Small grain forages, such as spring-planted oats or an oat-and-pea mix, have been a part of our forage feeding strategies for decades. Recently, we have seen more creative uses and applications of small grain forage. It is increasingly common to see oats planted mid-summer and harvested in the fall, or winter triticale or winter rye planted in the fall and harvested the following spring.
    Most farms relying on winter or spring cereal grain silage as part of their forage inventories have likely harvested these crops over the past few weeks. The quality of these small grain forages is not so much determined by the species, but rather soil fertility and maturity at harvest.  
    Soil fertility can have a relatively minor influence on the forage quality of corn silage and alfalfa. In contrast, it can have a rather dramatic effect on crude protein, potassium and magnesium content of small grain forages.  
    Plant maturity also plays a huge role in small grain silage quality. When harvested in the vegetative stages, it is common to observe small grain forages with less than 45% neutral detergent fiber. These forages are ideal candidates for lactating dairy cows. In contrast, small grain forages can also be harvested after seed head emergence, and these forages will have NDF content similar to straw.  
    A few nuances and considerations come with feeding cereal silages to lactating dairy cows. While not intrinsically true in all rations, most of the time, we see cereal silage replace legume silage in the diet because corn silage inventories on Upper Midwest dairies are relatively fixed. Comparing the similarities and differences of cereal silage and alfalfa is a great starting place to consider diet formulation.
    A primary consideration of any alternative forage in inventory is its protein content. In general, a minimum crude protein content of 14-15% is desired for inclusion in the lactating diet to help minimize purchased protein costs. Cereal forages, such as triticale or rye silages, harvested at the flag leaf or early boot stage of maturity may contain 15-18% CP. In addition to harvest timing, the protein content of grass silage is largely dictated by the soil nitrogen fertility.
    Cereal forages are much lower in calcium and can be very high in potassium because grasses are luxury consumers of soil potassium. This means dietary calcium and potassium levels need to be double-checked. Additionally, when grass crops are grown on high-potassium soils, dietary magnesium needs to be monitored closely. High potassium levels in grass forages and in the cow can interfere with magnesium utilization. Thus, we often supplement a bit more magnesium when grass forages are incorporated into the diet.
    Another difference in cereal grass forages is the type of fiber. As compared to alfalfa, cereal forages have less lignin and more hemicellulose. As a result, cereal forages have less indigestible NDF and greater NDF digestion potential as compared to typical alfalfa silage. That all sounds perfect, but research has shown that legume forages have a greater passage rate compared to grass forages. Alternatively, this means legume forages have a lower rumen fill effect and grass forages may result in more rumen fill, even when diets are formulated at the same NDF concentration. This may result in slightly lower dry matter intakes in high-producing cows consuming diets with more grass inclusion, even when diets are formulated on an equivalent NDF basis.
    That means we have to play a bit with diets containing more grass to find a dietary NDF level that maintains DMI, rumen health, milk components and milk yield. Despite nuances between feeding legume or grass forage in our diets, we have observed excellent milk production potential when high-quality grasses replace a portion of legume forage in the diet. Work closely with your nutritionist to evaluate the quality of your forages that work in your cropping system and are a best fit for groups of animals.
    Barry Visser is a nutritionist for Vita Plus.