A farmer who’s about to spend $250,000 on an implement or land does considerable homework before making such a purchase. Dr. John Goeser, nutritionist at Rock River Laboratory, wants farmers to also consider the investment they’ve made in corn for silage.
“We don’t often think about it as such, but the average dairy farm with 500 cows will have invested $250,000 into corn silage by the end of the year by the time silage is harvested, chopped and sealed,” said Goeser. “Are we doing everything we can to optimize a $250,000 annual investment?”
Farmers are farming in unprecedented times, due to global uncertainty in the food supply chain coupled with swings in commodity prices that affected feed costs and inputs over the last year. A significant range in growing conditions across the U.S. over the season adds to the challenge. “We’re in a sensitive spot as corn has been tasseling and lack of rainfall will set the stage for grain fill and starch content,” Goeser said. “I’m expecting a more variable crop.”
Factors such as diet, digestibility, animal performance and feed conversion efficiency are tied tightly to profitability and can have a considerable range. “Better performing diets and better performing cows can achieve 70% to 75% diet digestion and achieve upwards of 40 to 42 pounds of total digested feed,” said Goeser. “We know based on research that every pound of total digestible nutrient we can unlock equates to roughly 3.5 pounds of milk.”
Regarding hay and haylage crops, with more fiber in the crop, other valuable nutrients such as starch, protein and sugar are less. Goeser likes to see less than 40% fiber in hay and haylage crops. Year over year, comparing 2022 and 2021, fiber content is up. “Energy levels are down substantially for eastern haylages, so if you aren’t thrilled with your haylage quality (grass or alfalfa), you aren’t alone,” said Goeser. “TDN in the eastern half of the U.S. seems to be more affected by fiber digestibility. Fiber content is up just a little bit, dropping energy, but digestibility is substantially down due to growing conditions.” Goeser predicts the same quality for corn silage.
Starch digestibility of corn silage improves over time in the silo. When silage is chopped green, digestibility is low, but as it ferments, digestibility improves. At some point, optimal fermentation is reached and the silage feeds at its full potential. Last year, due to the growing environment resulting in more mature kernels relative to wetter plants, silage reached optimal potential. “This year, we’ll have to watch kernel maturity as well as whole plant moisture as we time harvest,” said Goeser. “We have to optimize every bushel of corn coming into silage to cut back on supplemental grain and the costs associated with that.”
Goeser previously assumed that either wet, cool conditions or warm, dry conditions would mean higher quality silage, but that isn’t always the case. Both cooler and warmer conditions can influence fiber digestibility. “Wet growing conditions led to lower fiber digestibility,” he said. “Warm and dry conditions equate to higher fiber digestibility. This is attributable to both plant height and stature.” Today’s superior seed genetics have drought tolerance and produce good ears even in dry conditions.
As corn dries and matures in the field, it accumulates more starch. “In theory, more starch/less fiber would be a good thing from an energy standpoint,” said Goeser. “But what we see is a drop off in starch digestibility. The optimal point for grain harvest in the field is around 64% to 70% moisture. As moisture drops to below 60% moisture, fiber digestibility decreases.”
The tendency is to harvest drier silage to capture more starch. “I’m not a fan of that idea because the drop off in fiber and starch digestibility coupled with the risk factor of what may happen if we let corn for silage get a little bit drier if we don’t get it harvested as quickly and fermentation isn’t as strong,” said Goeser. “Risk coupled with nutrient digestibility would lead us to think about harvesting a little bit on the wetter side to end up with higher quality silage.”
Kernel processing scores (KPS) have increased thanks to a combination of research and improvements in harvesting equipment. The new KPS goal is 75% to 80%. Goeser said the latter figure is possible, adding that KPS increases through fermentation. “A 60% KPS at day zero will equate to roughly 65% to 68% KPS after 120 to 240 days,” he said. “Set your goal five to 10 units below where you want it to be if you’re checking KPS at harvest.”
Goeser considers inoculants as an insurance policy to preserve every possible pound of digestible nutrient. “Corn silage is prone to yeast and mold deterioration upon feed out,” he said. “There are a couple of goals we can achieve. One is preserving feed as fast as possible after it’s sealed, and the other is more stable and cleaner feed upon feed out. Both upfront fermentation and feed out stability are important relative to preserving and achieving feed out of every ton we put in the silo.”
If it takes weeks to fill a bunker or pile, the crop quickly loses feed value. Goeser recommended making smaller piles that can be covered. For packing and covering, he suggested for every 100 tons delivered to the pile, multiply by 800 to determine the amount of weight in the pack tractors to effectively pack the pile.
Cover bunkers and piles as soon as possible. Leaving a pile open for an extra day or two, especially if there’s unexpected rainfall, can have detrimental effects on at least the top foot and up to three to four feet of the pile upon feed out, even if spoiled feed is removed.
Not long after corn silage harvest is finished, farmers select seed corn for the next year. “We tend to look at what brings value to silage quality and take that into account for seed selection,” said Goeser. “We look for good yielding silage, fiber digestibility and, in some cases, we can consider unique corn for silage such as brown midrib corn (BMR).” BMR and conventional corn are distinct and achieve very different objectives. BMR has higher fiber digestibility but lacks starch and grain content so farmers will need to consider supplementing the ration.
by Sally Colby