Feeding more corn silage can drastically reduce the need for increasingly expensive corn grain.
"Corn silage is like feeding a highly-digestible grass with high moisture corn attached,” says Bill Mahanna, Global Nutritional Sciences Manager for Pioneer Hi-Bred International.
Corn silage fiber digestibility (48 hour) averages about 60% to 62% compared to alfalfa's 50%. That higher digestibility reduces the need for supplemental energy from grain to support high milk production.
Mahanna doesn't advocate using corn silage as your sole forage. But feeding 60 lb. of corn silage (as fed) along with some alfalfa silage, he says, allows you to reduce both corn grain and supplemental protein.
"If you're feeding some quality alfalfa for its protein and balance rations around amino acids, you can lower your total crude protein to 16% to 17%,” he says.
To feed this high level of corn silage successfully, pay attention to these factors:
- Quantify the amount of starch in corn silage through forage testing, and recognize that significant differences exist due to hybrids and growing conditions.
- Remember that the starch in corn silage and high moisture grains (greater than 26% moisture) becomes more ruminally available during time in storage. In general, you'll see a 2% unit increase in rumen availability for every month in storage. So by spring, starch availability can easily increase by 8% to 15% units.
- Benchmark this changing starch digestibility in the lab by comparing a frozen sample of silage taken 60 days after ensiling to a spring sample.
- Have a plan in place to deal with particle size of all your forage. "It's the percentage of different forages in the ration that comprise particle size in the TMR,” says Mahanna. So make sure you, your nutritionist, feeder and forage harvester are all on the same page when it comes to particle size on both corn and alfalfa silage, and the amount of kernel damage in the corn silage.
- Use the Miner Institute's Z-Box to monitor for adequate amounts of physically effective fiber at chopping and again on freshly delivered TMRs.
- Frequently monitor kernel damage as material is being brought in for ensiling. There shouldn't be more than two or three kernel pieces larger than a quarter kernel in two large handfuls of chopped material, says Mahanna.
- Quantify the fiber digestibility of all forages.
- Use a corn silage-specific inoculant to reduce shrink. "When you have shrink, you lose the most digestible energy component in the feed and you have to replace it with an equal energy source such as corn or sugar,” he says.
- Continually monitor cows for over-crowded feedbunks and watch bunks for sorting. Both can contribute to bouts of acidosis.
- Moisture test silages often so that the forage-to-grain ratios of the TMR don't significantly change.