Light Test-Weight Corn Viable Option for Producers

SOUTH DAKOTA, US - A cool summer may lead to lighter test weights for corn, but that corn might be a good fit for pork producers seeking to save money.
calendar icon 5 November 2009
clock icon 4 minute read

South Dakota Cooperative Extension Swine Specialist Bob Thaler said a few factors should be considered before producers begin to add light test-weight corn to their swine feed.

“There's less starch and more fiber in light test-weight corn, so performance may be reduced if bushel weight is too light,” Dr Thaler said. “Research has shown that corn weighing 40-56 pounds-per-bushel will produce the same weight gains in growing-finishing swine when compared on an equal-moisture basis to corn that weighs 56 pounds per bushel.”

Dr Thaler said feed efficiency probably starts being affected at weights less than 50 pounds per bushel.

“In swine, consider using light test-weight corn in the growing, finishing, and gestation phases,” said Dr Thaler. “Also, since frost-damaged corn is less dense than mature corn, it is essential to use a scale when adding it to the mixer.”

Dr Thaler said that oftentimes, the dockage at the elevator for immature or frost-damaged corn more than offsets any reduction in pig performance that can come from using weather-stressed feedstuffs in swine diets.

“Producers can make money feeding lower-quality grains if the purchase price is low enough,” Dr Thaler said. “Since reductions in daily gains only occur when feeding extremely light-weight feedstuffs, producers can determine the economics of feeding weather-stressed grains by calculating the cost of poorer feed efficiency.”

Dr Thaler said the formula is straightforward.

“Subtract the cost of the old diet from the cost of new diet, and then divide that by the old diet cost,” said Dr Thaler. “Then take that figure and multiply it by 100.”

Dr Thaler said that if this value is greater than the percentage reduction in feed efficiency anticipated from using weather-stressed grains, producers should save money feeding the grain with light test-weight.

“However, if the percentage change in diet cost is less than the percentage change in feed efficiency, the feedstuff should not be used, it would not make economic sense,” Dr Thaler said.

Another concern with frost-damaged or light test-weight grains is mycotoxins produced by the mold on corn.

“In the upper Midwest, we typically only worry about DON (vomitoxin) and zeralenone on corn,” said Dr Thaler. “There are few, if any, additives that will bind these two mycotoxins.”

According to Minnesota Farm Guide, while adding mold inhibitors will prevent more mold growth and subsequent mycotoxin production, it will not neutralize the mycotoxins that are already in the grain, Dr Thaler said.

“The only thing a producer can do is to blend contaminated grain with ‘clean' grain to keep mycotoxin levels in the feed at acceptable levels,” Dr Thaler said. “A conservative approach is to keep all mycotoxincontaminated grains out of the diets of both breeding herds and nursery pigs.”

Hog producers should aim to keep Vomitoxin (DON) rates at 1 part per million (ppm) in growing/finishing diets. With Zearalenone, Thaler said keep its rate at 1 ppm in growing diets, and at 3 ppm in finishing diets.

“Using mycotoxin-free, frost-damaged corn gives producers a good opportunity to lower their diet costs,” said Dr Thaler. “Unless the corn is severely light, gain and feed efficiency will be unaffected, and even if feed efficiency is reduced, producers can still make money feeding light test-weight corn if they can buy it at a price that fits their operational needs.”

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