Without question, you’ve heard “Corn is king and alfalfa is queen” spoken among agronomists, nutritionists and dairy farmers. As climatic conditions change, and production costs and challenges increase, progressive producers are searching for practical alternatives. In the quest for alternatives, one crop that has been receiving more frequent attention is forage sorghum.
Both the highly digestible brown midrib (BMR) and the normal sorghum species are finding profitable and productive roles in the rotation on many farms well north of the traditional climatic sorghum regions. Right from the start, sorghum seed is saving $100 per acre compared to many corn varieties. Seed (8 to 10 pounds per acre) is drilled with a modern sleeved tube drill or planted on 15-inch rows with a milo adapted corn planter. The narrow rows quickly cover the soil for maximum sunlight interception, competition for weed pressure and protection from downpours leading to erosion. Drilled sorghum has produced 18% higher yields than 30-inch rows in our replicated trials with better standability. Any skips are quickly filled in with tillers.
Corn has increased costs from fungicide applications, and corn growers are still struggling to control tar spot. Forage sorghum has not needed fungicides and is immune to corn tar spot. Armyworm is still a concern for both crops. On the flip side, sorghum will eliminate corn rootworm so the next corn planting will not need the expense of ever-weakening genetic control. Finally, deer love sorghum just for hiding and will come out to eat the neighbor’s corn. When storms knock it down, as they did at the University of Tennessee research farm plot, it stands right back up in a week or so. Corn knocked down is lodged until harvest.
Research breakthroughs
Research conducted by Advanced Ag Systems LLC and that from the University of Wisconsin have found a single-cut system is far superior to the multi-cut system for sorghum species. Yields can be double or more for direct single cut, while harvest costs are greatly reduced, yet quality is nearly the same. Single cut drops the cost per ton to provide a greater profit margin from your crop. A more critical factor is that single cut is direct harvested. The high-quality forage is not dropped on the ground with subsequent soil incorporation that challenges the fermentation process and adds anti-nutrients to the crop. Weather risk is greatly reduced as the cut crop is not lying in the field subject to weather events but goes directly from stand to storage.
An area driving interest in sorghum is the phenomenal increase in triticale as a winter forage. Research by Advanced Ag Systems LLC has found triticale winter forage directly increases annual yield per acre by 35% while improving soil health and structure. The forage quality is outstanding and is key to eliminating the “summer slump” when included in the ration as the summer heat builds. In the spring, winter forage is ready to harvest first, then haylage harvest can follow immediately after. Any corn planting would have to be delayed until after haylage and could suffer significant yield loss. Sorghum, on the other hand, requires warm soils before planting and the soil is not ready until after haylage. Thus, rotating to sorghum after winter triticale forage produces high-energy forage, yet balances the farm’s workload. Summer sorghum and winter triticale forage rotation is a natural fit.
A rapidly increasing use is non-BMR forage sorghum as the preferred forage for raising dairy replacement heifers. Corn silage can be problematic. In addition to all the previously mentioned “growing” issues, the grain portion quickly increases body fat, more so than frame size to growing heifers. Body fat in the udder negatively impacts milk production. Researchers in 2019 found that “Sorghum silage-based diets can control the dry matter and energy intakes for heifers and maintain optimum growth rates.” Multiple farms have reported they have switched to non-BMR sorghum and grow much better heifers with much less cost. Do not use BMR sorghum, as the more highly digestible forage fraction will make the heifers into little fat porkers.
Sorghum forage
A breakthrough in sorghum forage is the use of nutrient-enhanced male sterile BMR sorghum for dairy rations and grass-fed beef. It would capitalize on all the benefits listed previously and would be a direct replacement for corn silage. This is not photoperiod sorghum that does not head. In their research, photoperiod sorghum never increased in percentage dry matter, nor in nutrition beyond the base level. Male sterile BMR sorghum is allowed to head but does not set seed unless there is fertile sorghum nearby. Without the seedhead, the significant problem of sorghum lodging at maturity is eliminated because several pounds of grain are not perched on top of an 11-foot-tall thin stalk. Without a seed sink to take nutrients out of the rest of the plant and put into a seed with poor nutrient availability, nutrients are held in the forage cells, significantly increasing the feed value. Delaying harvest for a specific period after heading has produced a forage with nearly the same energy as corn silage but with significantly higher protein. With the harvest of more research plots this fall, additional information will be coming on how to enhance the nutrient content of sorghum for dairy cows and for grass-fed beef.
Harvest timing
A critical part of sorghum production is harvest. Sorghum is not corn silage. Because of the high digestibility, we target a slightly longer length of cut. About three-quarter inch is considered the minimum, and 1 inch is preferred. At this length, there is less sorting by cows, more physically effective fiber in the rumen to enhance the extent of digestion and a significant reduction of potential leachate during storage with its concurrent loss of nutrients.
Do not use a processor. Processing was developed to break the larger corn kernels. The smaller sorghum goes right through without cracking and, if it did, still does not improve seed digestion very much in the cow. Not processing reduces chopping cost and speeds harvest.
This is also why we suggest an earlier harvest than routinely done in Texas. There, they harvest when soft dough (squeeze the kernel and it is the consistency of cooked oatmeal) is halfway down the head. We harvest when the kernels at the tip are just reaching soft dough. (Head matures from the tip down.) Because this stage is slightly higher moisture than typical corn silage, a key part is the use of a high-quality, science-based, research-proven inoculant that can readily ferment the crop at higher moisture levels without concerns of it going butyric.
In our multiple trials with inoculant, we harvested from 17% to 27% dry matter and in 256 samples had no butyric. This is because the higher sugar content allowed the inoculant to get a faster start in fermentation to reduce the likelihood of bad things from happening. Although corn is king and alfalfa is queen, one logical and practical alternative is forage sorghum. .png){kind=icon}
Dr. Keith A. Bryan is a technical service specialist, dairy and silage, with Chr. Hansen Inc. Email him at uskebr@chr-hansen.com
