Feeding raw & kibble mixed?

Ruby Red · 10-06-2009, 05:08 PM

I have read quite a lot about not mixing raw food and kibble. The argument that has been given is that kibble takes 12 hours to digest and raw meat 5 hours. This doesn’t seem very logical to me as kibble contains partially hydrolysed [broken down] protein which surely needs less digestion than meat [raw or cooked]. Once initial digestion has taken place in the stomach, material is moved into the small intestine and further break down takes place. Whether the origin was raw meat or from kibble is now irrelevant. Also, the body will deal with each food group (polypeptide/protein, fat, carbohydrate) in a different way using different enzymes and each will be digested at a different rate.

It would be very interesting to know where the often quoted figures mentioned above came from. Can anyone give me a reference to an original research paper that contains them? Has anybody ever done any controlled experiments to show that feeding a mix of raw food and kibble is detrimental? I, in fact, did this with my dogs to start off with and I encountered no apparent problems. It seemed to suit my dogs; they had no diarrhoea or any other apparent digestive problems.

Spyglass Sally · 10-06-2009, 05:49 PM

Those are excellent questions. I've tried to keep an eye out for similar type questions as I've read but haven't really come across much. I just did a little looking now and found

This in a Rottweiler forum (the journal link didn't work so I can't verify it):

There was a study done that proved that the stomach emptied of kibble in 900 minutes (+/- 60); canned 420-480 minutes, fresh 240-360 minutes. ( http://journals.cambridge.org/downlo...9390f92ddf4fcd ) If you look at the bottom of page 6 and top of page 7 in the PDF (not the actual numbered pages) you will see references to predominantly liquid meals and predominately meal based foods.

To me that is VERY significant. Raw meat has high levels of bacteria. If is slowed down significantly as it travels through the animals gut by the presence of very slow digesting kibble, the bacteria has time to marry and raise its family. It's colonizing that leads to food-pathogen illness. In humans, there is plenty of time to colonize: looooooong system. Hence the reason humans have a higher likelihood of getting food borne illnesses.
This from Nature's Variety website:

Can I feed both raw and kibble during the same mealtime?

Yes. Even though raw leaves the stomach and is digested more quickly than kibble, it is no different from adding canned food to kibble. In fact, the added moisture from the raw helps to speed the gastric emptying (the stomach will empty when the contents have been liquefied).
Also from NV's site:

If I feed my pet a mixture of Nature’s Variety Raw Frozen Diets and kibble at the same meal, should I be concerned about the different rate of digestion?
It’s important for pet parents to feel comfortable with their feeding process. We believe customers need not be concerned about mixing raw and kibble at the same meal. Raw is like canned food in terms of moisture content and rates of digestion; people routinely combine canned and kibble diets with no digestive upset or stomach emptying issues. There is no scientific evidence that combining kibble and raw food causes the raw foods to be digested at a slower rate. (Remember, when you feed any new food to your pet for the first time, it is best to transition slowly. Mix increasing amounts of your pet’s new food with decreasing amounts of the previous food over a 7 to 14 day period.)

I'll be interested what anyone else finds.

Ron · 10-06-2009, 06:06 PM

i just logged on to ask a similar question

Spyglass Sally · 10-06-2009, 06:36 PM

Found another interesting bit of info here:

Monica Segal explains this myth in her book "Your Dog's Diet, The Truth Behind the Hype".

Dr. D. Twedt DVM, a gastroenterologist at the Colorado State University, did a study to see how long it took for food to clear the stomach. The food he used to conduct the study happened to be kibble. The study was to determine what rate of gastric emptying would classify a dog as having a gastric motility disorder.

His study found that kibble took anywhere from 5 to 15 hours to empty the stomach. He found that the average emptying time was usually 5 - 8 hours and that anything over 10 hours would deem the dog to have a gastric motility disorder.

