A Story of Flax Seed and Chickens

I can list the stats, a nice dry list:

• 238 total pages that include 
• 19 pages of front matter (table of contents, list of figures, that sort of thing),
• 30 pages in an appendix with brief summaries of 57 papers on poultry feeding trials in which the authors attempted to alter the n-3 fatty acids in poultry meat or eggs through dietary means,
• 51 figures,
• 39 tables,
• 119 cited references; my library for the project contains over 150 papers so I managed to pare things down a bit
• mostly written in the past three weeks with only one day off.

I can tell you the story. It starts with a bit of chemistry: the molecular properties of fatty acids and how two particular kinds, the n-3 and n-6 groups, work in animals (that includes us too). They affect immune response and fat metabolism and some of them control genes, turning on or turning off the transcription of important proteins. In short, the kinds of fat that we eat affect the kinds of diseases we have. Clinical research trials (gold standard) and other types of studies have been linking n-3 fatty acids to the reduction of symptoms or delay of onset of all kinds of inflammatory diseases such as cardiovascular disease and metabolic diseases such as diabetes, and linking those same fats to improvements in visual and cognitive development in embryos and very young infants/animals. There have even been studies linking n-3 fatty acids to reductions in symptoms of aging and dementia. Aging isn't a disease but you get the idea.

But here's the problem: in western cultures, we don't eat nearly enough of those n-3 fatty acids. The best source is fatty fish but for reasons of culture, cost, sustainability, concerns over environmental contamination, we just don't eat a lot of those fish. We do eat lots of chicken, though. In the US in 2012, we consumed 45 kg of chicken meat per capita. That is about 100 lbs per person. I can guarantee you that someone is picking up my slack. My advisor's acerbic comment on this: "chicken tenders...". So if we get more of those n-3 fatty acids into chicken, western consumers are more likely to consume those enriched products. The outcome is not just more money for the chicken producers but improved health for us.

I take a brief side trip to discuss oxidation. The more unsaturated a fatty acid is, the more likely it is to oxidize. The good n-3 fatty acids are in fact the most unsaturated fatty acids that we know of in animals. So I was able to work in a page or so on "what makes chicken smell fishy". Chicken in particular is handled a lot, exposing cut-up parts to air. Consumers buy more parts than whole birds. All that handling increases the possibility of oxidation even if there aren't extra n-3 fatty acids in the meat. 

I then blather on a bit about fat sources in poultry diets and how birds digest fat. The two things that have the highest amounts of n-3 fatty acids are fish oil and flax seed. While adding fish oil to poultry diets does increase the n-3 fatty acids in poultry meat and eggs, it is far too expensive to use in a commercial setting. Anyway, the use of it simply displaces the original problem: we don't eat oil fish for reasons of cost, etc., and those same problems are still present in fish oil which is obtained from those same oily fish.

So, flax seed. There's not just seed. There is flax oil, flax meal (defatted seed that has been ground), ground whole seed, and whole seed. Flax seed has more n-3 fatty acids in it than any other non-marine source. It might seem like the perfect solution. But there are some "anti-nutritive factors" that have to be addressed. For starters, all the good stuff in flax seed is enclosed in that tiny, hard, seed coat. The seed coat is not soluble in water or acid (acid breaks apart proteins very well but it doesn't do such a good job on these kinds of sugar molecules). In fact, monogastrics like you and chickens don't have the digestive enzymes to break down the molecules in that seed coat. (Keep that in mind next time you order a flax-seed muffin; you derive no nutritional benefit from the whole seeds.) You can grind the flax seeds to mechanically break apart the seed coat. Flax seeds are very tiny and contain lots of oil. They are damned hard to grind and commercial grinding equipment doesn't work well on them. Once you grind flax seeds, you expose all the oil inside them to, well, you guessed it, oxidation. That's why flax oil should be sold and stored in dark bottles in the fridge. That stuff will oxidize in a matter of hours if exposed to light and room temperatures. Once it does, it will smell quite fishy!

Flax seed also has this strange and wonderful material coating the outside of the hard seed coat. It is called mucilage (think snot). The molecules absorb water extremely quickly. This mucilage gets into the chicken's gut and does all sorts of unpleasant things. It makes the digesta (mixture of food and gut secretions) viscous. Thick digesta takes longer to pass through the gut. Thick digesta doesn't mix well and the chicken's digestive enzymes can't get at the nutrients in the digesta. The chicken doesn't get the energy it needs so it eats more to compensate. Even so, the chicken eating flax will not gain as much weight as chickens who aren't eating flax. 

The same things happen inside of you but you'd have to eat a fuck-ton of whole flax seed before you gum up your gut in the same fashion.

Grinding the seeds doesn't remove the mucilage. The best (cost-effective) option is to feed the whole seed to chickens and find some other way to deal with the hard seed coat and the mucilage.

Which takes us to the next part of the story. Exogenous enzymes. No, that is not a euphemism for anything. It just means that we add to the feed digestive enzymes that the chicken doesn't possess on its own. Of course, lots of research has been done to figure out exactly which enzymes and how much of each are needed to break apart the insoluble molecules in the seed coat and the soluble molecules in the mucilage. Not surprisingly, a pretty diverse mixture of enzymes is needed to accomplish this. I natter on a bit about the history of enzyme use in the animal feed industry.

Then my story takes a big, deep breath. I take an entire chapter to review all of the important feeding trials in which chickens were fed flax in some form and what happened. I tabulate the amount of flax used, how long it was fed, how old the birds were, what kind of birds (broilers, layers, etc). I note outcomes such as performance (weight gain or egg quality, for example), and enrichment (what kinds of n-3 fatty acids were present in eggs and meat and in what concentrations). It lacks the compelling drama of "eat more n-3 fatty acid and be healthy" but it is a significant contribution. I developed a short table template and summarized every paper in the Appendix as well. 

In the next two chapters, I describe my own two feeding trials. It's the usual intro, materials and methods, results, discussion format. Most of the figures and tables appear in these two chapters. Very interesting things were taking place inside those chickens and we certainly managed to support our original hypotheses.

The important n-3 fatty acids in thigh meat from my first experiment. Birds in the control group got a standard corn-soybean meal diet. The energy and protein of that diet was adjusted for 15% whole flax seed. The diet of the enzyme group included 0.05% of the enzyme mixture, a pale yellowish powder that we mixed in with the rest of the ingredients. The a,b,c labels are part of the statistical analysis. If two of the same fatty acids are labeled the same, they are statistically the same. If two boxes are labeled with different letters, they are statistically and significantly different.

Finally, I end the story with what I call the "uber-discussion". I calculate the cost per pound of meat of adding whole flax seed and enzymes to chicken diets (about $0.50 per pound). And I compare the chicken meat parts from my two feeding trials to governmental definitions of "enriched" to determine if we in fact created something that could be labeled as such. We did. 

After all that, believe it or not, it's just the first draft. It's a honking large file that I can't email to my committee. I'm buying small thumb drives and will personally deliver it to them next week. 

I made my deadline though. I promised my advisor the complete draft by the times classes start up on Monday.