LINCOLN, Neb. — Drought has limited pasture availability and forced many producers into feeding total mixed rations (TMR) to cows. Including silage in a TMR can reduce ration cost, improve the energy content of the diet, and add moisture, which can serve as a ration conditioner. However, high commodity prices have encouraged many grain farmers to plant corn for grain rather than silage. Silage can also be made from small grains such as rye, wheat, oats, triticale, or barley, or from summer annual forages such as forage sorghum, sorghum-sudan or pearl millet. While these silages can usually be produced cheaper than corn silage and can certainly improve diet quality when included in poor quality hay based rations, producers should be aware that all silages are not the same quality.
The quality of all silages, including corn silage, is largely impacted by plant maturity, dry matter content of the forage at harvest, and the amount of oxygen removed through packing and covering. Therefore, regardless of the type of silage fed, samples should be sent to a commercial laboratory for nutrient content analysis. However, there are some generalizations that producers should be aware of when comparing types of silage.
The total digestible nutrients (TDN), a measure of energy for the animal, in corn silage is usually about 68 to 72% and the crude protein (CP) is around 8-10% when the grain in the silage is about 50% of the plant material harvested. This is usually the case when harvest occurs at the black layer and 30% dry matter. In a two-year study comparing winter wheat, winter triticale and cereal rye harvested at various stages of maturity in the spring there were not a lot of differences among species within stage. However, the nutritive value of these small grain silages varied significantly due to stage at which they were harvested.
Stage at harvest impacts both yield and nutrient content of small grain silages. In general, the yield increases as maturity increases and nutrient content decreases. Although, due to starch formation in the seed head the energy content of small cereals increases slightly from milk to sough dough.
|Energy (TDN) and protein (CP) content of fall planted winter hardy small cereals harvest at various maturity stages in the spring.|
|CP, % DM||18||14||12||10|
|Boot: head is not out of the stem but close to the top leaf|
Pollination: head is out and flowering is occurring (yellow anthers maybe visible).
Milk: When seed kernels from the head are squeezed, a white, milky substance will appear.
Soft Dough: Seed kernels are well-filled and are a playdough/clay texture when squeezed.
Again, the actual nutritive content of silage achieved will vary a lot from situation to situation as silage management such as moisture content, packing density achieved and covering all affect the end result. Sampling for nutrient analysis should be done after the silage is fermented as the energy content can change a lot during the process. On average small grain silages sampled on-farm in Nebraska lost 9% units of TDN from green chop to silage. These losses were as little as 2% units of TDN with well packed silage put up at the right dry matter (30 to 35%) and as much as 17% if put up too wet (20 to 25% dry matter). It is easy to overestimate the dryness of small grains and put them up too wet. If this happens it is better to feed the silage out earlier because the silage will continue to deteriorate as the clostridial bacteria growth uses up the lactic acid and makes it less stable.
Summer annual forages can also be used for silage, and as with small grains, are generally cheaper to produce than corn silage. Forage sorghum silage is about 80-90% the feeding value of corn silage due to the reduced starch content and the harder seed coat of the sorghum kernel compared to corn. Sorghum-sudangrass hybrids can also be used for silage but will have less grain in the silage. They will also have lower yields than forage sorghum but can be swathed and harvested earlier to allow for planting of winter hardy small cereals. As with all silages, conditions during harvest and packing impact the quality of the ensiled product and nutrient analysis should be obtained prior to feeding.
Producers who are purchasing small grain silage need to be aware that performance will not be the same as with corn silage, and therefore cost should not be either. The standing forage calculator can be used to help determine the price of these alternative forages relative to the price of corn silage.
Alternatives to corn silage such as small grain silage or sorghum silage can be economical additions to beef cattle diets when a TMR is fed. Producers need to be aware that silage quality can vary, due to many factors, but that small grain and forage sorghum silages usually have less TDN than corn silage. However, these silages can improve quality in diets containing low quality hay or residues and therefore should be considered as a viable alternative. Local University of Nebraska extension personnel can assist producers with developing rations containing these alternatives to corn silage.
For more information on silage management and use of small cereals and sorghum for silage check out the videos and proceedings from the 2022 Silage For Beef Conference.
Interviews with the authors of BeefWatch newsletter articles become available throughout the month of publication and are accessible at https://go.unl.edu/podcast.
— Karla H. Wilke, UNL Cow/Calf Systems and Stocker Management; Mary Drewnoski, Nebraska Extension Beef Systems Specialist
University of Nebraska-Lincoln