I believe the calculation of the Ca:Ph by simply adding the two sides of the ratio then dividing by the total number of foods, as many folks currently are doing, gives an inaccurate and sometimes misleading calculation.
The AMOUNTS of calcium and phosphorus in each food selected are DIFFERENT. Just because you use an equal amount of two or three foods, adding the ratios and dividing does not work. It is necessary to add the Calcium and Phosphorus amounts in mg and then divide the totals to reach an accurate ratio.
Food “A” has 100 mg Ca and 50 mg P has a 2:1 ratio
Food “B” has 240 mg Ca and 120 mg P also has a 2:1 ratio
Now Food “C” has 100 mg Ca and 150 mg P so it has only a 0.66:1 ratio
Using the ratio only method adding Food “C” to a food with a 2:1 ratio 0.66 + 2 = 2.66 divided by 2 results in a 1.3:1 ratio.
Using a calculation based on mgs -
Food “C” with 100 mg Ca and 150 mg P combined with
Food “A” with 100 mg Ca and 50 mg P
Results in a total of 200 mg Ca and 200 mg P for a ratio of 1:1.
Next combine -
Food “C” with 100 mg Ca and 150 mg P with
Food “B” with 240 mg Ca and 120 mg P
Results in a total of 340 mg Ca and 270 P and a ratio of 1.2:1
Different food combinations - even if you have they have same two ratios to begin with can have a different RATIO when combined and calculated based on the amount of Ca and P contained in them.
Using a more specific example would be “mixed vegetables” assuming equal amounts of each vegetable in the mixture.
Corn has a ratio of 0.02:1 - 1 TBS contains 0.19 mg Ca and 8.57 mg P
Peas have a ratio of 0.2:1 - 1 TBS contains 2.27 mg Ca and 9.79 mg P
Carrots have a ratio of 0.9:1 - 1 TBS contains 2.64 mg Ca and 2.8 mg P
Green Beans have a ratio of 1:1 - 1 TBS contains 2.54 mg Ca and 2.61 mg P
The total - ratio addition method is 0.02 + 0.2 + 0.9 + 1 = 2.12 / 4 = 0.53:1 ratioCalculating using mgs Ca is 0.19 + 2.27 + 2.64 + 2.54 = 7.64
P is 8.57 + 9.79 + 2.8 + 2.61 = 23.77
7.64 / 23.77 results in a 0.32:1 ratio
The USDA Nutritional Database gives the ratio for “mixed vegetables” as 0.4:1 based on the Calcium and Phosphorus amounts in mg.
Now some examples of adding Fruits to these mixed vegetables (assume you are feeding 4 gliders the above combination of vegetables totaling 4 TBS.
Cantaloupe has a ratio of 0.6:1 - 4 TBS contains 4.87 mg Ca and 7.25 mg P
plus the mixed vegetables - 4 TBS contains 7.64 mg Ca and 23.77 mg P
Total for 12.51 mg Ca and 31.02 mg P for a ratio of 0.4:1
Ratio only calculation for equal amounts of Cantaloupe (0.6:1) and the combined mixed vegetables (0.53:1) is 0.6 + 0.53 = 1.13 / 2 for a ratio of .56:1Papaya has a ratio of 4.8:1 - 4 TBS contains 8.4 mg Ca and 1.75 mg P
plus the mixed vegetables - 4 TBS contains 7.64 mg Ca and 23.77 mg P
Total for 16.04 mg Ca and 25.52 mg P for a ratio of 0.63:1
Ratio only calculation for equal amounts of Papaya (4.8:1) and the combined mixed vegetables (0.53:1) is 4.58 + 0.53 = 5.11 / 2 for a ratio of 5.1:1
HERE YOU CAN SEE THE PROBLEM WITH RATIO ADDITION CALCULATIONS
The ratio for Papaya is very high due to its very small amount of Phosphorus but when combined with the mixed vegetables - it brings only slightly more calcium in mg than the total for the mixed vegetables and the extremely high amount of phosphorus in the mixed vegetables over rides the high ratio in the papaya when calculated using the mg amounts in the total combination.
OK, now you folks are scratching your heads, or have already run away screaming “I don’t do math!” or “Now I am totally confused!” - I do not like to do the math every time either so I spent MONTHS developing a calculator to do it for me. My diet
Calculator - (an Excel spreadsheet) is located on my web page Gliderkids.com. It also includes the recognized glider diets
because it is not only the fruits and vegetables that must be considered for the ratios - the main diet
must be calculated also to get the overall ratio of food you are choosing for your gliders.
I have made every effort to make the calculations as accurate as possible. I have use the data from the USDA nutrition database online for each item. I chose to use the 100 gm portion values then calculated the wt in gms for 1 cup (using the USDA Nation Nutrient Database values) then set the calculation for TBS volume, as that is usually the measurement used for a single glider portion. As with any measurements of foods - there will be variations. A sliced apple and the same apple chopped would occupy different space when placed in a cup - but their gram weight would be the same. I do not think any of us weigh each portion fed to our gliders and in many cases we eyeball the 1 tbs volume for most fruits and veggies. The calculator is a tool to do the math based on gm/volume to give a best estimate of the nutrients we offer our gliders.
The calculator adds the calcium and phosphorus in mg then divides the total mg of each to give the combined ratio.
Of course we have no control over which glider eats their veggies or if one of the colony refuses to eat a particular item offered each night. We can only provide what we feel is a well planned diet
and hope each glider chooses to eat the right amounts.
To use the diet
Calculator (Excel Spreadsheet) you enter the amount of your selected recognized diet
(BML, HPW etc.) that you are feeding in TBS (or a fraction, 1 tsp = .333 TBS) then enter the amount of the fruit and vegetables you are offering with the diet
. At the top of the spread sheet the total Calcium, Phosphorus, the ratio, protein, sugar, fat, and fiber amounts for the total feeding will be calculated for you.
I have the spread sheet set to calculate by gm weight per 1 cup (USDA data base values) which is converted to gms per TBS (or fraction) based on 16 TBS per cup. By setting the calculations using wt/vol it calculates out to give the nutritional values in gms based on the volume used.It is important to look at the AMOUNT of Calcium and Phosphorus in the volume of food being fed not just the RATIO. It is also important to consider the main part of the diet (BML, HPW etc) as well as the fruits & vegetables
NOTE: I have a concern about using the "Mixed Vegetable" commercial combinations - if you read the label most say Corn, Peas, Carrots, Green Beans. Using standard regulations for listing ingredients this means there is MORE Corn than Peas and more Peas than Carrots and Green Beans (the best ratio of the bunch) is the smallest volume in the ingredients. If you divide out the vegetables in one of these packages and measure each vegetable there is likely to be quite a difference in the amount of each in the combination as well as variation Brand to Brand. It cannot be assumed that a serving will contain equal amounts of each vegetable as calculated above. In my diet
Calculator, I used the Nutrition data's amounts for mixed vegetables (RATIO = 0.4:1) but I expect an actual measurement for each item would give a lower ratio due to the amount of corn and peas in the mix.