Forage Shortfalls: What to Do?
Don't harvest your corn silage (CS) too soon. Yields are maximized near 65% moisture, and losses during feeding, storage, and harvesting are minimized. If there is a year to maximize yields, this is it.
Harvesting at 34 to 35% dry matter will also increase the energy concentration in your CS because starch levels will have increased. With sky high corn grain prices it's a benefit you can't afford to give up. Use a Koster tester to check dry matters on field samples that you chop up. Work done at Miner Institute has shown that these sample dry matters consistently run about 2 points higher than what your feed out dry matter is. In other words, a dry matter reading you get from your Koster tester that says 34% dry matter will come back 32% dry matter at feed out. You should take that into account when making your harvest decisions.
Kernel Processing should be a real benefit this year. If you are not kernel processing and you suspect that kernels will be hard, consult with your nutritionist prior to harvest. This is not the year to be sending corn kernels out the back of the cow into the manure. If you ration has enough effective fiber from other sources (other than CS) you may be able to chop finer (to break kernels) without any health risks to your herd. BUT, be sure to double check with your nutritionist first. 
Preserve your CS (and any hay crop you may still harvest) well. With tight forage supplies you can't afford to incur excessive storage losses. I'd recommend lining your bunker silo walls with plastic. It really does reduces spoilage. This may also be a year when the oxygen barrier silage covers will really help you. Give them a look. Inoculants will have a greater change of payback this year as well.
Might you have some 3rd, 4th, or even 5th cutting to harvest late this year? This may be the year to take all you can get off your fields. There certainly is risk (especially with alfalfa), but you may have little choice. 
If you find that you will be short of forage you need to act NOW to rectify the situation. What can you buy and at what price? The longer you wait the more difficult it will be to find forage to buy. Info on making decisions on buying standing corn silage is on a Cornell website listed below. 
Line up supplies of forage extenders now. Feedstuffs such as wet brewers (if you can get it), soy hulls, citrus pulp, beet pulp, wheat midds, cottonseed, and others are ingredients often used to extend forage supplies. This year will be a different story. The drought is so widespread that many of these supplies are spoken for. You need to act immediately to have a chance to secure these feeds. They will not be cheap (if you can get them).
Determine the inventory you have. You may want to estimate it now and then recheck it after CS harvest. All indications are that corn silage, although it looks so much better since we have received rain, will not yield as well as it looks. Worksheets are available for you to use to: determine your forage needs, to estimate your corn silage and corn grain yields, to estimate your forage inventory, to reconcile your needs and inventory., and to determine how to price standing corn for silage. You can access this information at: http://ansci.cornell.edu/dm/factsheets.html 
Consider heavier culling. This may include some youngstock. BUT, be careful! You'll need youngstock to maintain cow numbers and to rebuild the herd. You need to be selective. Those heifers that had respiratory problems as calves are prime candidates. Again, on the Cornell website listed above you can find decision aids to help you with culling decisions. Look for the material titled "Ten Key Herd Management Opportunities" and find "Identify and Potentially Cull Low Value and Low Profit Cows."