by Sally Colby
It’s been a year of guessing games for farmers. Everyone hoped for dry weather during planting, and then we cheered for rain. Now that it’s time for harvest, there are concerns about ongoing damp weather, and whether corn will be ready and fields will be dry enough for timely harvest. By now, the crop is already determined, and handling at harvest and subsequent storage are the last measures a farmer can take to ensure optimum feed quality.
Joe Lawrence, forage specialist for PRO-DAIRY, says there’s a lot of new information regarding fiber digestibility and the influence of weather on both digestibility and starch content. “Rainfall at pollination and harvesting at the proper dry matter are going to drive starch content,” he said. “Some work out of Dairy One over the past couple of years has shown that in general, hotter and wetter growing conditions are going to make less digestible forages.”
Lawrence added that current speculation is that due to weather conditions this season, farmers will likely see poorer digestibility. “While we can’t change the weather, we can start planning ahead to make sure we have a plan in place to utilize forages as best we can — before we get into feeding them.”
Depending on when corn was planted, the question might become ‘what portion of the crop is going to make it to harvest?’ Lawrence suggests categorizing fields that will make it to maturity and those that will not. “If we categorize them now, we can also plan on how we’re going to store it,” he said. “We’d really like to store that feed in separate storages to make the best use of it for different groups of animals.”
Lawrence referenced work on growing degree days by Bill Cox at the Aurora Research Farm. “If you have a crop that’s silking in the middle of August (between the 11th and 20th), if you do the math and add up the average GDD after that, the likeliness of getting that 750 to 800 GDD after the 15th or 20th of August becomes fairly slim if we use Oct. 20 as an end point.”
Lawrence says New York climate center projections indicate near-normal precipitation with above-average temperatures, which should prove beneficial in achieving a full-season crop. “That may negatively impact fiber digestibility,” he added, “but at least we can get a finished, mature crop.”
Although there’s no way to predict the date of the first frost, if there are fields that tasseled before the middle of August, it’s likely that those fields will reach maturity. Fields that silked after that date may have to be harvested at an immature stage.
Kernel processing has a major impact on the nutritional value obtained from the crop and how well it will feed. “We want to harvest silage in the 32 to 40 percent dry matter range,” said Lawrence. “There’s a big impact on kernel processing at that maturity. When we get into wetter, immature crops, there may be less benefit to processing those crops, but we also have less overall TTSD (total tract starch digestibility).”
Lawrence explains one example of the importance of packing density on a farm that was evaluated for potential additional bunk space. The average densities on the farm were low, which led to higher shrink from spoilage and extra respiration loss. “They were at 9.5 months storage for corn silage, which was much less than they wanted,” said Lawrence. “Their thought was, ‘do we need to build another bunk?’ We ran some quick math, and figured if we could get the density up to 18 pounds DM/cubic foot from 13 pounds DM/cubic foot and reduce shrink down to 15 percent, we could jump that storage in the same footprint to 14.7 months without pouring any more concrete.” So for farmers who have extra tonnage, maximizing that tonnage is a matter of packing to make it more dense.
Weather conditions during both growing and harvest influence the possible development of mold in feedstuffs. Cool, wet conditions can delay maturity and lead to fusarium toxins, while hot and humid conditions lead to aflatoxins.
Ron Kuck, dairy specialist for Jefferson County, New York, says it will be difficult to predict the likelihood of mycotoxins in silage this year. “Wet weather and injury to living tissue gives us a better chance of having both molds and mycotoxins,” he said. “We’ve had a lot of insect damage in alfalfa with potato leafhopper and western bean cutworm in corn for silage.” Kuck added proper fermenting means preventing mold that results in mycotoxins, and that mold in forage doesn’t necessarily result in mycotoxins. He suggests farmers work closely with their herd nutritionist to determine how to handle silage from harvest and storage to feedout.
Kuck says forage inventory should be taken now in order to determine feed on hand and what there is to work with. Inventory is also an opportunity to calculate shrink loss and what you can do to improve that figure next year. “Aim for correct timing for maturity, harvest techniques and storage management,” he said. “Try to separate storage by quality so you can access it to target certain animal groups on your dairy.”
For those harvesting late-season grasses, Kuck suggests using inoculants to enhance fermentation. Homolactic acid inoculants (such as Lactobacillus) drop the pH rapidly and can inhibit clostridial growth. “The other is L. buchneri, which produce acetic acid,” said Kuck. “We might have some wet forages, and L. buchneri is a good product, but what we want to use is something that will drop the pH very, very fast, and homolactic inoculants work well for that.”
Unfortunately, many farmers rained-on hay this year. “We might have a lot of poor fermentation in silage samples that resulted from soil contamination from raking up a lot of soil and dead mice and other bacteria that we don’t really want,” said Kuck. “That inhibits fermentation. When we get samples from first cutting back, take a good look at the fermentation profile. You might see higher acetic acid, which is explained by wet silages. Wet silages also promote clostridial growth, which consumes carbohydrates and protein. That means a lot less energy for cows.”
Good early-season weather resulted in many farmers filling bunkers or silos early in the year. What about storing additional harvested forage? Kuck says many farmers use ag bags as intermediary storage if they’ve run out of bunker or upright silo space. “Make sure you consult your CAFO advisor to plan siting if you do this,” he said. “You want to make sure you put it in a spot that when you do the feed-out this winter, you’ll be able to get to it without any issues.”