Increased dietary phosphorous prevents vertebral deformities in triploid Atlantic salmon (Salmo salar L.)

Triplicate groups of triploid and diploid Atlantic salmon were fed diets with a low (LP, total P: 7.1 g kg^?1), medium (MP, total P: 9.4 g kg^?1) or high (HP, total P: 16.3 g kg^?1) phosphorous (P) level from first feeding (0.18 g) to transfer to sea water (~50 g, duration: 203 days) and subsequently fed a commercial diet in sea water for 426 days (~3 kg). This study examined the short‐ and long‐term effects of dietary P on freshwater performance (mortality, growth), vertebral deformities (radiology), bone cell activity (ALP and TRACP enzyme activity in vertebrae and scales, and fgf23, bgp and igf‐I relative gene expression in vertebrae), bone mineralization (ash content) and some parameters related to fish condition (heart and liver size). Irrespective of ploidy, at seawater transfer, fish fed the MP diet had significantly highest length and weight and those fed the LP diet significantly lowest length and weight, while those fed the HP diet had intermediate lengths and weights. Increased dietary phosphorus reduced deformities in both ploidies at seawater transfer; however, triploids fed the LP and MP diets had more deformities than diploids fed the respective diets, while there was no ploidy effect observed for fish fed the HP diet. The vertebral bone ash content at seawater transfer was significantly higher in diploids than in triploids when fed the MP diet only. Alkaline phosphatase (ALP) and tartrate‐resistant acid phosphatase (TRACP) enzyme activities and relative gene expression of bone hormones involved in metabolism of plasma phosphate (fgf23) and bone growth (bgp) were not affected by ploidy at seawater transfer, but by dietary P level; LP increased ALP activity and reduced TRACP activity and fgf23 and bgp expression levels in vertebral bone. In scales, LP increased both ALP and TRACP activity. At the termination of the seawater period, the group‐wise pattern in occurrence of vertebral deformities was the same as at seawater transfer. The present results on mortality, growth, bone mineralization and development of skeletal deformities all demonstrate that triploids have a higher P requirement than diploids in fresh water. This study shows that an optimalization of P nutrition for triploid Atlantic salmon can improve health and welfare and reduce down‐grading of triploid salmon.     

Fat dynamics of Atlantic salmon Salmo salar L. smolt during early seawater growth

Growth of Atlantic salmon Salmo salar L. smolt is poor in the period immediately following transfer to seawater, and the fish may use endogenous reserves to meet metabolic requirements at this time. Fat dynamics of smolt that differed in ‘fat status’ (10–12 versus 5–7% body fat) at the time of transfer to seawater were examined in fish fed either high‐(31% fat, 41% protein) or low‐fat (18% fat, 49% protein) feeds during seawater rearing. Samples were taken at intervals over 14 weeks to monitor changes in fat of the fillet, viscera and remaining carcass (head, skeleton, skin and ‘belly flap’). Growth rates (SGRs) were low during the first 3–6 weeks, but improved with time and SGRs for the 14 weeks were approximately 1% d^?1. Fat status of the smolt appeared to influence growth in seawater, because the fish that had been held on the high‐fat feed in fresh water grew less well than those given low‐fat feed at that time. At transfer to seawater, the fillet housed 20–25% of the body fat, and the carcass over 50%. After 14 weeks, the fillet held 32–35% of the body fat, and viscera 19–26%, but the carcass, with 40–49%, was still the major fat depot irrespective of dietary treatment. Thus, the carcass is a major fat storage depot in Atlantic salmon smolt, but the fillet appears to become more important as the fish increase in size.     

Impact of smolt production strategy on vertebral growth and mineralisation during smoltification and the early seawater phase in Atlantic salmon (Salmo salar, L.)

