As the weather gets warmer and days to fall harvest become fewer, having an accurate count of your on-hand animal feed is critical to making decisions.
Calculating that feed comes down to how it’s stored.
“On inventorying, it’s a little bit easier with Ag-Bags, upright silos and baleage, but with a bunk silo, it can be a little more tricky with those oddly shaped structures,” said Joe Lawrence, dairy forage systems specialist with Cornell Pro-Dairy.
Knowing what you have in inventory, he said, can help answer the following questions:
- Do I have enough feed for the milking herd and young stock?
- Do I need to look at fillers for the ration to stretch forage inventories?
- Should I cull unproductive animals?
- Do I have more young stock than I need?
Regardless of the size, structure or shape of your storage, two components are needed to do an accurate assessment: volume and density.
If you have a bunk silo with walls, Lawrence said this is an easy calculation.
“I like to think about it in terms of rectangles and right triangles, so if you know the height and width of your bunk with walls, and if it’s crowned at the top, you can kind of look at it as that crown being two right triangles,” he said. “That makes it easier to calculate volume.”
Drive-over piles are more challenging. One way to look at them, Lawrence said, is to look at the pile as a solid rectangle, break it down into multiple components and then make your calculations.
Using a drone
Drones are becoming more popular to do bunk silo calculations.
“You can get a very accurate calculation of a pile regardless of its shape and size,” Lawrence said. “The drone will use topography to calculate volume.”
Density is trickier to calculate, but it can be done if you take the right steps.
“Step one is to establish a volume with the drone through the initial flyover,” Lawrence said. “Once the initial volume is known, then track the weight removed from the pile over a number of days [10-14 days] using the scale on the [total mixed ratio] mixer wagon or other scales.”
The third step is to do a second flyover to determine remaining volume.
“By knowing the change in volume and corresponding tons removed, a density can be calculated,” Lawrence said.
If you don’t like technology, try this simple way of measuring feed removal. If you have spray paint handy, place a line where the pile is. Then, come back about two weeks later and spray-paint another mark. You can then measure the amount of feed removed during that time.
“There is no perfect answer,” Lawrence says. “The important thing is to try to get a good estimation of density because if you don’t do that, you’ll get misleading numbers.”
Running low on feed? Here’s some options
If you’re farther south — like southern New York, Pennsylvania or Ohio — sorghum-sudangrass can still be planted for one or two cuttings this summer, Lawrence said.
Or you can let it grow longer for higher tonnage but just get one cutting.
“You have to decide if you’re looking for lactating-cow feed or non-lactating-cow feed. Because if you need non-lactating-cow feed, you could leave it and get the equivalent in one cutting as you would in two cuttings of higher-quality feed, but it’s going to be harder to manage,” he said. “At that point, you are leaving it into the fall when it’s drying down on its own.”
Hayfields that are underperforming or weedy, or a field that’s fallow, can be planted with oats in early to mid-August and provide a crop in about 45 days.
“You can get a pretty high tonnage of fairly good-quality feed, but harvest it before it heads out,” Lawrence said.
Another option is to plant oats and winter triticale together in August. The oats can be harvested in fall and triticale next spring. But there are steps to do it right.
“You have to really look at your seeding rate. Make sure the oats aren’t going to suffocate out the triticale or rye,” Lawrence said. “And also, make sure your cutter bars are set higher, so you’re leaving more stubble there in the fall, so you’re not doing damage to the winter crop. It can be done, but it is risky.”
Cereal rye and triticale are safe bets in New York, Michigan and parts of Wisconsin, so long as they are planted in September for winter survival.
The bigger challenge is harvesting in spring to provide a suitable yield of the crop while having time to plant corn after it.
Annual ryegrass and even perennial ryegrasses can be unpredictable in more northern areas for winter survival. Some years they overwinter fine, Lawrence said, while other years they winter-kill.
Planting it in summer and then hoping to get an additional cutting from it the following spring is a risky bet, Lawrence said.
“In the years it works, it can be a nice bonus feed, but I would advise against counting on it every year as part of your core forage inventory,” he said.
Ryegrass in late summer as a cover crop is also an option.
“The trouble is, in addition to being less winter-hardy than winter cereals, it needs to be planted in August if it is going to have a chance to make it,” Lawrence said. “So, even our early-harvested corn silage is generally on the late side to allow for it to be planted timely in a typical dairy farm crop rotation.”
There is also the concern over potential glyphosate resistance in annual ryegrass.
“This is something our weed scientists are increasingly concerned about and are raising this as a reason to be cautious in using ryegrass a cover crop, irrespective of its potential forage applications,” Lawrence said.