Hi Wendy,
For some unexplained technical reason, Aimee was unable to post the following reply to your comment. So, she has asked me to post the following comment on her behalf.
AAFCO requires manufacturers to provide feeding guidelines, but they do not offer any guidance on how to set them. i think this is a problem.
The actual calories/day that individuals may require varies among dogs of the same weight. One method of calculating calories for a dog is to use the equation body weight in Kg to the 3/4 power x 70 = Resting Energy Requirement. To that baseline, a āmultiplierā is applied for different life stages and activity levels. For example, for a typical neutered pet the multiplier is 1.6 and for an intact pet 1.8.
However, once a number is arrived upon, it is accepted that an individualās energy requirement may vary by 50% in either direction. So, for example, for a 35 lbs dog the RER = 557 kcals/day and using a multiplier of 1.6 for a typical neutered pet the MER is 892. Applying the 50% range in either direction gives you a calculated energy range for a 35 lb dog as 446-1338, a large range. And those are guidelines, so an individual pet may fall outside of that range.
In my experience, I note a trend that the more expensive a food is on a caloric basis, meaning how much it costs for say 100 kcals, the lower the suggested number of calories to feed each day WITH a general exception of companies that have veterinary nutritionists on staff full time.
This can be very problematic. AAFCO sets nutrient levels assuming an āaverageā caloric intake. When feeding requirements are set lower than an expected average, as some companies appear to be doing, nutrient intake may not be met. Unfortunately, it appears this very thing can occur. For example, the feeding guidelines for a particular freeze dried food bar is 1 bar/25 lbs. ~cost/100 kcals is ~ $1.70. They report 297 kcals for one of their bars. RER for a 25 lb dog is calculated at 431kcals and a MER range for a typical neutered dog 345-1035kcals/day. So these feeding guideline fall below the calculated range. (For comparison Purina ONE kibble cost is ~ 6 cents/100 kcals and recommended intake for a 25 lb dog ~ 640 kcals)
The National Research Council reports minimum nutrient requirements, along with adequate and recommended nutrient intake and safe upper limit on a metabolic weight basis Using the companyās provided data, and feeding 1 bar a day as per the feeding guidelines, the nutrients fed in some cases fall short of NRC min values. This to me is alarming, especially since the company is apparently owned by a PhD animal nutritionist.
My thought is that when it is known how many calories a day a dog needs to maintain body condition then that is the number of calories a day that should be feed of the new food adjust from that number to maintain body condition.
This is probably a longer answer than you were looking for but I hope it answers your questions
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