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Discussion Starter #1
So, it turns out I find dog food fascinating, so I've started to do a bit of research on cost/lb, cost/serving, calorie content of recommended servings, etc. I'm taking all of my data (aside from price) from the manufacturer's website. I'm seeing some weird trends in my numbers that don't quite line up with what I've been reading on DF, so I was wondering.... how accurate are kcal/cup and kcal/kg, serving sizes, etc. that are posted on company websites? I'm looking at foods from companies from a wide-range of price and quality levels (~77 different foods, mostly manufactured in NA).

I don't have any training in nutrition so I'm hoping someone else can give me an idea, at least, of whether the numbers that companies post on their websites are close to accurate or what kind of things might affect their accuracy.

If you're interested, what I have so far is here.
 

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Wow, great chart!! I don't have answers for you but I think this is an excellent project.

Why are there multiple columns for Bag Size, Cost, etc? For different varieties or different prices? Where are you getting info about prices from? Prices can really vary.
 

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Discussion Starter #3 (Edited)
Thanks! I'm going to clean it up a lot once I'm finished collecting all the data.

The multiple columns are for different retailers. I wanted to compare prices between Canadian retailers and American ones kind of, just to see what was available, and how big the price difference was. I'm also trying to make it most globally applicable, and I figured the best way to do that was to only do foods that are available in Canada and the US, because that increases the likelihood that they're available outside of NA (that was my reasoning, anyway).

If there are any foods anyone would like me to add, just let me know. :)
 

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What are the wierd trends you're confused about?
Just looking at the charts you have, you pretty much only have categories for kcal/cup and price.

First I'd trust kcal/kg more than kcal/cup since it's a more consistent measure. The total mass in 1 cup can vary depending on kibble size or density or what not.

The values they report I'm sure have some margin or error but should be accurate enough. However kcal alone doesn't necessarily mean anything in regards to food quality. Fat, carbs, protein all get metabolized into energy which is what the calories is measuring. Carbohydrates and proteins have comparable calories. Fat has more than double the caloric content of protein or carbs. So having data on the guaranteed analysis would be good too.

Also I'm not sure if the guaranteed analysis is by calories but I think it's by mass. If it's percent mass, then it is interesting to compare to the caloric content of the food. Since the amount you feed is based on kcals, it would be more interesting to convert the percentages to something like g/kcal. So something like 40% protein with 4000 kcal/kg would be (0.40kg/kg) / (4000 kcal/kg) = 0.1 g/kcal. That means a food that's 30% protein but only 3000 kcal/cup would be feeding the same amount of protein per serving strictly speaking from the numbers.
 

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Great project!

The numbers are supposed to be accurate but they are pretty much on their honor. FDA gets on pet food companies if something is or isn't there but not sure about whether the % is as stated. Bet you have noticed that some companies publish the absolute amount and some have minimums and maximums instead. The analyzed amount done back when the kibble was designed probably isn't exactly the same as the actual bag you bought today. Good companies work hard to make them the same but ingredients are going to differ from batch to batch.

How about cost per 1000 calories or calories per bag? I did that to compare Max's raw diet to what he had been getting in kibble and it turned out to be about the same per day. I was surprised but I think his kibble was on the low calorie side!
 

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Discussion Starter #7
I realize this chart is not perfect, and the information should be taken with a grain of salt. But when you work in research, you learn very quickly that almost NO research is perfect.... so I'm going with it.

The energy requirements were from this website and the equation in the top left corner, which I got from another website which I can't find at the moment because I found it through a series of websites on a different computer. The example on this page is the same formula I used (MER). Briefly: weight in lbs convered to kg: 50/2.2= 22.74kg^0.75=10.41*132 = 1373.67 cal/day. A quick calculation for an "Active" dog of the same weight using the Waltham equation is about 1300 cal/day.

