Duplicate groups of Atlantic salmon post-smolts were fed five practical-type diets in which the added lipid was 100% fish oil [FO; 0% rapeseed oil (0% RO)], 90% FO + 10% RO (10% RO), 75% FO + 25% RO (25% RO), 50% FO + 50% RO (50% RO) or 100% RO, for a period of 17 wk. There were no effects of diet on growth rate or feed conversion nor were any histopathological lesions found in liver, heart, muscle or kidney. The greatest accumulation of muscle lipid was in fish fed 0% RO, which corresponded to significantly lower muscle protein in this group. The highest lipid levels in liver were found in fish fed 100% RO. Fatty acid compositions of muscle lipid correlated with RO inclusion in that the proportions of 18:1(n-9), 18:2(n-6) and 18:3(n-3) all increased with increasing dietary RO (r = 0.98-1.00, P < 0.013). The concentrations of eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)] in muscle lipid were significantly reduced (P < 0.05), along with total saturated fatty acids, with increasing dietary RO. Diet-induced changes in liver fatty acid compositions were broadly similar to those in muscle. Hepatic fatty acid desaturation and elongation activities, measured using [1-(14)C] 18:3(n-3), were increased with increasing dietary RO. Limited supplies of marine fish oils require that substitutes be found if growth in aquaculture is to be maintained such that fish health and product quality are not compromised. Thus, RO can be used successfully as a substitute for fish oil in the culture of Atlantic salmon in sea water although at levels of RO >50% of dietary lipid, substantial reductions occur in muscle 20:5(n-3), 22:6(n-3) and the (n-3)/(n-6) polyunsaturated fatty acid (PUFA) ratio, which will result in reduced availability of the (n-3) highly unsaturated fatty acids that are beneficial for human health.

27It has been known for almost 25 years now that inclusion of intact phospholipids in the diet could 28 improve culture performance of various freshwater and marine fish species. The primary 29 beneficial effect was improved growth in both larvae and early juveniles, but also increased 30 survival rates and decreased incidence of malformation in larvae, and perhaps increased stress 31 resistance. Determination of absolute dietary requirements has been hampered by the use, in 32 different dietary trials, of a wide range of phospholipid preparations that can vary greatly both in 33 phospholipid content and class composition. Larval studies have been compromised further by the 34 need on many occasions to supply phospholipid through enrichment of live feeds with subsequent 35 re-modelling of the phospholipid and fatty acid compositions. Generally, the levels of 36 phospholipid requirement are around 2 -4% of diet for juvenile fish and probably higher in larval 37 fish. The effects were restricted to young fish, as a requirement for dietary phospholipids has not 38 been established for adult fish, although this has been virtually unstudied. As the majority of 39 studies have used crude mixed phospholipid preparations, particularly soybean lecithin, but also 40 other plant phospholipids and egg yolk lecithin, that are enriched in several phospholipids, it has 41 been difficult to elucidate which specific phospholipid classes impart beneficial effects. Based on 42 the few studies where single pure phospholipid species have been used, the rank order for efficacy 43 appears to be phosphatidylcholine > phosphatidylinositol > phosphatidylethanolamine > 44 phosphatidylserine. The efficacy of other phospholipid classes or sphingolipids is not known. The 45 mechanism underpinning the role of the phospholipids in larval and early juvenile fish must also 46 explain their lack of effect in adult fish. The role of phospholipids appears to be independent of 47 fatty acid requirements although the presence of an unsaturated fatty acid at the sn-2 position may 48 be important. Similarly, the phospholipid requirement is not related to the delivery of other 49 essential dietary components such as the bases choline and inositol. Studies also suggested that the 50 phospholipid effect was not due to generally enhanced emulsification and digestion of lipids. 51Rather the evidence led to the hypothesis that early developing stages of fish had impaired ability 52 to transport dietary lipids away from the intestine possibly through limitations in lipoprotein 53 synthesis. The current hypothesis is that the enzymic location of the limitation is actually in 54 phospholipid biosynthesis, perhaps the production of the glycerophosphobase backbone and that 55 dietary supplementation with intact phospholipids in larvae and juvenile fish compensated for this. 56

Road expansion and associated increases in hunting pressure are a rapidly growing threat to African tropical wildlife. In the rainforests of southern Gabon, we compared abundances of larger (>1 kg) mammal species at varying distances from forest roads and between hunted and unhunted treatments (com-paring

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For humans a daily intake of up to 500 mg omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) is recommended, amounting to an annual requirement of 1.25 million metric tonnes (mt) for a population of 7 billion people. The annual global supply of n-3 LC-PUFA cannot meet this level of requirement and so there is a large gap between supply and demand. The dietary source of n-3 LC-PUFA, fish and seafood, is increasingly provided by aquaculture but using fish oil in feeds to supply n-3 LC-PUFA is unsustainable. Therefore, new sources of n-3 LC-PUFA are required to supply the demand from aquaculture and direct human consumption. One approach is metabolically engineering oilseed crops to synthesize n-3 LC-PUFA in seeds. Transgenic Camelina sativa expressing algal genes was used to produce an oil containing n-3 LC-PUFA to replace fish oil in salmon feeds. The oil had no detrimental effects on fish performance, metabolic responses or the nutritional quality of the fillets of the farmed fish.

The aim of this study was to investigate effects of dietary levels of histidine (His) and iron (Fe) on cataract development in two strains of Atlantic salmon monitored through parr-smolt transformation. Three experimental diets were fed: (i) a control diet (CD) with 110 mg kg )1 Fe and 11.7 g kg )1 His; (ii) CD supplemented with crystalline His to a level of 18 g kg )1 (HD); and (iii) HD with added iron up to 220 mg kg )1 (HID). A cross-over design, with two feeding periods was used. A 6-week freshwater (FW) period was followed by a 20-week period, of which the first three were in FW and the following 17 weeks in sea water (SW). Fish were sampled for weighing, cataract assessment and tissue analysis at five time points. Cataracts developed in all groups in SW, but scores were lower in those fed high His diets (P < 0.05). This effect was most pronounced when HD or HID was given in SW, but was also observed when these diets were given in FW only. Histidine supplementation had a positive effect on growth performance and feed conversion ratio (P < 0.05), whereas this did not occur when iron was added. Groups fed HD or HID had higher lens levels of His and N-acetyl histidine (NAH), the latter showing a marked increase post-smoltification (P < 0.05). The HD or HID groups also showed higher muscle concentrations of the His dipeptide anserine (P < 0.05). There was a strong genetic influence on cataract development in the CD groups (P < 0.001), not associated with tissue levels of His or NAH. The role of His and Hisrelated compounds in cataractogenesis is discussed in relation to tissue buffering, osmoregulation and antioxidation.

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