Keeping Pigs Eating in Hot Weather Dr. Bob Thaler, South Dakota State University 605-688-5011 robert.thaler@sdstate.edu Session 4, June 1, 2006 1 2 Pigs are VERY adaptable to their environment Effect of air temp on rectal temp, respiration rate, & pulse rate of growing pigs 140 120 125 120 120 100 80 60 102.3 102.22 102.6 104 100 60 Rectal Pulse Resp 3 40 20 30 20 40 60 80 100 Room Temperature ( O F) 4 Thermal Neutral Zone, Upper & Lower Critical Temperatures Response to Heat Stress 18 16 14 12 10 8 6 4 2 0 LCT Cold Stress TNZ UCT Heat Stress Mcal intake Feed/gain ADG, lbs 5 68 F 77 F 6 1
Hot Weather and Added Fat If feed intake decreases energy and amino acid intake decreases Dietary fat Less heat of digestion than feed grains (corn) 2.25x energy of corn Can increase bridging of meal diets 7 e Intake (g) Daily Lysin Nutrient Levels Need to be Adjusted for Changes in Feed Intake 24 22 20 18 16 14 12 10 7.2 lbs 6.4 lbs 6.4 lbs Daily Feed Intake % Lysine 062% 0.62% 0.62% 0.70% 8 Hot Weather and Synthetic AA s Synthetic AA s Include lysine, threonine, methionine, tryptophan p Less heat of digestion than intact protein (SBM) Hot Weather and Diet Ingredients Added fat and synthetic AA s produce less heat for the pig to get rid of Summer diets must contain same lysine:me ratios as normal diets No benefit from added vitamins/minerals 9 10 Effect of Paylean During Heat Stress Effect of Paylean During Heat Stress May 2003 (n=880) August 2003 (n=870) High/Low Temp, o F 76-66 92-80 Day 0 BW, lbs 220 215 ADG, lbs 2.31 2.33 ADFI, lbs 6.10 6.11 May 2003 (n=880) August 2003 (n=870) High/Low Temp, F 76-66 92-80 Backfat, in.69.63 Loin Depth, in 2.34 2.34 Lean, % 55.6 56.2 F/G 2.64 2.64 11 Yield, % 76.8 77.6 12 2
Thermal Environment of the Pig Dry bulb air temperature - seldom temperature pig feels Air speed Humidity Group size Building materials, design, surface temperature (insulation) Effective Environmental Temperature (EET) What pig really feels Combined influence of many factors 13 Heat Exchange Between a Pig & It s Surroundings 4 basic forms of heat transfer for the pig Conduction Radiation Convection Evaporation * Understanding how a pig gains/loses heat is the key to providing the pig with the optimum environment 14 Conduction Radiation Transfer of heat by physical contact with another surface 10-15% of heat loss Main components: Core-to-floor temp difference ( T) Conductivity of floor Concrete vs plastic vs aluminum Contact area between pig & floor 50F 90F 15 Transfer of heat to a surface without direct contact 30-50% of total heat loss Main components: Pig s surface area exposed to other surfaces Difference in temperature between pig & surface ( T) Radiant Heaters 16 Uninsulated Concrete Sidewalls Insulated Concrete Sidewalls 80 o F Room 95 o F Outdoors 6 inch Concrete R= 1.33 90 o F Surface 6 inch Concrete + 1i inch Rigid insulation 80 o F Room 95 o F Outdoors 82 o F Surface R= 6.33 Heat Flow Heat Flow 17 18 3
Managing facilities for heat relief is different in September than in June Note how inside temperature lags outside temps large thermal mass in Sept Record daily high and low temperatures. However, this doesn t tell you patterns within 24 hrs. Data courtesy dicamusa.com 19 20 200 27 pigs/pen Wet/dry feeder Additional drinker in pen Tunnel ventilation 150 n interval Liter/15 mi 100 50 Summer Winter 0 0:15 2:15 4:15 6:15 8:15 10:15 12:15 14:15 16:15 18:15 20:15 22:15 15 Minute Interval ending: www.dicamusa.com Dr. Mike Brumm 21 Dicamusa.com Dr. Mike Brumm 22 Convection EET as Affected by Pig Wt and Air Speed Transfer of heat by physical contact with fluid (air, mud, or water) that is at a different temperature than that of the pig 35% of total heat loss Young pigs Greater surface area:weight ratio Main components: Surface-to-fluid temperature difference ( T) Speed of the fluid Contact area with the fluid Examples: Cold drafts Fans blowing to reduce heat stress 23 PIH-54 Less fat (insulation) i Greater heat transfer Maximum heat transfer occurs at 3.5 mph (310 fpm) 24 4
