1、Chapter 1-2LipidsGeneral1. Essential fatty acid2. Lipid Requirement3. Lipid spoilage4.Practical use of lipids in fish dietsThe function of lipids(1) normal growth and development(2) a part as metabolic regulators ergosterol VD2， cholesterol (胆固醇) sex hormone (性激素)(3) assisting in the absorption and
2、transit of fat-soluble vitamins(4) Source of energy 37.656kJ/g, easy to store(5) essential fatty acids (EFA) Characteristics of Lipid related to nutrition(1)Undissolvable in water, dissolvable in organic solvent , ether extract, EE (粗脂肪), CL instead of CF, basis of quantitative analysis (2)Close rel
3、ationship between melting point and structure Digestibility of lipid for fish and shrimp related to melting point the higher the melting point, the higher the digestibility (3) n-3 and n-6 series of polyunsaturated fatty acid must be supplied in the diet.Characteristics of Lipid related to nutrition
4、(4) Lipid can be hydrolyzed by acid, alkali and enzyme into glycerol and fatty acid. lipase of fish and shrimp(5) Spoilage Humidity, hot, light, oxygen, 油哈味 happen in manufacture and storage of diet (6) Sparing effect of protein (蛋白质节约作用蛋白质节约作用) digestibility 90% Triacylglycerols 三酰甘油 the main form
5、of dietary lipids hydrolyzed by digestive enzymes a mixture of free fatty acids and 2-monoglycerides absorbed （被吸收） used for synthesis of various cellular components （用于合成不同的细胞成分） catabolized for energy（分解作能量） Dietary lipids contain saturated fatty acid (饱和) unsaturated fatty acid（不饱和） Designation （
6、命名法） by methyl terminal or （从甲基端, most convenient） carboxyl terminal （从羧基端） 棕榈油酸 CH3(CH2)5CHCH(CH2)7COOH*16:1n-6carbon atomsdouble bondscarbon atoms between the methyl terminal and the first double bondcolon Polyunsaturated fatty acid (PUFA)（多不饱和脂肪酸） 18 or more carbon atoms and（18或更多碳原子） two or more
7、 double bonds （2个或更多双键） 16:0, 18:0, 18:1n-9, 18:2n-6 18:3n-3 20:5n-3 22:6n-3See P36, Table 1-14Homework (Write the Chinese name of the following fatty acids which are commonly used in nutrition and explain the meaning of the three numbers)16:018:0 18:1n-918:2n-618:3n-320:5n-322:6n-3硬酯酸硬酯酸油酸油酸亚油酸亚油酸亚
8、麻酸亚麻酸花生四烯酸花生四烯酸 EPA鰶鱼酸鰶鱼酸 DHA Factors affecting lipid utilization in fish and shrimp软酯酸软酯酸硬酯酸硬酯酸油酸油酸亚油酸亚油酸亚麻酸亚麻酸花生四烯酸花生四烯酸 EPA鰶鱼酸鰶鱼酸 DHA(1) Types of lipid affecting lipid digestibility low melting point, higher digest. Factors affecting lipid utilization in fish and shrimp软酯酸软酯酸硬酯酸硬酯酸油酸油酸亚油酸亚油酸亚麻酸亚麻
9、酸花生四烯酸花生四烯酸 EPA鰶鱼酸鰶鱼酸 DHA（2）levels of other nutrients in diet Ca: chelated at high level, lipid digest. decrease P and Zn: enhance lipid oxidation, reduce storage in body VE: prevent and destroy lipid peroxide Choline: important for phosphlipid synthesization (磷脂合成) fatty-liver disease occurred when
10、 lack of choline1. Essential Fatty Acid (EFA) These that fish cannot synthesize and must be supplied in the feed. linoleic acid (18:2n-6, 亚油酸) linolenic (18:3n-3, 亚麻酸) Fish and shrimp can synthesize n-7 and n-9 series fatty acid1.1 The quantitative EFA requirements (EFARs) EFARs requirement of fish
11、is related to their ability to modify these fatty acids metabolically. Fish vary considerably in their ability to convert 18-carbon unsaturated fatty acids to longer-chain, （能力差别很大） A major differencesfreshwater fish stenohaline marine fish (狭盐性海水鱼) Freshwater fish require either linoleic acid (18:2
12、n-6) or linolenic acid (18:3n-3), or both. Stenohailine marine fish require EPA (20:5n-3) and/or DHA (22:6n-3)The reason for the difference between freshwater fish and marine fishFreshwater fish：18:3n-3 22:6n-3，Marine fish：turbot, red seabream, 18:3n-3 22:6n-3Isotope labeled test（Owen，1975）：rainbow
