Are Large Bags of Dry Dog Food Cheaper than Small Bags?

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Dry food is by far the most popular form of pet food sold. I saw some data on petfoodindustry.com that said that dry food makes up almost 75% of all pet food sales in the world. There are several reasons for this. First of all, dry food is convenient and doesn’t require refrigeration. Second, dry food is usually cheaper than wet (or other forms) of pet food. Many pet owners like to reduce the cost of their dry pet food even further, by purchasing the largest bag possible. These large bags usually offer the lowest unit pricing (e.g. cost per lb.) and thus, they are viewed by most consumers as being the best value. I am here to tell you that this is not necessarily true.
 
large bags of dry dog food
 
There is little doubt that the cost per pound of food will be less for larger bags than for smaller bags of pet food. However, the cost per lb. of quality, useable nutrition is likely higher for the larger bags in all but extreme cases. The reason for this is because for most pets, large bags of pet food will last much longer than the food remains fresh. The potency of the vitamins and nutrients will become diminished every day that the bag is opened and thus, the real value of the food will deteriorate and your pet’s body will be unable to fully utilize the food and extract its intended nutrition in the same way that it would when that bag was first opened.
 

Shelf Life and Expiration Dates of Pet Food

You are probably thinking I am crazy. After all, that large bag of pet food has an expiration date on it that is many months (if not years, egad!) in the future. Thus, the food should be fine to use, right? Not so fast. The shelf life of a bag of food, as estimated by the expiration date on the bag, is calculated assuming that the package is unopened and sealed as it was when it shipped from the food manufacturer. Unfortunately, once you open the bag, the oxidation process starts immediately and the expiration date is, for all intents and purposes, meaningless.
 
Opened bags of pet food will immediately begin to oxidize. Oxidation causes a breakdown in nutrients and vitamin potency. The food gets ‘rusty’ and loses its nutritional punch, so to speak. Over time, the food that you paid good money for, and might once have been nutritious, becomes the equivalent of cardboard- lacking the essentials that a dog’s body needs.
 
Because pet foods are required to contain minimum levels of fats, these fats can turn rancid pretty quickly as well. Further damage can occur as bacteria and other toxins appear. Not only does the nutritional potency decline rapidly once the bag is opened, but you run a (small) risk of introducing toxicity into your pet’s body by serving them ‘older’ food.
 
There are several veterinarians and pet nutritionists that recommend choosing smaller bags of dry food based on the fact that the food will deteriorate once the bag is opened. How long does an opened bag remain fresh? According to Steve Brown, a thought leader in canine ancestral diets, an opened bag of food will last about a week. Dr. Ava Frick, a veterinarian and pet nutritionist suggests 5-6 weeks max. My recommendation is to plan on having an opened bag for 2 or 3 weeks maximum. And storing the food in closed containers, like Tupperware or even those pet food bins with the lids, will not markedly slow the deterioration process.
 
Choosing the right size bag of food for your pet depends on the size of your pet and how much they are fed. A 10 lb. bag of food could last a small dog or cat 4-5 months or more, while it might only last a large dog a few weeks. In the future, I will share how to estimate the optimal bag size for a given pet and food. For now, please rethink the strategy of buying the larger bags to save money and start using smaller bags instead. This will ensure that your pet is getting fresher food that their bodies can actually utilize for their nutritional needs while also lowering the risk of unwittingly serving them rancid food that might contain harmful toxins.
 

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19 Comments

  1. Excellent post! I’ve actually been concerned about this a lot lately as we are on a budget and have been buying bigger bags. What are your thoughts on repackaging the food and vacuum sealing it in smaller amounts?
    Lauren Miller (ZoePhee) recently posted…Unhappy Camper! Bad Shot Clinic Experience!My Profile

  2. I may need to re-think my buying habits You make a convincing case.
    jan recently posted…Two unlikely California shelter Chihuahuas find loving homes thanks to clever marketingMy Profile

  3. Easy loves this post, he never eats the food from the big bags… I had no clue why, but now I know the pup is smarter than me :o)
    easy rider recently posted…easyblog MISCHIEF MOANDAY WITH A SMILEMy Profile

  4. When we fed Kibble, we would always buy the largest bag available, usually in the 20-30 lb range. However, it never lasted any longer than 2 weeks since it fed our two medium to large sized dogs 😉 We stopped pouring the kibble into a container when I came across an article suggesting that dry dog food should remain in its original packaging. We loved those brands that came with ziplock closures on the bags of kibble (e.g. Annamaet, Earthborn) which we then stored in an airtight storage container in our laundry room.
    Barbara Rivers recently posted…August Pet Events ~ Assistance Dogs, Check the Chip Day, National Dog DayMy Profile

