Feed Lot

NOV 2018

Feedlots and cow/calf operations in the beef industry who feed 500 or more has annually on grains and concentrates; maintain 500 or more beef cows; backgrounder, stocker/grower, preconditioner; veterinarian, nutritionist, consultant

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FEED•LOT November 2018 15 tall you need posts deep enough to hold it, or build it on skids for portability. When setting posts for a permanent windbreak, consider the wind load the structure needs to withstand and the density of the windbreak," he says. "Wind pressure loads for a 10- foot high windbreak can exceed 20 pounds per foot if winds exceed 85 mph. This means that for a solid windbreak (which would need the strongest posts) with posts every 10 feet, the wind can exert over 2000 pounds of force on each post. Post diameter of 8 inches or greater with underground portion below frost line (which might be 3 to 5 feet, depending on your location) should be adequate in permanent systems," says Darrington. FL of the windbreak — more air velocity coming through rather than being pushed up and over," explains Darrington. "You don't want a solid wind- break because it significantly re- duces wind speed right next to the windbreak and if there is snow the wind dumps a lot more of it right behind the windbreak. A porous windbreak increases the size of the protected area, reduces the wind force/physical load on the windbreak, and limits snow drift formation on the downwind side," he says. "For 80% density, measure the width of the solid material you are using, and divide by 0.80. This gives you the center-to-center spacing needed to reach 80% density. For example, using 1 x 8's for the wind- break you'd have spacing of 9.0625 inches. If you round the numbers up or down to the nearest quarter inch, if rounding up the density is 78%, if down the density is 80.5%. This means that between each board there will be a 1.75 to 2-inch space," he explains. "If you use 1-by-6 inch boards (which are actually 5½ inches wide and 3/4 inch thick) spacing would be 1½ to 2 inches apart. This would be 7½ inches on center (from the center of one board to the center of the next)," says Darrington. "With 30% open and 70% sol- id the protected zone behind the windbreak extends 10 to 15 and sometimes up to 20 times the height of the windbreak. The protected area is always estimated based on the height. An example would be a 10-foot fence slowing the wind for about 100 to 150 feet behind it. If it's a straight windbreak with wind coming head on, perpendicular to it, this creates a triangular protect- ed zone behind it," he says. "Some producers make wind- breaks using vertical metal roofing. A 30-inch piece of roofing is enough space for calves to nestle against it and be completely protected. You need a bigger gap, however, to create adequate porosity, so snow won't collect right behind it. For cows, some people say these types of windbreaks are a little less effective because air speed coming through those larger cracks is high enough that if they are right next to it they may still get cold, but if they are a distance of one or two heights away from the windbreak, there is decreased velocity of air. Calves, however, can be very snug next to those 30-inch sections so you might get the benefits of both (solid windbreak plus some porosity). These are also faster to build, with fewer total pieces to put vertically. Spacing for 30-inch pieces of roof- ing metal would be 5 or 6-inch gaps between them, or about 36 inches on center," he explains. "To build a windbreak 6 to 10 feet PORTABLE WINDBREAKS — When rotating pastures or strip grazing, moving windbreaks when cattle are moved can be helpful. "For portable windbreaks make the base heavy enough and wide enough WKH\GRQ·WWLSRYHULQWKHZLQGRUVWDNHWKHPGRZQZLWKWZRIRRWOHQJWKV of rebar or T-posts," Darrington says. You can make these in sections so they can be moved with a tractor— either pulled around or picked up with a loader. "If you have to take WKHPYHU\IDU\RXFRXOGOLIWWKHPRQWRDÁDWEHGWUXFNWRKDXOWRWKHQH[W pasture, strapping them down securely for hauling. Sections should be built so they can connect together and be set up to create a corner which provides greater protection for multiple wind directions and reinforces HDFKLQGLYLGXDOVHFWLRQµKHH[SODLQV R 1-800-536-8438 "We can customize a system to meet your needs." ❖ Platform Scales (10 sizes/self-contained) ❖ Single Animal Weigh Cage (self-contained) ❖ Single Animal Scales (under squeeze chutes) ❖ Portable Calf Scales (3 designs for various weights) ❖ Hay Processor Scales

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