The author is the founder of DNMCmilk, which works with dairy producers and heifer growers in several regions of the U.S. and around the world.

Steve Martin
Don’t mess anything up” was the first thing my client said to me upon my arrival at the dairy. “Well, hello to you, too! I guess the cows are milking well,” I thought to myself.

After a little small talk, I learned that yes, the cows were actually milking better than ever. This I already knew as I see his production summary every week. It was nice, though, to hear him say it!

The next information shared was that we needed to start blending new crop silage. “Oh,” I said. “Do we have a sample back from the lab yet?” The answer was no.

So, the stage is set. We need to change the most important ingredient in the ration when the cows are truly milking better than ever before. “No worries,” I lied. “This will be a piece of cake.”

One of the reasons that corn or sorghum silage has become the leading forage choice for larger dairies is the consistency from day to day throughout the entire silage-feeding year. If the dairy is good at putting up silage, this is a huge advantage for achieving good milk production.

However, when it is time to open the new crop silage, there is always a little worry that we might stumble with the change. The goal is to have back-to-back awesome silage crops, but even if you had a really good harvest for weather, packing, moisture, equipment, and so forth, you still don’t know how that silage will feed until you open it up and let the cows offer an opinion.

There can be big risk

It’s true that the principles are the same with any major ingredient change, but silage changes seem to offer the most risk and thus need the most careful management. Other changes might be related to markets and contracts.

Consider a situation where a dairy has been using a high feeding rate of soybean meal as the primary protein supply. If canola meal was a better protein buy for the upcoming crop year, a significant ration change will be coming soon. If the cows are doing well when it is time to make this change, this should be approached with caution.

A common change I encounter is a bit different. Many of our clients have a main silage, usually corn silage, that is the base of the diet. In addition, we usually have what I call a secondary silage. These tend to be things like sorghum, small grains, or alfalfa haylage. These would likely be only a few pounds of dry matter, but they will contribute significantly to the smell and bunk presentation of a ration.

They also come in and out more frequently and require thoughtful ration changes. These secondary silages tend to have higher risks of butyric acid and other quality issues in my experience.

No matter the change, taking things slowly is the way to go. Blending is the key, especially when it comes to silage changes. My best recommendations are to open the new pit a few weeks before the old one runs out. If possible, feed the first few days of the new ingredient in a dry cow or heifer ration.

A little shrink may be okay

Don’t be afraid to throw away a few loader buckets of feed if needed. A small cost of some shrink is better than having cows off feed, losses in production, or worse. When you feel you are far enough into the pile to get a good sample, overnight a bag to the lab. Once again, a $20 bill to UPS is better than problems with the cows.

A nearly unavoidable issue with silage pit changes is that you are feeding the back heel of the old pile at the same time as you feed the front heal of the new pile. Don’t be afraid to throw away the last few scoops of the old pile. Bad feed is bad feed, and it costs more money to feed it than to toss it.

I get questions about how long to blend silage piles. From a rumen standpoint, it can take a few weeks for the microbes to fully adjust to the differences in the new silage. So, start at 25% new silage and 75% old silage for one week. By then, you should have a good analysis back from the lab.

For the second week, you could go to a 50:50 ratio. By this point, you could have a second lab analysis back and know how the cows are reacting to the change.

If small changes are made based on subsequent lab results, and the cows are doing well, the third week at 75% new and 25% old should be fine. Since it seems difficult to accurately estimate when to start this blending, this 75:25 ratio can continue until you get to the end of the old pile.

I have heard that nutritionists might have a tendency to create reasons to change diets frequently, or at least with each farm visit, to justify their expense. In my experience, the dairies that get the most milk seem to have less frequent ration changes.

There is a balance here that must be struck, however. Changes from silage inventory realities are obviously required. Adding a little more of this or a little less of that based on manure, cud chewing, components, or milk flow can be helpful, but a healthy resistance to change for the sake of change should be the norm. Evaluate cost per cow opportunities for changes in ingredient prices and be sure the feed cost savings is worth the potential risk of yet another ration change.

A key point to managing the need for a change or the decision to keep the current ration in place is to have a well-thought-out ingredient and ration laboratory analysis program. Routine results from forage and ingredient testing with spot checks on ration nutrient levels can adequately inform the nutritionist.

Let it ferment

The difference in starch digestion characteristics in new versus old crop corn silage is the best example of this. Hopefully, silage inventory management is in place to not open new crop silage for as long as three or four months postharvest. This will help with the starch rate differences and must be checked every time.

Some ration changes are big and others are small. All should be approached with care while keeping a close eye on lab results and cow performance. As well, nothing beats boots on the ground to touch, feel, and smell the new silage and monitor manure, cud chewing, bunk presentation, and so forth.

When the cows are milking “as good as ever,” we seem to take all of this a little more carefully. It is true that cows at the top of their metabolic game should be handled with care, but every change needs to be closely managed from the perspective of the cow as well as changes in feed cost inputs.