Its More Than Corn: Feed Formulations
So far I have discussed what influences the nutrient requirements for animals and have provided some basic information regarding feed values for several popular feedstuffs. In this post, I will try to explain in simple terms, how a ration is formulated, after knowing what the requirements are.
When feeding concentrates, it is often necessary to blend two or more feeds together into a mixture that contains the required nutrients for the specific animal.
- Draw a square.
- Write the % crude protein for the final ration in the middle of the square.
- Write your grain, with its % crude protein on the upper left corner.
- Write your protein supplement, with its % crude protein on the lower left corner.
- Subtract the %CP of your grain, from the %CP of the ration and write on the lower right corner. This will tell you the parts of supplement necessary.
- Subtract the %CP of the ration, from the %CP of the supplement and write on the top right corner. This will tell you the parts of grain necessary.
- Add the two results together and use this as the denominator to determine the percentages of each on a Cwt basis
From the square above:
- Barley is 11%CP, was subtracted from 25.5%CP for the ration, to result in 14.5 parts of soybean meal.
- Soybean meal is 44%CP and the 25.5%CP for the ration was subtracted from it to result in 18.5 parts of barley.
- We then add the parts together to get 33 total parts to the ration.
- We then take 18.5 parts barley / 33 total parts to get 56% x 2000 lbs = 1121 lbs of barley for a ton ration.
- Then, we take 14.5 parts SBM / 33 total parts to get 44% x 2000 lbs = 880 lbs of SB< for a ton ration.
- While very simplistic, this would yield a ration, balanced for 25.5% CP.
If you wanted to use the square to formulate for three feeds (two grains + protein supplement), utilizing two grains, you first need to calculate the average %CP for the two grains. Let’s say you wanted to use oats and corn, in a 1:2 ratio. You would take 11.8%CP for oats x 1 and get 11.8. Then take 9.6 %CP for corn x 2 and get 19.2. Add 11.8 + 19.2 to yield 31.0 and divide it by the total parts / 3 and the result is a 10.33%CP for a mix of oats and corn at a ratio of 1:2. Use the 10.33% CP for the grain and 44%CP for the SBM and run the square as before. Your final result would be a ration that contained 755.2 lbs of corn, 377.6 lbs of oats and 67.2 pounds of SBM for a ton ration.
While the square method can be used for calculating the amounts of two to three components, it is not practical when more are utilized due to availability and/or cost.
x = lb corn + lb oats per 100 lb mix
y = lb supplement per 100 lb mix
x + y = 100 lb of mix
0.1033x + 0.4000y = 12.00 (lb protein/100 lb mix)
-0.1033x + 0.1033y = 10.33
0.2967y = 1.67
y = 1.67/0.2967 = 5.6% supplement in mix
x = 100 – 5.6 = 94.4% corn and oats 2:1 in mix
What value should be used first when formulating a ration?
Energy requirements should be given priority. If energy needs to be altered, substituting roughage for concentrate or vice versa can easily be done. Once the energy has been balanced, the protein level is typically next for consideration. The protein level is adjusted by substituting a high protein feed for an equal amount of low protein feed or vice versa. After energy and protein requirements have been met, calcium and phosphorus levels are next. Since most economical sources of phosphorus also contain calcium, it is usually considered first.
What about cost?
Throughout the entire process of formulating the ration, the cost of the available feedstuffs is considered. Costs of feedstuff are in continual flux. Regional location plays a major role in determining the cost of available feeds. Byproducts are often used to substitute for more expensive traditional feeds. For example, in California, depending on where you live, you might feed cull kiwis, tomato pumice, almond hulls, cull carrots, bakery products, or brewery remnants.
How is this all put together when estimating feed requirements?
Let’s consider that a rancher has 100 calves that he would like to grow out before finishing on a feedlot for their last 90 – 120 days. The steers are currently averaging 500 pounds and he would like to get them to 900 pounds, before shipping. This means that average of 400 pounds needs to be put on each steer or a total of 40,000 pounds on the 100 head. He plans to self feed these animals on a ration as follows:
Feedstuff % of Ration
Bermuda grass hay 40.00
Rolled corn 30,00
Rolled barley 20.00
Soybean Meal 44% 9.00
Defluorinated phosphate 0.33
Ground Limestone 0.33
Trace mineralized salt 0.33
Experience has indicated that steers of this age and weight will require over an average period of time approximately 7 pounds of the above ration to gain 1 pound. This means that a total of 280,000 pounds of feed, with the above percentages, will be required for getting the steers to the desired point. We then calculate the needed quantities as follows:
280,000 X .40 = 112,000 pounds of hay (56 tons)
280,000 X .30 = 84,000 pounds of corn (42 tons)
280,000 X .20 = 56,000 pounds of barley (28 tons)
280,000 X .09 = 25,200 pounds of SBM (12.6 tons)
280,000 X .0033 = 933 pounds of phosphate (.5 tons)
280,000 X .0033 = 933 pounds of limestone (.5 tons)
280,000 X .0033 = 933 pounds of salt (.5 tons)
With older steers and with steers carried to heavier weights, the feed requirement per pound of gain will increase to as much as 8 or 9 pounds of feed per pound of gain. Reducing the roughage to concentrates ratio will tend to lower the feed required per pound of gain, whereas increasing the roughage to concentrates will increase the feed required per pound of gain. While decreasing the roughage to decrease pounds fed per pound gain, it is important to not decrease it to a point below 20 percent of the ration, as this will negatively impact activity in the rumen and lead to steers going off feed and perhaps even losing weight and will likely result in health issues.
Stay tuned for part 7, Pasture Talk