Some raw-feeding proponents grabbed at the figure that some dogs took 15 hours to empty the stomach of kibble and used this as a reason to promote the evils of kibble. They obviously did not read the whole report or they would have seen that healthy dogs, not suffering from gastric motility disorders, emptied their stomachs of kibble within 5 - 8 hours.

I also was able to locate the "missing link" of the journal article in my first post here. Excerpt from the article:

The types of food used were (1) dried food with 10 % moisture, (2) canned food with 70 % moisture and (3) fresh food (fish) with 75 % moisture. After food ingestion the animals had no access to water or to any other type of liquid.

In group 1, the food remained unchanged in the stomach for 480 to 600 min (mean 534 min) after completion of the meal. After 900 f 60 min the stomach appeared to be completely empty.

In group 2, the food started to enter the duodenum after 270 f 30 min. The stomach appeared to be empty 420-480 rnin after eating.

In group 3, the food was observed in the duodenum 30 min after ingestion and emptying was complete 240-360min after ingestion.

However, this method is not very accurate due to problems with determining the very beginning of gastric emptying; besides, radiographs were taken at intervals of 60 rnin (Arnbjerg, 1992)

So it would seem to me that there isn't a lot of published research to support the practice, although experiential evidence may support it for some pets. I guess anyone who's put some human food on top of kibble to make it more appealing has tried this experiment themselves to a limited degree.

AussieGirl · 10-06-2009, 06:45 PM

I have never mixed the two firstly because of reading in so many places it can cause a stomach upset by the digestion of the meat being slowed down and basically it was no big deal to me not to mix them so figured why do it and maybe end up with a ridiculous vet bill from it, it was no extra work for me when I was feeding them seperately. Secondly kibble makes the gut work ineffectively (I tried to get the Raw feeding myths page that covers this but it keeps coming up as an error

not sure whats going on there) but here is a little part of it from another post

Quote:

The result of feeding dogs a highly processed, grain-based food is a suppressed immune system and the underproduction of the enzymes necessary to thoroughly digest raw meaty bones (Lonsdale, T. 2001. Raw Meaty Bones). This does NOT mean, however, that the dog does not "have" those enzymes. Those enzymes are present, and once the dog is taken off the grain-based, plant matter-filled food those enzymes quickly return to the proper working level that allows for optimal digestion of raw meaty bones.

so perhaps the fact that the kibble makes the stomach work ineffectively is a contributing factor, I just figured why go to the trouble of feeding raw and then add kibble to it if it's going to affect her digestion of the raw. I have heard of a few people say they had mixed raw and kibble and their dog had been fine, I am just one of those people that would rather not risk it - I'd feel so bad if I made her sick and I would not be impressed with vet bills.
I'm curious to see what you guys come up with on this one

KeeperBoy · 10-06-2009, 07:21 PM

All I can say is that I mixed raw and kibble once... NEVER AGAIN. I thought Keepers was going to end up at the e-vet. He was puking, pooping and his poor tummy sounded like a freight train.

Spyglass Sally · 10-06-2009, 07:56 PM

This isn't really your point, AussieGirl, so excuse me for digressing

, but I'm looking at the quote from Lonsdale and I hope he's not saying that dogs need to be off grains to produce adequate enzymes to digest RMB. If a dog is eating all grains, it won't produce the enzymes needed to digest meat because it would be a waste of energy. But it would produce them if it were eating meat with the grains.

I would agree with Lonsdale that feeding dogs a highly processed, grain-based food would suppress immune system for a variety of reasons (as it will with humans), but the implication that grains, as part of a well balanced diet, are bad for a dog is not supported in anything I've read. I haven't read his book, so I'm not sure if he's saying that or not, but I'd hate to leave that impression.

Dr. Pitcairn writes "Whole grains are a very cost-effective and environmentally sensitive way to provide the mainstay of your pet's diet. Not only do grains supply carbohydrates and an array of vitamins and minerals, they are inexpensive sources of protein as well. When one type of grain is combined with other grains, the biological effectiveness of its protein is greatly enhanced because of the balance of amino acids is more complete."

