GRASS SEED STRAW
by Mike Mehren Ph.D.
Feeders of grass seed straw fall into two distinct camps. Some absolutely hate it because they have had some kind of wreck. The second group thinks it’s a great feed for wintering cows. Unfortunately there’s also a group of radical extremists that thinks it’s great feed for calves! This isn’t a new feed, and I probably don’t have much information that’s new to you, but sometimes a review helps refresh the old memory!
If you remember nothing else, think of grass seed straw as a feed that is extremely variable. Don’t fall into the trap thinking that all grass seed straw is pretty much alike. It does need to be checked for endophytes, protein, and energy. Here’s an example of that variability. The figures are 100% dry matter basis.
The TDN value was omitted from the table above, because I believe most labs use the wrong equation for making this determination on straw. TDN for alfalfa and grass hay is calculated by the formula 88.9 minus (% ADF times 0.79) at many forage laboratories. For our Crab Grass Straw sample this Equals 47.8% TDN, the equation modified for straw is 85.9 minus (% ADF times .837). For that same straw this equals 42.4 TDN. Performing this same set of tasks for the Blue Grass straw equals 61.9% TDN and 57.5% TDN. This may seem like a bunch of academic gobbledy-gook to you, but think about it for a minute. Dairy quality alfalfa hay has a TDN of 62-63%. I’ve never seen any research that concluded that grass straw had 99% as much energy as pre-bud dairy hay. I’ll stick with the lower values. It helps me design rations using grass straw that will perform equal to or better than expected.
The big question is, which is the better buy? In these two examples it’s pretty obvious that the Blue Grass Straw would be worth the extra $7.00. We don’t know anything about the Crab grass straw. There was nothing said about whether it’s a turf variety or a forage variety of grass. It may well have a toxic concentration of one of the endophytes. You might also notice that in the poorer quality straw there was a lot of ash. In this case ash represents dirt that was picked up during the baling process. We can assume that the person taking the sample didn’t go along the ground picking up straw for his sample.
Normally, ash should not exceed 10%. Other factors that we don’t know about either sample would be whether there was heating and mold, or rain damage. The sample could have been taken right after the straw was baled, and we may be buying the straw three months later. A lot of damage could have been done during that time. The samples don’t predict how well your animals will eat the straw. We have progressed to the point that some grass seed straw sellers are having the straw tested for nutrient content and are certifying that their straw has been tested for endophytes and found to be safe for feeding cattle or horses.
Endophytes are fungi that are introduced into grass seeds to make them resistant to disease, pests, and drought. They are very necessary for the turf varieties to be excellent products for lawns or golf courses. They weren’t developed with animas in mind. The amount of endophyte can be determined by sending a sample to the OSU Vet Diagnostic Lab, P O Box 429, 30th and Washington Way, Corvallis, OR 97331. Phone is 541-737-2872. Cost is $35.00/sample. Getting a good sample for analysis is very important. It would be worth your while to discuss this with the lab before sending in a handful of straw and getting worthless data in return.
Years ago O.S.U.
analyzed samples of grass straws from many different varieties. These
studies were done at Corvallis and Union. They give an excellent picture
of just how variable the straw is. The following table is taken from
The lower the protein and higher the ADF and NDF are, the poorer the quality of the straw. Some of the straws would require so much supplemental protein and energy that it might be best just to meet the cow’s needs with other hay and put that straw out for bedding and a little extra fiber if the cows are still hungry.
On the other hand, some of the straws could be fed as the primary source of feed to cows that are in good body condition and are due to calve four to five months later. The only supplement that would be needed would be a mineral and vitamin. Body condition was mentioned because it is so critical to good straw use. Thin cows, heifers, and old cows are NOT good candidates for an all-straw diet. They definitely won’t gain enough weight before calving so that they have a chance to breed back.
A series of rations that I use when the straw will be fed with alfalfa hay follows:
These figures are approximates. The proportions may need to be changed depending on weather or cow body condition. For instance, you might feed the 50:50 mix early in the feeding season to cows that need to gain some weight.
Feed as much of that mix as the cows will clean up each day. Remember that when you are feeding on the ground, that 15 to 25% of the feed will be wasted. Also remember that after calving, when the calves are 2 months old, they will begin to eat a substantial amount of feed. You should be feeding enough alfalfa that they are able to eat that, rather than the straw.
I recently heard about a hay chopper/feeder that is pretty ingenious. It has two drag chains on it that can be operated independently and at different speeds. If feeding a hay and straw both products are mixed before feeding and the operator controls how much of each is fed. This has quite a few advantages: better than hay in the a.m. and straw p.m.; hay one day, straw the next; or both fed from separate bales at the same time. Those methods give the aggressive cows a chance to eat the hay, while the timid ones are stuck with straw.
We have seen that grass straw can range from a pretty valuable feed for keeping the cost of feeding a cow under control, to one that should best be used for bedding. The only way to know is through testing for feed quality. For those varieties that may have endophytes, have that checked so that information can be used if you have to feed an infected straw.
Michael J. Mehren, Ph.D. is a livestock nutritionist from Hermiston, Oregon that probably should have some grass seed straw added to his diet. He may be contacted by Email at email@example.com.