水产动物营养与饲料学-双语教学课件chapter 1-3-Carbohydrates

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 when their diets
sucrose, α-glucose and β-fructose maltose （麦芽糖）, two α-glucose cellobiose (纤维二糖), two β-glucose molecules
• Polysaccharides（多糖）
macromolecules composed of large numbers of monosaccharides
The most important carbohydrates in fish • glycogen, • glucose, • lactate (乳酸盐) • pyruvate（丙酮酸盐）
Glycogen（糖原）
muscle glycogen: 0.15%, about 6% of that in the liver liver glycogen: 2.5% of fresh weight
amylopectin (支链淀粉) (75%)，250-5000 glucose units
• Polysaccharides（多糖）
Dextrin (糊精) a water soluble breakdown product of starch
Glycogen (糖原) • the animal starch, • 5000-25000 glucose units, • chiefly in the liver，some in the muscle.
rainbow trout 6 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.
carp 2 hours after oral administration of glucose
Glycogen（糖原）
intense physical activity, （剧烈运动时） muscle glycogen
broken down in a few minutes, recovery phase
the original level is not reattained even 24 hours later, liver glycogen content diminishes markedly.（肝糖原含
• 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）
of protein, • makes use of amino acids for gluconeogenesis (葡糖异
生), especially alanine serine, phenylalanine tyrosine
Dietary CHO Digestive tract
*α-amylase, glucosidase (maltase, cellobiase, saccharase, lactase), galactosidase (lactase), fructosidase (saccharase), chitinase, chitobiase,
* 2.1 The nutritional values of carbohydrate among fish
(1) carbohydrate may serve as precursors for the 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 concentration of glucose in the blood
rainbow trout, 35 - 50mg/100 ml
carp,
30 - 47 mg/100 ml
maximum blood-glucose level occurred
(1) the time of feeding (2) the quality of diet
liver or kidney
* glycolysis, tricarboxylic acid cycle (TAC), pentose phosphate shunt, gluconeogenesis, glycogen synthesis
* 2.2 Utilization of carbohydrate in fish
Chapter 1-3 Carbohydrates
1. General 2. Utilization of carbohydrate (CHO) 3. Digestibility and importance of crude
fibre
1. General
1.1 Function of CHO
(1) energy source (2) to assist the formation of the carbon
monosaccharide molecules are joined together by means of ether linkages （醚键）
lactose, consist of α-glucose and β-glucose and is the sole disaccharide of animal origin
(2) the least expensive source of dietary energy, catabolized （分解）for energy
(3) protein sparing effect of CHO (4) starch is also important for the binding properties of
(3) intense activity increase many times in the course of a few minutes
dramatically the muscle lactate (乳酸盐) ≈ pyruvate (丙酮酸盐)
the blood lactate
at a slower rate
associated with • Complexity of the carbohydrate （糖的复杂性） • The ability of fish to use various sources of carbohydrate
Red sea bream No significant difference in growth rate for the various
量显著减少）
1.3 Determination of carbohydrate
• Not 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
• Polysaccharides（多糖）
Cellulose （纤维素） the building material for plant cell walls,
2000-8000 β-glucose units.
Cellulases（纤维素酶）, the enzymes for cellulose cleavage （分解）, only produced by micro-organisms
carbohydrate sources.
Channel catfish dextrin and starch were used for growth but not mono- and disaccharides.
Salmonids high concentration of digestible carbohydrates, results in an increase in liver size and glycogen content
Starch • in the cells of plants in the form of granules（颗粒）
of various sizes (1-150 μm) • each starch granule is composed of
amylose (直链淀粉) (25%) ， 100-200 glucose molecules
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 of carbohydrates（糖的分类）
• Monosaccharides（单糖） • Diaccharides（多糖）
1.4 Factors affecting the blood-glucose content of the fish
(1) the time of feeding (2) the quality of diet (3) intense activity
(1) the time of feeding (2) the quality of diet
extruded and pelleted feeds.（淀粉对于膨化饲料和颗粒 饲料的粘结性很重要）
in natural diet in the wild • ingest very little CHO, • meet their energy requirements chiefly by breakdown
Chitin （几丁质） forms the skeletal portions of crustaceans （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，
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）
materials, but not the crude fibre（粗纤维） * N-free extract, NFE(无氮浸出物)
=100% - moisture% - CP% - EE% - ash% - CF%
Crude fibre include: cellulose,
lignin, pentosans（戊聚糖）