Carbohydrates Lecture Notes PDF

Field of veterinary medicine Veterinary medicine program Carbohydrates nutritional significance Prof. dr/ Mohamed Yusuf lecture 2 20/10/2024 Chemically, carbohydrates are composed of carbon, hydrogen, and oxygen. Carbohydrates are the major dietary source of energy for animals. sol...

Field of veterinary medicine Veterinary medicine program Carbohydrates nutritional significance Prof. dr/ Mohamed Yusuf lecture 2 20/10/2024 Chemically, carbohydrates are composed of carbon, hydrogen, and oxygen. Carbohydrates are the major dietary source of energy for animals. solar energy + 6 CO2 + 6 H20 → C6H2O + 6 O2 The simplest form of a CHO is a monosaccharide. Monosaccharides include glucose, fructose and galactose Two monosaccharides link to form a disaccharide, sucrose, lactose, Polysaccharides are composed of three or more monosaccharides. The two primary polysaccharides are starch and cellulose. The glucose molecules in starch are linked via alpha linkages. The alpha linkages broken by both mammalian and microbial enzymes In contrast, glucose molecules in cellulose are linked via beta linkages. The beta linkages may be broken by only microbial enzymes. Feedstuffs high in starch include grains Feedstuffs high in cellulose include forages. Other carbohydrates include pectins and hemicellulose. Pectins and hemicellulose are only digested and utilized by microbes.  Significant difference between CHO digestion and absorption in ruminants vs non-ruminants 1- In the monogastric diet, 2- The monosaccharides are starch is the primary carbohydrate. readily absorbed into the In the small intestine, starch is digested bloodstream via the small by pancreatic amylase in conjunction intestine. with other enzymes.  As a result of the size and location of the microbial population, some monogastrics are able to utilize forage (Horse).  The utilization efficiency of fibrous compounds in monogastrics is the greatest in the horse; therefore, fibrous feedstuffs are included equine diets.  In Ruminants, the primary site for carbohydrate digestion is the reticulorumen.  The dietary carbohydrates are initially subject to rumen microbial digestion.  The primary substrates digested and metabolized by the rumen microbial population include sugars, starch, hemicellulose, and cellulose The end products of digestion in ruminants are volatile fatty acids and some monosaccharides.  The primary end-products of rumen fermentation of carbohydrates are the Short chain fatty acids (SCFAs)  The primary SCFAs are acetic acid, propionic acid, and butyric acid.  The SCFAs are absorbed across the rumen or the small intestine and metabolized to produce energy-yielding compounds such as glucose. N.B  High starch diets are characterized by relatively higher propionic acid  Higher fiber diets are characterized by relatively higher acetic acid.  In mature ruminants, intestinal digestion of carbohydrates is limited Lignin  Chemically, lignin is a polyphenolic polymer.  Lignin is associated with fibrous feedstuffs.  Lignin is indigestible by both microbial and mammalian enzymes.  Lignin also decreases the digestibility and availability of Nutrients of the feedstuff.  As a plant matures lignin content increases. Gas production:  Methane (CH4) is a hydrocarbon that is a primary component of natural gas.  Methane is also a greenhouse gas (GHG), so its presence in the atmosphere affects the earth's temperature and climate system.  The typical composition of rumen gas is CO2, 40%; methane, 30-40%; H2, 5%;  Small proportions of O2 and nitrogen (from ingested air).  A b o u t 4.5g o f methane is formed f r o m every 1 0 0 g o f carbohedrate digested, and the ruminant loses about 7% of its food energy as methane. Means of lowering methane production.  Unsaturated fatty acids are added to the ration; these then become saturated by the influence of microorganisms.  Hydrogen is needed for this. And this is a good way to reduce the amount of methane formed in the rumen. Factors Governing Microbial Digestion of Crude Fiber I, II, III and IV I Animal Factor A- Sudden change of ration and adaptation of 1 Species of the animal ruminal microorganisms to ration changes. 2 Age of the animal B- Effect of ration on rumen PH. 3 Ruminal environment C- Addition of antibiotics to the ration. D- Health condition of the animal.  II- Plant factors 1 Age of the plant 2 Type of roughage III-Ration composition 1 Starch and soluble carbohydrates 2 Level of dietary protein 3 Minerals and vitamins Cobalt is one of the trace elements needed by microorganisms. IV- Feed preparation 1 Alkali treatment of roughage converts CF into more degradable 2 Grinding of roughage: The grinding of roughages therefore reduces the digestibility of their crude fiber by as much as 20% 3 Pelleting of roughage may decrease CF digestion because of the increased rate of passage. Function of carbohydrates 1- Source of energy for normal life processes 2-Formation of biologically important compounds, glycolipids, glycoproteins, heparin and nucleic acids. 3- Starting materials for the biosynthesis of fatty acids and certain non-essential amino acids. 4-Stored in the animals as glycogen and fats.  Importance of crude fiber (cellulose and hemicellulose) for animals 1- Govern the bulk of a ration to meet the DM requirements 2- Prevent the formation of doughy like mass in the rumen; make canals in the the digesta, thus increasing the surface area of the digesta exposed to microbial and enzymatic digestion. 3- Protective effect against some metabolic and digestive disorders as lactic acidosis, abscessed liver, rumen parakeratosis, displaced abomasum. 4- The relative quantities of the SCFAs, produced in the rumen are greatly affected by the diet (roughage: concentrate ratio)when dairy cattle fed on rations high in concentrates and low in roughage the acetate will decrease and propionate increase and by turn reduction in milk fat.