It's one thing to stay with the same forage hybrids year after year - if they perform. It's another to avoid searching for new ones that offer more beef per bite of silage.
There's little time left to make forage seed decisions for 1999. Examining your feeding strategy, agronomic features of hybrids and your production needs can steer you toward the right forage decision. Selecting hybrids now and following through with proper harvest and storage will help you get the most from your silage.
Selection Basics "There are basically three points to hybrid selection," says Wayne Fithian, technical services agronomy coordinator for Golden Harvest Seeds. "Analyzing each will guide you to hybrids best suited for your operation."
* Performance history of the hybrid. Did it perform well in plots or fields in your area? Fithian says farmer strip plots or those planted by universities in cooperation with seed companies give strong performance indicators.
"Always try to base hybrid decisions on performance trends over multiple locations and/or years," he adds.
* Adaptation. Does it fit the needs of the farm or the field? Is it resistant to the right diseases? Does it have drought tolerance and will it perform on your soil type?
* Nutritional value. What role does silage play in your feeding operations - primary energy source or fiber? Fithian says if silage is the primary energy source, examine total digestible nutrients (TDN), acid detergent fiber (ADF) or the method you use for nutritional measurement. If it's going to be used as a roughage or fiber source, tonnage should be the primary criteria.
Make Ration-Friendly Choices Jim Beck, product manager for forage and silage products at Novartis Seeds, says how hybrids fit into rations is just as important as traditional agronomic features.
"If you're using corn silage in a growth ration, there are five important nutritional traits of hybrids that should also be considered," Beck says.
* Percent starch content.
* Percent whole grain digestibility (stover and grain).
* Percent lignin content.
* Level of neutral detergent fiber (NDF).
* Percent crude protein of the plant.
Beck adds that a lower lignin content will help increase digestibility, opposed to hybrids with high lignin.
Nutrition Matching nutritional needs of cattle to hybrids can be daunting at times. Using nutrition prediction formulas with silage quality testing ensures you'll get the right amount of TDN in the ration.
"Most rough energy estimates are based on ADF. Looking at the ADF differences between hybrids will give you an idea of how well each fits your ration," Fithian says.
Comparing the three hybrids shown in Table 1 illustrates the importance of screening hybrids for performance and quality characteristics.
* Hybrid A yielded well and produced a high-quality forage. This hybrid would be the best choice for a ration using silage as a primary energy source.
* Hybrid C produced the highest yield, but has a lower overall feed value. This hybrid would fit best in a high grain ration where silage is being used more for roughage than energy.
* Hybrid B has acceptable quality but lacks yield.
"Another method being used to measure feed quality is in vitro digestibility," he adds. "ADF is a pretty good road map, but it's not absolute. We can refine it further with in vitro, where the forage is exposed to actual rumen fluids containing the microorganisms that digest the feed. Then how much is digested over a specific number of hours is measured.
"The other component of corn silage we need to consider is NDF," Fithian says. "It's part of the fiber fraction, but it is digestible to some extent, digesting slowly. If the silage has a high NDF, it reduces the animal's intake. So, if forage is the primary energy component, you should select for low ADF and a low NDF, or a high in vitro digestibility."
Harvest It Right Assuming Mother Nature doesn't get in the way, harvesting silage on time and ensiling it correctly can be planned almost to the day. However, if your best-laid plans aren't going to work, harvesting early is an option, according to Keith Bolsen, animal science professor at Kansas State University.
He says for corn, sorghum and small grain cereal silages, it's better to harvest early rather than late, but don't harvest above 70-72% moisture.
"Earlier harvested silage will have a lower pH, a higher acid content and a chance of greater dry matter (DM) loss than late-harvested silage. However, the later-harvested crop will be difficult to chop and pack. It also will be more aerobically unstable during the feedout phase than early-harvested silage," Bolsen says.
Ideally, a longer period to harvest at higher moistures is the goal. Determine this harvest window by working back from your optimum harvest date. Beck says to select your harvest date based on the tonnage you need; your historic yield factor and the number of acres you will harvest. Once this is done, you can match hybrids to a specific period.
"Depending on the size of your operation, staggered or synchronized planting is a good approach," Beck says. "You'll get more selection and yield if you select hybrids with very high forage yield during short maturity dates. Pick two or three hybrids to plant so you have a maturity synchronization in the fall.
"Design your harvest window to maintain an optimal harvest moisture level of 68-72% for silage going into a bunker, or 62-65% if you're putting it into an upright silo."
The corn milkline is a good indicator of moisture content. If the corn is at 1/3 milk line, it's generally about right for bunker storage. It's generally ready for sealed storage at 2/3 milk line.
The appearance of milk lines doesn't relieve you of moisture testing, however. "The milk line may not always accurately indicate whole plant moisture content, and some hybrids don't have a distinct milk line, "Fithian says. "A moisture test is the best way to determine actual forage moisture content and should always be used to time harvest for hybrids that are new to your program."
Make moisture conclusions based on kernel appearance after you get to know how a hybrid matures under your management and field conditions.
"No matter the moisture level, move silage from the field to the pile or silo quickly. Reducing the amount of time forage is exposed to air reduces losses. For the same reason, try to maintain a more vertical than horizontal grade when filling a bunker type silo. Pack it right as well," he adds.
Store Correctly Storage losses are a concern, no matter how good the silage hybrid is. Typically, a 5-15% DM loss in good silage is normal and loss from bad silage can range from 25-50% DM. Generally, losses result from effluent, respiration and aerobic activity.
"Minimum losses and high-quality silage can be achieved in any type of silo if it's well managed," Bolsen says. "In general, vertical silos are more efficient than bunkers and smaller-capacity silos are less efficient than larger-capacity ones."
Bolsen adds that during feedout, the silage face should be maintained as smoothly as possible and perpendicular to the floor and side walls. This minimizes the square feet of surface exposed to air. Removing 6-12 in. each day is sufficient to prevent exposed silage from spoiling.
"Bacterial inoculants also help prevent spoiling," Bolsen says. "More than 200 studies involving 1,500 silages and 25,000 silos indicate that bacterial inoculants are beneficial more than 90% of the time."