This study investigates the effect of different smolt production strategies on vertebral morphology (radiology), composition (mineral content) and mechanical strength (load-deformation testing) in Atlantic salmon (Salmo salar). Rapid-growing underyearling (0+) smolt were compared with slower-growing yearling (1+) smolt and a reference group of wild smolt (w). The underyearling and yearling smolt were transferred to seawater in October 2002 and May 2003, respectively. The underyearling smolt were reared under continuous light and the yearling smolt under natural light during the first twelve weeks in seawater, at ambient temperatures. Thus, the underyearling smolt hit seawater at 13 °C and were reared at 10-13 °C during the early seawater phase, whereas the yearling smolt hit seawater at 7 °C and were reared at 7-10 °C during the early seawater phase. All groups displayed increased longitudinal growth (up to 9% increase in relative length) of the caudal vertebrae during parr-smolt transformation. However, at transfer to seawater, the underyearling smolt had significantly lower vertebral mineral content (0+ 44%, 1+ 47%, w 50%) and higher incidence of deformed vertebrae (0+ 1.5%, 1+ 0%, w 0%), and at twelve weeks after transfer to seawater significantly lower vertebral mineral content (0+ 36%, 1+ 41%, w 43%), yield-load (0+ 6492 g, 1+ 8797 g, w 9150 g) and stiffness (0+ 7578 g/mm, 1+ 15,161 g/mm, w 20,523 g/mm), and significantly higher incidence of deformed vertebrae (0+ 2.5%, 1+ 0.3%, w 0%). There was a significant correlation between the mineral content and mechanical properties of the vertebrae. The underyearling smolt had significantly elevated plasma concentrations of total Ca, and P and Ca²⁺ during the parr-smolt transformation and in the early seawater phase.The results show that underyearling smolt may have an increased risk of developing vertebral deformities. It is possible that this risk can be reduced by postponing the start of the short-day treatment. This will reduce the temperature during smoltification, the temperature and daylength during the early seawater phase, and increase the age at smoltification.     

Dietary phosphorus requirement of juvenile Atlantic salmon, Salmo salar L.

The objective of this study was to determine the dietary phosphorus (P) requirement of juvenile Atlantic salmon, Salmon salar L. Triplicate groups of fish (mean initial weight 1.4 g) were fed semipurified, casein-gelatine-based diets containing one of five levels of P (4, 8, 10, 15 and 25 g kg⁻¹) from Ca(H₂PO₄)₂·H₂O, or a commercial feed (17 g kg⁻¹ P) for 9 weeks. Weight gains did not differ significantly among treatment groups fed the experimental diets but were slightly less than gains in fish fed the commercial feed. Feed efficiency (wet weight gain/dry feed consumed) was similar in all groups, averaging 1.45. Availability of dietary P, estimated from apparent retention and apparent digestibility, was 86%. Whole-body P concentrations declined in fish fed diets containing less than 10 g kg⁻¹ P. Fitting a logistic curve to dietary P vs. whole-body P concentrations indicated that a minimum of 11 g kg⁻¹ dietary P (9 g kg⁻¹ digestible P) was required by juvenile Atlantic salmon to maintain whole-body P concentrations at initial levels. Calculation of a dietary requirement using a simple factorial model which incorporated measurements of P availability, feed efficiency and normal whole-body P concentration indicated that the dietary requirement was approximately 10 g kg⁻¹. The dietary requirement established in this study (10–11 g kg⁻¹) is higher than previously reported for Atlantic salmon or other fishes. Possible reasons for the wide range of reported dietary P requirements in fishes are discussed.     

The effect of water temperature on vertebral deformities and vaccine-induced abdominal lesions in Atlantic salmon, Salmo salar L

This study investigates the effects of water temperature (T) on vaccine-induced abdominal lesions (i.p. injection with oil-adjuvant vaccine) and vertebral deformities in Atlantic salmon. Quadruple groups of vaccinated (V) or unvaccinated (U) underyearling smolts were reared in tanks under four different temperature regimes for 6 weeks in fresh water (FW) followed by 6 weeks in sea water (SW). The four different T regimes were 10 °C FW-10 °C SW (10-10), 10 °C FW-16 °C SW (10-16), 16 °C FW-10 °C SW (16-10) and 16 °C FW-16 °C SW (16-16). After the temperature regimes were finished, the fish were group-tagged and transferred to a common sea cage for on-growth until harvest size. At termination, weight was significantly affected by both T and V, while lesion score and deformities were affected by T only. The weight difference between the largest and smallest U group was 20.3% (16-10 U: 2.4 kg, 10-16 U: 1.89 kg), while the largest difference between U and V fish within a T regime was 28.7% (16-16 U: 2.1 kg, 16-16 V: 1.5 kg). Fish from the 16-16, 16-10 and 10-16 regimes had a significant higher lesion score than those from the 10-10 regime. Fish from the 10-16 and 16-16 regimes displayed a significantly higher prevalence of vertebral deformities (palpation : 13-27%, radiology: 88-94%) than fish from the 10-10 and 16-10 regimes (palpation: 2-3%, radiology: 27-65%). Vertebra number 26 (located beneath the dorsal fin) was the most frequently affected vertebra in smolts, while vertebra number 43 (located above the anal fin) was most frequently affected in adults.     

