Dan LoyProfessor of Animal ScienceDirector, Iowa Beef Center
Iowa State University
I. Cattle Performance and Comfort under Different Environmental Conditions
January 2013 Feedlot Inventories 1,000 Head
Texas 2,730
Nebraska 2,550
Kansas 2,250
Iowa 1,280
Colorado 1,030
US Cattle Feeding Regions
Market share change 2012-2013
Percent of US Cattle on Feed
2012
Percent of US Cattle on Feed
2013
Change
Texas 20.9 20.4 -.5%
Kansas 16.9 16.9 NC
Nebraska 18.7 19.1 +.4%
Iowa 9.2 9.6 +.4%
Source: World weather online
Source: World weather online
Source: World weather online
Location of Cattle Feeding and Average Annual Precipitation
Location of Cattle Feeding and Days less than 0°C
Environmental Challenges
• Cold Stress
• Heat Stress
• Mud
Effect of Environment on Energy
Requirements
EFFECTIVE AMBIENT TEMPERATURE
THERMONEUTRALZONE
Low High
Heat StressCold stress
OptimumforPerformanceand Health
LowerCriticalTemperature
UpperCriticalTemperature
Cold Stress
Hair as insulation
Lower Critical Temperature °C
•Coat Description LCT
•Summer or wet 15
•Fall 7
•Winter 0
•Heavy winter -8
Effective Temperature
Wind Speed Temperature (celcius) (kph) -23 -18 -12 -7 -1Calm -23 -18 -12 -7 -18 -27 -21 -16 10 -524 -32 -26 -21 -16 -1048 -43 -37 -32 -27 -21
*Maintenance Requirements increase 1.25% for each degreeof cold stress.
Heat Stress• Affected by effective
ambient temperature• Air temperature• Solar radiation• Air movement• Contact surfaces• Precipitation
Heat Stress
• Beef NRC (2000)
• Maintenance requirement increased when temperatures exceed 30 C– 7% for rapid shallow breathing– 18% for open mouth panting
July 19, 2011 - 3:00 pm• 35 degrees C
• SunnyFeels like 44 degrees CWind 9.3 km/hr southHumidity 58%
Images and data from Dr. Grant Dewell, DVM, Extension Beef Veterinarian, ISU
Black Steer Full Sun
40.0 C51.6 °C 50.8 °C
43.7 °C
54.0 °C
Black Steer Shade Monoslope
41.9 °C
38.6 °C
41.8 °C
42.2 °C41.0 °C
Black vs White Steer Full Sun
45.3 °C
42.0 °C
52.4 °C
http://www.iowabeefcenter.org/heatresources.html
NRC (1981)
Effects of Mud on Performance
Mud depth Intake reduction
10-20 cm 5-15%
30-35 cm 15-30%
NRC (1981, 2001)
Plus: reduced insulation value of hair coat and increased energy cost for walking
Effects of Mud on Cattle Performance
• Reduction in intake
• Loss of insulation value of hair coat
• Increased energy expenditure to move between feed, water and resting location
Energy Requirements vs. Previous Temp.
50
60
70
80
90
100
110
120
-20 -10 0 10 20 30 40
Previous Temperature, OC
NE
m R
equ
ired
, M
cal/
BW
0.75
Questions?
Thanks !!!
Dan LoyProfessor of Animal ScienceDirector, Iowa Beef Center
Iowa State University