13、trout：70 of 18:3n-3 22:6n-3，flounder：dietary 18:3n-3 increased to 4，no increment of 22:6n-3 in liver lipid4 types of EFARs among freshwater species 18:2n-6, 18:3n-3, 20:5n-3 and 22:6n-3(1) 18:3n-3 or EPA and/or DHA ayu (香鱼), coho salmon （银大麻哈鱼）, channel catfish, rainbow trout(2) Equal mixture of 18:
14、2n-6 and 18:3n-3 chum salmon （大鳞大麻哈鱼）, common carp, Japanese eel(3) 18:2n-6 only tilapias(4) n-3 fatty acid shrimpEFAR for stenohaline marine fish n-3 PUFA, 20 carbon flounder（Cowey，1976）： weight gain, Cod liver oil（15in 22:6n-3） 18:3n-3 20:4n-618:2n-6 Judgement for EFAR(1) Deficiency sign(2) Growth
15、 rate and FE(3) EFA plenty index (必需脂肪酸充分度指标) indicated as the ration of 20:3n-9 / 20:4n-6 20:3n-9 / 22:6n-3 in liver phospholipid Common carp: 20:3n-9 / 20:4n-6 0.6 20:3n-9 / 22:6n-3 0.4 Steel head trout: 20:3n-9 / 22:6n-3 0.4EFAR in fish: 0.52.0of dietSteelhead trout：18:3n-3, 1 20:5n-3 & 22:6n-3：0
16、.51.0White salmon： 18:2n-618:3n-3：11 20:5n-3 & 22:6n-3：0.51.0 Eel: 18:2n-6 + 18:3n-3, 0.5+0.5%Common carp: 18:2n-6 + 18:3n-3, 1+1%Zilliis tilapia： 18:2n-6 or 20:4n-6, l， Nile tilapia： 18:2n-6, 0.5，Channel catfish：18:3n-3, 1.0，Yellowtail: 20:5n-3 & 22:6n-3, 0.5，Sea bream: 20:5n-3 & 22:6n-3, 2.0，Floun
17、der: 20:5n-3 & 22:6n-3, 1.l1.5，CrustaceanEFAR：linoleic acid ( 18:2n-6） linolenic acid（18:3n-3） EPA（20:5n-3） DHA（22:6n-3）Similar to freshwater fish in lipid metabolism, but weaker, the better the growth , the more 22:6n-3 addition directly.the effects of exceeding dietary EFA level on EFAR(1) Negativ
18、e effect on feed storage(2) Depress growth rate(3) Body moisture level increase, protein level decrease油鲱Table 1 Chemical composition of rainbow trout of 160g liveweight after feeding with fat-supplemented dry compound feed compared with a control diet of 5% crude fat content.（体化学组成） Control(no adde
19、d fat)Added fat consisting ofSunflower seed oilCod-liver oilFish oilDry matter29.231.331.930.7C r u d e protein17.816.916.517.2Crude fat8.711.512.310.8Ash2.22.32.22.3 Factors affecting EFAR(1) species(2) Dietary lipid levelEFARs increase with increasing of dietary lipidRainbow trout maximum growth r
20、ate with dietary lauric acid % (月桂酸含量) 5， 18:3n-3: 1； 8， 18:3n-3: 2； 10/15，growth performance decrease（Weight gain, FE)1.2 The principal gross signs of EFA deficiency (EFA缺乏的主要症状) Dermal signs (fin rot) (皮肤病，烂鳍) A shock syndrome (休克综合症) Myocarditis (心肌炎) Reduced growth rate (生长率下降) Reduced feed effi
21、ciency (饲料效率下降) Increased mortality (死亡率上升) Reduced the reproductive performance of some species (生殖性能下降)1.3 Desaturate (去饱和) and chain elongate （链延长） in fish species, 18:2n-6 or 18:3n-3 absence in the diet desaturation and chain elongation oleic acid (18:1n-9) (油酸) 20:3n-9. incorporated into tissue
22、 polar lipids, in place of 20:4n-6, 20:5n-3 or 22:6n-3The ratio of 20:3n-3/20:5n-3 might be a useful index of EFA status in rainbow trout, the ratio 0.4 in the diet, satisfactory with EFA EPA and DHA for larvae ayu and red sea bream larvae (香鱼和真鲷仔鱼） for normal growth and development rotifers (轮虫) an
23、d Artemia spp.(卤虫) lack of n-3 PUFAs or low level of n-3 PUFAs, high mortalities (死亡率), abnormalities (畸形), underdeveloped swim bladder （鳔发育不全） scoliosis (脊椎侧凸) EPA and DHA for larvaeessential for various fish larvae, ayu red sea bream striped jack （条纹 (鱼参)） gilthead sea bream (金头鲷) striped bass （条纹
24、石(鱼旨)1.4 The essential fatty acid functionTo fulfill a variety of metabolic functions (1) As component of phospholipids in all biomembranes(2) As precursors for eicosanoids (类花生四烯酸的前体)Biomembranes must be in a fluid state to function properly at various temperatures.Membrane fluidity depends on the
25、proper balance of saturated and unsaturated fatty acids as components of membrane phospholipids.1.4 The essential fatty acid function dietary n-3 PUFA related with homeoviscous regulation (恒粘性调节)fish alter their biomembrane phospholipid composition in response to changes in environmental temperature
