The author is an associate professor with Virginia Tech’s Department of Dairy Science, Blacksburg

In dairy farming systems, small grain crops are commonly planted for a variety of reasons. From a soil health perspective, small grains may be planted to protect the soil from wind and rain erosion, to reduce soil compaction and penetration resistance, to improve soil porosity and soil water retention, and to limit nutrient leaching and runoff. From a dairy nutrition perspective, small grains are typically planted as a forage source for dairy cattle.

Good for forage

When selecting species for small grain silage, different factors should be considered, such as the climatic conditions at the farm, the crop rotation, and the nutritional composition of the forage. Due to their hardiness, rye (Secale cereale), triticale (Tritricosecale), or wheat (Triticum aestivum) may be the best choices for areas with very cold winter seasons. Due to their faster growing and development rates, barley (Hordeum vulgare), rye, or triticale may be the best choices when two crops are to be grown within the same season.

From a nutritional perspective, review of a database with more than 36,000 analyses has shown that rye and triticale typically have the greatest crude protein concentration and the greatest fiber digestibility, compared to barley, oats, and wheat. On the flip side, of the five species evaluated in a recent study, barley and wheat showed the greatest starch concentration.

An interesting observation from the analysis is that, generally speaking, small grain silages have relatively high concentrations of potassium. This is important to consider when including small grain silages in rations for close-up cows given that, if these silages are included in great proportions, then it could be challenging to obtain rations with low dietary cation-anion difference (DCAD).

In regard to harvesting, small grains are typically harvested at boot or soft dough stages. There are certain advantages and disadvantages about harvesting at one stage or the other. First of all, harvesting at boot stage will result in less dry matter (DM) yield than harvesting at soft dough stage.

This will translate into a more expensive silage per ton of DM. As far as forage quality, a recent study from the USDA Dairy Forage Research Center has shown that triticale harvested at the boot stage resulted in greater crude protein (CP) and lower neutral detergent fiber (NDF) concentrations than triticale harvested at soft dough stage.

In addition, the digestibility of the fiber was substantially greater for triticale harvested at boot stage than for triticale harvested at soft dough stage. Bottom line, the nutritional quality of small grain silages is greatest when harvested at the boot stage.

Timing is everything

When putting silage cost and forage quality together, dairy farmers and nutritionists might have conflicts when determining the optimal harvest time. For instance, is harvesting cheaper but lower quality silage (soft dough stage for example) better than harvesting a more expensive but higher quality silage (boot stage, for example)?

To answer this question, I evaluated the inclusion of these two silages using a least-cost formulation approach under eight different scenarios. The scenarios included three main factors: high versus low commodity prices, high (60 percent) versus low (40 percent) forage diets, and harvesting at boot versus soft dough stages.

As optional ingredients, I allowed corn silage, alfalfa hay, corn grain, soybean meal, corn gluten meal, corn gluten feed, cottonseed meal, and urea to be included in the formulas. The reason to include these was the availability of price databases.

Paid off sometimes

Under a low commodity price scenario, one main finding from the analysis was that including small grain silage harvested at the soft dough stage resulted in a cheaper but more complex diet than including small grain silage harvested at boot stage. The more complex diet implies, in this context, that alfalfa hay had to be included in the ration to supply some of the protein that the silage harvested at the boot stage provided.

On the flip side, in a high commodity price scenario, small grain silage harvested at soft dough stage does not fit well (actually it was excluded) when high-forage diets were formulated for high-producing cows. It seems that when protein supplements are expensive, the lack of that “extra” protein in the small grain silage harvested at soft dough stage forced alfalfa hay to be included in the ration, therefore “kicking out” the small grain silage.

Under the high commodity price scenario, but when formulating low-forage diets, small grain silage harvested at soft dough stage was included in the diet by the model. However, again alfalfa hay was also included to boost the protein concentration.

When commodity prices are high, harvesting small grains at the boot stage provides cheaper and less complex rations than harvesting small grains at soft dough stage. This appears to be true even when harvesting small grains at the soft dough stage may result in cheaper silages.

Additionally, the earlier cutting of the small grain forage would release the field earlier, likely ensuring better growing conditions for the following summer annual crops. Harvesting small grain forages at boot stage seems to be a good practice to manage risk during high commodity prices scenarios.

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