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1、Chapter 1-3Carbohydrates,1.General2.Utilization of carbohydrate(CHO)3.Digestibility and importance of crude fibre,1.General1.1 Function of CHO(1)energy source(2)to assist the formation of the carbon skeleton for non-essential fatty acid（非必需脂肪酸的碳骨架）(3)for the synthesis of fats（合成脂肪）,1.2 The classes o
2、f carbohydrates（糖的分类）Monosaccharides（单糖）Di-and oligosaccharides（二糖和寡糖）Polysaccharides（多糖）Monosaccharides（单糖）hexoses(glucose,galactose,fructose)pentoses they are the building blocks for formation of di-,oligo-and polysaccharides,Di-and oligosaccharides（二糖和寡糖）monosaccharide molecules are joined togeth
3、er by means of ether linkages（醚键）lactose,consist of-glucose and-glucose and is the sole disaccharide of animal origin sucrose,-glucose and-fructose maltose（麦芽糖）,two-glucose cellobiose(纤维二糖),two-glucose molecules,Polysaccharides（多糖）macromolecules composed of large numbers of monosaccharidesStarchin t
4、he cells of plants in the form of granules（颗粒）of various sizes(1-150 m)each starch granule is composed of amylose(直链淀粉)(25%)，100-200 glucose molecules amylopectin(支链淀粉)(75%)，250-5000 glucose units,Polysaccharides（多糖）Dextrin(糊精)a water soluble breakdown product of starchGlycogen(糖原)the animal starch,
5、5000-25000 glucose units,chiefly in the liver，some in the muscle.,Polysaccharides（多糖）Cellulose（纤维素）the building material for plant cell walls,2000-8000-glucose units.Cellulases（纤维素酶）,the enzymes for cellulose cleavage（分解）,only produced by micro-organismsChitin（几丁质）forms the skeletal portions of crus
6、taceans（甲壳类）insects，in the cell walls of yeasts（酵母）,Polysaccharides（多糖）Lignin（木质素）in the cell walls of woody plants together with cellulose,not a carbohydrate,but a derivative of benzene(苯衍生物)indigestible，,The most important carbohydrates in fish glycogen,glucose,lactate(乳酸盐)pyruvate（丙酮酸盐）Glycogen（糖
7、原）muscle glycogen:0.15%,about 6%of that in the liver liver glycogen:2.5%of fresh weight,Glycogen（糖原）intense physical activity,（剧烈运动时）muscle glycogen broken down in a few minutes,recovery phasethe original level is not reattained even 24 hours later,liver glycogen content diminishes markedly.（肝糖原含量显著
8、减少）,1.3 Determination of carbohydrateNot by direct analysis,but by difference（差额）after the contents of moisture,crude protein(CP),fat(EE),ash,and crude fibre(CF).includes the water-soluble carbohydrate and certain other materials,but not the crude fibre（粗纤维）*N-free extract,NFE(无氮浸出物)=100%-moisture%-
9、CP%-EE%-ash%-CF%Crude fibre include:cellulose,lignin,pentosans（戊聚糖）,1.4 Factors affecting the blood-glucose content of the fish(1)the time of feeding the quality of diet intense activity,the time of feeding the quality of dietthe concentration of glucose in the blood rainbow trout,35-50mg/100 ml car
10、p,30-47 mg/100 mlmaximum blood-glucose level occurred,the time of feeding the quality of dietrainbow trout6 hours after high starch intake,（摄入高淀粉饲料后）9 hours after high glucose intake,18 hours after high protein intake.carp2 hours after oral administration of glucose,(3)intense activity,increase many
11、 times in the course of a few minutes,dramatically,the muscle lactate(乳酸盐),the blood lactate,pyruvate(丙酮酸盐),at a slower rate,2.Utilization of carbohydrate Warm-water fish can use much greater amounts of CHO than cold-water and marine fish.channel catfish the growth rate of fingerlings was greater wh
12、en their diets contained some carbohydrates rather than only lipids for all the non-protein energy.the maximum tolerable concentration should be used with regard to the fish species.（饲料中应该最大限量地用糖类）,*2.1 The nutritional values of carbohydrate among fish(1)carbohydrate may serve as precursors for the
13、dispensable amino acids and nucleic acids,（作为非必需氨基酸和核酸的前体）,which are metabolic intermediates necessary for growth.the least expensive source of dietary energy,catabolized（分解）for energyprotein sparing effect of CHOstarch is also important for the binding properties of extruded and pelleted feeds.（淀粉对
