A:   We do not routinely run rations because we would need to know much more information. For example, I would need to know all possible ingredients available, their nutrient composition (we could get close on this), but most importantly, the cost of these ingredients. In the case of backgrounding calves, it is also very important to know what type of performance you would like to have (mainly ADG for backgrounding calves). With that said, I can make some general comments and then address your question about distillers grains.

For a gain of 1.5 to 2.0 lb per day, which is likely the target, you will need to feed approximatley 50% concentrate, 50% forage. If you use a lower quality forage such as straw, then you may need a bit more concentrate. If you use distillers grains instead of corn, you can feed a little less concentrate. If you use wet distillers instead of dry distillers, then you can feed a little less WDGS to get the same gain, or feed the same amount and get slightly better gain.

In forage based diets, we calculate that distillers grains has 127 to 145% the energy value of corn in forage based diets (3 experiments have observed 127, 130, and 145%). This does depend on the level in the diet or amount you are feeding. Dry distillers appear to have a little lower energy value than wet distillers.

The limitation to using distillers is probably one of 2 things, fat or sulfur. Distillers grains generally contain 30 to 32% protein, 11 to 13% fat, and 0.5 to 1.0% or more sulfur. Distillers are low in Ca (<0.10%) and high in P (0.8%).

In forage based diets, it is generally thought that adding more than 4 to 5 percentage units of fat is the maximum you can add without compromising forage digestion by microbes in the rumen. This would equate to about 40 to 50% inclusion in the diet (or 5 to 6 lb of DM per day depending on how much this 500 lb calf is consuming. You have to use DM (dry matter) not as-fed amounts which is critical for the wet distillers grains since that is either 65% water (35% DM) or can be "modified wet distillers" and contain 50 to 55% water (45 to 50% DM).

Cattle that are fed too much sulfur can develop problems such as reduced performance, or it can become acutely toxic and cause a neurological problem called polioencephalomalacia (polio, or PEM, or brainers). It is not well documented, but when diet sulfur gets above 0.45 to 0.5% in the diet in forage based diets and the sulfur source is distillers grains, then you may have some of these challenges.

Regardless of whether fat or sulfur are the problem, you are probably wise to keep the distillers inclusion to less than 50% of the diet (on a DM basis) or 5 to 6 lb of DM assuming these calves are eating 10 to 12 lb of DM per day.

The distillers are certainly easier to feed than corn as cattle can overconsume grain and become acidotic. This challenge is minimized with distillers grains as it does not have the starch that the grain does.

Likewise, wet distillers grains have some positive characteristics in that they help with mixing diets and keeping the forage mixed together with the distillers and other feeds. Dry distillers is generally a bit more expensive (not always though), is easier to store and handle, but does not mix in the diet well since it is dry. Low amounts work great though and is generally fed a protein supplement.

The last comment is that you may need to add calcium (limestone is the best, cheapest source) if you feed low forage diets as grains and distillers are very low in calcium. You will certainly not need phosphorus, since distillers contains large amounts, which is good as mineral P is very expensive. The only considerations are whether you will use a supplement and provide Vitamins A and E, trace minerals (as a package at a very low rate), and any ionophores such as rumensin or bovatec (or others) to help with efficiency. If so, you will need to get those in a supplement, but again, be sure there is no phosphorus if you are using distillers and some calcium depending on how much forage you are feeding.

Assuming your alfalfa is worth something if you sold it, I would minimize alfalfa, maximize straw, and use WDGS (all based on assumed prices). But again, 30 to 40% straw may be the maximum to get the gains you want, but we have backgrounded calves on 50% wet distillers grain and 50% straw and had good success (with a supplement like I mentioned).

Another option for you to explore is purchasing WDGS in the summer and storing it with low quality forage (straw) in a bunker. There is a manual available on this topic under the "byproduct feeds" tab at the beef website.