Let's Take A Look At Some Dog Food Labels

 I get asked quite often what I feed my dogs. I am quite willing to share that information. Purina, Hills, and Royal Canin are all good choices. I feed Archie a regular Purina diet, the cat gets a Hills prescription diet to prevent urinary blockages, and Azza thrives on Royal Canin's Ultamino hydrolyzed protein diet. The prescription diets made by these three companies are incredibly useful for a wide array of diseases. Nothing magic here, we know that diet can reduce and delay clinical signs of many types of disease for both people and animals. A managed diet can improve performance. It can help a beef cow put on more weight faster, and can help a "no antibiotics ever" broiler chicken have a healthier gut to reduce bacterial infections. 

But the important point is that all three of these companies conduct feeding trials using real dogs to determine the nutritional profiles of their foods. Other companies analyze samples of their food in a lab only, for example burning it in a crucible to determine protein content. These kinds of assays are certainly useful, but they provide no information on bioavailability of important nutrients. Only feeding a living animal the actual food can tell you if that protein can be digested and used by the animal. If a dog food label says "food is formulated to meet the nutritional levels established by AAFCO," that food has only ever seen the inside of beakers and test tubes, not the inside of a dog. Grain-free? "Human-grade" ingredients? "Natural"? All marketing. All bullshit. All to make you, the human with the credit card, feel good. 

So this windy opening sets the stage for Archie's current situation. He got a stick jammed in the roof of his mouth a month ago or so, and some pieces of it broke off and were left behind in the tissues around his left upper molars. His bad breath prompted me to take a look in there...where I found this nasty hole in the roof of his mouth surrounded by friable, brown (necrotic) tissue. It bled when I touched it. I managed to get a large piece of stick out of the hole but even after starting some antibiotics, things weren't improving as much as I would have liked.

Of course, my imagination immediately went to the worst case scenario--abscess, lysis of the bony palate, formation of a fistula (an inappropriate hole between two spaces), damage to the roots of those huge molars. All Very Bad Things. I had to get a referral to another vet to get some dental radiographs made since my vet doesn't have dental rad equipment (it's specialized). That vet flushed a couple more small pieces of stick out, and helped calm my worst fears. She added a second antibiotic to go after the anaerobic bacteria, and recommended that I feed Archie a canned diet for two weeks to give the roof of his mouth a rest. 

Archie had not shown any evidence of pain or reluctance to eat or play, but he's a pretty stoic dog in general. Two weeks of canned food seemed reasonable. Except that I haven't calibrated any canned diets. I have no idea how much canned food to feed him. 

See, I feed Archie a calculated number of calories per day, including treats. He currently eats 1 cup of Purina Pro Plan Performance 30/20 Chicken and Rice kibble per day, divided into two meals, plus two tablespoons of plain yogurt, between 20 and 40 g of frozen green beans, and 10-20 kcals of treats. I adjust this basic plan for training and trialing days when he gets lots more treats. The kibble has 484 kcal/cup, so on most days Archie consumes around 510 kcal.

Let's examine three canned food options. Rachel Ray's Nutrish dog food comes in small plastic tubs. It looks and smells like human stew. The lamb and rice stew label says to feed an adult dog 1.5 tubs per 10 pounds per day. Archie weighs about 24 pounds so according to the label, I would need to feed him THREE tubs per day. Each tub is calculated to contain 244 kcal. Let's do the math, shall we? If I gave Archie THREE tubs of this stuff a day (not sure I could get this volume of food into him, but he certainly would give it a go), he would consume 732 kcal each day. If I give him the chicken and rice stew at the recommended volume, at 290 kcal/tub, he'd be getting 870 kcal per day. That is astonishing!

I also bought some Canidae Small Breed canned food. The chicken, salmon, and pumpkin recipe, which looks and smells as gross as that sounds, contains 123 kcal/can. The label recommends 2 cans per 6 lb of weight, so if I follow those recommendations, Archie is supposed to eat EIGHT cans of this per day. EIGHT! That's 984 kcal per day. OMG, that's even worse than the Nutrish stew. That's almost TWICE the numbers of calories that Archie needs each day.

ProPlan Focus canned food is my third example. If fed as recommended, Archie would need to eat 1.5 13-ounce cans per day of the (large breed) chicken and rice formula (their "small breed" options are grain-free and I don't feed grain-free). That comes out to about 475 kcal per day, which is in line with what he actually needs. So not only is the Purina food tested on real animals, the feeding guidelines are reasonable, not grossly over the top.

