1. I. Cattle Performance and Comfort
under
Different
Environmental
Conditions
Dan Loy
Professor of Animal Science
Director, Iowa Beef Center
Iowa State University

2. January 2013 Feedlot Inventories
1,000 Head
Texas
2,730
Nebraska
2,550
Kansas
2,250
Iowa
1,280
Colorado
1,030

3. US Cattle Feeding Regions

5. 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%

6. Source: World weather online

10. Source: World weather online

13. Source: World weather online

14. Location of Cattle Feeding and Average
Annual Precipitation

15. Location of Cattle Feeding and
Days less than 0 C

16. Environmental Challenges
• Cold Stress
• Heat Stress
• Mud

17. Effect of Environment on Energy
Requirements
Lower
Critical
Temperature
Cold stress
Low
Upper
Critical
Temperature
THERMONEUTRAL
ZONE
Optimum
for
Performance
and
Health
Heat Stress
High
EFFECTIVE AMBIENT TEMPERATURE

18. Cold Stress

19. Hair as insulation

20. ower Critical Temperature C
•Coat Description
LCT
•Summer or wet
15
•Fall
7
•Winter
0
•Heavy winter
-8

21. Effective Temperature
Wind Speed
(kph)
Calm
8
24
48
-23
-23
-27
-32
-43
Temperature (celcius)
-18
-12
-7
-1
-18
-12
-7
-1
-21
-16
10
-5
-26
-21
-16
-10
-37
-32
-27
-21
*Maintenance Requirements increase 1.25% for each degree
of cold stress.

22. • Affected by effective
ambient
temperature
• Air temperature
• Solar radiation
• Air movement
• Contact surfaces
• Precipitation

23. Heat Stress
• Beef NRC (2000)
• Maintenance requirement increased when
temperatures exceed 30 C
– 7% for rapid shallow breathing
– 18% for open mouth panting

24. July 19, 2011 - 3:00 pm
• 35 degrees C
• Sunny
Feels like 44 degrees C
Wind 9.3 km/hr south
Humidity 58%
Images and data from Dr. Grant Dewell, DVM, Extension
Beef Veterinarian, ISU

25. Black Steer Full Sun

26. 40.0 C
51.6 °C
43.7 °C
54.0 °C
50.8 °C

27. Black Steer Shade Monoslope

28. 41.9 °C
41.8 °C
38.6 °C
42.2 °C
41.0 °C

29. Black vs White Steer Full Sun

30. 42.0 °C
45.3 °C
52.4 °C

31. http://www.iowabeefcenter.org/heatresources.html

32. NRC (1981)

35. Effects of Mud on Performance
Mud depth
Intake reduction
10-20 cm
5-15%
30-35 cm
15-30%
Plus: reduced insulation value of hair
coat and increased energy cost for
walking
NRC (1981, 2001)

36. 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

38. NEm Required, Mcal/BW0.75
Energy Requirements vs. Previous Temp.
120
110
100
90
80
70
60
50
-20
-10
0
10
20
Previous Temperature,
30
O
C
40

39. Questions?

40. Thanks !!!
Dan Loy
Professor of Animal Science
Director, Iowa Beef Center
Iowa State University