14、于膨化饲料和颗粒饲料的粘结性很重要）,in natural diet in the wildingest very little CHO,meet their energy requirements chiefly by breakdown of protein,makes use of amino acids for gluconeogenesis(葡糖异生),especially alanine serine,phenylalanine tyrosine,Dietary CHO,Digestive tract,*-amylase,glucosidase(maltase,cellobiase
15、,saccharase,lactase),galactosidase(lactase),fructosidase(saccharase),chitinase,chitobiase,*glycolysis,tricarboxylic acid cycle(TAC),pentose phosphate shunt,gluconeogenesis,glycogen synthesis,liver or kidney,*2.2 Utilization of carbohydrate in fish associated withComplexity of the carbohydrate（糖的复杂性）
16、The ability of fish to use various sources of carbohydrate,Red sea breamNo significant difference in growth rate for the various carbohydrate sources.,Channel catfishdextrin and starch were used for growthbut not mono-and disaccharides.Salmonidshigh concentration of digestible carbohydrates,results
17、in an increase in liver size and glycogen contentSimilar effects in red sea bream,plaice,yellowtail.,Chum salmon fry(大麻哈鱼鱼苗)glucose,maltose,sucrose,dextrin,and gelatinized starch were used for growth,but not fructose,galactose or lactoseWhite sturgeon（美洲鲟）Glucose and maltose dextrin or starch.,Chino
18、ok salmon（大鳞大麻哈鱼）20%of dietary CHO,growth rates in descending order:glucose,maltose and sucrose,dextrin and fructose,galactose，potato starch,and glucosamine,Carp(growth rate and FE)30%of dietary CHO,in descending order:maltosedextrinGlucose-starch,The ability to use dietary carbohydrate among specie
19、sCommon carpChannel catfishTilapia could use higher level of carbohydrates,30%See P33,Tab1-13,The ability to use dietary carbohydrate among speciesRainbow trout YellowtailSalmonids PlacieYellowtailRed sea bream 25%dextrin or gelatinized starch,Oral glucose tolerance test（口服葡萄糖耐量实验）Phenomena:a persis
20、tent hyperglycemia(持续的高血糖)Reason:Relative inability to utilize high concentrations of carbohydratesLow levels of endogenous insulin Non-insulin-dependent diabetes rather than insulin-dependent diabetes（更可能是非胰岛素依赖性糖尿病）,have been conducted withBrook trout（溪红点鲑）Rainbow troutCommon carpGrass carpChannel
21、 catfishRed sea breamYellowtailSimilar with rainbow trout fed diets containing 15%and 30%glucose,Insulin levels in plasma during glucose tolerance tests（血浆胰岛素水平）,Low in common carp red sea bream yellowtailInsulin was measured by a radioimmunoassay procedure(放射免疫测定法)using antiskipjack（抗鲣鱼）insulin ser
22、um.,3.Digestibility and importance of crude fibre,Crude fibre（概念）A complex of organic compounds which includes,Higher proportions of vegetable matter in compound,higher level of crude fibre.,cellulose,lignin,pentosans,In chinook salmon Small amount of-cellulose had a beneficial effect on growth and
23、protein utilization.Large amounts had an adverse effect on growth.,*The reasons for its benefits More choice of feedstuff sources(拓宽原料来源)Partial cellulose breakdown by micro-organisms in the intestine to give glucose(3)A slower rate of passage through the intestinal tract,consequently leading to a b
24、etter utilization of the other dietary constituents.（通过肠道的速率降低）With increasing CF uptake,the gastric evacuation rate（胃的排空率）also increased,while the digestibility of the dry matter decreased.,Table 1 Effects of different CF contents on the apparent digestibility coefficiency(ADC)of dry matter,stomach
25、 evacuation time(minutes)and the ratio of stomach:body weight（胃体比）in rainbow troutCF contents(%)0 10 20 ADC of dry matter(%)71 66 59 Stomach evacuation time(min)782 379 412 stomach:body weight 1.4 1.8 1.9,See P35*Table 2 Optimum crude fibre content of diet in fish speciesFish species CF(%)Steelhead trout 10Black carp 8Leiocassis longirostris（长吻鮠）48Grass carp 1015Wuchang fishBluntnose black bream（团头鲂）1015Common carp 610Tilapia 310 Shrimp 5,The end,