Water temperature and dietary histidine affect cataract formation in Atlantic salmon (Salmo salar L.) diploid and triploid yearling smolt

The aim of the present study was to investigate cataract development in diploid (2N) and triploid (3N) Atlantic salmon smolts and post‐smolts at two water temperatures (10 and 16 °C) given diets with different histidine supplementation (LH, 10.4 and HH, 13.1 g kg^?1) before and after seawater transfer. In freshwater, a severe cataract outbreak was recorded in both ploidies reared at 16 °C. The cataract score was significantly higher in triploids compared to diploids, and the severity was lower in both ploidies fed the HH diet. The cataract development at 10 °C was minor. Low gill Na⁺, K⁺‐ATPase activity in fish reared at 16 °C before seawater transfer was followed by osmoregulatory stress with elevated plasma electrolyte concentrations and high mortality in sea water. Both diploids and triploids reared at 10 °C developed cataracts during the seawater period, with higher severities in triploids than diploids and a reduced severity in the fish fed the HH diet. The findings of this study demonstrate the importance of environmental conditions in the husbandry of Atlantic salmon, and particularly triploids, with regard to smoltification and adjusted diets to mitigate cataract development in fresh and sea water.     

Water flow and diurnal variation in metabolite production rates of Atlantic salmon (Salmo salar L.) post‐smolt

Diurnal variation of carbon dioxide (CO₂) and total ammonia production in Atlantic salmon post‐smolt were studied at different water flow rates. The experiment comprised four groups each with two replicates representing specific flow levels of 0.5, 0.4, 0.3 and 0.2 L kg^?1 min^?1. During the first diurnal cycle, the seawater samples were collected eight times during 21 hr. In the second diurnal cycle, six samplings were performed during a prolonged sampling period of 35 hr. The highest CO₂ concentrations were observed in the lowest water flow group (0.2 L kg^?1 min^?1) between 4 and 10 p.m. for the first sampling period and at about 2 p.m. for the second sampling period. The overall real CO₂ production rates were in the range 1.7–5.5 mg kg^?1 min^?1 including diurnal variation in all groups for both sampling periods. In general, a second‐order polynomial model describes the relationship between specific water flow and real mean CO₂ production rate (p < 0.001). Maximum concentrations of total ammonia nitrogen (TAN) occurred around 7 and 8 p.m. in all groups and was highest for the 0.2 L kg^?1 min^?1 group for both sampling periods. Note that maximum concentration of TAN and CO₂ both occurred in the afternoon. The TAN production rates were in the range 0.06–0.44 mg kg^?1 min^?1 including both sampling cycles.     

The effect of dietary vitamin A on the immunocompetence of Atlantic salmon (Salmo salar L.)

Atlantic salmon, Salmo salar L. were maintained on diets containing low (0.37 mg kg^–1 diet), normal (1.95 mg kg^–1 diet) and high (15 mg kg^–1 diet) levels of vitamin A fed at 1.5% body weight per day. After 4 months, liver vitamin A levels reflected dietary intake and growth rates of all three groups were similar. Kidney leucocyte migration and serum bactericidal activity were found to be significantly reduced in fish fed low levels of vitamin A. On the other hand, high levels of vitamin A in the diet were found to augment serum antiprotease activity relative to the levels found in the other dietary groups. However, phagocyte respiratory burst activity, bactericidal activity and eicosanoid production were unaffected by the dietary vitamin A regime, as were lymphocyte functions (lymphokine and antibody production) and both serum lysozyme and classical complement activity. That the overall immunomodulatory effect of vitamin A was small was reflected in the resistance to Aeromonas salmonicida. No significant differences were found between the different vitamin A intake groups despite a trend to decreased resistance in the low vitamin A diet group.     

