistance to White Spot Syndrome Virus (WSSV) in the shrimp species Penaeus vannamei were estimated by using five different statistical models to analyze challenge test data. Data were recorded on the offspring of 338 full-sib families experimentally infected with WSSV, corresponding to four consecutive generations. Both the linear model (LBM) and the threshold model (TBM) defined disease

Aquaculture, 2008

... Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophi... more ... Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophila infection in challenge tests. ... 1925] , [Ehlinger, 1964] , [Ehlinger, 1977] , [Gjedrem and Aulstad, 1974] , [Refstie, 1982] , [Gjedrem, 1983] , [Bailey, 1986] , [Cipriano and Heartwell, 1986 ...

Aquaculture, 2004

Progeny testing could have a potential in aquaculture particularly in species where the males spa... more Progeny testing could have a potential in aquaculture particularly in species where the males spawn over several years, and also in the monitoring of genetic changes between generations and sub-populations of salmonids, where the males are used for only one ...

Applied Animal Behaviour Science, 2006

ABSTRACT This experiment aims at validating the percentage of visible white in the eye as an emot... more ABSTRACT This experiment aims at validating the percentage of visible white in the eye as an emotional indicator, related to the frustration–contentedness axis, in cattle. Earlier experiments showed that the calculated percentage of white in the eyes was larger in frustrated or scared cows compared to cows that were offered a positive stimulus. This eye change was therefore suggested to be a dynamic indicator of emotions in dairy cattle, a high percentage of white in the eye indicating frustration, and a low percentage indicating satisfaction. In the present paper, the hypothesis was that treatment with the anti-anxiety drug diazepam should reduce the percentage of white in the eye in frustrated cows, but have no effect on the percentage of eye white in non-frustrated or rewarded cows. The test animals were 20 randomly selected commercial dairy cows (Norwegian Red Cattle). Two experiments were performed on hungry cows. The four different groups in the first experiment are described in the following. Ten cows were introduced to a frustrating situation, being thwarted from access to visible food (treatment I). Ten cows were introduced to a positive situation, access to food (treatment II). The 10 cows in group I were introduced to the same frustrating situation, but were now pretreated with diazepam (treatment III). The 10 cows in group II were introduced to the same positive situation after pretreatment with diazepam (treatment IV). The two groups in the second experiment were 20 untreated (treatment I) and 20 diazepam-treated www.elsevier.com/locate/applanim

Applied Animal Behaviour Science, 2008

This study was designed to assess whether pre-spawning maternal cortisol administration and an ad... more This study was designed to assess whether pre-spawning maternal cortisol administration and an additional stressor, here modelled by mild hyperthermia experienced during incubation, affected the behavioural responses of farmed Atlantic salmon (Salmo salar) offspring when exposed to a novel environment. Mature females were injected prior to stripping with 0, 50 or 100 mg/kg cortisol. After fertilization the eggs were kept at incubation temperatures of either 8 or 10 8C. Four months after hatching, the fish were introduced to a novel environment, i.e. an aquarium (38 l). In each trial two individuals originating from different exposure groups were video recorded and their activity (number of turns, time spent not swimming, time spent at the bottom) and feeding behaviour were measured. Maternal cortisol increased time spent non-swimming and also time spent at the bottom, while cortisol and temperature together additionally affected number of turns. To the best of our knowledge this study is the first in fish to demonstrate a possible link between the maternal endocrinological state at spawning and the offspring's behavioural reactivity to novel situations. #