Here's the bottom line. Read labels. Don't be fooled by marketing. Measure your pet's food and calculate kcal per serving (can, cup, etc.). Are they healthy now? Figure out how many calories they eat per day--including all treats. Kibble is always going to be more nutritionally dense than canned food, which is mostly water. The volume of canned food will always be more than the equivalent kilocalories of dry food. And consider feeding Purina, Hills, or Royal Canin.

What I Learned Today: Four Ways to Make Chicken Meat Taste Fishy

I'm stealing this idea for a blog post theme from a friend. I think it will make a good umbrella under which I can occasionally post about odd and intriguing things that I learn about.

Today I want to write a bit about four different mechanisms for making poultry meat smell fishy. This is certainly not a desired experimental outcome--chicken tenders that smell like fish? That's gross. But this very outcome has been reported by some researchers conducting broiler and layer feeding trials. How this can happen was a matter of some debate during my thesis committee meeting last week. It wasn't heated in the sense of being antagonistic but it certainly was intense. Since it seemed to be a topic of interest, I thought it would be time well spent to read some papers and try to figure out why this happens. What I found out is kind of interesting so I thought I'd write about it here too.

We first have to start with the larger issue: why do fish smell fishy. Living fish and fresh fish don't smell fishy. The fishy odor develops in marine products after they have been harvested. The smell is mainly caused by the formation of a molecule called a trimethylamine (although several dozen other kinds of molecules are also involved in creating the fishy odor).

See, animals that live in the ocean have a bit of a problem. They live in a saline solution but their cells also contain saline solutions. The concentration of sodium and potassium ions inside and outside of cells is delicately balanced. If those ions are out of balance, cells can't make energy and things generally go downhill from there. A very large number of biochemical processes depend on this balance being kept just so. So back to fish. They have developed some special biochemical mechanisms to keep the sodium and potassium ion concentrations in the correct balance. One of these depends on a molecule called trimethyl oxide. When a fish is killed, these molecules are slowly and inexorably converted to the insanely stinky trimethylamines.

You might take fish oil supplements. I don't take them myself but I give them to the dogs. I learned that the fish oil in those capsules has been subjected to an amazingly complicated purification process which includes a deodorization step to remove the trimethylamines.

So the first way we can make poultry meat smell fishy is to feed chickens diets that contain fish meal or fish oil that has not been purified to levels acceptable for human-grade consumption. Chickens consume the trimethylamines and their eggs and meat will smell fishy.

It also turns out that some chickens and some people have a genetic mutation in their DNA so that they don't make working copies of a particular enzyme that breaks down trimethylamine. We need this enzyme because our gut bacteria naturally make trimethylamines as part of their life cycles. If we don't have the mutation, no problem. The enzyme breaks down the molecules in our gut. But if you or a chicken has this mutation, then you can still smell fishy even if you never consume any fish product of any kind because the trimethylamine that is made by your gut bacteria is never broken down. So the second way for (some) poultry meat to smell fishy is to have strains of chickens with the mutated gene. People with the mutated gene have a disease called trimethylaminuria and they smell fishy too.

However, our gut bacteria have plenty of tricks up their tiny sleeves. They can make trimethlyamines out of choline. Choline is an essential nutrient which means that we must consume it in our diets; it is essential for chickens too. Diets deficient in choline can cause disease. However, if we feed chickens diets that contain large amounts of choline, we overwhelm the ability of their systems to break down all the resulting trimethylamines...and their meat and eggs can smell fishy. This third mechanism is not well quantified (how much choline is "too much", does it depend on age or type of chicken, does it depend on other dietary elements) but we know it happens.

And finally, the fourth mechanism for making poultry meat smell fishy has nothing at all to do with fish or bacteria. When you are trying to create a consumer product that is "enriched in omega-3 fatty acids" you are trying to increase the concentration of long-chain polyunsaturated omega-3 fatty acids in the parts of the chicken that we eat. I know, that's a mouthful. We generally abbreviate that mess to LC n-3 PUFA. Long-chain means the carbon backbone of the fat molecule contains between 18 and 22 carbons linked together. Polyunsaturated means that some of the carbons are linked with special molecular bonds called double bonds. You should already know that diets high in saturated fatty acids, fats with no double bonds at all, are strongly correlated to increased risk of heart attack and stroke; to be healthy we are supposed to consume fewer saturated fats and more unsaturated fats. Some of the omega-3 fatty acids can have up to six double bonds. We are trying to put more of these kinds of fatty acids into chicken meat and eggs. But there is a problem.

When a fatty acid has lots of double bonds, it is more susceptible to peroxidation than the unhealthy fatty acid that lacks all those double bonds. Peroxidation refers to a specific process by which a chain reaction breaks the unsaturated fats apart at their double bonds. Not only does lipid peroxidation form free radicals (very, very bad things to have floating around your cells) but the fatty acid fragments are converted into other molecules such as aldehydes and ketones. And most of these are quite stinky. 