I'm using the kcal/kg and the kcal/cup to figure out how many cups per pound of each food in order to compare them. Most websites, especially for the higher end foods, are pretty good about stating how much a cup of each food weights (usually around 3.4-3.8oz). When this measure is missing, I've been using kcal/kg/kcal/cup to figure out the number of cups per kg (which is then converted by dividing by 2.2; 2.2 lbs/kg). The kcal/cup and lbs/serving measures are more for cost (i.e. cost per serving, since I have no way to know how many cups are in 30lbs of food because all the foods have different densities based on ingredients and kibble size). Since most foods that are manufactured in the US don't indicate serving size in grams or ounces, cups is all I have to go by. Where serving size is offered in grams I have been using it to find the weight (in lbs) of the serving. I may add an asterix to that. So far, the range of cups/lb is ~3.6-4.9.

I haven't been touching the guaranteed analysis because I just don't know enough about it - do you think its something worth adding? The cost per 1000 calories is a good idea, since it gives a more accurate picture of how much it would cost to feed your specific dog. Plus its easy. :)

One of the weird trends that I see is that the "Serving size" by calories of a lot of the foods seems to be LESS than the recommended amount for an average 50lb dog (which when calculated based on the formula I looked up is ~1350cal/day). However some websites have also said a 50lb dog would should get ~1150 cals/day. Anyway, based on the kcals/cup and the recommended serving size in cups, the range of serving sizes in kcal is HUGE. Like, 600-1300 kcal/day. This is confusing to me because everyone on the forum keeps saying that the recommended feeding guidelines for most foods indicate feeding more than the dog actually needs....? Maybe I'm doing my energy requirements wrong? Something else screwing me up is some foods recommend an amount for active dogs and non-active dogs, but not all foods do - in this case I've been averaging the recommended serving.

I also found this website this morning because apparently I wasn't smart enough to google it yesterday. From reading it, sounds like calories are calculated from guaranteed analysis, not the other way around, i.e. they calculate the % protein, fat, carbs, and use those numbers to calculate the kcal/kg.
 

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Yeah I have no clue how they determine their recommended serving sizes but if I followed them for Jubel he'd be overweight for sure. He gets just under two cups a day and they recommend just over three last time I checked.

Edit: he's on 4health salmon & potato right now 327 kcal/cup so he's getting about 950 kcal a day. 4.5 years old, 49#, and active.
 

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Thanks for the links. According to them, Katie is eating about two-thirds the amount she should. She's about 44lbs, average activity (I guess), and eats about 760 kcals/day (1 3/4 cups) of Earthborn Coastal Catch. That's on the lower end of the recommended feeding amounts on the package (1 3/4-2 1/4 cups for 35-50lbs), but almost 340 kcals less than the 1100 recommended by the chart on the first page you linked.

The calorie chart recommendation seems high; I weigh about 110lbs and barely eat 1100 kcal a day. Out of curiosity, how does a dog's energy needs compare to a human's?
 

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I also found this website this morning because apparently I wasn't smart enough to google it yesterday. From reading it, sounds like calories are calculated from guaranteed analysis, not the other way around, i.e. they calculate the % protein, fat, carbs, and use those numbers to calculate the kcal/kg.
That makes sense. So the % values should be mass DMB. Whether you include guaranteed analysis is of course up to you. I just think it would be interesting to have the of main ones like protein and fat as g/kcal rather than a percentage. It would reflect what foods are actually high protein rather than just low filler though I suspect the correlation stays relatively the same.

I'm not really surprised that the recommended values can be all over the place. It just one of those things that has huge ranges to begin with cause it's too dependent on the individual. Weight isn't nearly the only thing that matters. Age, activity level, breed, etc can all affect metabolism and what the daily caloric intake should be. I eat about 4000 kcal per day while the "recommended" amount for me would be more like 2500. My dog eats closer to half the calculated amount for his weight and "low activity level." In the end people are going to feed the amount that works for their dog so I would just use a set number of kcals as the standard daily serving for your chart. That should keep things more consistent.