However, grains are one group of foods that definitely need to be cooked in order for the dog to utilize the nutrients. In the wild they would get them predigested in the gut of prey. Pitcairn recommends quick cooking oats, cornmeal, millet and bulgur as they are generally well accepted and high in nutrition.

I can't get to the raw feeding myths page either, but I did look at the cached page (sneaky, no?

) and I think they are saying that raw is better nutrtionally than kibble, and that the process of making kibble renders many of the nutrients ineffective.

This group in general, and AussieGirl in particular, have really done a lot of good in helping many of us transition from kibble to raw. But I know for some it's not possible, or only partially possible. Quality kibble is better than cheap kibble, and partly raw is better than none.

I'm with you, I don't see any reason to mix the two and would rather not risk it...even though I think it would be fine.

AussieGirl · 10-06-2009, 09:12 PM

Dr Lonsdale does actually recommend feeding a portion of their diet "table scraps" so that would include some grains

Quote:

Table scraps
Wild carnivores eat small amounts of omnivore food, part-digested in liquid form, when they eat the intestines of their prey. Our table scraps, and some fruit and vegetable peelings, are omnivore food which has not been ingested. Providing scraps do not form too great a proportion of the diet they appear to do no harm and may do some good. I advise an upper limit of one-third scraps for dogs and rather less for cats. Liquidising scraps, both cooked and raw, in the kitchen mixer may help to increase their digestibility.
Things to avoid
•Excessive meat off the bone — not balanced.
•Excessive vegetables — not balanced.
•Small pieces of bone — can be swallowed whole and get stuck.
•Cooked bones — get stuck.
•Mineral and vitamin additives — create imbalance.
•Processed food — leads to dental and other diseases.
•Excessive starchy food — associated with bloat.
•Onions, garlic and chocolate — toxic to pets.
•Grapes, raisins, sultanas, currants — toxic to pets.
•Fruit stones (pits) and corn cobs — get stuck.
•Milk — associated with diarrhoea. Animals drink it whether thirsty or not and consequently get fat. Milk sludge sticks to teeth and gums.

I think his point is some is okay and even beneficial but their diet should be "meat based" not "grain based".

bruinsBoxers · 10-07-2009, 08:19 AM

but I'm looking at the quote from Lonsdale and I hope he's not saying that dogs need to be off grains to produce adequate enzymes to digest RMB. If a dog is eating all grains, it won't produce the enzymes needed to digest meat because it would be a waste of energy. But it would produce them if it were eating meat with the grains.

One reason that many raw feeders do not feed grains is because grains feed cancer cells . Any many breeders have seen a decrease in cases of cancer over generations of exclusively grain free raw fed dogs .
I had read this same thing in a few books . I can't remember which one since I read so many . But there is one about cancer and pets that had some very eye opening info .

Ruby Red · 10-07-2009, 11:05 AM

A big thank you to everyone who has replied, especially Sally for going to all the trouble of researching into this and for quoting some really interesting data. To Andrea, I’m sorry your dog had problems when you mixed kibble and raw, but one bad experience doesn’t necessarily mean it was the mix that was the problem – it could just have been a rogue batch of raw or some other factor.

It would seem that there is no real evidence against mixing kibble and raw, or adding anything else suitable for dogs to the mix in terms of their ability to digest it. We just need a balance and to find what is suitable for our dogs.

The experiment that looked at gastric emptying used essentially dry kibble with very low moisture content [10 per cent]. If the kibble were soaked in water it would be well hydrated and should therefore digest at a faster rate. I have mentioned elsewhere [bloat post I think?] that on days when mine get kibble meals it is now always pre-soaked as per my vet’s recommendation.

While I don’t mix raw and kibble as a rule – I did during the transition stage without any problems. I find very little evidence in the discussion above to make me think that mixing raw and kibble makes it indigestible or is in any way detrimental to a dog's health.