Many parts of the Midwest faced moderate to severe drought this summer, leading to substandard hay growth and early corn silage harvest. Many of these areas received recent rains, but it is too late to impact total yields for hay and corn silage this harvest season, leaving some farms scrambling to find forage alternatives. With an early corn silage harvest, some may be able to use recent moisture for a fall cereal grain crop.
    Small grain forages, such as spring-planted oats or an oats-and-peas mix, have been a part of our forage inventories for decades, but now we are also seeing more creative uses and applications of small grain forages. 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. While there is nothing nutritionally unique about feeding small grain forages to lactating dairy cows, a few subtle nuances can help maximize small grain forage quality.

Soil fertility significantly impacts forage quality
    Unlike its minor influence on corn and alfalfa silage quality, soil fertility can have a rather dramatic effect on the crude protein, potassium and magnesium content of small grain forages. Small grain forages grown without adequate nitrogen fertility will often be 3 to 5 percentage units lower in crude protein as compared to small grain forages with adequate nitrogen fertility.
    In addition, small grain forages are annual grasses and are luxury consumers of potassium from the soil. As such, small grain forages can be widely variable in potassium content, ranging from 1.5% to 3.5%. That variation becomes important if the small grain forage is going to be used in the prefresh diet because the potassium content affects the dietary cation-anion difference (DCAD).
    A similar situation is true for the magnesium content of small grain forages, which is dependent on the liming history and pH of the soil. Magnesium levels in small grain forages can range from 0.10% to 0.30%, depending on soil magnesium status. Cows fed transition diets low in magnesium are more susceptible to transition tetany. Because soil fertility can affect mineral content of small grain forages, sending samples to the laboratory for complete wet chemistry mineral analysis is always a good practice.

Maturity also plays key role
    The energy and fiber content of small grain forages are highly variable and primarily dependent on the stage of maturity at harvest. The harvest stage is most often determined by the need to get the crop off the field to allow a subsequent crop to be planted or developed. When small grain forages are harvested in the vegetative stages, it is not uncommon to observe forages with less than 45% neutral detergent fiber (NDF). Similarly, winter triticale and rye harvested the following spring can have low NDF content. Small grain forages harvested in the vegetative stages with low NDF content are ideal candidates for lactating cow diets.
    Small grain forages also can be harvested after seed head emergence, and these forages will have NDF content similar to straw. Mature small grain forages will have NDF greater than 60% and make desirable dry cow and heifer feed. The quality of NDF in small grain forages is also highly variable and changes rapidly as plants mature. The uNDF240 content of small grain forages harvested at early maturities can be as low as 10% of dry matter but when harvested at mature stages, uNDF240 can rise to more than 30% of dry matter. Likewise, the rates of NDF digestibility fall dramatically with advancing maturity.
    One exception to this maturity challenge with small grain forages is oats planted mid- to late-summer and harvested in the fall. Oats growing under conditions of diminishing day length develop very differently than oats planted in the spring and grown under conditions of expanding day length. Fall oats do not lignify to the same extent nor do they fully develop seed, resulting in very high sugar content (we have observed fall oats with greater than 15% sugars) and extremely high NDF digestibility potential.

Find the right fit
    It would be easier if we could say that one species of small grain forages is best for lactating cows and another species should be reserved for other animals. Unfortunately, that is not the case. Quality of these forages varies greatly with soil fertility and plant maturity. This, on top of a year with a wide array of weather challenges and field conditions, means that what works for one farm will not work for another. Work closely with your nutritionist to evaluate the quality of your forages, manage your inventories, and feed the forages that best fit both your cropping system and your different groups of animals.
    Barry Visser is a nutritionist for Vita Plus.