When this happens, the meat tissues can change color, will taste bad (rancid), and will develop an off-flavor that is often described as "fishy" even though it isn't caused by the same molecules as fishy odors in fish. This is not an immediate process in general. Normal, every-day chicken meat will undergo peroxidation given enough time but it will happen sooner in "enriched" chicken meat.

So that's the fourth mechanism to make poultry meat taste fishy: enrich that meat with long-chain polyunsaturated fats and fail to protect the fats from peroxidation by lax handling, storage, and/or lack of antioxidants in the meat or diet.

It turns out this animal nutrition business is rather complicated. And there is no way to avoid the related issue of human nutrition and health--we and chickens are what we eat.

The Student Gig

I've got some big news! You'll recall that a few posts back I was bemoaning the fact that I wasn't having any more fabulous, exotic travel adventures. But quitting my job and going back to school has certainly opened up new kinds of adventures. I suspect that for some of you, becoming a student again sounds like entirely too much work. Well, I'm getting ready to take the student gig to a new level.

But first, some backstory (isn't there always a backstory?). With the exception of microbiology which I'm taking next term, I have finished the additional coursework that I needed to apply to the vet schools that I'm interested in (I have a short list of four schools at the moment).

All of the vet schools in the US use a single, online application form. They all use the same deadlines too. Applications are due this September for consideration for entry into vet school for fall of 2015. Yes, that's a year in advance. Actually, you are informed by March 2015 or so if you are accepted but you won't start vet school until that fall.

So I was wondering what I could do for the next 18 months. I didn't want to keep taking classes; I don't need them and college is damned expensive. I figured that I would try to get a job in a vet clinic as a tech and hang out here and see what happened. No point in moving anywhere until I knew where I might end up (my vet school choices are scattered across the US; OSU is one of them, however). And my chances of being accepted to vet school on the first application are not guaranteed. Many excellent candidates have to try a second time. I might be among them. 

I thought that for the spring and summer, I might try to get in on an undergraduate research project. I approached the professor who taught the Animal Nutrition course in the fall. I really enjoyed the course, and I learned that she had quite a lot of funding for undergrad research. So in January, I went to talk to her about this.

As she asked me more questions about my background, she got more excited, finally proposing something that I never even saw coming. 

She asked me to do a Master's degree with her in the 18 months' "gap". She's got research funding and several projects from which we could choose. She mentioned a fellowship that could pay my tuition and a small monthly stipend. She felt it was all quite doable.

I immediately sought some advice and information from a couple of other people in the department. Was I crazy to even consider this? It will be a lot of work. But the advantages are perfectly clear. Being accepted into an Animal Sciences graduate program then executing and completing a research project and thesis will be a significant boost to my vet school application. Half of the battle of going to grad school is finding an advisor and a project and funding. All of those things are being handed to me!

But wait, there's more! This professor works with poultry. Chickens, you are thinking? Really? Consider this: chickens are just about the only meat source without any major religious prohibitions and as a result chicken and egg production are taking off internationally. There is a TON of funding for poultry research from both the government and private sources. There are excellent, well paying jobs in the poultry industry all over the world. I am in fact interested in a possible international work experience. Why aren't more students flocking (heh, bad pun, it stays!) to poultry science? As one prof told me, chickens aren't cute and furry. Bah, I said. You don't have to take them home and make them pets. With respect to my vet school application, I am weak in my experience with production animals so working with chickens will help me out a lot there too.

Even better, the professor who asked me to work with her has a very strong focus on nutrition. It works both ways, you see. Better  nutrition for the chickens results in better nutrition for people who consume chicken products. Among other things, she studies how poultry diets affect the nutrient profiles of eggs. I am particularly interested in the tangled intersection of diet and disease (details are best reserved for a future post), but many vet schools don't even teach basic nutrition courses anymore. So I also see her offer as an opportunity to learn about specific topics of great personal interest to me.

So, in short, I applied and was accepted to the OSU graduate program starting in the spring term (which starts a short two weeks from now). In about 18 months, if all goes as planned, I will be getting a Master's degree in Animal Sciences with a focus on poultry science and nutrition. It was confirmed today that I'll get the fellowship that will cover my tuition.

And although this had little to do with my decision, I would mention that since I already have a BS and a PhD but not an MS, upon completion of the degree I'll have a complete set! Not a matched set since the other two are in geological sciences, but a complete set nonetheless. Sort of like shopping for dishes at Goodwill. My professional email signature will get really interesting. Imagine what it will look like if I add DVM to the list!