Prenatalt stress defineres som stress opplevd av et (drektig) mordyr som kan virke inn på avkomme... more Prenatalt stress defineres som stress opplevd av et (drektig) mordyr som kan virke inn på avkommets utvikling . Hos pattedyr er det vist at prenatalt stress kan føre til økt dødelighet og redusert vekst, svekket immunfunksjon, i tillegg til nedsatt utforsknings-og lekatferd, dårlig laering-og stressmestringsevne, samt suboptimal seksuell og maternal atferd . Videre kan også morfologiske parametre påvirkes av prenatalt stress, det er dokumentert økt forekomst av morfologiske anomalier hos prenatalt stressede avkom . Med tanke på fisk har man forholdsvis god kunnskap om hvordan stress influerer spesifikke reproduktive mekanismer, men det finnes relativt få studier som undersøker hvorvidt stress erfart av kjønnsmoden hunnfisk influerer avkommets karakterer. Innen kommersiell fiskeoppdrett eksponeres fisk i alle livsstadier for en rekke akutte og kroniske biotiske og abiotiske stressorer, i tillegg til at stamfisken regelmessig håndteres i forbindelse med kjønnsmodning og stryking. Dette kan tenkes å initiere en stressrespons tilsvarende som hos pattedyr med en forøket aktivitet i HPI-systemet med etterfølgende økt sekresjon av kortisol som kan påvirke avkommets utvikling. Stresset hunnfisk vil derfor kunne ha et forøket nivå av stresshormoner i blodet, som kan gjenspeiles i eggene hennes. Eksperiment viser at en korrelasjon mellom mordyrets nivå av hormoner i blod og rogn eksisterer. Formålet med dette forsøket var å undersøke hvorvidt prenatalt stress hos oppdrettslaks påvirker avkommets utvikling og stressmestringsevne, samt belyse hvorvidt avvikende morfologi kan fungere som en objektiv, pålitelig indikator med tanke på stress og velferd innen kommersiell akvakultur.

Canadian Journal of Fisheries and Aquatic Sciences, 2010

We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris i... more We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris infection from survival records in a pedigreed family material of wild Atlantic salmon (Salmo salar) in a controlled challenge test. We used a statistical model that distinguishes between survival time for the fish that died and the ability to survive the entire test as two separate traits. Eleven of the 49 full-sib families suffered 100% mortality, 15 families had between 10% and 25% survival, and the four least affected families had survival rates between 36% and 48%. Estimated heritability of survival on the liability scale was 0.32 ± 0.10. Time until death for fish that died during the test and the ability to survive the entire test were not expressions of the same genetic trait. Simply selecting survivors as parents for the next generation is expected to more than double the overall survival rate in only one generation, given similar exposure to the parasite. Improving the genetic capacity to survive the infection will probably not eradicate the parasite, but when used as a disease control measure, such improvement may contain the infection at a level where the parasite ceases to be a major problem.

Journal of Fish Diseases, 2003

The present study demonstrates that farmed Atlantic salmon, Salmo salar, health is positively and... more The present study demonstrates that farmed Atlantic salmon, Salmo salar, health is positively and significantly affected by synergistic effects between very long-chain polyunsaturated fatty acids of the n-3 family eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) and iron, where positive effects of high dietary levels of EPA/DHA are enhanced when combined with low levels of iron. Based on cumulative mortalities in the different experimental groups, relative percentage of survival (RPS) for the high EPA/DHA-low iron group was 70% during an outbreak of furunculosis and 96% during an outbreak of cold water vibriosis compared with the controls. A non-additive effect between EPA/DHA and iron was confirmed by statistical analyses that revealed a significant effect of EPA/DHA alone and an interaction of iron with EPA/DHA. Liver cell cultures treated with EPA/DHA revealed that the synergistic effect could be related to an EPA/ DHA dependent regulation of mRNA for proteins important for transport (transferrin) and storage (ferritin) of iron in the salmon. In keeping with this finding, the transcriptional down-regulation of iron metabolism in vitro was reflected in decreased in vivo iron stores with increasing levels of dietary EPA/ DHA. Hence, to avoid overloading of the iron transport/storage-systems resulting in increased susceptibility to bacterial infections, high levels of dietary EPA/DHA should be accompanied by low levels of dietary iron.

