Don’t leave alfalfa quality in the field

By: Randy Welch

Improving forage quality continues to be a hot topic for dairy managers and nutritionists as they look for ways to support higher levels of herd production.

The seed industry has responded with new technology that offers alfalfa growers improved forage digestibility and quality potential; however, harvested forage relative feed quality (RFQ) and neutral detergent fiber digestibility (NDFD) can still be reduced during harvest.

Often, forage plots rate higher in quality than mechanically harvested commercial fields. When that’s the case, it’s time to evaluate which production and harvest factors may be robbing alfalfa quality and draining forage quality profits.

Two main factors lowering forage quality are leaf loss and ash content. Determining how to reduce leaf loss and minimize ash content in harvested forage will help producers optimize the benefits of new seed technology.

Scrutinize harvest processes

As dairy operations have grown in size, the dairy owner-manager is typically not the person who does the cutting, merging, raking, chopping, baling, hauling, packing and feeding of the final forage product to the cows. The owner-manager may have relinquished some control over the harvest process by hiring harvesters or staff to complete these important steps.

When that happens, it’s up to the owner-manager to evaluate each harvest step to ensure that the forage quality isn’t being lost through leaf loss and excessive ash.

In 2015 and 2016, our interns worked with forage agronomist Dan Undersander at University of Wisconsin to conduct alfalfa quality studies assessing the effects of various harvest operations. At the beginning of an on-farm study in 2015 (Figure 1), relative feed value was measured on standing alfalfa at 150.96.

After discbine and merger operations, that figure dropped to 144.09. After the chopper operation, relative feed value sank to 126.73.

A 2016 study assessed leaf content (Figure 2) from precut to harvest and found similar drops in quality. Precut measurements showed an average of 44.5 percent leaves and saw that number fall to 32.3 percent at harvest.

What both studies show is how quickly quality can decline at each step of the harvest process. Bottom line: When leaves are lost, both forage quality and yield suffer. Encouraging crews to focus on quality throughout the harvest process will help minimize these losses.

Keep plants healthy

Keeping plants strong and healthy is one way to help alfalfa retain leaves. The use of fungicides increases plant health and leaf retention. Fungicides particularly protect the bottom third of the alfalfa plant from disease defoliation, which helps increase the amount of leaves in the forage mass and significantly boosts quality levels in the harvest system.

Fungicide applications – one at the beginning of the season and another in later fall – can fortify alfalfa health. If field conditions allow, the first application should be made 15 to 20 days before the first crop harvest is anticipated.

Aerial applications can be a good alternative on larger acreage, especially when fields are too wet for a ground rig. Fungicide can be applied prior to the first and second cutting. Making an application as alfalfa is put to bed in the fall will help plants stay healthy longer and capture more sunlight for increased vigor.

Monitor harvest timing

Harvest timing can be a major balancing act for producers. Pending rain, short harvest windows for hundreds of acres and getting the timing right for proper moisture levels can force crews into the field under less-than-ideal conditions. No matter what the challenges are, it’s key to make harvest decisions based on forage quality whenever possible.

New seed technology is helping preserve alfalfa quality longer and providing harvesters with valuable extra time to bring in higher-quality forage.

However, the risk of forage quality loss can still be significant during the various harvest operations, including cutting, merging, raking, baling and chopping. For example, if leaf dust is observed around a chopper, leaves – and valuable feed – are being lost.

Minimize ash content

When soil from the field gets into harvested alfalfa, it displaces valuable nutrients one-for-one in the dairy diet, delivering no nutritional value and possibly creating cow health issues. Forage tests can be used to verify the amount of mineral ash content and soil ash contamination.

Forage samples showing ash mineral content of 8 to 9 percent indicate that no soil ash has been added to the forage. However, nutritionists often report seeing ash content levels at more than 12 percent and sometimes as high as 18 percent, which means a large portion of the feed has no nutritive value.

While some soil particles may enter the standing forage crop from rain splash, others are brought in when cutters or disc harvest equipment isn’t adjusted properly. Merger tines may bring soil onboard while scraping the soil on uneven ground. Chopper heads can also pick up soil. Operator attention to machine settings can help minimize soil intake.

Remain vigilant

Producers must pay attention to detail throughout the harvest process in order to protect forage quality. Each time alfalfa is touched in the field, there’s a chance of reducing forage quality by knocking off leaves or adding soil contamination to the feed.

While a certain percentage of leaf loss will occur, and some ash will make its way into the harvested forage, everyone involved in the harvest process needs to remain focused and keep feed quality top of mind.