Feeding sorghum crops as alternatives to corn
The combination of poor margins for row crops and the threat of continued dry conditions are prompting many producers to re-evaluate cropping plans. Warren Rusche, SDSU Extension Cow/Calf Field Specialist encourages them to consider crops like sorghum which require fewer inputs and use water more efficiently.
How well do these crops fit livestock production? Rusche said the answer depends on the class of livestock fed and feedstuff. There are two general options for sorghum crops for feed usage: grain and forage.
As for grain sorghum or milo, Rusche said it produces a crop that can substitute well for corn. The energy content of milo is usually about 85 percent of that for corn grain, which is usually reflected in price.
Because milo is more variable in starch and protein content than corn, Rusche said periodic feed testing is warranted if it will be the base of a finishing diet. “The seed coat of milo is essentially indigestible, so the crop needs to be ground or rolled for feeding. In general, grinding milo finer results in improved feed efficiency compared to coarser particle sizes,” he said. “Grain sorghum residue is very similar to corn stalks and makes an excellent resource for fall grazing cows.”
When it comes to forage sorghum, Rusche said it works best as a silage crop and has been grown successfully by a number of producers. “The crop can produce silage yields similar to corn but with 40 percent less water. Reduced cash input costs per acre represent another advantage,” he said.
Sorghum silage is lower in energy content compared to corn silage. Typical compositions are listed in Table 1. “Of course, actual composition can vary depending on hybrids, harvest maturity, and storage losses, so producers should sample their own feedstuffs for analysis,” Rusche said.
The impact of using sorghum silage depends on the class of livestock, explained Rusche. “Sorghum silage works well in gestating cow diets. Growing and backgrounding cattle would most likely gain more slowly because of the lower energy content compared to corn silage unless cattle feeders add additional amounts of energy dense feeds such as grains or distillers,” he said. “There likely would be only small differences for finishing cattle because of the small amount of roughage included in those diets.”
Another factor to consider is the effect crop choice has on the entire operation. “One advantage of corn over forage sorghum is that producers have the option of harvesting as either silage or grain, depending on weather and market conditions,” Rusche said.”Once farmers decide to plant forage sorghum, they have also decided to devote those acres to forage production.”