Fish & Shellfish Immunology, 2008

Seven innate immune parameters were investigated in 64 full-sib families (the offspring of 64 sir... more Seven innate immune parameters were investigated in 64 full-sib families (the offspring of 64 sires and 45 dams) from two year-classes of farmed rohu carp (Labeo rohita). Survival rates were also available from Aeromonas hydrophila infection (aeromoniasis) recorded in controlled challenge tests on a different sample of individuals from the same families. Due to strong confounding between the animal additive genetic effect and the family effects (common environmental+non-additive genetic), reliable additive (co)variance components and hence heritabilities and genetic correlations could not be obtained for the investigated parameters. Therefore, estimates of the association of challenge test survival with the studied immune parameters were obtained as product moment correlations between family least square means. These correlations revealed statistically significant (p<0.05) negative correlations of survival with bacterial agglutination titre (-0.48), serum haemolysin titre (-0.29) and haemagglutination titre (-0.34); and significant positive correlation with ceruloplasmin level (0.51). The correlations of survival to aeromoniasis with myeloperoxidase activity, superoxide production and lysozyme activity were found to be not significantly different from zero (p>0.05). Assuming that the negatively correlated candidate traits are not favourable as indirect selection criteria, the results suggest that ceruloplasmin level could potentially be a marker for resistance to aeromoniasis in rohu. The use of this immune parameter as an indirect selection criterion for increased resistance to aeromoniasis in rohu will, however, require that the parameter shows significant additive genetic variation and a significant genetic correlation with survival. Further studies are therefore needed to obtain a reliable heritability estimate for ceruloplasmin and its genetic correlation with survival from aeromoniasis.

Environmental Biology of Fishes, 2007

Developmental stability reflects the degree to which phenotypic expression is unaffected by rando... more Developmental stability reflects the degree to which phenotypic expression is unaffected by random accidents or developmental noise. Developmental stability may be measured by phenodeviance or fluctuating asymmetry (FA), and estimation of developmental stability has attracted substantial interest because it appears to represent a relatively simple method to identify sub lethal stress exposure and to assess animal welfare. As a part of a long-term study, the work presented here primarily aimed to investigate impacts on developmental instability in farmed salmon offspring ten months post hatch attributable to maternal cortisol administration prior to spawning and mild hyperthermia exerted during incubation. Main results show that maternal cortisol enhancement increased the level of FA in pectoral and pelvic fins, but did not affect the frequency of malformations in offspring. Mild hyperthermia during incubation increased weight and fork length and also increased pelvic fin FA. Malformed fish were heavier and longer than the normal ones, and pelvic fin asymmetry was positively related to condition factor. These results illustrate plausible lasting impacts on offspring development due to the maternal endocrinological state at spawning and indicate that developmental instability in farmed salmon juveniles may mirror aspects of the broodstock's housing conditions.

Canadian Journal of Fisheries and Aquatic Sciences, 2010

We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris i... more We estimated additive genetic variation and heritability of survival after Gyrodactylus salaris infection from survival records in a pedigreed family material of wild Atlantic salmon (Salmo salar) in a controlled challenge test. We used a statistical model that distinguishes between survival time for the fish that died and the ability to survive the entire test as two separate traits. Eleven of the 49 full-sib families suffered 100% mortality, 15 families had between 10% and 25% survival, and the four least affected families had survival rates between 36% and 48%. Estimated heritability of survival on the liability scale was 0.32 ± 0.10. Time until death for fish that died during the test and the ability to survive the entire test were not expressions of the same genetic trait. Simply selecting survivors as parents for the next generation is expected to more than double the overall survival rate in only one generation, given similar exposure to the parasite. Improving the genetic capacity to survive the infection will probably not eradicate the parasite, but when used as a disease control measure, such improvement may contain the infection at a level where the parasite ceases to be a major problem.

Aquaculture, 2005

Susceptibility to the salmon louse Lepeophtheirus salmonis was recorded in three year-classes of ... more Susceptibility to the salmon louse Lepeophtheirus salmonis was recorded in three year-classes of Atlantic salmon with 300 (year-classes 2000 and 2001) and 50 (year-class 2001) full-sib families. The number of lice during natural infections was recorded on individual ...

Aquaculture, 2005

A total of 339 full-sib families (representing 143 paternal half-sib families) and 337 full-sib f... more A total of 339 full-sib families (representing 143 paternal half-sib families) and 337 full-sib families (representing 145 paternal half-sib families) were respectively challenged with White Spot Syndrome Virus (WSSV) in a controlled environment and tested for growth performance under ...

