Introduction to Carbohydrates

Introduction to Carbohydrates

• Carbohydrates chemically are polyhydroxy aldehydes and ketones, often referred to as CHO due to their composition of carbon, hydrogen, and oxygen
• Carbohydrates, unlike amino acids, do not have a specific requirement; energy requirements drive their consumption
• The body stores excess carbohydrates as fat
• Carbohydrates serve as an energy source because they are the most economical option, while protein and vitamins are more expensive for feed
• Plants are abundant in carbohydrates
• Carbohydrates typically make up approximately 70% or two-thirds of a diet

Chemistry of Carbs

• Monosaccharides are the basic units of carbohydrates
• Pentose contains five carbons
• Hexoses contain six carbons, making them the most abundant
• Examples of hexoses include glucose, galactose, fructose, and mannose
• Pentoses are not a dominant carbohydrate in feeds; xylose, a pentose, exists in hemicellulose
• Disaccharides are formed by two monosaccharides connected via a glycosidic bond
• Glycosidic bonds can be α-1,4, α-1,6, or β-1,4 linkages
• Examples of disaccharides include sucrose, lactose, maltose, and cellobiose
• Sucrose is composed of fructose and glucose.
• Lactose is composed of glucose and galactose.
• Maltose is composed of two glucose molecules
• Cellobiose is composed of two glucose molecules.
• Maltose and cellobiose have different types of glycosidic bonds
• Lactose-free milk is made by adding the enzyme lactase, which breaks the glycosidic bond in lactose, separating it into glucose and galactose
• Lactose is a key sugar found in milk
• Polysaccharides are composed of numerous monosaccharides linked by α-1,4 or α-1,6 linkages
• The alpha (α) designation indicates the bond type, and the numbers specify the bond position
• An α-1,4 linkage results in a straight chain, exemplified by amylase, a glucose polymer
• An α-1,6 linkage results in a branched chain
• Animal enzymes can hydrolyze α bonds, but are unable to hydrolyze β bonds

Amylopectin and Glycogen

• Amylopectin, found in plants, is a form of glucose containing both α-1,4 and α-1,6 linkages, acting as glucose storage
• Glycogen functions as glucose storage for animals, mainly in the liver and muscle
• Free glucose is found circulating in the blood
• Muscles contain a large amount of stored glycogen
• Racehorses depend heavily on glycogen reserves for energy during races.
• The liver stores a larger proportion of glycogen, but muscles store a greater overall amount

Cellulose

• Cellulose, a straight chain glucose polymer, contains β-1,4 linkages, unlike alpha linkages
• Beta (β) glycosidic bonds typically occur in fibrous carbohydrates and are chemically different from alpha bonds
• The two monosaccharides linked by a beta bond are flipped relative to each other, involving a change in stereochemistry, which needs specific enzymes to break
• Ruminants benefit from the breakdown of cellulose bonds by microbes in their rumen before it reaches the small intestine for absorption
• Animal enzymes can break α-1,4 linkages, but not β-1,4 linkages
• Microbes in the colon can break β-1,4 linkages, but this occurs after the small intestine, so the monomers are not absorbed here in non-ruminants
• Ruminants have microbes that digest fiber. These microbes can break β-1,4 linkages, allowing nutrient absorption from fiber

Hemicellulose

• Hemicellulose is made up of 5 and 6 carbon sugars and uronic acid in a polymeric form
• Often associated with lignin
• Hemicellulose varies as its composition differs throughout the polymer and from plant to plant
• The ability of microbes to digest hemicellulose depends on the amount of lignin present
• Lignin is not easily digestible, even for ruminants

