“Heat Stress Time Already?”
by Chris Reinhardt, feedlot specialist
For folks in agriculture, last summer seems like only minutes ago. Between the drought and the heat, none of us want a heavy dose of 2011 again.
But the other thing about agriculture is that we deal with what nature doles out. And last year we in the feedlot business learned something about heat stress. We learned it costs performance, it costs a lot of time and human energy to alleviate, and it can even cost animal lives.
So what if we actually anticipated that it could get hot this summer? Summer and heat in Kansas go hand-in-hand. It shouldn’t be a surprise to anyone if temperatures soar above 90 and cattle start to stress. Frankly, it surprises me every time anyone acts surprised.
So we know it’s going to get hot, and thanks to folks like Dr. Terry Mader of the University of Nebraska, we know what factors contribute to heat stress and what factors we can mitigate. High temps by themselves don’t cause a great deal of stress, but combine high temperatures with high humidity, lack of wind, and solar radiation, and you’ve got a recipe for disaster.
The good news is that it’s still April and the real challenge is still a couple months away, giving everybody plenty of time to prepare. PRE-pare: it means getting ready BEFORE the event happens. There’s not much we can do about temperature or humidity, but we can work on airflow and solar exposure.
If feedlot pens are properly mounded (8 feet high; 10 feet across the crown; 20-25 square feet of mound surface per animal on each side of the mound) and air movement outside the pen is not restricted with trees, cattle will use the mounds to catch what breezes may come through. The other area that we can affect heat stress is the construction of shades.
The beauty of this is that shades don’t just keep us out of a wreck—they can add performance! Shades during the summer—even in a dry climate—are worth:
| ADG | 0.31 lb | 0.42 lb |
| dry matter intake | 0.66 lb | 1.45 lb |
| F:G | 0.33 | 0.36 |
| hot carcass weight | 13 lb | 35 lb |
| marbling | 22 points | 17 points |
| Source: | (Gaughan et al., Journal of Animal Science, 2010) | (Mitlohner et al., Journal of Animal Science, 2001 |
To make this work, shades should be: (1) taller than your loader, (2) provide 20-25 sq. ft. of shade per head, and (3) be oriented lengthwise North-South so that the shaded area moves throughout the day to allow the previously shaded area to dry.
It’s time.