Aquaculture, 1992

... INTRODUCTION Oxolinic acid (OA) has proved its value as an antimicrobial agent under fish far... more ... INTRODUCTION Oxolinic acid (OA) has proved its value as an antimicrobial agent under fish farming conditions (Austin et al., 1983; Austin and Austin, 1987; Ar-chimbault et al., 1988). ... Vet., 19: 39-43. Austin, B. and Austin, DA (Editors), 1987. Control of bacterial fish diseases. ...

Aquaculture, 2005

In 1997, CENIACUA (Centro de Investigaciones para la Acuicultura en Colombia) in collaboration wi... more In 1997, CENIACUA (Centro de Investigaciones para la Acuicultura en Colombia) in collaboration with AKVAFORSK (Institute of Aquaculture Research, Norway) initiated a family-based selection scheme in Penaeus (Litopenaeus) vannamei to improve growth rate and survival in ...

Aquaculture, 1988

Aquaculture, 68 (1988) 299-304 299 Elsevier Science Publishers BV, Amsterdam - Printed in The Net... more Aquaculture, 68 (1988) 299-304 299 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands Species and Individual Variation in Lysozyme Activity in Fish of Interest in Aquaculture BJORN GRINDE'*, OYSTEIN LIE', TRYGVE POPPE' and RAGNAR SALTE' 'Department of ...

Aquaculture, 2006

Two infection protocols, individual oral (IO) and waterborne infection (WB), were evaluated to ch... more Two infection protocols, individual oral (IO) and waterborne infection (WB), were evaluated to challenge Penaeus (Litopenaeus) vannamei with White Spot Syndrome Virus (WSSV). Five different batches of full and half-sib families were infected experimentally and tested for growth performance under commercial growth conditions. The genetic variance for WSSV resistance was estimated using a linear sire-dam repeatability model that considers test-day survival as the dependent variable. The heritability estimates using the IO protocol ranged from 0.01 ± 0.00 to 0.02 ± 0.01, whereas the heritability estimates using the WB infection protocol were not significantly different from zero. The genetic correlations measured as the product moment correlation between full-sib family breeding values for resistance to WSSVand harvest body weight in ponds were unfavourable in three of the five batches and favourable in one of them. The dosage of WSSV was better controlled with IO oral infection than with other methods, with all animals being exposed to approximately the same risk of infection at the same time. This should improve the accuracy of the genetic parameters and hence improve the accuracy of the breeding values. It should, however, be noted that once the outbreak was established and the mortalities began, the shape and the magnitude of the slope of the mortality curves showed little difference in the infection pattern between batches irrespective of the dosage and infection protocol, and in most of the cases the cumulative mortality was greater than 80%. The main reason for this is probably the high densities of animals in the tanks needed for the genetic evaluations.

Aquaculture, 2006

Genetic parameters for resistance to White Spot Syndrome Virus (WSSV) in the shrimp species Penae... more Genetic parameters for resistance to White Spot Syndrome Virus (WSSV) in the shrimp species Penaeus vannamei were estimated by using five different statistical models to analyze challenge test data. Data were recorded on the offspring of 338 full-sib families experimentally infected with WSSV, corresponding to four consecutive generations. Both the linear model (LBM) and the threshold model (TBM) defined disease

Aquaculture, 2008

... Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophi... more ... Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophila infection in challenge tests. ... 1925] , [Ehlinger, 1964] , [Ehlinger, 1977] , [Gjedrem and Aulstad, 1974] , [Refstie, 1982] , [Gjedrem, 1983] , [Bailey, 1986] , [Cipriano and Heartwell, 1986 ...

Aquaculture, 2004

Progeny testing could have a potential in aquaculture particularly in species where the males spa... more Progeny testing could have a potential in aquaculture particularly in species where the males spawn over several years, and also in the monitoring of genetic changes between generations and sub-populations of salmonids, where the males are used for only one ...