Pectin and Lignin

• Pectin; a healthy carbohydrate that takes time to digest
• Polysaccharides rich in α-1,4 linkages and galacturonic acid
• The more α-1,4 linkages, the more digestible
• Pectin is similar to hemicellulose, but with less lignin, making it more digestible
• Apples, carrots, beet pulp, and beans
• Lignin; a carbohydrate that is closely associated with carbs
• Provides plants with rigidity and structure
• Is a polyphenolic compound
• Heterogeneous like hemicellulose
• Forms cross linkages with cellulose and hemicellulose
• Cross linkages lower digestibility, so more lignin indicates lower digestibility of cellulose and hemicellulose

Fiber Determinants, and Plant Cell Makeup and Structure

• Age of the plant indicates total lignin content
• The older the plant, the greater the lignin content
• The greater the lignin content present, this can make digestibility difficult, even for the microbes
• Cellulose and hemicellulose are the major carbs found in forages (grasses)
• Starch (glucose polymer) constitutes the main carb for grains (corn, barley, and wheat)
• Legumes (beans) contain more lignin than grasses
• Can be more digestible
• The cell center is rich in protein, minerals, and sugars
• Primarily consisting of cytoplasm and water-soluble carbs (starch and sugars)
• Plant cells have two cell walls: a primary and secondary cell wall
• The primary cell wall is thin, contains lots of lignin, more external
• The secondary cell wall is thicker, contains mostly cellulose (β-1,4 linkages)
• The primary cell wall is the barrier that allows enzymes to do their job
• Microbes need to break through both the primary and secondary cell walls for digestion
• The middle lamella provides strength to plant’s skeleton
• When making silage, adding enzymes or acid to break down forage and improve digestibility of plants.
• Fiber/plant digestibility can be improved by genetic modification, diet processing (e.g. heating)
• Managing the plants is the easiest and cheapest way to modify digestibility

Crude Fiber

• Crude Fiber is is the resulting organic residue after digesting with H2SO4 (sulfuric acid) and NaOH (sodium hydroxide)
• H2SO4 = acid and NaOH =base
• Used to remove everything that is NOT fiber, it removes proteins, sugars, starches, and lipids, but also removes portions of structural carbs and lignin
• Crude Fiber in the current measurements can be used to determine actual fiber content, as some of the fiber (structural carbs) is removed before the measurement
• Limitations of Crude Fiber: Treats all fiber components as uniformly digestible
• Treats all fiber components as uniformly digestible

Fiber Component Digestibility and Recovery

• Cellulose, hemicellulose, and lignin are NOT all equally digestible
• Ruminant microbes utilize some cellulose and hemicellulose, but not lignin
• Not all lignin and hemicellulose is recovered by the crude fiber method
• The amount of crude fiber is not accurate because the acid removes lignin and hemicellulose

Dietary Considerations

• The crude-fiber method is more of an issue when formulating a diet for cows
• Cows have a high volume of fiber in their diet, making it important to measure accurately
• Peter Van Soest developed a method that separates dry matter into two parts: one of uniform digestibility and one of non-uniform digestibility, with NDS = neutral-detergent solution (feed is boiled in this).
• This is a better methodology for determining fiber content than the crude-fiber method
• Boiling feed results Neutral Detergent Solubles (NDS): portion of uniform digestibility
• Consists mainly of lipids, sugars, starches, pectins, proteins, and NPN (non-protein nitrogen) with a digestibility of about 98% -The goal is to remove the above components and result in NDF being left
• Homogenous

Neutral Detergent Fiber (NDF)

• Portion of non-uniform digestibility
• Consists of plant cell wall components: cellulose, hemicellulose, and lignin (all of which make up fiber)
• Lignin affects the digestibility of the overall fiber (digestibility will be dictated by the amount of lignin)
• Not homogenous because lignin amount varies and affects the nutritive value
• NDF represents the true fiber fraction
• NDF = 100% - NDS; NDF + NDS = 100% (two components MUST add to 100%)

Other Fiber Analyses

• Acid-Detergent Fiber (ADF) is what remains after hemicellulose is removed
• ADF residue contains cellulose and lignin, so NDF – ADF = hemicellulose
• Less digestible than NDF due to higher proportion of lignin
• To understand the amounts of hemicellulose, lignin, and cellulose, with ADF as an intermediate.
• ADF is better than sulfuric acid

