Forage: Conserving DM a million dollar problem
By Lawrence R. Jones, PhD
With current elevated feed prices, a typical Northeast dairy farm will harvest about $1,000 of forage per cow. For a 1,000-cow farm, this represents a $1,000,000 investment. What is astounding is that good businessman will fight for 2%-3% difference in interest rates, but often ignore a 2%-3% difference in dry matter loss. In today’s economy, a 3% forage dry matter loss represents $50/cow per year.
Conserving forage dry matter is a three-step process:
1) Get the forage harvested, packed, and covered. During the first four days, pH should drop to a low level (corn silage, < 4; haylage, 4.2-4.8) which is indication of a good fermentation.
2) Ensure the forage is covered to keep oxygen out.
3) Feed forage without heating when oxygen is reintroduced.
Packing (corn silage, > 50 lbs./ft3; haylage, > 44 lbs./ft3) and covering (oxygen limiting barrier) are important for storage, leading to good fermentation (rapid pH drop) and conserving dry matter. As feeding management degrades (more feed exposed to air for longer times) additional steps are needed to conserve forage dry matter.
There are four options for conserving dry matter. Each has benefits, but also costs.
• The first option is to achieve an excellent fermentation during ensiling in combination with an excellent feeding program. Excellent fermentation is achieved with proper dry matter content (35% DM), appropriate lactic acid-producing bacteria with sufficient simple sugars, and exceptional packing. The other key is to have less than 15% of the feed exposed to air overnight during feedout. This means taking more feed off a small area.
As a baseline of treatment choices, I will assign a cost of $1/ton for this option, which is the cost for a high-end product which promotes rapid fermentation (i.e., cascade of lactic acid producing bacteria with pH appropriate stimulating enzymes).
• If slow feeding is a problem, such that feed heats occasionally on the feed table, a second option is adding a blend of organic acids (propionic acid and acetic acid) during TMR mixing to keep the forage cool. Ideally, the organic acid is added directly to the forage that is heating, usually at a rate of 3 lbs. per ton.
Since the heating occurs during hot/humid conditions, I will assume it is needed for 60 days in the Northeast. Using $1/lb. for organic acid and $1/ton for a high-end product with rapid fermentation (as in Option 1), the cost of this option averages $1.50/ton ($4/ton for 60 days and $1/ton for 305 days).
• The third option is to rely on nature for fermentation and continue with an excellent feeding program to control feed heating. The natural bacteria on the plant will ferment (drop pH) more slowly, resulting in more dry matter loss. Also, the end fermentation will depend on the random and unpredictable types of bacteria present on the plant.
For this option, I am assuming a 3% dry matter loss due to the slower fermentation which equates to $3/ton of silage stored. Forges which rely on natural fermentation tend to have higher acetic acid levels, making them reasonably stable during feedout.
• The fourth option is to treat the corn silage with L. buchneri bacteria to make additional acetic acid. This approach is needed if the feed is warm before you even feed it (poor face management or poor packing), or you are moving feed from one location to another. L. buchneri-based products tend to have additional bacteria to provide an average fermentation (a tempered pH drop). L. buchneri bacteria do not tolerate low pH (< 4.1) and will not thrive in acidic conditions. L. buchneri bacteria convert lactic acid to acetic acid which helps keep feed cool, but dry matter is lost in the fermentation process. L. buchneri bacteria are appropriate when the heating losses during feeding are larger than the fermentation losses caused by making additional acetic acid.
This option will cost about $1.50 for the L. buchneri product and a 2% dry matter loss ($2.0/ton), for a total cost of $3.50/ton.
Forage has become extremely expensive, and conserving forage dry matter is an important part of reducing feed costs. Packing and covering, leading to good fermentation (rapid pH drop), will conserve dry matter.
Extra diligence is needed to keep feed cool during feeding. Lack of diligence to managing feedout of corn silage can result in $2.5/ton additional costs. As feed management degrades (more feed exposed to air for longer times) additional steps are needed to conserve forage dry matter.
For short-term problems, organic acids (propionic:acetic blend) will keep forage cool. For more widespread problems, an L. buchneri product will provide higher levels of acetic acid, but at the expense of dry matter conservation during fermentation.
Well-managed silage at harvest and feedout, treated with a high-quality additive to achieve a rapid pH drop yields the most benefit at the lowest cost.