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Wednesday, September 28, 2016

Nutritional Research, Corn In Pet Foods, And Resources....The Last Word?

Long-time readers know that pet nutrition is a big interest of mine, and I've written more on this topic than just about any other.  Recently I've had a reader, Peter, debating with me on the pros and cons of corn in pet food on an older post from 2013 ("Corn In Food...No, It's Not Bad").  One of the things that I've been bringing up is the source of my information versus his.  I thought this was worth a post of its own, hence today's blog entry.
Up until about eight years ago I believed many of the myths about pet food ingredients (no corn, meat must be the first ingredient, etc.).  But then I started attending lectures at veterinary conferences and reading articles on the subject, quickly realizing that I had been previously misinformed.  Honestly, I had based my opinions on what I heard others talking about rather than really looking at the science behind what I was saying.  When I did look into the real data I was ashamed that I had been so ignorant and that I had helped perpetuate certain myths.  That's when I really started writing and talking about the truth behind pet nutrition.
I'm not going to go back and repeat points that I've made previously.  You can do a search for pet nutrition on my blog and find quite a lot of articles and information.  My point in today's post is to point out where I have gotten my information, and that there is significant scientific validity to what I write or say.  I'm not looking at "common sense" (something that is often an argument given against me, yet has no real science), I'm looking at hard data by highly educated and respected specialists.  Here are some resources that have helped me form my opinions on pet food.
Small Animal Clinical Nutrition, 5th Edition, Hand et al, 2010--Great text and pretty much the gold-standard on nutrition in dogs and cats.  Lots of good information in this book, but let me give a quote from page 95:
"Multiple protein sources are often combined to improve the overall quality and amino acid profile when foods are formulated. This method of improving protein quality is termed protein complementation (Zapsalis and Beck, 1985).  Protein sources are combined based on their amino acid excesses and deficiencies so that the nutritional weakness of each source will be counterbalanced by the strengths of other sources, resulting in a food with high-quality protein. Corn and soybean meal are typically used in animal food formulations to take advantage of protein complementation."
Studies showing that corn gluten meal has a crude protein digestibility in cats comparable to meat, fish, chicken, and poultry:
Funaba M, Tanaka T, Kaneko M, et al.  Fish meal versus maize gluten meal as a protein source for dry cat food.  Journal of Veterinary Medical Science, 2001; 63:  1355-1357
Funaba M, Matusmoto C, Matsuki K, et al.  Comparison of maize gluten meal and meat meal as a protein source in dry foods formulated for cats.  American Journal of Veterinary Research, 2002; 63: 1247-1251.
Kane E, Morris JG, Rogers QR.  Acceptability and digestibility by adult cats of diets made with various sources and levels of fat.  Journal of Animal Science. 1981; 53: 1516-1523.
Funaba M, Oka Y, Kobayashi S, et al.  Evaluation of meat meal, chicken meal and corn gluten meal as dietary protein sources of protein in dry cat food.  Canadian Journal of Veterinary Research, 2005: 69: 299-304.
In some of the above studies do you know what source consistently had the highest digestibility?  Soy protein!  Even greater than meat sources.
Studies showing that protein quality of corn gluten meal is considered the same as various sources of animal meat and meal:
Brody T.  Protein. In: Nutritional Biochemistry.  San Diego, CA:  Academic Press Inc, 1994; 295-352. 
Jurgens MH, Animal Feeding and Nutrition, 6th ed.  Dubuque, IA:  Kendall/Hunt Co, 1988: 172. 
National Research Council.  Improvement of Protein Nutrition.  Committee on Amino Acids, Food and Nutrition Board. National Academy of Sciences, Washington, DC, 1974.
Robinson DS.  The nutritional value of food proteins.  In: Food Biochemistry and Nutritional Value.  New York, NY:  Wiley & Sons Inc, 1987; 117-151.
Studies analyzing amino acid digestibility of dog foods:
Bednar GE, Patil AR, Murray SM, et al.  Starch and fiber fractions in selected food and feed ingredients affect their small intestinal digestibility and fermentability and their large bowel fermentability in vitro in a canine model.  Journal of Nutrition 2001; 131: 276-286.
Murray SM, Patil AR, Fahey GC Jr, et al.  Raw and rendered animal by-products as ingredients in dog diets.  Journal of Animal Science, 1997; 75: 2497-2505.
Muir HE, Murray SM, Fahey GC Jr, et al.  Nutrient digestion by ileal cannulated dogs as affected by dietary fibers with various fermentation characteristics.  Journal of Animal Science, 1996; 74: 1641-1648.
Yamka RM, Kitts SE, True AD, et al.  Evaluation of maize gluten meal as a protein source in canine foods.  Animal Feed Science and Technology, 2004; 116: 239-248.
Gajda M, Flickinger EA, Grieshop CM, et al.  Corn hybrid affects in vitro and in vivo measures of nutrient digestibility in dogs. Journal of Animal Science, 2005; 83: 160-171.
Yamka RM, Kitts, SE, Harmon DL.  Evaluation of low-oligosaccharide and low oligosaccharide low-phytate whole soya beans in canine foods.  Animal Feed Science and Technology, 2005; 120: 79-91.
Clapper GM, Grieshop CM, Merchen, NR, et al.  Ileal and total tract digestibilities and fecal characteristics of dogs as affected by soybean protein inclusion in dry, extruded diets.  Journal of Animal Science, 2001; 79: 1523-1532.
I have read additional articles and professional opinions by the following specialists, which have helped form my knowledge on various aspects of pet nutrition.  You can look up the various alphabet designations for each, but they mean that these are people highly specialized in animal internal medicine and nutrition.
Denise A. Elliott, DVSc (Hons), PhD, DACVIM
Justin Shmalberg, DVM, DACVN
Preston R. Buff, PhD, PAS, DACAN
Joe Bartges, DVM, PhD, DACVIM, DACVN
Cecillia Vellaverde, BVSc, PhD, DACVN, DECVCN
Jennifer Larsen, DVM, PhD, DACVN
Scott Campbell, BVSc (Hons), MAVSc, DACVN
I have also spoken to and heard lectures within the last year from the following specialists:
Sherry Sanderson, DVM, PhD, DACVIM, DACVN, University of Georgia College of Veterinary Medicine.
Angela Lusby, DVM, PhD, DACVN, University of Tennessee College of Veterinary Medicine.

