CORN fields covered in snow hide a valuable but underused commodity called corn stover, according to Michigan State University extension specialists James DeDecker and Kevin Gould.
The term "stover" refers to all of the leaf, stalk and cob tissue commonly left after grain harvest. Grain gets all of the attention but accounts for only 50% of the corn crop by weight. Specifically for Michigan, this means the average acre of corn yields approximately four tons of stover material on an annual basis.
Corn stover has traditionally been returned to the soil as an important source of organic matter and plant nutrients. Yet, increasingly tight margins in the crop and cattle sectors have caused producers to seek additional value from this abundant co-product.
Volatility in hay and corn grain markets, made worse by the drought of 2012, has pushed livestock producers to seek out alternative forages. Due to its relatively low cost and abundant availability, DeDecker and Gould said corn stover is quickly gaining recognition as a viable option for a portion of the forage component in ruminant livestock rations.
The greatest drawback for corn stover, according to DeDecker and Gould, is the fact that it contains only one-third of the protein of average-quality hay. Careful supplementation of stover with high-protein feeds like forage brassicas or dried distillers grains can overcome this deficit, however.
North Dakota State University recently did a project comparing lactating beef cows fed a diet of corn stover and distillers grains with cows fed corn silage, wheat middlings, barley hulls and straw.
The researchers at the Carrington Research Extension Center found:
* Calves of cows on the stover/distillers grain diet gained 2.73 lb. per day during the 92-day study, while calves of cows fed the other diet gained 2.57 lb. per day.
* The decrease in cows' condition score during the summer feeding period was nearly identical — 1.1 for cattle on the stover/distillers grain diet versus 1.0 for cows on the other diet.
* The daily ration cost for the stover/distillers grain diet was $1.71, compared with $2.22 for the other diet.
"Cow numbers continue to decrease in North Dakota and nationally as a result of drought, grazing land being converted to cropland and the high cost of conventional feed ingredients, yet underutilized and undervalued feed resources such as corn stover and distillers grains are available to producers in North Dakota," said animal scientist Vern Anderson, who led this study.
"Our past research indicates that beef cows are capable of using a wide variety of feeds, including crop residues (corn, wheat, pea, barley, straw, regrowth or cover crops) when properly supplemented," he added. "This study indicates that diets formulated with corn stover and nutrient-dense supplements such as distillers grain can be very successful in supporting excellent growth and performance in the cow and her calf."
DeDecker and Gould pointed out that if stover is going to be utilized for feed, it is important to remember that removing crop residue from the field has the potential to negatively affect long-term soil health. Stover protects the soil from the erosive forces of wind and water. It also returns carbon and nutrients to the soil as it is decomposed by soil biota.
Fortunately, a tool known as the Lucas soil organic matter calculator now makes it possible to use baseline soil data and information regarding production practices like tillage, manure and cover crops to predict how much corn stover could be removed without compromising soil health. DeDecker and Gould said harvesting stover should only be done in fields receiving abundant organic matter inputs in other forms.
Grazing is likely the simplest way to capture additional value from corn stover. An average acre of stover will feed a single cow for 30-45 days.
Like any grazed forage, feed quality declines with every day the animals are on stover, and supplemental feeding will, more than likely, be necessary to maximize utilization. However, extending the fall grazing season can be invaluable in years when forage yields are low and prices are high.
Producers commonly face several obstacles to stover grazing, including field location, fencing options and access to water. Despite these challenges, however, DeDecker and Gould said grazing is almost always more efficient than stover harvest, transport and manure hauling.
Mechanical stover harvest is facilitated by using a stalk shredding-type combine head during grain harvest and removing the chaff spreader from the rear of the combine. If a stripper head is used, an additional flail shredder or discbine pass will generally be required. Specialized combine attachments have been developed to windrow corn stover, but they are not necessary for a successful harvest.
Raking may or may not be recommended based on an individual's yield goal or the crop's moisture level. While baling for dry storage can work in ideal circumstances, stover is often too wet to preserve in this manner. Ensiling chopped or baled material is often the best approach and also improves the feed value of the stover.
At an average removal rate of two tons per acre, the fertilizer value of corn stover and equipment costs associated with harvest together total about $59 per ton. The current market value for hay is $150 per ton. Even with protein supplementation, a stover-based ration could save 71 cents per head per day, or $127.61 per cow over a standard 181-day winter feeding period.
Despite the potential savings, Michigan State University Extension recommends using ration balancing software when deciding how much stover to feed.
Corn stover has long been an important resource on the farm, but the number of ways it can be used is expanding.