Analytical Processes and Grain Structure

• NDF needs to be completed before ADF and lignin analysis.
• Corn is a major source of carbohydrates
• Major components of corn include the endosperm, germ, and pericarp

Endosperm, Germ, and Pericarp

• Tip cap that seals the end of the kernel and bran, which connects the tip cap to the pericarp
• The endosperm makes up 80-84% of the kernel, it's high in starch, and has some protein
• The germ which makes up 10-14% of the kernel, and has a high oil concentration. It is in the centermost region of the corn
• The kernel has outer layer, with Approximately 6% of kernel, is mostly carbohydrate, protects and struggle with penetration
• Overall, corn is approximately 8% protein in the kernel, but it is mostly starch structure

Starch Exposure in Diet

• Breaking the corn (or grinding), allowing utilization and exposure of starch
• This is a form of diet processing

Carbohydrate Digestion

• Begins saliva
• Mouth of amylase contains the saliva, and the saliva breaks down the dextrins alpha polymers
• Amylase, however, does not break disaccharides
• Ruminant saliva does NOT contain amylase, but amylase breaks amylose
• Low pH can assist in the degradation of carbohydrates, however, the digestion small process isn't as important
• Small intestine amylase

Digestion locations

• Maltase, maltose, isomaltase, sucrase, lactase, all small digestion
• Isomaltose and alpha 1.6 linkages that form host amylase • Host enzymes and microbial enzymes can participate in digestion during fermentation
• Most microbes, fermentation the absence in participation for fermentation
• Constant nutrient food fermentations

Microbes

• Constant mixing microbes
• The components make a better rumen
• Microorganism bacteria, of great component
• Both biomass of biomass that contain great abundant is important.
• Birth microorganisms introduced by c section

Carbohydrates

• Ruminants in the animals or feed of microbes
• Not glucose bacteria
• Carbo bacteria
• Methane carbohydrates, as a carbon
• Conditioned bacteria and feeds can be affected by factors such as diets
• Components affect proportion

Propionate

• Carbohydrates converted methane
• Carbon formate methane
• Energy lost of fermentation
• Fermentation of intake
• Forage in the fermentation ratio
• Finely high VFA

VFA Absorption

• Rumen GI tract's have VFAs fermentation ratios and diets
• Monogastric minimal CHO
• No minimal in CHO amylase

Amylase

• The microbes contain the amount of digestion fermentation
• Disaccharides ares broken down by microvilli
• The major enzyme is broken down to maltose, lactose, and glucose.
• The forages are broken down to microbes

Microbes Lactate

• High carbon formation and VFAs
• High carbon formation and digestion levels
• Lower diet microbes protozoa

Gas Reduction

• The diets produce a lot of methane
• Formic acetate can also yield a lot of methane
• A leading acetate can also produce higher levels of gas
• Cattle, gas, and methane are reduced by some factors from a combination of data and studies.

Digestion Continued

• Better animal rumen, a healthy fiber fermentation
• DMI, rumen fiber, diet energy level can yield better rumen with some amount more microbes
• A better ruminant and more animal increase overall diet and microbe balance.

Balance and pH

• Normal pH to diet
• Carbohydrates glucose
• Fiber and non ruminants for VFA's levels digestions
• Lignin and VFA's has can affect how much levels increase or decrease

High or Low Grains

• High or low amount, or decrease for fatty acids
• Not fat high corn
• Acidosis and pH
• Decrease acidotic state from rumen to grains

Disease and Parasitosis

• Lactate accumulation and acid levels are reduced
• Acidosis due to lack of pH
• SARA has acidosis, and a more mild ruminant level Manipulating pH by limiting after meals

Acidosis and Parakeratosis

• Low grain levels will allow for epithelium diets
• Known as "twisted stomach"
• Prevents digestive and blocks issues will prevent flow