There is an extensive list of agronomic, storage, nutritional and anti-nutritional factors associated with forage that could be considered the most important metrics. From crop yield to disease and insect resistance, to density and shrink, to ash and lignin, and further on to NDFd, starch availability, total tract starch digestibility, chop length, particle size, etc., and the list goes on. But does “forage hygiene” make the list? If so, where does “clean alfalfa haylage” rank on your list?
Focus on critical control points
Targeted focus on critical control points (CCP) can significantly enhance yield, fermentation, nutrient preservation and overall quality of haylage, including the hygiene or cleanliness of the alfalfa haylage to be included in the TMR. Let’s review the CCP for making high-quality alfalfa haylage, focusing on CCP 5: minimize contamination.
CCP 1: Safety
Have we done everything possible to ensure safety for us, our employees and our family members?
CCP 2: Decision-making
Who is empowered to make the decision to start or stop the harvest and ensiling process? Who will make the decision regarding whether certain loads of forage are included in the bunker or separated for feeding immediately?
CCP 3: Maturity
With advancing alfalfa maturity, yield increases but digestibility decreases. It is important to minimize the indigestible tons harvested, hauled, stored and fed to improve overall efficiency. In addition, you can decrease manure load by feeding forages harvested at the optimal maturity.
CCP 4: Moisture
Regardless of maturity, the single-most important criterion for successfully ensiling haylage is moisture. Stay below 65 percent moisture. At 6 percent moisture or higher (less than or equal to 35 percent dry matter [DM]), we greatly increase the risk of formation of butyric acid. Butyric acid is the primary indicator haylage has gone through “clostridic fermentation” leading to a reduction in sugar, elevation in pH, degradation of protein, increase in DM loss, off odors and poor feedout performance with potential health effects when fed to high-producing dairy cows.
CCP 5: Minimize contamination
- Ash: Minimize the inclusion of soil and ash when harvesting alfalfa for haylage. Soil contamination of alfalfa is undesirable for two reasons: It accumulates indigestible ash that serves as filler in a nutrient-dense TMR, and it potentiates higher numbers of clostridia spores to be ensiled with the forage. The additional clostridia spores lead to an undesirable fermentation.
Higher-than-normal ash levels in alfalfa haylage can be a result of picking up additional ash from the soil during mowing, wilting, windrowing and chopping or substantial DM (sugar) losses due to a secondary fermentation. We are harvesting alfalfa as highly digestible nutrients for high-producing dairy cows; we are not landscaping. By mowing at slightly slower speeds, we reduce the amount of scalping due to “bounce” of the haybine or discbine.
In addition, it may be necessary to raise the cutter height. Raising the cutter height (i.e., from 2.5 to 3.5 inches) will reduce total DM yield but will increase DM digestibility and reduce contamination with ash.
- Clostridia: Clostridia contamination of forage, primarily wet alfalfa haylage, leads to extensive DM loss, elevated butyric acid levels and potential negative impacts, especially for fresh and transition cows. While clostridia species that produce butyric acid in silage (e.g., butyricum, tyrobutyricum, sporogenes, etc.) can be reduced and effectively controlled with a reputable bacterial silage inoculant and improved management practices, Clostridium perfringens may also be present and can have significant anti-nutritional effects on high-producing dairy cows.
- Enterobacteria: Enterobacteria, such as salmonella, E. coli, klebsiella and shigella, are organisms typically found in the intestines of humans and animals. These organisms are undesirable in silage because they compete with beneficial bacteria for nutrients prior to and during ensiling. Their growth is known to increase the buffering capacity of the crop once ensiled, which raises pH and lowers aerobic stability.
Although most of the enterobacteria are regarded as non-disease-causing, some do contain a toxin that has been associated with feeding problems on dairy farms. Also, if your silage ever gets contaminated by soil or manure, there is an increased chance your feed will contain one or more enterobacteria species.
Clostridium perfringens and some enterobacteria have been implicated in hemorrhagic bowel syndrome (HBS) as well as other digestive disturbances. The loss of cows is obvious, but what about the chronic subclinical losses that occur daily without noticeable effect?
CCP 6: Inoculant
Apply a science-based, research-proven bacterial forage inoculant designed specifically to inhibit clostridia fermentation and, in some cases, mitigate mycotoxin-producing organisms. Reputable companies will gladly share their controlled research and field observations when asked.
CCP 7: The bunker
The final CCP focuses on diligent management at the bunker. Additional avoidable losses can range from 10 to 30 percent and occur at the bunker when attention to details wanes. Oxygen is the enemy.
The steps necessary to achieve and maintain oxygen-free conditions are vital to successfully ensiling alfalfa:
- Fill the bunker rapidly to minimize losses due to plant respiration.
- Match the delivery rate of harvested alfalfa arriving to the bunker with what the push tractor and packing tractors are capable of handling.
- Ensure enough packing tractor weight to obtain bulk density greater than or equal to 45 pounds per cubic foot, as fed.
- After the last load is delivered and packed, get off the pile, as additional time spent on the pile will not improve density.
- Completely seal the bunker and/or pile. Oxygen is the enemy.
Fungi: yeasts and molds
From the standpoint of contamination, oxygen promotes yeast and mold growth in stored forages. Yeasts are capable of significantly altering normal digestive and metabolic processes in the rumen, especially by decreasing NDFd, and they can contribute to milkfat depression.
Just because there are molds doesn’t mean there are mycotoxins, and just because there are no visible molds doesn’t mean there aren’t mycotoxins. It is important to note, however, aspergillus, fusarium and penicillium molds are thought to be the most problematic for mycotoxin production.
Molds originating on the crop in the field or resulting from poor ensiling practices are undesirable for two primary reasons: They result in spoilage that alters nutrient composition, feeding values and feed inventory, and they produce a variety of mycotoxins that can cause moderate to severe disease-like conditions in lactating dairy cows due to low-level consumption over extended periods of time. Today’s high-producing dairy cows have a faster turnover of rumen contents due to higher DM intake (DMI) than the lower-producing cows of the past. Because of this, they have less ability to detoxify feedstuffs because feed spends less time in the rumen where the natural detoxification process occurs.
The effect of mycotoxins generally is characterized by reduced DMI or feed refusal, decreased nutrient absorption and impaired metabolism, suppressed immune function and altered microbial growth. Since many of these symptoms can also result from other types of diseases, or environmental challenges, the presence and effect of mycotoxins can easily go unnoticed.
Conclusion
Ash, bacteria and fungi have the potential to contribute significant anti-nutritional components to alfalfa haylage. They may come in with the harvested crop, or the micro-organisms may become established and grow during storage and feedout. Although shrink or digestible nutrient loss is a potential outcome of undesirable spoilage micro-organisms, they are also likely to have a negative effect on the digestive system and the overall health of your high-producing dairy cows.
Is clean alfalfa haylage on your list of key metrics for quality forage? Is clean feed a priority? If not, should it be? 
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Keith A. Bryan
- Technical Services Manager, Dairy Probiotics and Silage Inoculants
- Chr. Hansen Animal Health & Nutrition