In addition to harvest as forage, the recent construction of ligno-cellulosic ethanol biorefineries in the Midwest has created market opportunities for corn farmers to sell stover biomass for processing into liquid fuel. Three ethanol plants in the central Corn Belt are now in the process of contracting with farmers to supply approximately 275,000 tons of corn stover per facility in 2014. These emerging markets provide practical ways for corn growers to extract additional value from their product and remain competitive.
Montana is known for having high-quality beef genetics and is continually looking for new markets. This year, after receiving funding from U.S. Livestock Genetics Export Inc., Montana Department of Agriculture meat and livestock marketing officer Marty Earnheart, Montana State University interim dean and director of the College of Agriculture and Agricultural Experiment Stations Dr. Glenn Duff and two Montana beef genetic industry producers are poised to travel to South Africa in late January to assess the South African beef genetics market.
"Our high-quality beef genetics are a multimillion-dollar industry, with demand growing constantly," said Ron de Yong, director of the Montana Department of Agriculture. "Usually, after visiting markets and getting to know our counterparts overseas, we can begin expanding our reach and generating business opportunities for Montana's beef genetics industry."
The South African beef sector has been identified as an emerging market for Montana's beef genetics industry (embryos, semen and live animals for breeding purposes). A 2012 report by the Republic of South Africa Department of Agriculture, Forestry & Fisheries found a beef consumption deficit, i.e., more beef is consumed than produced. Additionally, a market analysis found growing beef consumption across Africa, with the population on the continent set to double by 2050.
"Capitalizing on this program has been a boon for Montana beef producers in the genetics business," Duff explained. "The work done by the Montana Department of Agriculture and Ms. Earnheart has had a profound impact on the Montana beef industry."
For example, Duff pointed out that the mission to Russia in 2010 has generated some $23 million of trade revenue for Montana's beef genetics industry.
Adding supplementary fat to rations to improve reproduction in beef heifers has been a topic of interest throughout the last decade. A variety of research projects have turned up variable results, explained South Dakota State University assistant professor Elaine Grings.
Some studies have found that feeding fat increases pregnancy rates, while others have revealed that over-conditioning heifers through fat supplementation will decrease pregnancy rates. If fat supplementation is used, it's recommended that fat supplements be fed to heifers for only about 60-90 days pre-breeding.
Since these reviews were published, research has continued to look at fat supplementation for beef heifers, with more attention paid to the actual source of fat, Grings noted.
Every fat source contains a unique make-up of individual fatty acids, and it is the specific fatty acids that may be responsible for the observed effects on reproduction. Three fatty acids of interest in heifer nutrition include oleic acid, which is found in relatively high levels in canola seeds, soybeans and many nuts; linoleic acid, which is high in some safflower seeds, sunflower seeds and cottonseed, and linoleic acid, which is found in high levels in flax (linseed) and camelina seeds.
Dietary fatty acids are hydrogenated in the rumen of cattle. In this process, hydrogen atoms are added to unsaturated fats, changing the proportions of the different fatty acids reaching the intestine for absorption. This makes studying and understanding fat supplementation of ruminants difficult. Feeding certain fatty acids does not always result in these same fatty acids being absorbed for use by the body.
The December 2013 issue of The Professional Animal Scientist included a report by researchers at the University of Illinois on a study testing the effect of different fat supplements on the reproductive performance of developing beef heifers.
Seven-month-old, fall-born Angus x Simmental heifer calves were fed a control supplement of corn and soybean meal or a supplement containing one of three fat sources: (1) whole raw soybeans (high in linoleic acid), (2) a mix of corn, soybean meal and a commercially available ground flax product (high in linoleic acid) or (3) a mix of corn, soybean meal and a commercially available hydrolyzed animal fat source (high in oleic acid) at a rate of about 4 lb. per day.
Heifers grazed pastures of tall fescue and red and white clover. Heifers were bred by artificial insemination (AI) after 193 days of supplement feeding. Bull breeding followed for 45-days after AI.
Heifers fed the control supplement gained 1.03 lb. per day, which tended to be less than the average of 1.11 lb. per day for heifers fed fat supplements. Heifers fed soybeans gained less than heifers fed flaxseed — 1.06 versus 1.14 lb. per day.
Conception to AI averaged 60% and was not affected by supplementation type. The overall pregnancy rate for fat-supplemented heifers averaged 85%, which tended to be less than control heifers, which averaged 93%. Plasma fatty acid profiles were not affected by supplementation type.
In this study, fat supplementation did not improve reproductive performance in beef heifers. Reproductive performance was acceptable in all treatments, with 60% of heifers conceiving to AI. It may be that if reproduction is not limited in some way, fat supplementation does not provide an additional benefit.
This study is in agreement with other studies and reviews that indicated that fat supplementation may not have much benefit in well-developed heifers and that short periods (60-90 days) of fat feeding may be more beneficial than longer periods.