Historically, cover crops were utilized to reduce erosion and increase soil organic matter during the winter months. In a traditional system, these crops are planted in the early to mid-fall after corn or soybean harvest and are killed prior to spring planting. In recent years, double-cropping these winter forage species to increase forage supply has become popular. Instead of killing the cover crop before spring planting, producers harvest and store the forage for later feeding. A winter annual double-cropping system allows producers to take advantage of the environmental benefits of cover crops while expanding and diversifying the forage inventory on their farm. This system has been particularly useful for producers who need additional forage due to poor growing conditions the year before.
Nutritive Value of Winter Cereal Grain Silage
Winter cereal grains, including rye, wheat, oats, barley, and triticale, are popular choices for producing harvested forages in a winter annual double-crop system. These forages are harvested in the early spring and are often used to make silage. Figure 1 shows the average nutrient composition of winter cereal grain silage in comparison to corn and legume silages.
The moderate protein and NDF content of the winter cereal grain silages make them viable substitutes for portions of other forages in the diet, which can help extend forage stores in the spring and summer. However, it is important to note that forage quality will have a big impact on how cows respond to these diet alterations. For example, partial replacement of good quality corn silage (high starch, highly digestible NDF) with mediocre or poor quality rye or triticale (high NDF and uNDF) may result in reduced performance depending on inclusion rate.
A recent study in Pennsylvania investigated the effect of partial replacement of corn silage (41% NDF, 35% starch) with high quality triticale silage (51% NDF; 17% CP) or wheat silage (51% NDF; 15% CP). Control cows fed the corn silage diet (44% of diet dry matter) produced 92 lbs. of milk per day at 3.8% fat and 3.0% protein. Inclusion of 10% triticale silage or wheat silage at the expense of corn silage reduced milk yield slightly to 90 lbs. per day but did not affect milk fat or protein concentrations. Although production was slightly reduced for cows fed triticale or wheat silage, this study demonstrates that high quality triticale or wheat silage can maintain a competitive level of production when incorporated into the diet in place of corn silage at a rate of 10%.
Choosing the Right Crop
While there are some similarities among these forages, there are a few things you should ask yourself when deciding which crop will work best for your farm.
Who are you going to feed it to? If you plan to use this crop to supplement the lactating cow diet, maximizing forage quality should be prioritized over yield. For highest forage quality, small grains should be harvested in the early boot stage (just prior to seed head emergence). Yield will increase after this stage, but quality, and thus, the feeding value for lactating cows, dramatically decreases. If, however, you plan to use this crop to feed heifers or dry cows, a more mature harvest (soft-dough stage) can increase forage yield with moderate decreases in quality that could still be acceptable for these animals.
Is your spring weather conducive to the ideal harvest window? The rate at which forage quality declines with maturity varies depending on the crop. Some cereals, like wheat and triticale, are somewhat forgiving because forage quality declines more gradually after its peak at the early boot stage. In contrast, the forage quality of rye rapidly deteriorates after the boot stage so harvest timing is much more critical if high quality forage is desired. Wet conditions during the spring can make it difficult to get into the fields to achieve the ideal harvest window for maximum quality.
Can you meet the optimum planting window in the fall? The ideal planting window for winter cereals generally varies according to winter hardiness. For example, barley is the least cold tolerant of the winter cereals and must be planted much earlier in the fall to reduce likelihood of winterkill. This can be difficult to achieve if the corn or soybeans aren’t out of the field at that time. In contrast, rye can be planted as late as early November due to its cold tolerance.
Winter cereal grains can provide a good source of supplemental forage for the dairy if harvested at the proper stage of maturity to maximize forage quality. The ideal winter cereal crop for your farm may vary from field to field and year to year depending upon weather and other crop conditions.