AN_SCI 3212 1st Edition Lecture 4 Outline of Last Lecture II. Water Continued…a. Factors that Affect IntakeOutline of Current Lecture III. Energy & Bioenergeticsa. Energyi. Gross Energy (GE)ii. Digestible Energy (DE)iii. Metabolizable Energy (ME)iv. Net Energy (NE)v. Heat Increment (HIvi. Heat of Fermentation (HF)b. Consequences of Heat Increment and Heat of FermentationCurrent LectureEnergy & Bioenergetics Food  Energy = Life- Chemical energy goes in and aids in the production of ATPo Carbohydrates o Fats o Other- ATP is produced using the chemical energy and expels heat and chemical wasteo Body’s energy currency- Chemical waste expelled from the production of ATPo Carbon dioxideo Water- Metabolism uses ATP and creates more heatEnergyThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.In the context of animal nutrition, nothing is more important to understand than ENERGYAll animal functions and biochemical processes require a source of energy to drive themNormal metabolism involves many different forms of energy transfer- Chemical to heat (e.g. brown fat oxidation)- Chemical to mechanical (e.g. muscle work)- Chemical to electrical (e.g. glucose to ATP to brain signals Partition of Dietary Energy- Gross Energy (GE)  Digestible Energy (DE)o Fecal Energy lost- Digestible Energy (DE)  Metabolizable Energy (ME)o Gaseous and Urinary Energy lost- Metabolizable Energy (ME)  Net Energy (NE)o Heat increment lost- Energy Utilization o Key Concept: Not all energy in foodstuffs is actually available to animals It is an inefficient process- There is always a lossGross Energy (GE)- The quantity of energy (in the form of HEAT) resulting from the complete oxidation of food, feed, or other substance- Also referred to as heat of combustion- GE is measure with a bomb calorimetero Measures how much heat is generated- Max amount of energy that can be obtained from a foodstuffo From the breaking of the carbon-carbon bonds until only CO2 and H2O remain.  CO2 is the lowest energy form of carbon (completely oxidized)Digestible Energy (DE)- DE = GE of food consumed – energy lost in feces- Requires careful measurement of food intake and the collection of feces- Fecal losses can vary from <10% in milk-fed animals to >80% in animals consuming very poor quality roughage Metabolizable Energy (ME)- ME = GE of food consumed – energy lost in feces, urine, and combustible gases- Commonly used means to evaluate feedstuffs and to establish feeding standards fro poultry because feces and urine are excreted together- Most ME data for non-poultry species tend to be calculated (estimated) values due to the tedious and time-consuming aspects of collecting urine and gassesMetabolisable Energy (ME) & Ruminants- In ruminants gaseous products include lots of CO2 and methane- Methane expired represents lost gross energy - Low quality diets increases the amount of methane producedo Methane output increases as hay increases from 63% to 100%- Formula often used for ruminants o ME =DE x 0.82 (only an estimate!)Net Energy (NE)- That portion that is available to the animal for maintenance or various productivepurposes (e.g. making milk, eggs, doing work, growth)- Net Energy (NE) = the metabolic energy (ME) – the heat increment (HI)Heat Increment (HI)- Represents the heat produced by the digestion and metabolism of a foodstuff over and above what is produced prior to food ingestiono (HI is NOT equal o total body heat production!)- Feeding rats/dogs lean meats results in a HI = 30-40% of gross energy (GE)- In ruminates…o At Half maintenance HI = 3% of GEo At 2 x maintenance HI = ~20% of GE = >40% of ME- HI is not constant – it depends on how the feedstuff/nutrient is usedo Proteins and high protein foodstuffs have higher heat increment It takes more energy and more energy to be lost when digesting - The more the nutrient is absorbed and deposited into tissues the lower the HIHeat of Fermentation (HF)- Heat from Hayo Hay  Fiber- Bacterial Fermentationo Heat- Difficult to measure in ruminants due to need to fast animals for prolonged period and need for large animal calorimeter- Estimated to be 5-10% of GEConsequences of HI and HF- HI and HF can be useful in cold environmentso Can use heat to stay warm- In contrast, during hot environmental conditions, HI and HF can be detrimentalo Can overheat animals Causes animals to go off feed- Body’s