ANS 320, Quiz 2 Study Guide
ANS 320, Quiz 2 Study Guide AN S 320
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This 3 page Study Guide was uploaded by Danielle Garrison on Tuesday September 20, 2016. The Study Guide belongs to AN S 320 at Iowa State University taught by Morris in Fall 2016. Since its upload, it has received 42 views. For similar materials see Animal Feeds and Feeding in Animal Science at Iowa State University.
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Date Created: 09/20/16
Review – Quiz 2 Consists of: Digestibility Feed efficiency Energy systems Feed efficiency o Major contributor of profitability – feed most expensive thing for farmers Calculate gross feed efficiency and feed conversion ratio o “Gross” Feed Efficiency: live weight gain per intake Gain/intake; also known as Gain to Feed ratio Higher number better; animals gaining more on less feed o Feed Conversion Ratio (FCR): intake per live weight gain Intake/gain; also known as Feed to Gain Lower number better; animals eating less per amount gained Explain relative feed efficiency among species (most to least efficient) o Cattle (beef) less efficient o Fish is the most efficient Understand digestibility experimental design o Animal is generally placed in a metabolism crate or crate o Have to calculate: Feed intake including orts (spilled food) Fecal output Appropriate diet samples o Adjustment period: first 10-14 days Free digestive tract of prior undigested feed Feed to a constant rate Isocalorically – maintain body weight NOT collecting feces or urine during this time o Collection period: next 4-7 days (varies) Monogastrics: 3-5 days; Ruminants: 5-7 days Record feed intake – MUST HAVE ACCURATE INTAKE DATA Collect ALL feces excreted and weigh Large animals: collect 5-10% subsample Small animals (dogs): collect 100% (all) subsample o Post collection: determine chemical composition and/or energy concentration of feed samples, feces, and orts Then calculate digestibility Dry Matter Intake (DMI): avg amount of feed (as fed) x %DM of feed o Smaller than as fed intake Fecal Output (FO): avg amt of feces excreted x %DM (Feces) DM digestibility (DMD): (DMI – FO)/DMI) x 100% o Limitations of Digestibility Trials: Apparent Digestibility: feces composed of undigested nutrients and endogenous materials that did NOT come from diet Limit fed animals, alters passage rate Spillage and waste of feed and feces Errors in analyses Sorting and selection of feeds Can be useful for total mixed rations (TMRs) Calculate Digestibility o Digestibility (%) = (Consumed – Excreted)/Consumed x 100 Tiger Example: o Consumes 12 lbs meat daily o Diet contains: 70% water, 30% DM 60% protein (DMB) o Excretes: 1 lb of feces daily Contains: 75% water and 25% DM o What is protein digestibility of diet? DMI: 12 lb xx 0.30 = 3.6 lb diet consumed Protein consumed: 3.6 lb x 0.60 = 2.16 lb Dry feces excreted: 1 lb x 0.25 = 0.25 lb Fecal protein: 0.25 lb x 0.25 = 0.0625 lb Protein digestibility: (2.16 lb – 0.0625 lb)/2.16 lb x 100 = 97.11% Calculate TDN o TDN = %DP + %DCF + %DNFE + %DEE DP = CP x CP digestibility % DCF = CF x CF digestibility % DNFE = NFE x NFE digestibility % DEE = EE x EE digestibility % x 2.25 Strengths and limitations of TDN – basic estimate of digestible energy o Limitations: Errors in chemical analyses and sample collections (any factors that affect digestibility will impact TDN) Doesn’t include all energy losses in metabolism Doesn’t include urine or methane gas (3-10% feed energy) losses Doesn’t include – work of digestion, heat of fermentation, heat of nutrient metabolism Overestimates energy value – forages Underestimates energy value – concentrates/grains Not helpful in measuring animal performance Energy partitioning system and its uses o Calculate various components of this system o Define GE, DE, ME, and NE Gross Energy (GE): Total potential energy of the feed; measured by bomb calorimeter Water, ash, vitamins = no energy Digestible Energy (DE): GE – FE Not used to express energy in poultry or reptiles Metabolizable Energy (ME): DE – (FE + UE) Net Energy (NE): ME – HI (heat increment) HI: increase in heat lost because of energy costs of digestion and metabolic processes (digestion, fermentation, nutrient metabolism) o For management: contributes to thermal regulation in cold climate and heat load in warm climate Must fill maintenance requirement before filling production requirement Math consists of: NFE, TDN, Digestibility, ADIN Nitrogen Free Extract (NFE): o NFE (as fed): 100 - moisture - CP- EE - CF – Ash o NFE (DMB): 100 – CP – EE – CF – Ash Total Digestible Nutrients (TDN): o TDN = %DP + %DCF + %DNFE + %DEE DP = CP x CP digestibility % DCF = CF x CF digestibility % DNFE = NFE x NFE digestibility % DEE = EE x EE digestibility % x 2.25 Digestibility: o (Consumed – Excreted)/Consumed x 100 Acid Detergent Insoluble Nitrogen (ADIN): measure of N remaining in acid detergent fiber residue of feed sample o Total Nitrogen – ADIN = Available N OR ADIN + Available N = Total N o N that is attached to ADF residue and is unavailable to animal as protein o ADIN x 6.25 = amt of unavailable CP
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