Actually since you're doing an xcel spreadsheet, it would be cool if you actually just had a place where you can set the daily kcal intake. You can even have a box to enter weight to calculate the typical daily kcal value. Then for the rest of the sheet, simply reference that value to calculate out stuff like cost per serving, servings per bag, g food per serving, g protein per serving, g fat per serving, etc. It'll all just be the same equations for every food except scaled by a different constant so it shouldn't be too hard to actually implement and it makes the chart adaptable for different dogs.

Just a thought :)
 

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Discussion Starter #11 (Edited)
I keep coming across more and more interesting article. This one helps to explain why the serving sizes are so off, and why many dogs actually use "less" calories than is suggested by the bag. Probably its a difference between whether the standard or modified equations are used to do nutrition calculations - which we have no way to figure out.

Zhaor - that is a great idea. Servings by calories makes much more sense than servings by cups, considering how much that is varying. I might still include the cups/serving (but derived from the required caloric intake) in the calculations, especially if this ends up becoming an actual interactive tool instead of just a general reference. Unfortunately the most up-to-date version is only on my work computer - I had to rush out of the office because FI was held up at work and he usually lets the dog out to pee, etc. in the afternoon.
 

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AAFCO uses a different caloric estimation.....hmm that's interesting.

It did remind me of something. I think the NRC reports that it's about a 75-90% absorption ratio for commercial dog food. I don't know if it is but it may be taken into consideration when they calculate recommended values. Lets take their example of purina 866 kcals recommended vs 674 for NRC. So the NRC is about 77.8% of the purina recommendation which may actually be reasonable considering purina is probably on the lower end in terms of ease of absorption.

I would wonder if the AAFCO modified calculations are to account for absorption as well.
 

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Discussion Starter #13
I think the NRC reports that it's about a 75-90% absorption ratio for commercial dog food.
I found a book by the NRC, "The Nutritional Requirements of Dogs", from 1974. Just wondering if that's where this came from?

Not disputing it, I just want to read whatever source those numbers came from because apparently my new hobby is researching dog food, lol.
 

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I think I read it in the 2006 edition but yeah, same book more or less. The 2006 one mostly just combine cats and dogs into one book I think. A lot of the studies it talks about are still from 1970-80s.
 

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Discussion Starter #15
The calorie chart recommendation seems high; I weigh about 110lbs and barely eat 1100 kcal a day. Out of curiosity, how does a dog's energy needs compare to a human's?
Just to clear up some confusion about the word "calories" first - I am using Calories (with a big C) and kcal interchangeably, as they are in the US/Canada. A calorie is a measure of energy contained in chemical bonds, etc. and kcal = 1000 calories (With a small c). When referring to nutrition labels, a "calorie" is the same as a kcal. Its supposed to be capitalized, but it generally isn't.

Now, regarding human vs. dog energy consumption.... To begin with, the human body generally does a very poor job of functioning on less than 1200-1400 calories per day. This is essentially the number of calories required to maintain a healthy body weight without any external movement (i.e. in a coma and breathing on your own). This number (like everything) varies a little bit from person to person, based on height and weight. There's some extensive math behind the numbers. "Resting energy expenditure is directly related to the size of the BCM and is independent of age and sex.... The body cell mass (BCM), is the total mass of metabolically active cells, and is therefore that component of body composition which is responsible for all ofthe oxygen consumption, carbon dioxide production, and the work performed by the body."

The accepted average for body weight maintenance assuming normal living (i.e. walking, breathing, eating, talking) for an average woman of average height is ~2000. For men it is ~2500. Again, there is some variance in these numbers (as Zhaor pointed out), and they are more based on activity level because the more active you are and the more muscle mass you have, the more calories you require to maintain them.

Calorie-wise, I'd imagine dogs are relatively similar to people. They have similar biochemistry (in the grand scheme of things). As indicated above, caloric needs are correlated solely with BCM, so probably a dog with the same weight and body-fat percentage (fat cells are not metabolically active) as a person would require about the same number of calories.
 
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