Growing knowledge: Forage experts discuss low lignin alfalfa options at Wyoming forage field dayWritten by Emilee Gibb
Sheridan – “We want to increase that digestibility, rate of passage and how much the animal can eat, and it’s all going to eventually end up, if we’re feeding it to dairy cows, in milk production, steers or something, their gains and those types of things,” said Colorado State University Forage Specialist Joe Brummer.
The annual Wyoming Forage Field Day, hosted by the Sheridan Research and Extension Center, explored several significant and up-and-coming topics in Wyoming forage production on June 14.
Brummer and Alforex Seeds Director of Product Development Don Miller led presentations on the development and performance of low lignin alfalfa varieties.
Lignin is a complex organic compound that is indigestible for ruminants. The amount of lignin increases as a plant matures. Brummer noted that lignin interfaces with cellulose and hemicellulose to create rigidity and allow the vascular system to move water through out the plant.
However, its interaction with cellulose and hemicellulose decreases total digestibility.
“At the end of the day, what happens is the lignin in the mature plant tissue interferes with animal digestion and negatively affects forage quality,” said Miller.
When compared to grasses, alfalfa has a higher amount of lignin, accounting for approximately seven percent of its dry matter components. Alternatively, lignin amount is approximately four percent of dry matter in grasses. As such, the lignin amount in alfalfa makes it less digestible.
“But it’s also an opportunity, right? If that grass plant can stand up there with only four percent lignin, can’t that alfalfa plant stand up there with four percent lignin? So it gives us an opportunity to look at reducing the amount of lignin in those alfalfa plants,” remarked Brummer.
According to Brummer, there are two basic approaches to producing alfalfa varieties that are lower in lignin.
Alforex has utilized conventional breeding and natural selection to produce a crop that is reduced in lignin by seven to 10 percent. It began releasing low lignin varieties in 2015 that can be used in organic operations.
Forage Genetics International has used HarvXtra technology, which is a form of genetic modification, to silence key lignin enzymes. The technology results in a 10 to 15 percent decrease in lignin. There will be limited seed available in 2016, and it will be stacked with the Roundup Ready trait.
“Now when we started talking about low lignin in the industry, this was about 10 to 12 years ago. It seemed to be a very difficult project to do that. From our breeding program, the question was, could we do it with conventional plant breeding?” asked Miller.
He stressed that it was important for Alforex to not simply focus on low lignin in their breeding operation but other essential qualities so there was not a yield lag compared to conventional alfalfa.
“Now we’re actually at the same level of lignin that we used to be at 28 days, even though we’ve delayed our harvest seven days. Also, we have seven more days of growth, so we have more tonnage out there,” claimed Miller.
Low lignin varieties boast greater quality with a higher rate and extent of digestion in livestock. In the case of Alforex’s seed, it has moved the plant maturity curve back seven days. This increased quality enables producers to have greater harvest window flexibility.
“We might want to cut at 28 days, but we get that rainstorm, and we’re delayed a week. We can still maintain pretty high quality,” noted Brummer.
Brummer reasoned that being able to cut later could potentially reduce the number of cuttings per year, therefore reducing wheel traffic and lowering harvest costs. Cutting later also gives the plants the potential to reach a greater percentage bloom that would be beneficial for local pollinators.
He cautioned, however, “That’s kind of a catch 22, especially with the Forage Genetics International’s transfer of genes and bees. So we have to look at that a little bit to see how far those genes are going to travel in the environment by letting these go to a later bloom.”
Miller also noted that being able to harvest last could potentially improve stand longevity by increasing plant health and reducing stress.
Low lignin varieties also boast a leafier canopy and leaves lower down on the plant.
“We’re going to have to market this and get that relative forage quality (RFQ) test, so we can market it at a premium to get that higher price per ton,” said Brummer.
Miller cautioned producers that relative feed value (RFV), neutral detergent fiber (NDF) and total digestible nutrients (TDN) testing will not show the advantage of low lignin over conventional alfalfa. RFQ, acid detergent lignin and a newly developed test called total tract neutral detergent fiber digestibility (TTNDFD) will show the advantage.
Some data has been collected comparing milk yields between cattle fed the low lignin and conventional varieties using the TTNDFD testing technology from the University of Wisconsin with significant improvements. Miller stated that Alforex is currently performing feeding trials to determine growth differences in feeder cattle.
“We’re actually participating in a feeding trial in Wisconsin right now where they use 500-pound Holstein steers. We provided the university with enough seed to put out 20 acres of our variety, and then they’ve got check varieties, too. We’ll see the weight gain on these new low lignin varieties on animals, too, so we’ll have that next year.”