26、（改变生物膜磷脂组成来应对环境温度变化）During acclimation to cold-temperatures the total amount of phospholipid in the fish biomembrane does not change,（在适应冷水期间，生物膜磷脂总量不变化）1.4 The essential fatty acid function changes occur in the relative proportion of individual phospholipids, （每种磷脂的相对比例） in the fatty acid compositi
27、on of the phospholipids,（磷脂的脂肪酸组成） in the distribution of fatty acid within the phospholipid molecules（磷脂分子中脂肪酸的分布）during cold adaptionrainbow trout, 20 5, in both liver and gills phosphatidylethanolamine (磷脂酰乙醇胺) phosphatidylcholine (磷脂酰胆碱) goldfish intestine and carp muscle, similar changesreverse
28、 occurred during hot adaption in individual phospholipids in the fatty acid composition during cold adaptation, in trout membranes, n-3 PUFA in trout liver membrane phopholipids, saturated fatty acids, monounsaturated fatty acids 22:6n-3 in phosphatidylcholine, 20:5n-3 in phosphatidylethanolamine2.
29、Lipid Requirementmust consider the quantity and the quality of the fat to meet the demand for EFAs. an elevated dietary fat content has a beneficial effect on growth, feed utilization protein utilization, a lower rate of N excretion and hence to a diminished level of water pollution.（降低氮排泄，减轻水污染）Tab
30、le 2 Effects of raising the fat content of dry compound feedstuffs from 5% to 9% by means of supplementation with various oils, with respect to growth, feed conversion ratio and protein utilization by rainbow trout during a 96-day period. No added oilSunfloweroilCod-liver oilFish oilCrude fat level
31、(%)Crude protein (%)4.740.19.038.28.938.38.238.6Initial weight (g)Final weight (g)Gain (%)Feed conversion ratio (kg/kg gain)PERPPV35.3127.72611.981.2622.435.2169.63821.282.0434.539.6168.13241.461.7929.534.2141.13131.571.6628.2Table 3 Effects of various fat and protein contents in the diet of rainbow
32、 trout on feed conversion ratio (kg/kg gain)Dietary fat (%)Crude protein content (%)45 40 35 30101.231.311.421.6912.51.151.281.441.62151.151.221.311.42Table 4 Relative feed conversion ratio (with respect to 10% sunflower-seed oil =100%) for feed mixtures supplemented with 10% of various fats and sup
33、plied to young rainbow troutDietary fatRelative feed conversion (%)Sunflower-seed oil (红花油)100Ocean-perch oil（海鲈油）（海鲈油）81Soya-bean refining fatty acids（大豆提炼的脂肪酸）79-91Mixed animals fats（混合动物油）92Rapeseed oil low in erucic acid（低芥子酸酸菜籽油）91Rapeseed oil high in erucic acid（低芥子酸酸菜籽油）93Soya-bean oil, refin
34、ed（提炼过的豆油）91-95Soya-bean oil, raw（粗豆油）95Linseed oil（亚麻籽油）95Rice oil（大米油）98Bone fat（骨油）98Lard（猪油）98Corn-germ oil（玉米胚油）104Beef tallow（牛油）108Olive oil（橄榄油）110Micronized hardened fatty acids（微粒硬化脂肪酸）（微粒硬化脂肪酸）128Table 5 An optimal fat percentage in dry compound feeds for various species of young fishFish
35、 speciesOptimal fat level (%)Rainbow trout 1520black carp (matured)68（4.56）Grass carp38Common carp58Allogynogenetic crucian Silver carp 异育银鲫5Nile tilapia610Mud carp 鲮45Leiocassis longirostris Gnther长吻鮠510Fenneropenaeus chinensis 中国对虾46 Elevated fat contents in the diet an elevated fat content in the
36、 trout a slight decrease in the protein content These change does not bring about any appreciable change in the quality of the fish flesh from the standpoint of the consumer（消费者感觉不到这种改变对鱼肉品质的影响）Table 6 Chemical composition of rainbow trout of 160g liveweight after feeding with fat-supplemented dry c
37、ompound feed compared with a control diet of 5% crude fat content.（体化学组成） Control(no added fat)Added fat consisting ofSunflower seed oilCod-liver oilFish oilDry matter29.231.331.930.7C r u d e protein17.816.916.517.2Crude fat8.711.512.310.8Ash2.22.32.22.3油鲱3. Lipid spoilageA harmful effect on fishOc
