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Exam 3 Notes.docx - Environment 1 Environment of an animal...

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Environment 1. Environment of an animal affects the degree to which genetic potential is expressed 2. Effort has been directed toward defining the “optimum climate for maximum production 3. Production costs, emphasis is now on finding the more “economical” level of production 4. Most economical may not be maximum 2 General classifications of animals 1. Cold blooded= exotherms & Poikilotherms a. Don’t maintain constant body temperature i. Saves energy ii. Snakes /fish 2. Warm blooded = endotherms 3. Homeotherms a. Maintains a constant body temperature NOTES 10/27 To maintain a constant body temperature: 1. (heat produced) + (heat received) = heat loss or HP = HL 4 Major Avenues of Heat Gain or Loss 1. Radiation = Rd Exchange of heat between objects that are not touching Heat flows from warm to cold places e+ or – 2. Conduction = Cd Transfer of heat (warm to cold) objects which are touching
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3. Convection = Cv ( + n - ) Flow of heat through air or water, blood 4. Evaporation = Ev Flow of heat via vaporization from the lungs or perspiration from the skin Evaporation is the reason an animal can live at 116 97F w 90% humidity Heat balance equation ∆Tc = +- Rd +- Cd +- Cv – Ev + Hp = 0 o ∆Tc = change in core temperature o Rd = Radiation o Cd = conduction o Cv = Convection o Ev = evaporation o Hp = heat produced by the animal Digestion huge generation of heat (rumen) o Hypothermia: could freeze to death o Hyperthermia: can’t maintain heat Thermoneutral Zone (TNZ): Range of temperatures where an animals is comfortable (neither too hot or too cold) How to tell if in TNZ Posture Appetite Sweating Normal Respiratory Rate Movement Lethargic Location 1. Are they comfortable 2. Are they healthy Power of observation 3. Is this the environment they choose (if given a choice) 4. *Lowest maintenance required 5. Maximum gain and efficiency\ Cold Stress 1. Animal performance is decreased in cold climates 2. Not as severe a reduction is cold stress as in heat stress 3. An increase in Insulation can help tolerance to cold 4. Fat layer Specie (pigs are fattest specie) Age (infants have very little body fat) 5. Surface Are/Unit Body weight can affect heat loss Heat loss is a function of Surface Area Smaller animals have increased surface area/body weight, they lose more heat Chickens lose more heat in relation to their body size than cattle Heat production is a function of weight for metabolic size
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Wind Chill 1. Can increase a cold stress or “Effective Temperature” ET is the sum of all environmental effects on the animal, including temperature, humidity and wind chill NOTES 10/30/17 1. Methods to control cold stress Windbreaks Trees, shrubs, or man-made shelters Work to increase energy intake of animals increase heat increment Heated buildings (extremely expensive) Heat Stress 1. Livestock productivity is decreased in hot climates Direct effect of heat Increased parasite problems
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