If you harvested corn for silage this past fall, this article provides some guidelines to consider. It’s risky to generalize when addressing crop quality or quantity, given the wide coverage provided by FARMING magazine. The situation may be even more varied this winter, because some parts of the region had their worst drought in at least 20 years while crops were good to excellent in other areas that got several timely midsummer rains.
On the plus side, an alfalfa trial in central New York was cut five times with some plots yielding about 9 tons of dry matter per acre, something that’s all but unheard of in the eastern U.S. On the minus side, some farmers in northern New York reported no measurable rainfall for two months this past summer. All that said, here are some nuggets to consider:
Manage crop inventories
Crop inventory management is always recommended but is especially important where forage supplies are limited. Cows hate sudden changes in forage quality or type, so it’s better to feed a moderate rate of corn silage year-round than to feed a lot for the next six months or so and then run out next summer.
However, there are two caveats. First, especially where corn silage is stored in bunker silos or drive-over piles, feed enough to prevent spoilage. Opinions differ as to whether “splitting a bunk” – feeding only a portion of the face for a period of time – is a good idea. You’ll suffer spoilage losses on the face of the silage left exposed for days or weeks, but in some cases this may be preferable to not feeding enough each day and winding up with warm and or moldy silage. I generally recommend against bunk splitting but there may be times when it’s the best option. In most cases proper planning should prevent this scenario.
Second, I’ll note again that brown midrib (BMR) corn silage is different in many ways. For example, a difference is in the feeding rate needed for an economical milk response. Research and farmer experience have concluded that when feeding BMR corn silage the ration needs to include at least 10 to 12 pounds (dry matter basis) of this forage. Therefore, if your BMR corn silage is 33 percent DM you would need to feed at least 30 to 36 pounds of silage. These rates are minimums – many farmers feed somewhat more than this.
I remember years ago hearing of a state university dairy herd that was getting BMR corn silage for the first time. They started feeding the BMR silage at a modest rate – as I recall, 6 to 7 pounds of dry matter per cow per day – and were very disappointed when the cows barely budged in milk production. Then after “asking the experts” they doubled the rate of BMR in the ration and the cows jumped 8 or 9 pounds – and this was a high-producing herd!
With that in mind, what should you do if you have BMR corn silage but not enough to feed year-round at the minimum recommended rate? Assuming that the crop is properly ensiled and not subject to high storage losses, it may be best to wait until warm weather to start feeding BMR. Many farmers do this after concluding from experience that responses to BMR corn silage are better during times of potential heat stress.
Real vs. ideal
Ideally you shouldn’t start feeding “new crop” corn silage until it’s fully fermented, and then some. The “then some” is because changes continue in the crop long after what’s considered normal fermentation is complete. Any changes in fiber digestibility occur quickly, during the heating/cool-down process, but starch digestibility continues to increase for several months after whole-plant corn is ensiled. These increases are significant enough to have an impact on rations – in this case a positive economic impact since higher starch digestibility in your corn silage means less corn you have to purchase as grain. We’ve heard of dairies feeding high rates of corn silage that during the spring pulled a sizable amount of corn meal out of their rations – and the cows went up in production!
That’s the ideal, but the reality this winter, following a severely dry summer in much of the region, is that many farmers didn’t harvest nearly as much 2016 corn silage as they’d intended. But this doesn’t necessarily mean that you should start feeding new crop corn silage any sooner. If you put up enough corn silage that you wouldn’t have to start feeding new crop until January or later, you should just be getting into what for many will be a short crop.
What to do now? Certainly have a “meaningful discussion” with your dairy nutritionist, but also do an inventory of all silages. There are silo capacity tables in print and online for all types of silo storages. The variables are type of crop and (for bunker silos and drive-over piles) silage density since this is influenced by how well the crop was packed as it was ensiled. If necessary, ask your Extension educator or dairy nutritionist for assistance in approximating (or ideally, measuring) silage density. Drive-over scales make this a lot simpler – if you used them during harvest. If you have several silo storages, make a simple diagram with what forage is stored in each along with the approximate amount. With this information you and your dairy nutritionist can estimate how long the silage in each silo should last, given the current rates of feeding. Knowing this now gives you more time to make the necessary adjustments in ration formulation or perhaps even purchasing supplemental forage. I don’t like the idea of moving silage, but if you have to move it from seller to buyer, it’s better to do so during the winter when spoilage losses should be less.