Seasonal differences in smolt traits and post-smolt survival of wild Atlantic salmon, Salmo salar, migrating from a northern boreal river

Abstract  Seasonal differences in smolt traits and the post-smolt survival of wild Atlantic salmon, Salmo salar L., were investigated by smolt trapping and Carlin-tagging in the River Simojoki, northern Finland between 1991 and 2004. The annual trapping season was divided into two halves based on the median catch date. Smolt length was significantly higher during the first half of the season, while differences in smolt weight were typically small. Smolt age was always significantly higher during the first half of the season because older smolts tended to migrate earlier in the season. Many smolts migrating during the early season and almost all smolts migrating later had started their new growth, indicating that smolts grow in the spring before sea entry. The differences in recaptures between smolts tagged during the first and second halves were insignificant. Although variations in smolt traits and environmental conditions can produce inter-annual variation in post-smolt survival, their seasonal differences seem to be too small to have an effect.     

The aetiology of spinal deformity in Atlantic salmon, Salmo salar L.: influence of different commercial diets on the incidence and severity of the preclinical condition in salmon parr under two contrasting husbandry regimes

A large-scale trial of the effect of different commercial diets on the incidence of preclinical spinal deformation, as assessed by radiography, and the influence of two contrasting rearing systems was carried out. Two sets of three populations of Atlantic salmon, each of 20 000 first feeding fry of identical hatchery origin, created from equal numbers of eggs from 15 different families, were reared under commercial conditions on two different farms. Three commercial (closed formula) extruded fish meal-based diets were used in this study (diets A, B & C). Each diet was fed to one population of 20 000 fish at each site. Fish were fed a percentage of their body weight per day, with feeding rates set at commercial levels, based on water temperature, day length and fish biomass. Additional hand feeding was used to ensure satiation in all tanks. Fish in each tank were bulk-weighed and counted at the beginning and at 2-week intervals throughout the study. The fish were grown for 30 weeks. In addition, phosphorus (P) digestibility was evaluated by in-feed absorption testing in rainbow trout. The morphology of the radiographic lesions conformed to those described previously. Statistical analysis using multivariate regression analysis showed that date of sampling, site and diet were all statistically significant (P < 0.001) on univariable analysis. Farm A had significantly more affected fish than farm B (P < 0.001), which may have been attributable to variation in dissolved oxygen levels. The available dietary P levels were low in each diet. The number of fish affected in the group of fish being fed diet B was significantly lower than in the groups being fed diets A or C (P < 0.001). It appears most likely that the occurrence of preclinical radiographically apparent defects in parr which are believed to lead to the condition known as 'spinal deformity' is predominantly caused by a deficiency of available dietary P in first-feeding fry. The availability of dietary P may also vary considerably between diets formulated using different ingredients. Phytate-P associated with plant ingredients may affect the availability of P as well as other essential dietary nutrients. Additionally, diets for the production of salmonids in fresh water are currently formulated to keep P effluent to a minimum compatible with healthy spinal development. These various factors combine to make it crucial that small Atlantic salmon, especially first-feeding fry, are provided with carefully formulated diets fortified to an adequate level with a high quality source of available P.     

An estimation of dietary iron requirement of Atlantic salmon, Salmo salar L., parr

A study was conducted to determine the dietary iron requirement of fingerling Atlantic salmon Salmo salar L. During the first 4 weeks of the experiment, fish with an initial weight of 5 g were fed a casein–gelatine-based purified diet which contained 11 mg iron kg^?1. Thereafter duplicate tanks (200 fish in each) were fed the casein–gelatine purified diets containing supplemental iron levels of 0, 10, 20, 30, 40, 60, 100, 200 or 400 mg iron kg^?1 (added as FeSO_?4* 7H₂O) for 12 weeks. Weight gain, body length and mortality were monitored. Liver iron and ascorbic acid concentration were analysed in addition to whole-body iron, manganese and zinc concentration. Several haematological parameters were also measured. There were no significant differences in weight gain and survival of salmon fed diets containing different iron levels. Haematological values, hepatic and whole-body iron concentrations were, however, significantly affected by the dietary iron content. Liver vitamin C concentration decreased with increasing dietary iron levels. Dietary supplementation with iron significantly reduced whole-body manganese, but no effect of dietary iron on whole-body zinc was found. Based on haematology and hepatic iron concentration, the iron requirement of Atlantic salmon was determined to be between 60 and 100 mg iron kg¹.     

