– Francis L. Fluharty, Ph.D., Department of Animal Sciences, The Ohio State University
The 2007 summer’s drought conditions in much of Ohio, West Virginia, and Kentucky caused much concern as many people were asking ‘what can I feed’ and ‘what’s the value of corn stover’? Since those are still relevant questions as cattlemen do what they can to reduce feed costs, here are a few thoughts to consider.
First, the good news is that we have several sources of alternative sources of high-energy feeds in this area including corn, distillers grains, and pelleted soybean hulls. However, the price and availability of these is not always cost effective. Additionally, many producers do not have the facilities to store distillers grains or soybean hulls, or the ability to purchase them in semi-load amounts. This has led many people to turn to corn stover or even soybean stubble bales as an alternative source of feed. Usually, our problem in this part of the country is meeting a cow or heifer’s energy needs, because our grass/legume mixtures are relatively high in protein. When feeding corn stover or soybean stubble, this is NOT the case, and a readily digestible protein source must be used.
Cattle need adequate protein to grow, mount an immune response, reproduce, maintain a pregnancy, or give birth to and nurse a healthy calf. Adequate protein supplementation also facilitates the digestion of feed stuffs.
Forages have lignin, an indigestible complex chemical compound that gives strength to plant cell walls. Corn stalks have a higher percentage of lignin than leafy forages, and soybean stubble has much more lignin than corn stalks. Immature, leafy forages and grains don’t have very much lignin, and thus their rate of digestion is much greater.
Two things must happen to aid in the digestion of low protein, high lignin feeds. Adequate supplemental protein must be provided and the particle size of the material should be reduced. This is why cattle ‘chew their cud’. They are re-chewing forages to break down the particle size so that more surface area is available for fungi growth and bacterial attachment which results in digestion, as well as breaking down the particle size of lignin-bound material so that it can pass out of the rumen undigested.
If low-protein feeds that are high in lignin such as straw, corn stover, and soybean stubble are not chopped and supplemented with appropriate sources of protein, then animal performance is reduced.
All that being said, current economics mean that many producers are doing things differently than they have routinely done in order to keep feed costs under control. While some cattlemen are simply selling females, others are separating older cows from heifers and 2 year-old females, feeding twice daily, chopping or grinding forage, or feeding alternative sources of energy.
As we consider alternative feeds, it’s very important to know the energy and protein levels in your feed, but it’s just as important to take into account a feed’s digestibility. If corn has a digestibility of 95%, and corn stover has a digestibility of 55%, which one is a better source of energy?
Put potential feed alternatives on a price per pound rather than simply comparing the bushel price of corn to the bale price of stover. If corn is $3.36 per bushel, it’s $.06 per pound ($3.36 / 56 lb = .06/lb). If a 1000 pound bale of stover costs $30, it’s $.03 per pound ($30 / 1000 lb = .03/lb). However, the net energy for maintenance (NEm) of stover is only 51% of that for corn (1.14 Mcal/kg versus 2.24 Mcal/kg). Therefore, on an energy basis for maintenance, they cost the same. However, the net energy for gain (NEg) of corn is 2.7 times higher than that of corn stover (1.55 Mcal/kg versus .58 Mcal/kg) making corn a more economical energy feed for gain.
If corn is $.06 per pound the price per pound of corn stover would have to be $.022 to be equivalent for gain ($.06 / 2.7 = $.022), making the price of a 1000 pound bale of stover be $22 to be equal for energy. All of this assumes that corn stover and corn grain have the same digestibility, and protein content, which they don’t. If corn grain is 95% digestible, and corn stover is 55% digestible, then poor feed intake becomes a problem with corn stover, due to the length of time that the stover remains in the rumen before it is digested or chewed to particle sizes small enough to pass out of the rumen, and the corn grain becomes even more economical.
This is just one example. When considering the value of other energy feeds such as distillers grains, corn gluten feed, or pelleted soybean hulls, it’s still important to put things into perspective by looking at a price per pound of digestible nutrients.
In many parts of the world, straw is fed as a roughage source to ruminant animals. While long-stem straw has a very low digestibility, the grinding of straw increases consumption. This leads to higher digestible energy intakes.
This brings up an important thing to consider. As the result of work done by Dr. Steve Loerch here at The Ohio State University, one effective option producers rarely consider is hay chopping. Chopping hay allows the cows to eat 25-30% more energy. Costs of chopping hay (equipment, labor, etc.) should be compared to costs of purchasing supplemental energy. For some producers, this may be a cost effective option. We have come to realize the potential of hay chopping from an observation at the OARDC Beef Center in Wooster. Steers fed a chopped hay based diet gained 2.5 lbs/day while those fed round baled hay (same hay source) in a rack gained less than 1.5 lbs/day.
So, if you are using corn stover, baled soybean stubble, straw or similar low quality forages as a cow feed, here are some key points to remember:
* Dry beef cows will need a diet that is 8% protein in the middle third of pregnancy and 9% protein in the last third of pregnancy. Pregnant yearling heifers will need a diet that is at least 11-12% protein, and heifers and cows nursing calves will need a diet that contains at least 12% protein.
* If heifers and young cows are not separated from older cattle, they may be pushed aside when given supplemental feeds, and they may not receive the protein or energy they require.
* With low-quality feeds, it is best to feed combinations of ruminally available (urea, soybean meal) and ruminally escape (corn gluten meal, distillers dried grains, fishmeal) protein sources.
* Soybean meal is an excellent protein source with low-quality forages, because approximately 80% of the soybean meal is degraded in the rumen, and the rumen microbial population must be given a source of N so that they can reproduce, before they can digest the low-protein forages.
* If you are using corn stover, straw, or baled soybean stubble as the main source of forage, it may be necessary to supplement a high-energy feed to your cattle such as corn, DDGS, CGF, or SBH in order to keep the animals in the proper body condition.
* If labor is an issue, and it is not feasible to feed protein supplements daily, it might be appropriate to use protein tubs or protein kegs for supplementation with low-protein feeds such as straw, corn stover, or soybean stubble. However, expect to pay 2 to 4 times more for the same amount of protein than you would have paid if a soybean meal and distillers dried grain combination had been used as a top-dress.
* Keep in mind that the mineral nutrition of your cow herd should not be compromised due to using alternative feeds. Having a good mineral program will enhance performance, allow the animals to convert energy more efficiently, improve calf survivability and growth, and reduce the post-partum interval from calving to rebreeding.