South Dakota producers who saw low test weight wheat this summer may have an opportunity to add value by marketing it through pigs, said Bob Thaler, SDSU Extension Swine Specialist.
"Pigs are an excellent way to market grains, especially light weight and weather-stressed grain that may be docked at the market," Thaler said. "As long as the light weight grains are properly formulated and mixed, it can be a win-win situation for both the grain farmer and pork producer."
Low test weight grains typically contain more protein and fiber and have less starch and energy than normal test weight grains, Thaler explained. However, depending on the test weight it can be fed to pigs with little to no effect.
"Multiple research trials have shown that you can reduce grain test weight up to 10 percent without affecting feed efficiency, and you can lower it up to 25 percent without affecting daily gain," he said.
Basically this means that pork producers can feed down to 54 pounds wheat without affecting growth performance and down to 45 pounds without affecting gain.
"Once you get below 54 pounds of wheat, feed efficiency will suffer," Thaler said. "However, if the wheat is purchased at a reduced enough rate producers can still make money - even with poorer feed efficiency."
Know the mycotoxin status
A key in feeding light test weight grains Thaler said, is knowing the grain's mycotoxin status.
"If it is free of mycotoxins, then you can strategically feed it in specific phases," he said.
Since light test weight wheat is lower in energy, Thaler said it should be fed in grow-finish and gestation diets.
"Once they get past 80 pounds pigs can compensate for the lower energy by eating more feed so gains should be the same," he said. "Since we limit-feed gestating sows anyway, it is the perfect feedstuff for them. However, since we want to maximize feed/energy intake for lactating sows and nursery pigs, it's best to keep it out of those phases."
If the grain does contain mycotoxins, then it should only be fed in the late grower and finishing phases Thaler said, and blended with "clean" grains to get the diet's total mycotoxin concentration at or below recommended levels.
More on feeding wheat to pigs
Wheat is an excellent feedstuff for pigs since it is higher in protein, lysine, and phosphorus than corn said Thaler.
"It can be the sole grain source in swine diets. Light weight wheat can also be the sole grain source for grow-finish pigs and gestating sows. However, producers can blend it with normal test weight corn to offset the energy reduction of the diet if they want," he said.
Because light test weight grains have less bulk density and will fill up a mixer quicker, Thaler said when using light test weight wheat or other grains it is essential that a scale is used on the feedmill or grinder mixer.
For example, a 2-ton/4,000 pound mixer can hold 66.7 bushels of normal, 60 pound wheat, but that same mixer can only hold 3,602 pounds of 54 pounds wheat.
"Therefore, if just adding ingredients volumetrically, the diets will not contain enough wheat or the desired nutrient levels," he said.
He added that wheat, whether normal or light test weight, should not be finely-ground.
"It should be ground or rolled to 700 microns, and rolling is preferred over hammermills for wheat," Thaler said.
Also, light test weight wheat and grains will be dustier than normal grains during feed processing, and since they contain more fiber, which it may take more management to make sure it flows through automatic feeding systems and feeders properly.