Effects of dietary cadmium on calcium homeostasis, Ca mobilization and bone deformities in Atlantic salmon (Salmo salar L.) parr

Atlantic salmon parr were reared for 4 months on experimental fish‐meal‐based diets supplemented with 0 (control), 0.5, 5, 25, 125 or 250 mg Cd kg^?1 feed to assess the effects of dietary Cd on active Ca uptake, mobilization of Ca from internal reservoirs, and development of bone malformations. The accumulation of dietary Cd in tissues was, in decreasing order, intestine > kidney >> gill > bone. No significant accumulation of Cd in the scales was observed. Strongest inhibition of ATP dependent Ca uptake (measured as Ca²⁺‐ and Na⁺/K⁺‐ATPase) was observed in the intestine of salmon fed 25 mg Cd kg^?1. This suppression in active intestinal Ca uptake did not lead to disturbed plasma Ca levels. Significant reduction of Ca from the scales in salmon fed 25 mg Cd kg^?1, indicates remobilization of Ca to maintain Ca homeostasis. At the end of the experiment no significant differences were observed in bone Ca levels, nor were any bone malformations observed in any of the dietary Cd‐exposed salmon. This indicates that bone as an endogenous Ca reservoir is spared compared with scales. It was concluded that dietary Cd‐induced disturbance of Ca homeostasis did not lead to bone deformities, even when Atlantic salmon were fed high amounts of cadmium. This indicates a low risk of spinal deformations being developed in Atlantic salmon sub‐chronically exposed to high Cd concentrations in the feed.     

Magnesium requirement of Atlantic salmon (Salmo salar L.) parr in seawater-treated fresh water1

This experiment was undertaken to establish the magnesium (Mg) requirement in young Atlantic salmon, Salmo salar L., in seawater-treated fresh water. In Norwegian hatcheries it is a common practice to add sodium hydroxide and/or sea water (1–2%) to improve pH and conductivity of the natural fresh water. Parr with initial weight of 8 g, were divided in six triplicate groups in brackish water containing 54 mg Mg L^?1 and fed a basal casein-gelatine diet supplemented with minor amounts of krill and fish meal (containing 200 mg Mg kg^?1) for an initial period of 3 weeks. Thereafter the fish were fed this diet supplemented with either 0, 100, 200, 300, 400 or 500 mg Mg kg^?1 (as MgSO₄) for 12 weeks. Growth and feed efficiency were recorded. Concentrations of Mg and other divalent cations (Ca and Zn) were measured in whole fish, serum and vertebrae. Sodium concentration in vertebrae was also measured. Growth and feed efficiency were unaffected by the levels of dietary magnesium used in the experiment. Magnesium concentrations in the whole body, serum and vertebrae Mg appeared to be more sensitive than growth and feed efficiency to differences in dietary Mg intake. The group fed the unsupplemented diet showed significantly lower Mg concentration in these tissues than the other groups. Whole-body calcium concentration was negatively correlated with dietary Mg and Ca:Mg ratios in the vertebrae were significantly affected by the dietary Mg levels. Zinc concentration in whole body, serum and vertebrae was not altered by the dietary Mg levels. Further, vertebral Na concentration did not vary between the dietary treatments. In conclusion, a minimum Mg supplementation level of 100 mg kg^?1 dry diet (in total, 326 mg kg^?1) was needed to maintain Mg concentration in the whole body and serum and for proper bone mineralization.     

Mercury comparisons between farmed and wild Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.)

Wild and farmed Atlantic salmon ( Salmo salar L.) and Atlantic cod ( Gadus morhua L.) were collected to assess changes in mercury with size in wild vs. farmed fish. Mercury concentrations were compared with Health Canada and United States Environmental Protection Agency consumption guidelines. Lipid dilution of mercury was examined by comparing lipid-extracted (LE) and non-lipid-extracted (NLE) flesh samples in both farmed and wild fish. Mercury concentrations in the flesh and liver of farmed salmon were significantly lower than concentrations in wild salmon of similar fork length ( P <0.001), possibly due to growth dilution in rapidly growing farmed fish. Mercury concentrations were higher in LE tissue compared with NLE ( P <0.05), suggesting lipid dilution of mercury in farmed fish with a high lipid content. Farmed cod, which do not grow more rapidly than wild cod, did not have significantly different flesh and liver concentrations compared with wild cod of similar fork length ( P >0.05). Between species of farmed fish, cod had significantly higher mercury concentrations than salmon ( P <0.05), but neither farmed nor wild salmon mercury concentrations exceeded federal consumption guidelines. These results suggest that rapid growth rates and a high lipid content may play important roles in regulating concentrations of contaminants such as mercury.     

