Producers must put silage into the silo at the right dry matter if it is to ferment properly and be palatable for cattle
Corn silage can be highly nutritious feed for dairy and beef cattle but it is more variable than barley silage so producers need to consider that when growing, cutting, ensiling and using it.
Agriculture Canada researcher Karen Beauchemin talked about corn silage in mid-September during an event held in a corn field near Lethbridge, organized by AJM Seeds. At that time, area corn crops destined for silage needed another few weeks to reach optimum maturity and feed value.
“Corn silage in Western Canada has the potential to be really high quality, really high nutritive value, but so does barley silage and they overlap. But corn silage, ultimately, can be higher in energy because it can have higher starch content,” Beauchemin said.
“It’s all about starch, in my opinion. Protein in silage corn is always going to be lower than barley. That’s a given. Starch can be the same as barley but it has the potential to be much higher than barley, so that’s what you’re growing corn silage for.”
Quality is key if feeding corn silage to dairy cattle or when backgrounding calves. Both livestock types require good nutrition for either optimum milk production or a sound start. It’s less important for feedlot cattle, where provision of roughage is the goal.
“The more important the energy is, the more you have to err towards getting higher starch content in your silage,” said Beauchemin.
That means careful selection of corn variety hybrids that will reach maturity before a killing frost and that are properly cut, processed and ensiled.
A longer season hybrid cut before optimum maturity may yield 20 percent starch but an early maturing hybrid cut at the same time could be 30 percent starch and thus be a more valuable feed.
Much depends on the number of corn heat units the crop receives during the season but growers can at least control variety selection and management.
“Even if you have the right corn product, in a cooler year, you could have less kernels on your ear,” added Adrian Moens of AJM Seeds.
The number of rows in a corn ear is determined at the plant’s six-leaf stage, while length of ear is determined at the 12-leaf stage. Extensive cloud during the growing season may also result in shallow kernels, resulting in less starch.
Beauchemin said statistics show there is a 50 percent chance of receiving more than 2,300 corn heat units in any given year in the Lethbridge area. However, current corn heat unit maps don’t reflect the warming climate and are being recalculated.
Nicole Rasmussen of Corteva said producers should also realize every corn seed company calculates maturity dates differently, which should be taken into account when selecting varieties.
“It’s not somebody’s right and somebody’s wrong. It’s just that we’re different and we need to understand that difference,” said Rasmussen.
Ideally, corn cut for silage is about half grain and half forage. Moisture content is a factor in quality.
“I see a lot of corn silages that are way too dry,” said Beauchemin. “They’re harvested and chopped and they’re over 40 percent dry matter. There’s no reason for that. You have to have a silage that goes into the silo at the right dry matter if you’re going to get it to ferment and the cows to eat it.
“If it goes in the silo too dry or not chopped properly, that negates all the work you did in the field.”
Dry matter content of 32 to 38 percent is considered optimum.
Material that is too dry is difficult to pack property, leaving air pockets that allow spoilage. Excess moisture can result in seepage and promotes growth of yeasts and moulds. That reduces cattle feed intake.
Processing is also required. Ultra-early corn varieties in particular are harder to crack and should be processed so each kernel is at least quartered. Cobs must also be broken up.
Beauchemin said starches in barley and corn are arranged differently. In barley, the starch is readily available within the kernel and once cracked it is quickly handled by microbes in the rumen. Starch in corn is covered by a layer of protein, and gut microbes can’t access it unless the kernels are broken.
“If you’re experienced with feeding barley, corn is really an easy switch. But if you went from feeding corn to barley, it takes much more management,” Beauchemin said.