COPPER FOR BEEF CATTLE by Mike Mehren Ph.D.

What do you know about screenings? We may put them in a general category; however there are a lot of different types of screenings. To name a few, there are oat screenings,
corn screenings, corn dust, wheat screenings, canola screenings, pea and lentil screenings, and grass seed screenings.

Screenings are that portion of the grain or dry product that is not used for the primary product or products the mill produces. It constitutes everything that is removed other than the cleaned seed or kernels Screening is done primarily by different size screens that the product passes over. Scalping is a term used that refers to screening also. One type of screening allows the grain to fall through, while the other allows the by-products to fall through. Another part of screening is called dust; these very light materials are removed by air. Screenings can contain bits of grain, hulls, dirt, chaff, weed seeds, and anything else that got mixed with the crop being harvested. Since the protective shell of a seed or kernel has been broken, screenings have a greater chance of molding than grain. Screenings are a valuable alternative to grain and roughage. However, they change from load to load, mill to mill, and day to day. If you choose to use them for a large portion of your ration, someday-someway something bad will happen! The type of ration I’m talking about would look something like this:

Unknown Screenings	75%
Chopped Hay	20%
Supplement	5%

Some screenings may not come from a feedmill. Therefore they are not a by-product of the feed industry. Regulations for that industry may be quite different from those mills making feed for livestock. There could possibly be pesticides or herbicides. There have been incidents where the screenings were infested with ergot (a type of fungus that looks like a black grain seed). It can cause abortion and poor performance. Screenings may contain excessive amounts of ash. You and I call this dirt. You may not be able to see the dirt. I sampled a pile of screenings recently that looked and smelled fine. The analysis from the feed test lab showed that it had 24% ash. Since minerals like calcium, phosphorus, sodium, and potassium are also lumped into the ash, not all 24% was dirt. Most grains have 2-4% ash on a dry matter basis. That much excess ash definitely reduced the TDN of the screenings. The average TDN of that kind of screening is 65%. The analysis showed this screening to have 50% TDN. They were much less valuable than an average grain screening product. The ration above was being fed to finish cattle. They were not gaining well at all. The manager expected 3.0 lb daily gain. They weighed about 1000 lb and he didn’t think they had gained 1 lb daily for the last month. He did buy some whole corn and replaced most of the screenings with it, and the cattle went on to finish.

A growing ration similar to that above using the mix shown below would have a good chance of getting cattle to gain 1.5 to 20 lb daily. One example is shown below.

Unknown Scrngs	35%
Chopped Hay	60%
Supplement	5%

Grain dust is that part of the by-product that is removed by air. It contains the very smallest and lightest portions of the grain and other seeds. It normally is higher in energy than a screening. It is hard to feed unless you have some moisture in the ration. Today Hermiston is enjoying a 40 mph breeze. Trying to load grain dust into a mixer of any kind is an exercise in futility. A gentleman that I worked for used to dump a little corn silage on the area of dust he wanted to load; he claimed that really did a great job controlling his loss. If you manage to get the dust into the mixer and you have no ration ingredients that are high moisture, you might consider adding 5 to 15% water to the ration. If water is added, do it daily; don’t add water to a pile of feed that will be fed for the next week. You risk heating and molding of the entire batch. Remember any feed that blows away or fails to make it to the mixer is a form of shrink that needs to be accounted for.

Below are some average values for screening products fed in the Northwest

Product %	TDN %	Crude Protein
	...........100% dry matter................
Grain Screenings	65	14
Grain Dust	73	11
Oat hulls	40	4
Oat mill by product	33	8
Soy Hulls	77	13
Wheat millrun	75	17
Wheat Scrngs	71	11
Grass Seed Scrngs	61	9
Corn Scrngs	91	10
Barley Scrngs	77	12
Pea Scrngs	70	17
Lentil Scrngs	70	17
Buckwheat hulls	16.6	3.5
Canola Scrngs	21	74

What is average? If it’s only one sample, that becomes the average which means there isn’t much accuracy. The more samples, the more confidence you can put on an average
value. It gives you a starting point. Many screening products come with a guaranteed minimum quality for crude protein, ash, and crude fiber. Those are good values to use even if the person selling the product says that their screenings are usually much higher in protein and lower in ash and fiber.

When feeding any by-product or waste product it is especially important to watch feed intake and health very closely. Huge swings in feed intake are a good sign that the cattle are not getting the same feed every day. You may be mixing the feed the same, but it doesn’t taste, smell, or digest the same to the cattle.

Like any by-product, if a load or loads all of a sudden are offered to you out of the blue, Don’t just buy all available. Check into them first. Where did they come from? Who is selling them? Why or how did you get chosen as the lucky customer? Is there a guarantee on amount, quality, and timeliness of delivery? Somehow I would like to see and smell them and take a sample to a feed lab BEFORE I bought them. They may work out just fine especially if a reputable broker or feedmill is selling them.

Michael J. Mehren, PhD. is a livestock nutritionist who is screening the ticket scalpers before buying tickets to next year’s Super Bowl. He can be contacted by Email at mehrens@eotnet.net.