Livestock Management RANCHING
How to Recognize Heat Stress in Cattle
By Heather Smith Thomas
H
EAT STRESS — AND DEATH LOSS FROM HEAT STRESS — costs cattle producers about $369 million in losses every year, estimates Dr. Don Spiers,
University of Missouri department of animal science. Normal temperature in a beef cow is about 101.5
degrees. This temperature rises when the animal can’t dissipate body heat during hot weather. Individual animals have different levels of heat retention. “We followed groups of animals through 4 periods
of heat stress and found they always have their own ranking. Animals with low minimum temperatures always have low maximum temperatures,” he explains. “Another clue how high body temperature will go
during the day is how fast the air temperature rises in the morning. If it will be a hot day, the temperature increase between 6 a.m. and 8 a.m. shows how hot it’s going to get, and you have some warning of what’s coming,” he says. You have time to do something early in the day with at-risk cattle rather than responding after the fact when animals are starting to die.
Monitor respiration rate “Even if you can’t measure body temperature, you can measure respiration rate — which is a more rapid
58 The Cattleman August 2013
response to heat than is body temperature,” says Spiers. Anything below 40 breaths per minute is healthy.
“Anything above 80 breaths per minute is a sign of heat stress. When they get up to 120 it’s more serious, and by the time they get up to 160 breaths per minute with their tongues sticking out and drooling, they have a real problem,” he says. If you are moving cattle on a hot day and some start panting with mouths open and drooling, it’s time to halt and let them rest. Dr. John Gaughan in Australia developed a pant-
ing score index, from 0 to 5. This involves counting respiration rate and observations about what the cattle are doing. • At 0 there is no panting and breathing rate is
below 40. • Score 1 is 40 to 70 breaths per minute (and it’s easy
to see the chest movements) but the mouth is closed and there is no drooling. You don’t have to count for a full minute to check respiration rate; you can count for 15 seconds and multiply by 4, or 30 seconds and double it. • Animals at score 2 are breathing 70 to 120 breaths
per minute; they have a little drool, but the mouth is still closed.
thecattlemanmagazine.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118