  5. I used to buy the large bags but after smelling mold in the bottom of a half-empty bag of Wellness Core last year, I stopped. Even with the two big girls and Ducky, it would last longer than 2-3 weeks; but that moldy smell inside the bag just about blew my mind. The Wellness folks were very nice about it. Sent me coupons to cover the cost of about 2-3 smaller bags along with a letter (and at least two emails) profusely apologizing for the situation. But now I buy smaller bags. It might cost a little more up front, but at least I use it before it has a chance to go bad.
    Callie, Shadow, and Ducky’s Mom recently posted…What Would Mom Want Me To Do?My Profile

  6. Since we all eat the same food, the big bag lasts 3 weeks at most which works out well and it is stored in a dark sealed container. We are amazed at how many people don’t even close a bag after opening it and just put it in a cupboard open. We tell them it won’t stay fresh and they are always shocked, so we say how would you like a bag of chips that was sitting open for a week or more not sealed and then they start to get it. No one wants old food and old food isn’t good either.
    Emma recently posted…Why You Should Give The Gift Of NipMy Profile

  7. With two large breed pups eating the same food, even the largest bag doesn’t last long. Good info to know and glad to hear I’m following guidelines, albeit completely by accident.

  8. That is something I never really thought about much. With three dogs on the same food, I think our large bags last about 2 weeks, maybe 3 at the most. It’s something I’ll pay closer attention to.
    We used to buy 10 lb bags for the cats too, but after Conrad died we were smart enough to go to a smaller bag for just Sam…but I’ll have to see how long that bag actually lasts since she is now eating more wet food.
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  9. Yet another reason to skip the dry food. If you do buy it, be one of those people who paw through the bags to get the oldest expiration date.
    Anne recently posted…Do Cats Get Cavities?My Profile

  10. With three dogs we go through a big bag pretty quick! 🙂
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  11. Great post! With 3 large dogs all on different food for different reasons, I tend to buy the smaller bags. I have never checked the exp date, now I will! 🙂
    Golden Daily Scoop recently posted…Protecting Your Dog’s Paws NaturallyMy Profile

  12. It seems to me that larger bags of dog food, much like large quantities of human food go stale if nothing else. I know I’d hate eating stale cereal and the like staples, so I make it the rule to get Sam’s food in smaller quantities and keep it in an airtight container. I want it to be as fresh and nutritious as possible. Thanks for shedding light on this issue.

  13. I’m finding Honey’s food a tough issue for the boat. She’s done so well on Fresh Pet for so long and I can’t argue with results. But it’s not going to be possible to buy or keep refrigerated food once we move aboard.

    The vacuum sealing comment is a good idea.

    I know THK dehydrated food has a fairly short expiration date as well. And while I love the food, Honey tires of it quickly. Looking for that right combination of fresh and processed food that we can get shipped to a wide variety of places.

    Makes my head hurt. And it would be so much easier if Honey were a vegetarian. Then she could eat with us more often.
    Pamela recently posted…Why Should Cats Have All The Fun?My Profile

  14. Great post! We used to buy big bags but realized storing the half open bag did not make sense for our pups- smaller bags it is! The boys get to walk with us to many of the pet stores- so it\’s an adventure they get to have more often now 🙂

  15. This is a great read and something I learned about only recently. I figured keeping the bag in my expensive, sealed Container Store bin was helping it to stay fresh! Fortunately, I never buy more than a 5lb bag of kibble for The Ginger Sisters since they are on a rotational diet and I like to switch brands every bag. They eat The Honest Kitchen for breakfast, so it usually takes 3-4 weeks for them to finish a small bag of kibble.
    Lara Elizabeth recently posted…Open Farm Makes This Vegetarian Feel Good About Feeding Her DogsMy Profile

  16. Thank you so much for this; I’ve always wondered how long Laika’s food is actually staying fresh. I definitely notice how much more gung-ho she is when we open a new bad vs feeding from one that’s a few weeks old. The cost issue is interesting as well, I’m always trying to keep an eye on the average price – and luckily for us it’s usually cheaper to buy locally than it is to order online.
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  17. Interesting, lucky my bag of food lasts less than a month shorter now that the little piranhas are eating it
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