Considering feed quality in winter feed rations
Published on Feb. 15, 2020
“We had some issues this past year with hay quality because we had a late spring and a lot of rain during the summer. The fall was wet and muddy which made things inconvenient,” states Iowa State University Extension’s Dr. Garland Dahlke during a webinar hosted by the university on Dec. 20.
During the webinar, Dahlke discussed the impacts of feed quality in winter feed rations.
“Due to the weather, a lot of growers this year got rushed and ran into a hurried harvest situation in their second crop haylage,” Dahlke says. “I think a lot of producers did it because they wanted to save quality. The protein content was around 20 percent and most growers wanted to get it down before it started raining for another week.”
Dahlke notes most of the crop then went into bunker silos with 81 percent moisture and 18 percent dry matter. He says this is a problem because it impacts fermentation and pH, which is generally over five, when it should be 4.5 or less than four for corn silage.
Dahlke notes a forage analysis for hurried-harvest hay may look normal. However, the fermentation analysis will be off and issues will arise when feeding it.
“Basically what happens is the protein in the feed starts to break down. It starts forming non-protein nitrogen because the protein is breaking down due to fermentation. There will also be some bacteria growth that we really don’t want to happen. There might be listeria, E.coli or salmonella growth so we should really try to avoid it,” he says.
Dahlke says instead of haylage, a hurried harvest might produce something more similar to compost.
Although he admits there is not much a grower can do with haylage in this situation, he does point out they might be able to use it in small doses in feedlot rations.
However, Dahlke highly recommends growers should avoid feeding it to growing calves and cows prior to calving season.
“The other end of the equation is a delayed harvest,” Dahlke notes. “Research from Iowa State found delayed-harvest haylage might be manageable in cool weather.”
Dahlke explains the same study found corn silage from a delayed harvest was roughly 60 percent dry matter. He notes corn silage averages 38 percent dry matter when harvested at optimal times.
“The first problem we run into with that much dry matter is it will have a harder time fermenting versus if it is on the wetter side, this then causes some obvious storage issues,” he says.
“Cool weather is the saving grace for delayed-harvest haylage,” he adds. “Because it was harvested later in the year, the cold weather comes quicker, and when things are cold, there won’t be as much trouble with storing it.”
He suggests using it up before temperatures start to rise around March and April to avoid running into rot and mold.
“The second problem with a delayed harvest is generally plants become overly mature and the crude protein content will go down,” he explains. “The neutral detergent fiber (NDF) will also go down, and the sugar content will see up to a 50 percent decline. The ammonia and nitrogen contents will be less as well.”
“Today, there are some management practices we have been doing for years and we still do regularly,” Dahlke points out. “However, some of these practices are actually putting mycotoxins in contact with our plants.”
Dahlke lists a few of these practices, which include driving over silage with a tractor to get a good pack, round bales that are left to sit out or aren’t properly packed, top dressing, no-till planting and reduced-till planting.
“Getting a good pack is important but we are also inoculating our silage with whatever is on our tractor tires,” Dahlke says. “No-till planting and reduced-till planting don’t work for vegetables because they don’t disrupt all of the plant viruses and molds underground. We can be a little more flexible with this in corn, soybean and alfalfa varieties because they are bred to be a little more hardy.”
However, Dahlke also explains when molds, viruses and mycotoxins are left in the soil, plant varieties grow up through them and become inoculated in some instances. Therefore, before we even harvest the feed we have a mycotoxin problem.
“Top dressing fields with manure or municipal waste is another surefire way to introduce mycotoxins,” he says. “In fact, three years ago I received a call from a producer in eastern Iowa who was trying to breed 150 heifers. He had them all synchronized and bred. However, only 25 of the 150 were bred.”
“Of course, he started questioning his hormones and his semen but I suggested sending in a sample of his feed because he had been top dressing,” Dahlke adds. “We sent feed samples to DairyLand Labratories, Inc. and then to a university in Australia, which is the mecca of mycotoxin research around the world. In fact, they look at a panel of 400 different mycotoxins.”
He continues, “This was good for us because DairyLand Labs’ report came back with zearalenone, which was way high at 1,200 parts per billion and we consider it high at 300 parts per billion. But the Australia lab showed that he also had beta-trichothecenes, ergot akaloids, fumonisins, aflatoxin, ochratoxin, alpha-trichothecenes. Overall, there were 71 different toxins and they all cause different responses.”
Because of this Dahlke also wants producers to be aware if they have one mycotoxin, they probably have more.
Dahlke notes there are numerous mycotoxins, although a few are more commonly recognized than others. He also states the Rock River Labs and DairyLand Labs provided him with data on numbers of mycotoxins they have seen this year.
“Vomitoxin is a reddish mold that likes cold weather, so we usually see it in cool, wet years,” he explains. “Data from Rock River Labs shows we might see and upward trend of vomitoxin this year.”
“Aflatoxin is the mycotoxin most everyone is familiar with,” Dahlke continues to explain. “Aflatoxin is a green mold commonly seen on corn and is generally seen in drought years.”
He continues, “Zearalenone is another mold that acts similar to estrogen and the Rock River Lab reports show a downward trend for this one. The T-2 toxin generally occurs in wet conditions and when top dressing fields with manure or municipal waste.”
“Why should we care about mycotoxins?” Dahlke asks. “Death is the first reason. Some mycotoxins can kill cattle overnight. Some can also cause neurological problems resulting in downer cows, ketosis, anorexia, impaired immune function, impaired milk production, impaired reproduction, cancer, ulcers, twisted stomachs, sore and arthritic limbs, poor performance and overall unthriftiness.”
Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.