I've presented multiple articles on the issue of corn in pet foods because it is the main point that Peter and I have been debating.  However, any information that I have shared on any point of pet nutrition can be attributed to one or more of the above sources
There are other specialists that I've heard lecture over the years whose names I can't remember, but you can get the idea. I don't come to my opinions on my own, based on random thoughts.  I don't listen to the food company representatives as my only source of nutritional information.  I'm looking at and listening to the words of people who are far smarter and more knowledgeable than myself, often with multiple degrees and certifications.  Please, don't believe me. Instead, believe someone with two doctorates and two specialty certifications on top of that!  Who is going to be more informed on proper animal nutrition and biochemistry? The specialists above, or the person writing the holistic website, even if that writer has a DVM degree?
Now I know that some people will look at the above very impressive qualifications and studies and say "Well, they're supported by the food companies, so of course they're going to validate the crappy nutrition these companies produce!"  Unfortunately, that's not the way that works.  Do you really think that this many specialists (and more!  these are only the ones from my personal experience!) and this many studies in multiple international journals are all on the payroll of the "Big Bad Pet Food Co."?  Do you really think that the one blogger you read, or the handful of websites that push "all natural" resources, or that small niche brand of pet food honestly know more and are more qualified than the rest of nutritional science?  Believing so is the height of hubris and close-mindedness.  Thinking that no nutritional research is valid because it is all funded by pet food companies (which it isn't) means that nobody can adequately contradict that science.  So all we are left with is various opinions, NONE of which have scientific validity.

In many discussions on nutrition I challenge people who have a view contrary to mine to support their position with valid scientific studies.  I do so because we are dealing with scientific principles, and in science peer-reviewed studies are the gold standard for data.  No, they're not always perfect, and sometimes such studies are proven wrong.  But they are the best that we have and far better than simply saying "X ingredient is bad because I think so."  If we are automatically going to dismiss studies because of a false perception that they are completely determined by pet food manufacturers, then we have to dismiss ALL nutritional studies.  How reasonable is that?

So I'll make a new challenge. Forget giving me references to studies that show that I'm wrong.  Point me to people who have a DVM and PhD in veterinary nutrition, are a diplomate of an appropriate College of Veterinary Nutrition, or similar qualifications which are equivalent to my sources above.  If anyone can show me someone with comparable training and background to my own resources who disagrees with what I and the above specialists say, I will absolutely be willing to look at their opinions.  But remember that you and your sources are not disagreeing with me, they are disagreeing with the above specialists and researchers.

If you can't provide studies or people with backgrounds and specialties in animal nutrition who support contrary viewpoints, then you really have no leg to stand on and are being intentionally oblivious to the truth of nutritional science.  Pet owners who would ignore the views of the dozens of people that I've referenced above are being willingly ignorant.  I can inform people.  I can't change closed minds.

If someone really wants to get an opinion other than mine, and one far more expert and educated, look a the web page for the American College of Veterinary Nutrition and find the closest diplomate.  Ask them what they think of corn, by-products, grain-free diets, and other nutritional myths.  You'll find that what I've written over the years is what nutritional specialists believe.

I would like to say that this is the last word on this topic, and that I've adequately shown how absolutely overwhelming the information is that form the opinions I share.  Unfortunately I'm sure that won't be the case, and I'm interested to see how Peter and others contradict or challenge me, and how they are able to support their views.