How to Ration Your Corn Silage Inventory
April 4, 2020
Provided the farm still has some corn silage in storage, it is imperative to start stretching its use now. Make minimal dietary changes early in order to avoid drastic changes when last year’s silage runs out. This approach leads to minimal changes in animal performance, if any at all. The following steps provide a guideline for stretching your corn silage stocks.
1) MAKE AN INVENTORY TO DETERMINE HOW LONG CORN SILAGE WILL LAST.
Research from the University of Wisconsin and Cornell University suggest that for adequate preservation corn silage needs to be packed at or greater than 14 lbs. of dry matter (DM) per cubic foot. To verify one’s silage is within these parameters, cut a cubic foot and weigh it. Let’s use the figures of 14 lb. per cubic foot and the usually recommended moisture of 65%. Test the DM of the silage either with a Koster tester or a microwave. A cubic foot of silage with 35% DM and weighing 40 lb. will have 14 lb. of DM per cubic foot (40 x 0.35 = 14 or 14/.35 = 40).
To calculate how many pounds of silage there are in the bunker multiply:
Length (feet) x width (feet) x depth (feet) x density (lbs./cu. ft.).
For example, a bunker 100’ long by 30’ wide and an average height of 12’ will have:
100’ x 30’ x 12’ = 36,000 cu. ft.
36,000 cu. ft. x 40 lb./cu. ft. = 1,440,000 lb. silage
1,440,000 lb. silage / 2000 lb./ton = 720 tons of silage
To feed 500 animals at 30 lb. per head (500 x 30 = 15,000 lb.), there is enough corn silage for 96 days (1,440,000/15,000 = 96).
2) USE DIFFERENT FORAGES IN YOUR RATION AT RATES RELATED TO THEIR AVAILABILITY TO MINIMIZE DRASTIC RATION COMPOSITION CHANGES LATER ON. TESTING FORAGES FOR NUTRIENT CONTENT AND NITRATES WILL HELP RE-BALANCE THE DIET.
If you will run out of corn silage before the new crop (remember to allow for 21–30 days of fermentation) then start stretching the silage now, to avoid sudden changes later. Don’t disregard using blends of other forages with co-products to increase their quality — soy hulls and distillers’ grains are great choices! Do not underestimate in advance the value of other feedstuffs such as ditch hay or other lower-quality hays whose value can be upgraded with the co-products mentioned.
Because of their high-fiber and protein content, the use of distiller’s grains can help stretch out your forages, decrease feed costs and improve the nutrient content of the diet. Soy hulls can also help out by providing some fermentable fiber to the ration. Researchers at the Dairy and Food Sciences Department tested ensiling corn plants-wet distiller’s grains combinations at 75:25 and 50:50 ratios. The crude protein content was 15.6 and 20.7 percent for the 75% and 50% corn silage blends, respectively. In spite of the high pH of the green chopped corn plants (5.7) the initial pH of both blends was 4.6 and 4.0 for the 75% and 50% chopped corn plants, respectively. This was attributed to the low initial pH (3.1) with which the wet distiller’s grains came from the ethanol plant. By day 14 in the silo-bag, acetic acid concentration in both blends exceeded 3 percent of the dry matter. By day 129 the acetic acid concentration on the 75% chopped corn plants blend reached 5.7 percent, a value similar to that observed by University of Wisconsin researchers in bacterium-inoculated, high acetic-acid silages. The low pH and high acetic-acid concentration resulted in adequate preservation as well as improved “shelf-life” in the feed bunk.
Using ditch hay to feed cattle is a common practice across the U.S. It provides livestock producers with a source of readily available forage which can be very useful particularly during feed shortages. Assessing the feeding value of ditch hay however poses challenges since it is highly variable in nutrient content. The reason for this variability however doesn’t seem to be as much the plant species composition, but rather the time of harvest.
During 2015, North Dakota State University (NDSU) Extension analyzed 182 samples of harvested ditch hay from across the state. The results showed that most of the ditch hay consisted of cool-season grasses, predominantly smooth bromegrass. The best compromise between yield and quality appears to be during early July. The average values also show more mature brome grass hay to contain 10% crude protein (CP) and 55% total digestible nutrients (TDN).
Testing forage will be important with this season’s corn silage as they will be highly variable in moisture as well as grain content between farms.
Try to avoid sudden changes in ration composition due to forage shortages. Concentrates and co-products can be shipped relatively inexpensively, bulky feeds such as hay, on the other hand, are more expensive to transport and prices may be high. Check with your Extension field specialists. They can help balance your diets in order to stretch out your forage supplies.