Cataract formation in Atlantic salmon,Salmo salar L., smolt relative to dietary pro- and antioxidants and lipid level

The development of cataracts in Atlantic salmon, Salmo salar L., was studied in 16 groups of smolts fed diets differing in prooxidant (iron, copper, manganese) and antioxidant (vitamin E, vitamin C, astaxanthin) composition and lipid level for 23 weeks in sea water, using a 2(7-3) reduced factorial design. The seven dietary variables were systematically varied at low (requirement level and 150 g lipid kg(-1)) and high levels (below known toxic levels and 320 g lipid kg(-1)). A mean endpoint cataract incidence of approximately 36% was observed. High dietary levels of vitamin C and astaxanthin reduced cataract frequency, whereas high dietary lipid level, iron and manganese were associated with increased cataract frequencies. Considering the nutritional status of selected organs of the fish, only the status of ascorbic acid correlated negatively to cataract development (P < 0.05). The lens glutathione (GSH) status was not correlated to cataract frequency, nor statistically explained by the dietary variables. However, the study shows that balancing the diet with respect to pro- and antioxidant nutrients may significantly protect Atlantic salmon against development of cataracts. An incidence of reversible osmotic cataract observed at week 14 was positively correlated to plasma glucose concentration.     

Glucose tolerance in Atlantic salmon, Salmo salar L., dependence on adaption to dietary starch and water temperature

Individually tagged Atlantic salmon, Salmo salar L., were fed three different adaptation diets containing low, medium or high levels of extruded starch, before intraperitoneal injection of glucose. The injections were done at winter and at summer temperatures. This was to investigate whether the tolerance for glucose varied according to adaption diet and/or according to season. The results showed a temperature-dependent response. At winter temperatures (2°C) the Atlantic salmon had problems adapting to both medium and high levels of dietary starch. This was indicated by lower growth response in the adaptation period, as well as by delayed glucose regulation. At summer temperatures (12.5°C) the Atlantic salmon could tolerate and utilize both medium and high levels of dietary starch. In summer also all groups responded evenly to the tolerance tests with respect to blood glucose regulation. Incorporation of liver glycogen was higher at summer than at winter temperatures in the high- carbohydrate group. No effect was found on haematocrit values as a response to diet or season.     

Transport of alpha-tocopherol in Atlantic salmon (Salmo salar) during vitellogenesis

The transport of α-tocopherol was studied during vitellogenesis in Atlantic salmon that were fed diets with two levels of α-tocopherol. α-Tocopherol levels were measured in the flesh, liver, ovary and serum, and in the serum the α-tocopherol levels in the very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) and very high density lipoprotein (VHDL or vitellogenin) were also measured. Atlantic salmon store α-tocopherol mainly in their flesh because the muscle mass comprises 50% or more of live weight. During vitellogenesis the α-tocopherol content declined to about 10% of the level prior to maturation. The relative range of level of α-tocopherol in the lipoproteins was: HDL> LDL> VLDL> VHDL, irrespective of dietary levels of α-tocopherol. From the recent knowledge on lipid transport during vitellogenesis and the present data, we hypothesize that α-tocopherol is transported from peripheral tissues to liver by HDL and further transported from liver to ovary by LDL. Vitellogenin appears to play a minor role in the transportation of vitamin E to the ovary.     

Influence of dietary fatty acids on the lipid composition of lipoproteins in farmed Atlantic salmon (Salmo salar)

The dietary influence on the fatty acid composition of neutral lipids and phosphatidylcholine of very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) of Atlantic salmon (Salmo salar) was studied, using soybean oil, capelin oil and sardine oil as lipid sources in the diets. The fish had a mean weight of 3 Kg and had been fed the experimental diets for 24 months. The results show that the fatty acid composition in the feed are important for the composition of the core lipids as well as the surface components of the lipoproteins.