Applied Animal Behaviour Science, 2006

ABSTRACT This experiment aims at validating the percentage of visible white in the eye as an emot... more ABSTRACT This experiment aims at validating the percentage of visible white in the eye as an emotional indicator, related to the frustration–contentedness axis, in cattle. Earlier experiments showed that the calculated percentage of white in the eyes was larger in frustrated or scared cows compared to cows that were offered a positive stimulus. This eye change was therefore suggested to be a dynamic indicator of emotions in dairy cattle, a high percentage of white in the eye indicating frustration, and a low percentage indicating satisfaction. In the present paper, the hypothesis was that treatment with the anti-anxiety drug diazepam should reduce the percentage of white in the eye in frustrated cows, but have no effect on the percentage of eye white in non-frustrated or rewarded cows. The test animals were 20 randomly selected commercial dairy cows (Norwegian Red Cattle). Two experiments were performed on hungry cows. The four different groups in the first experiment are described in the following. Ten cows were introduced to a frustrating situation, being thwarted from access to visible food (treatment I). Ten cows were introduced to a positive situation, access to food (treatment II). The 10 cows in group I were introduced to the same frustrating situation, but were now pretreated with diazepam (treatment III). The 10 cows in group II were introduced to the same positive situation after pretreatment with diazepam (treatment IV). The two groups in the second experiment were 20 untreated (treatment I) and 20 diazepam-treated www.elsevier.com/locate/applanim

Applied Animal Behaviour Science, 2008

This study was designed to assess whether pre-spawning maternal cortisol administration and an ad... more This study was designed to assess whether pre-spawning maternal cortisol administration and an additional stressor, here modelled by mild hyperthermia experienced during incubation, affected the behavioural responses of farmed Atlantic salmon (Salmo salar) offspring when exposed to a novel environment. Mature females were injected prior to stripping with 0, 50 or 100 mg/kg cortisol. After fertilization the eggs were kept at incubation temperatures of either 8 or 10 8C. Four months after hatching, the fish were introduced to a novel environment, i.e. an aquarium (38 l). In each trial two individuals originating from different exposure groups were video recorded and their activity (number of turns, time spent not swimming, time spent at the bottom) and feeding behaviour were measured. Maternal cortisol increased time spent non-swimming and also time spent at the bottom, while cortisol and temperature together additionally affected number of turns. To the best of our knowledge this study is the first in fish to demonstrate a possible link between the maternal endocrinological state at spawning and the offspring's behavioural reactivity to novel situations. #

Prenatalt stress defineres som stress opplevd av et (drektig) mordyr som kan virke inn på avkomme... more Prenatalt stress defineres som stress opplevd av et (drektig) mordyr som kan virke inn på avkommets utvikling . Hos pattedyr er det vist at prenatalt stress kan føre til økt dødelighet og redusert vekst, svekket immunfunksjon, i tillegg til nedsatt utforsknings-og lekatferd, dårlig laering-og stressmestringsevne, samt suboptimal seksuell og maternal atferd . Videre kan også morfologiske parametre påvirkes av prenatalt stress, det er dokumentert økt forekomst av morfologiske anomalier hos prenatalt stressede avkom . Med tanke på fisk har man forholdsvis god kunnskap om hvordan stress influerer spesifikke reproduktive mekanismer, men det finnes relativt få studier som undersøker hvorvidt stress erfart av kjønnsmoden hunnfisk influerer avkommets karakterer. Innen kommersiell fiskeoppdrett eksponeres fisk i alle livsstadier for en rekke akutte og kroniske biotiske og abiotiske stressorer, i tillegg til at stamfisken regelmessig håndteres i forbindelse med kjønnsmodning og stryking. Dette kan tenkes å initiere en stressrespons tilsvarende som hos pattedyr med en forøket aktivitet i HPI-systemet med etterfølgende økt sekresjon av kortisol som kan påvirke avkommets utvikling. Stresset hunnfisk vil derfor kunne ha et forøket nivå av stresshormoner i blodet, som kan gjenspeiles i eggene hennes. Eksperiment viser at en korrelasjon mellom mordyrets nivå av hormoner i blod og rogn eksisterer. Formålet med dette forsøket var å undersøke hvorvidt prenatalt stress hos oppdrettslaks påvirker avkommets utvikling og stressmestringsevne, samt belyse hvorvidt avvikende morfologi kan fungere som en objektiv, pålitelig indikator med tanke på stress og velferd innen kommersiell akvakultur.