Maximizing homegrown forages is appealing to many dairy producers, especially as they face tough market conditions. This can be easier said than done, as it is not simply a matter of inserting forage where concentrate feeds once were. Many considerations should be made to ensure you don’t lose money in the quest to save it.
Forage digestibility
Crop selection is the first step in maximizing on-farm forage use, and forage digestibility is a major consideration. Dry matter intake (DMI) often suffers with less-digestible forages due to increased rumen fill. With lower DMI comes less space to meet the nutritional requirements of high-producing dairy cows and the need to supplement with higher-cost products, such as fat, to reach the same caloric density as a ration with high-quality forages.
Brown midrib (BMR) corn silage and low-lignin alfalfa are often grown to maximize forage quality and subsequent inclusion in rations. If these options don't fit your operation, selecting silage-specific corn varieties with traits for high fiber (NDF) and starch digestibility can work well. These higher digestibility varieties allow forages to be fed without reaching rumen capacity for undigestible NDF (uNDF). They can also allow for lower or more effective supplementation rates of non-forage fiber sources such as corn gluten feed or soyhulls.
In situations of low-quality forages, non-forage fiber sources are often used in an attempt to recapture fiber digestibility lost in the forage due to crop maturity, suboptimal growing conditions or poor varietal selection. While they can complement an already strong forage program and are used to extend forages in situations of low inventory, using them to “fix” the fiber in a ration is often a losing game. If you are not short on forage inventory, you are swapping on-farm forages for purchased feed. Although BMR, low-lignin and other highly digestible forage varieties come with a price tag, it can be expensive to pay for fiber digestibility that could have been achieved in the field.
High corn silage diets
While 50-50 corn silage-to-haylage ratios used to be commonplace, many high-producing herds have moved to 80% or more of their ration’s forage coming from corn silage. Although NDF levels of the crops can be similar, corn silage tends to have much lower uNDF compared to alfalfa. Lower uNDF allows for a larger pool of potentially digestible NDF and therefore more calories coming from forage. The higher amount of digestible fiber and the typically smaller particle size of corn silage leads to increased passage rate out of the rumen and thus less rumen fill.
Greater ration consistency is another benefit of high corn silage diets. As opposed to haylage, which changes from crop to crop, corn silage is relatively consistent since it has just one harvest point. This allows for fewer changes to the ration. Corn silage also yields significantly more per acre than haylage. While alfalfa may only yield a little more than 4 tons of dry matter (DM) per acre, corn silage averages approximately 7 tons of DM per acre. Though alfalfa certainly has its own benefits, when a farm is land tight, corn silage will provide more feed inventory on the same acres.
Cocktail mixes
Cocktail mixes – with a variety of grasses, clover and other similar crops – have been popular options for some farms, particularly in areas where alfalfa crop winterkill is prevalent. Mixes may include both warm- and cool-season varieties that can provide some insurance based on the growing conditions experienced that year.
Maturities of the individual crops can conflict, however, particularly if the varieties thrive in differing environments. Quality can be severely sacrificed if you wait for tonnage prior to harvesting. Grasses often mature earlier; if they are allowed to head out, the quality of the feed produced will be dramatically reduced. The amount of NDF and uNDF will rise, leading to higher rumen fill potential, and the overall protein of the crop will fall. If you choose to mix crops in the field, consider which crops’ harvest windows will be relatively close.
You may also need to consider the nutrient requirements of the individual crops, as some may thrive on higher application rates of certain nutrients. Italian ryegrass, for example, requires nitrogen to maximize quality and often thrives on manure applications between cuttings. However, manure applications may prove disruptive to other varieties in the mix. Work with your agronomist to determine the most appropriate mixture and management for your situation.
Agronomic tools
You may consider agronomic tools such as fungicides to maximize quality of forage crops. Fungicides may help minimize susceptibility to mycotoxin development and improve fiber digestibility through improved plant health in corn. Reducing mycotoxins can allow for lower feed costs by minimizing the need for mycotoxin binders or deactivators. BMR corn silage, with lower lignin levels, often benefits more from fungicide application, as lignin is a defense mechanism for the plant.
The return on investment (ROI) for fungicides on alfalfa has been inconsistent; maintaining a short cutting window (30 days or fewer) between crops may be enough to prevent development of disease. The cutting window for low-lignin alfalfa varieties can stretch longer, and the need for disease prevention may be more pronounced. In a 2015 study at the University of Wisconsin – Madison Arlington Agricultural Research Station with both low-lignin and conventional alfalfa varieties, Dr. Damon Smith and Dr. Scott Chapman found a significant dry matter yield improvement with both the 30- and 40-day cutting window and significant improvement in defoliation and subsequent milk production with fungicide application during a 40-day cutting window. The study found a higher likelihood of a positive ROI with the longer cutting interval.
Harvest strategy
After laying the groundwork for high-quality forages in the field, the next step is ensuring proper harvest to retain quality. Harvesting at the appropriate moisture (65% to 68% for corn silage and 55% to 60% for haylage) sets the stage for success in storage. Haylage moisture is of particular importance; alfalfa’s higher protein and mineral content creates a buffering effect, which works against a pH drop. Thus, alfalfa silages have greater potential for clostridial fermentation, which produces butyric acid and potentially harmful end products such as biogenic amines.
Regardless of crop type, a proven inoculant should be applied. A good inoculant will direct the fermentation toward higher lactic acid production, reducing fermentation dry matter loss. Inoculants may also help mitigate risk when the crop falls outside of ideal harvest conditions. In some cases, such as a slower-than-ideal feedout rate, an inoculant with L. buchneri may reduce the spoilage potential. L. buchneri produces acetic acid, which kills yeasts that would otherwise result in spoilage.
When evaluating inoculant options, note the concentration of the bacteria doing the actual work of fermentation. Some inoculant bacteria survive incredibly well against environmental challenges but contribute very little in terms of lactic acid production. Apply a proven, high-quality inoculant to help maximize retention of both the quality and tonnage of forages once they have left the field.
Work with your nutritionist and agronomist to identify the forage strategies best suited for your operation. Increasing forage in a ration can backfire if not done correctly. Filling the rumen with undigestible fiber and reducing caloric content of the ration can lead to reduced milk production and negate the lower ration cost. Investing in the production of high-quality forages, however, allows for greater usage of homegrown forages while maintaining or possibly gaining in production.