38、curance of spoilage （酸败的发生）(1) By physicochemical means due to adsorption of odoriferous substance;（吸收臭味物质）(2) Biochemical means due to the action of tissue enzymes or micro-organism;（组织酶或微生物）(3) Autoxidation means as a result of the oxidation of fatty acids by atmospheric oxygen, which is of greate
39、st importance for spoilage of fats.（通过脂肪酸在空气氧中自动氧化作用）(3) the autoxidation of fatty acids The unsaturated fatty acids react spontaneously（自然地） and in the absence of any further additives when in contact with atmospheric oxygen.The process begins with splitting of H atom and the formation of hydropero
40、xides （氢过氧化物）,and later a kind of chain reaction and proceeds at an accelerating rate,（链式反应，反应进程加快）As the number of double bonds increases, that is in the order monoenoic (单酯酸), dienoic (二酯酸) and polyenoic acids (多酯酸), the tendency to oxidation is enhanced. (氧化加快)3.1 Reaction processRH + O2 R + OHR
41、+ O2 ROO （ Peroxides ，过氧化物）ROO + RH ROOH + R AH or AH2 (antioxidant, 抗氧化剂 )R + AH2 RH + AH ROO + AH2 ROOH + AH ROO + AH ROOH + A A + A A2ROO + A ROOASubstances formed in the process（生成物）(1) Peroxides （过氧化物）(2) The fission products of fatty acid chains（脂肪酸链的裂解产物）(3) Polymerized glycerol derivatives （
42、多聚甘油衍生物）Negative function of Peroxides(1) Inactivate certain vital ingredients (VA, E, B6，C)(2) Growth depression(3) Poor feed utilizationAntioxidantsare used up in the course of their antioxidative action, （在抗氧化反应中耗竭）and are effective in controlling spoilage for only a limited period of time.（在有限的时
43、间内可有效控制酸败）Higher fat content in the feed require greater amounts of antioxidants.* Antioxidants Ascorbic acid Citric acid Tartaric acid (酒石酸) Phosphates Phospholipids Vitamin E Synthetic antioxidants EMQ（乙氧基喹啉）, BHT（二丁基羟基甲苯）, BHA（丁基羟基茴香醚）Added level：from 100 to 200 mg/kg dry diet3.2 Symptoms of dise
44、ase when received oxidized fats Discoloration（褪色） Anaemia（贫血） Lethargy（呆滞） Fatty liver（脂肪肝） Kidney lesions（肾损伤） Gill adhesions（鳃粘连）In carpOxidized oil is responsible for the “sekoke” disease poor growth, muscular dystrophy,(肌肉营养失调) high mortality (死亡率高)adding -tocopherol (-生育酚), the progress of the
45、disease can be halted.Toxicity mechanismIn carpThe absorption of peroxides proceeds by conversion into oxo-derivatives in the intestine（含氧衍生物） a marked adverse effect on the biosynthesis of di- and triglycerides via glycerol-3-phosphate.（对由甘油-3-磷酸合成甘油二酯和甘油三酯有显著影响）not affect the transformation of gly
46、cerol-3-phosphate into phosphatidyl acid, （不会影响到甘油-3-磷酸转化为磷脂酰酸）4. Practical use of lipids in fish dietsConsidering aspects of lipid use in practice(1) Feed formulation(2) Lipid types(3) Antioxidants4.1 Feed formulationLipids serves as an important source of dietary energy , especially for cold-water
47、 and marine fish, which have a limited ability to use dietary carbohydrates for energy. in yellow tail, increasing lipid contentdietary protein , 70% to 55%,without any reduction in growth in rainbow trout, dietary lipid content, 15% to 20% dietary protein content, 48% to 35% weight gain did not red
48、uce.all diets should be formulated(1) to meet the optimum ratio of energy to protein, （满足适宜的能蛋比）(2) to contain an adequate amount of lipid.（含适宜的 脂肪含量）(3) to contain proper types of lipid NRC, Tab 8-5(1) to meet the optimum ratio of energy to protein, （满足适宜的能蛋比）imbalance of the DE/CP ratio (Too much
49、dietary lipid ) result in excessive fat deposition in the visceral cavity and tissues, reduced yield, reduced product quality, Problem of storage(2) proper types of lipid food fish nutritional value the fatty acid composition of the dietary lipid has a significant influence on the tissue fatty acid composition of the fish.Hard fats have the advantage that they are less liable to oxidation and consequent spoilage（凝固的脂肪不易氧化和酸败） Trans fatThe end