EET as Affected by Pig Wt and Air Speed EET as Affected by Pig Wt and Air Speed PIH-54 As temperature increases, effect of higher air speeds decreases If pig temp & air temp are equal, NO heat can be lost via convection PIH-54 If air temperature is greater than pig temperature, higher air speeds make the pig MORE heat stressed! Need evaporative cooling!!! 25 26 Recommended Ventilation Rates Minimum Hot weather Sow & Litter 20 cfm/sow 500 cfm/sow Nursery 12-30# 2 cfm/pig 25 cfm/pig Nursery 30-75# 3 cfm/pig 35 cfm/pig Finishing 75-150# 7 cfm/pig 75 cfm/pig Finishing 150-250# 10 cfm/pig 120 cfm/pig Gestating 12 cfm/sow 150 cfm/sow Breeding 14 cfm/sow 300 cfm/sow Effect of Wind Direction on Airflow in Curtain Sided Facilities MWPS-32 27 Slide courtesy Dr John Carr, Iowa State University http://www.vetmed.iastate.edu/departments/vdpam/swine/healthmgt/air/ventilation/ 28 Stirring Fans Stir Fan Placement 29 MWPS-32 30 5
Cross-flow fans blowing S to N Once a pig gets to 50 lbs, it starts feeling heat stress above 70 0 F, and losses occur above 85 0 F At higher temperatures, little body heat is lost via conduction, convection (unless a evaporative pad is utilized), and radiation If the pig is to survive in hot conditions, it must lose heat through evaporation 31 32 Transfer of heat by water conversion to vapor Drippers & sprinklers Main components: Relative humidity Air temperature Air speed Wetted surface area Volume of air respired Evaporation 33 Evaporative or Direct Cooling Wetting the pig and then allowing moisture to evaporate provides substantial cooling (1050 BTU s lost for every lb of water evaporated) Good systems wet the pig & allow the water to evaporate Increased air speed Lower humidity = increased evaporation so want intermittent wetting 34 Sprinklers or Fans? Sprinklers for Grow-Fin Control Fan 500 fpm 78 F Sprinkler 2 min on 10 min off 78 F Fan + Sprinkler ADG, lb 1.51 1.62 1.68 1.71 F/G 3.29 3.27 3.13 3.18 Turner et al, 1997 35 Start sprinkling at 80 0 F & wet all pigs goal is: 2 min on-time 60% pen coverage Once pigs are wet: STOP sprinkling allow water to evaporate If continually wetting: relative humidity will rise evaporation will decrease 36 6
Sprinkler vs Fogger Control (no cooling) Fogger (small droplets, always on) Sprinkler (1 on, 29 off) ADG, lb 1.30 1.42 1.64 Nichols et al, 1983 Non-corrosive nozzles Provide a solid cone of water droplets 60% pen coverage DO NOT use a fogger Foggers cool the air Raise relative humidity & decrease evaporation Wetting and drying cools the animal Sprinklers 37 Place nozzle 6 above the dunging area 38 Sprinklers Want combination of interval + nozzle size to equal 1 gal of water/hr/10 pigs (0.1 gal/pig/hr) Large facilities total flow (gpm) at one time is an issue Timers on sprinklers allow for drying 39 Edstrom controller to control 4 solenoids in sequence 40 Recommended Flow Rates Nozzle Size Recommendations On/Off Interval On/Off Interval Pigs/Pen 2 min/10 min 1 min/30 min 10.017 gal/min.10 gal/min 20.033 gal/min.20 gal/min 30.050 gal/min.30 gal/min Pigs/Pen Nozzle Size, gpm 10.20 20.40 30.60 40 2 nozzles at.40 50 2 nozzles at.50 41 MWPS-34 42 7
Evaporative Pad Coolers Evaporative Cooling Pads (KoolCell Pads) Incoming air drawn through wet pads Air evaporates water from pads Temp reduced Moisture increased Temperature will decrease until RH nears 85%. When incoming air is humid (relative humidity >70%), air temp decrease will only be 5-10 F. When incoming air is relatively dry (<55% RH), air temp reduction may be 15 F or more. 43 44 Impact of Relative Humidity on Effectiveness of Evaporative Cooling Average Temperature Decrease with Evaporative Cooling Outside RH% Outside Temp (F) 30 50 70 Pad Exit Temp (F) 80% efficiency 76 62 66 70 84 67 73 78 92 73 79 85 100 79 87 93 Meyer and Van Fossen, ISU, 1971 45 Van Fossen and Meyer, ISU 46 Evaporative Pad Cooler Issues Exchange with the Environment Uneven Wetting Water Quality Algae growth use dilution of copper sulfate Mineral deposits Routinely drain 10-15% Alternative muratic acid or vinegar in water Covers Static pressure control point Winter 47 Forced Convection Natural Convection Evaporation Skin Temperature 95 F? Conduction to Floor Goal is to minimize the amount of energy a pig spends to maintain its core temperature in spite of all these factors Radiation wit th Surfaces 48 8
Summary Questions??? Diet issues Paylean Fat Amino Acids Begin wetting at 80 o F Let the pig dry Increase air flow in the pig zone 49 50 9