By Harvey Ussery – Anyone with an entry-level working knowledge of electronic spreadsheets can adapt the spreadsheet I designed for assisting with poultry feed formulation. I have reduced the spreadsheet as presented here to its essentials for the sake of simplicity. In actual practice, I have several additional columns (for example, to calculate feed costs as I plug in different weight values for ingredients). You can add more columns as well, populating them with appropriate formulas to calculate whatever values you wish to track (perhaps fats and carbohydrates in addition to protein) when learning what to feed chickens. In this simplified version, however, we will calculate only the percent of protein in the mix, and the amounts of premix and individual ingredients to use as we make up single 25-pound batches.
Note first of all that the ingredients for the poultry feed formulation are divided into “Premix” and “Grind/Whole Portion.” It would be extremely inefficient to measure out the supplements, which are added in relatively small amounts, into the mix when making up individual batches. Therefore, we mix together the premix ingredients for, say, 500 pounds, then weigh out into individual plastic bags the appropriate amount for a 25-pound batch, then store the bags until needed.
The actual list of ingredients on your poultry feed formulation spreadsheet will likely differ from that of mine, of course. I like to note in the list, in parentheses, the percent protein of each ingredient. (I do this just as a reminder to myself — it has nothing to do with the calculations of the formulas.) Note that I’ve also added a reminder to myself never to add more than 2-1/2 pounds of crab meal in any formulation (since its selenium, a necessary trace mineral, can actually have a toxic effect in large amounts).
I have used colored backgrounds to highlight the two key types of cells in the poultry feed formulation spreadsheet. (The colored shading is for illustration only — there is no need to use colored backgrounds in your spreadsheet.) Cells with a light yellow background are cells into which you will enter data. That is, you will enter weights for individual ingredients you are considering. Cells with a light green background are cells into which you will enter formulas.
In the second poultry feed formulation spreadsheet, I have printed the formulas to be entered into the requisite cells. In an actual electronic spreadsheet, of course, the formula itself is not displayed in the cell-only the numerical result of the formula’s calculation is displayed. Please note that the exact syntax for formulas in your spreadsheet program may differ from that in the formulas given here. (I use Gnumeric, an open source spreadsheet program.) Use the Help section of your spreadsheet program to determine the exact syntax required-otherwise, your formulas will not function.
The first formula to enter is in Cell B18, which simply sums all the values in the cells above it [=sum(B3:B16)], to give a total of all the individual weights you enter for the ingredients. (Note that as I enter values in Column B, I always ensure that this total comes out to 100 pounds, since that makes it easier to think in terms of percentages.)
Next, we add formulas in Column C to calculate the amount of protein added by each ingredient, based on the weight of the ingredient added multiplied by its percent protein. Thus in Cell C6 (for fish meal), the formula is =B6*0.6-that is, the weight of fish meal entered in Cell B6 multiplied by 60 percent protein.
Having added a formula for every ingredient contributing protein (and note that there are no formulas entered for ingredients like kelp meal or Nutri-Balancer which do not), we now add a formula in Cell C18 to total all the individual amounts of protein calculated by those formulas, then divide by 100, to express the percent protein in the mix as a decimal: =sum(C3:C16)/100
Download Poultry Feed Formulation Spreadsheets Here
You may download the poultry feed formulation spreadsheet calculator described in this article as a tool for designing your own feed mixes. Select the appropriate version for your particular needs:
- If you use Excel, the spreadsheet program in Microsoft’s Office suite, click on this link to download the spreadsheet.
- Those who prefer open source tools will probably have Open Office, the closest open source equivalent to Microsoft Office, in their system. If you use Open Office, click on this link (feed-calculator.ods) to download the spreadsheet. Versions of both Open Office and Microsoft Office are available for use on Macintosh systems. Users of less common spreadsheet programs, such as the open source Gnumeric, are doubtless savvy enough to download the feed calculator as either an Excel or an Open Office file, and convert to their own native format.
- Whichever version you choose to download, also click on this link (feed-calculator-instructions.txt) for a plain text file that describes the use of the spreadsheet calculator.
Once you have downloaded the appropriate version of the calculator spreadsheet, you may rename it anything you wish, and file it in any convenient place.
At this point, we are able to enter experimental values in Column B for any or all the ingredients, and the formulas entered thus far will “automagically” recalculate the amount of protein contributed by individual ingredients, and the percent protein for the mix. Now we add formulas in Column D to divide the amounts of all the ingredients figured on a hundredweight basis by four, to calculate the amounts of each to use when making up a 25-pound batch, a more practical amount to work with if mixing by hand.
The first formula entered in Column D (Cell D10) is a bit special, in that it first totals the amounts of ingredients per hundredweight to make the premix, then divides by four, in order to define the amount of premix to measure out per 25-pound batch, that is: =sum(B3:B9)/4
The other formulas in Column D are more straightforward. They simply divide the amount of the ingredient entered in Column B by four, to define the amount of that ingredient to measure out when making a 25-pound batch of feed. Thus in Cell D12, the amount of alfalfa meal to use per 25-pound batch is: =B12/4
Finally (basically as a check), we add a formula in Cell D18 to total the entries in Column D: =sum(D10:D16) (If we have a total in B18 of 100 pounds, the amount returned in D18 will always be 25 pounds.)
To see how the poultry feed formulation spreadsheet works, let’s imagine we want to formulate a winter layer feed with a target protein value of 15 percent. We simply insert reasonable values for the individual ingredients (for a total of 100 pounds at Cell B18), and the spreadsheet recalculates the percent protein for the total mix at Cell C18, and the amounts of each ingredient needed to make a 25-pound batch. (Note that we can make any amount of premix at a time we wish, but Cell D10 tells us how much premix to weigh out and set aside for 25-pound batches.)
I said we enter “reasonable” amounts for ingredients. I cannot tell you what amounts to use in your own poultry feed formulation – you still have a lot of homework to do on your own in formulating your feeds, and learning how to take into account how much to feed chickens. For example, our amount for Nutri-Balancer will be based on Fertrell’s recommendation for this supplement, and on the fact that our winter flock is confined to the poultry house on deep organic litter. In this case, two pounds of Nutri-Balancer per hundredweight is appropriate.
In the case of our winter layer feed, we enter the values shown in “Sample winter layer mix.” Note how, as we enter values in Column B, the sheet automatically recalculates new values in Columns C and D.
Suppose we want to formulate a starter feed for heritage chicken breeds on pasture with mother hens. (See “Sample mix for chicks on pasture.”) Since growing chicks do not need nearly as much calcium as adult layers, we greatly reduce the aragonite. We boost the fish meal to just over 5 percent of the total (which is the maximum we want to add for this ingredient), since growing chicks have higher protein needs than adult layers. Since the chicks will be eating plenty of fresh green grass, clovers, and weeds, we omit the alfalfa meal entirely. Note that the percent protein for this mix is 17.6 percent, well below the 22 percent that would be recommended for fast-growing meat hybrids such as Cornish Cross. However, heritage breed chicks have not been bred for such high-protein input. Also, the mother hens will certainly be supplying additional protein to the chicks in the form of insects and worms. Thus a protein percentage that is low by industry standards is perfectly appropriate for this home-mixed feed.
Originally published in 2007 and regularly vetted for accuracy.