Midterm 2

• • Canula is the rumen canula, allowing access to rumen fluid for collection and donation
  • In situ means inside, while in vitro means outside, used for incubating fluids like in the stomach
  • Optimum levels are crucial to avoid deficiencies or toxic levels, both of which can be fatal
• Digestibility and Digesta Passage:

  • Digestion markers are usually made of molecules that are not usually digested, secreted, or absorbed by the gut
  • Transit time measures the time from marker administration to first appearance in feces
  • Mean Retention Time (RGrit) is the average time the marker takes from excretion after administration
  • Digestibility is the amount or proportion of nutrients or energy in a feed or diet that are absorbed by the GI tract
  • Apparent Digestibility percentage is calculated as intake in kg minus feces output in kg divided by intake, representing the percent of nutrients retained
  • Partial Digestibility occurs from the esophagus to the ileum and helps determine if products are absorbed efficiently
  • The ileum assists in absorption as lipids, carbs, and proteins have been digested by microbes at that point
  • Ap. Ileal Digestibility is calculated as intake minus ileal output
• Composition of Food:

  • Air dry matter is heated to 105°C to create a moisture-free material for analysis
  • Water is essential for metabolism, acting as a solvent, transport medium, diluent, and causing hydrolysis and oxidation
  • Water regulates temperature, acts as a lubricant and cushion, and is structurally vital for all body functions
  • Biological responses are intracellular and extracellular, with varying water percentages in blood, skeleton, and muscle
  • Measuring Water Content:
  • Direct method involves chopping, grinding, and baking meat to measure final mass
  • Bioelectrical impedance analysis measures water content and percent body fat through low-level currents
• Sources of Water:

  • Metabolic, free, and preformed water sources contribute to an animal's hydration
  • Adequate Intake of Preformed Water:
  • Calculations based on water content in food items like iceberg lettuce
  • Metabolic Water:
  • Byproduct of metabolism from breaking down energy, yielding nutrients into CO2 plus energy
  • Different macronutrients yield varying amounts of water
• Losses of Water:

  • Various bodily functions like urine, sweat, and lactation contribute to water loss
  • Water requirements are influenced by food composition, intake, metabolism, production, activity, and environment
  • Deficiencies and Toxic Levels:
  • Dehydration and intoxication can lead to death if water balance is not maintained
• Dietary Energy:

  • VFA's are used to produce glucose in the liver through Glucose Neo Genesis
  • Carbs provide energy for muscle contractions and heat production
  • Energy sources from carbohydrates, lipids, and proteins differ in energy yield
• Calorimeter:

  • Measures calories by combusting samples and measuring heat produced
  • Gross Energy calculation involves intake energy, fecal loss, urine loss, gas loss, heat digestion, and fermentation
• Atwater’s Physiological Fuel Values:

  • Atwater values assign energy values to carbohydrates, lipids, and proteins
  • Basal Metabolic Rate calculates the minimum energy cost of existence for endothermic animals
• Measuring Metabolic Energy Requirements:

  • Net energy is used to measure energy in feeds for cattle and dairy farmers
  • Different species use various energy measurement methods like net energy, metabolizable energy, digestible energy, etc.
• Atwater values for energy content: carbohydrates (4.15 kcals), lipids (9.40 kcals), proteins (6.65 kcals)
• Basal Metabolic Rate (BMR) calculates the minimum energy cost of existence under endothermic conditions, including resting, thermoneutral environment, and postabsorptive state
• BMR is not linear; larger animals have a more efficient BMR, meaning elephants have a more efficient BMR than a mouse
• Small animals consume more energy per unit of body mass because they have more surface area
• To calculate metabolic body size, use body weight to the power of 0.75
• Carbohydrates examples: starch, cellulose, glucose, sucrose, fructose, maltose, galactose, hemicellulose, glycogen, amylose
• Lactose and glycogen are not found in plants
• Monosaccharides: glucose, fructose, galactose
• Disaccharides: sucrose, maltose, lactose
• Polysaccharides: non-structural carbohydrates like starch, glycogen, amylose; structural carbohydrates include hemicellulose and cellulose.
• Oligosaccharides: mannanoligosaccharide, inulin, fructan
• Hexose carbohydrates: galactose, glucose, fructose
• Structural vs. Nonstructural Carbohydrates:

  • Structural carbohydrates support plant structure and are easily digestible
  • Nonstructural carbohydrates are used for storage and other functions
• Plant Cell and Fibrous Carbohydrates:

  • Plant cell content carbohydrates include sugars, starches, OA, and FOS
  • Fibrous carbohydrates include pectins, hemicellulose, lignins, and cellulose
• Polysaccharides and Starches:

  • Starches include glycogen, amylose, and amylopectin (branch-chained molecules)
  • Starch is the most abundant polysaccharide in cereal grains
• Cellulose:

  • Most abundant organic compound in nature
  • Homopolysaccharide with straight chains of glucose molecules linked by beta 1.4 linkages
  • Main component of plant cell walls
• Hemicellulose:

  • Principle component of the cell wall
  • Heteropolysaccharide with mixed subunits of glucose, mannose, arabinose, and galactose
• Lignin:

  • Noncarbohydrate fraction of the plant cell wall
  • Enhances cellulose and hemicellulose in the plant cell wall
  • Phenylpropane polymer
• Pectin:

  • Soluble fiber and heteropolysaccharide made of glucose beta 1.4 linkages
  • Found in the middle lamella of plant cells
• Soluble Fibers:

  • Include gum, beta glucans, glycine
  • Used to maintain foregut health
• Insulin:

  • Soluble fiber made of fructose subunits
  • Distributed in plant roots and stems
  • Promotes beneficial bacteria in the hindgut
• Chitin:

  • Structural carbohydrate in bacteria, fungi cell walls, and exoskeletons of insects and marine invertebrates
• Analyzing Carbohydrates:

  • Crude fiber is unreliable and inconsistent
  • Nitrogen-free extract measures all carbs except cellulose and lignin
• Detergent Fiber Method Analysis:

  • Recovers insoluble fibers, soluble fibers, and other carbs are lost then calculated by difference
  • Standardized in 2002
• Total Dietary Fiber:

  • Non-starch polysaccharides separated into soluble and insoluble dietary fiber fractions
  • Widely used in human nutrition
• Autoenzymatic Digestion:

  • Occurs in the small intestine via active transport
  • Includes enzymes like amylase, maltase, sucrase, lactase
• Alloenzymatic Digestion:

  • Occurs in the hindgut and foregut in ruminants
  • Depends on glycolysis and fermentation of carbohydrates
• Feeding the Microbiome:

  • Fibers are important for the microbiome
  • Functions include gut hypertrophy, mucin production, and sodium absorption
• Digestion:

  • Non-ruminants produce enzymes in the small intestine and ferment VFAs in the large intestine
  • Ruminants produce VFAs in the foregut and hindgut
• Carbohydrate Imbalances:

  • Red pandas have a carnivorous GI tract but are herbivores
  • Mucin casts are produced to help fix damaged intestinal lining