Fat-Adapted Horses and the Omega Balance

tl;dr: How horses can get diabetes, and what can be done about it.

In The Perfect Health Diet, the Jaminets point out that while a ruminant like a cow may each lots of carbohydrate in the form of indigestible fiber, what actually makes it into their blood stream is nearly pure fat, along with about 10% protein, thanks to the fermentation of fiber into short-chain fatty acids. (No link, sorry, and I can't find my copy to quote it directly.) P.S.:

“When we look past the digestive tract at what nutrients are actually delivered to the body, all mammals obtain a remarkably similar set of nutrients. By calories, mammalian diets are always composed of a majority, typically 50-75%, of saturated and monounsaturated fats (including the short-chain fatty acids produced by fermentation of fiber); a mix of carbohydrates and protein, usually totaling around 25-40%; and a modest amount of polyunsaturated fat, typically less than 10%.”

(Link here. Thanks to Peter in the comments!)

This ends, of course, when they're put on the feed lot, and they develop a nice layer of fat and fatty deposits in their muscles, if a grain-based diet doesn't kill them first.

I stumbled across this link looking for some information about athletes on a fat-based diet:

“Feeding Oil or Fat for Horses - A Review” (Carney, 2012)

I got what I was looking for, and it turns out it's fascinating. Stance Equine is a company that "...pioneered the feeding of no grain, low sugar and starch feeds to horses to avoid the metabolic chaos caused by high NSC [non-structured carbohydrate] feeds. The Stance Equine feeds are based on the unique attributes of copra, coconut meal and coconut oil."

"The Domesticated Lifestyle

"The modern, domesticated horse lives in an environment markedly different to the evolutionary one. Horses are often kept in paddocks and stables, restricting access to quality pasture. This, coupled with the high-energy demands of performance, can make safely meeting horses energy needs, a tall order...."

Huh. That sounds familiar... Horses on the Paleo diet.

Well, not quite, as (from the first link): "The option of feeding horses the balanced and natural diet on which they evolved is, in most cases, unfeasible due to space, time and financial constraints. Besides which it is most unlikely that the natural diet of horses would suffice to meet the energy needs demanded of many performance pursuits."

Of course, as it requires a lot of time and chewing. Nevertheless, this puts horses squarely in the same position as a human athlete, who also can't afford to spend all their time hunting ruminants, and so must make do with a second-best diet.

"The Grain Solution

"Traditionally, horse diets have often included large quantities of grain (ie. starch) in an attempt to sate energy needs. However, horses have a limited capacity to digest starch and high starch feeding practices can result in starch overload into the hindgut (Kohnke et al 1999; Rowe et al 2001). A number of metabolic disorders - such as tying up, laminitis, colic, and excitable behaviour - are associated with high grain diets. Advances in feed processing technologies have reduced the risks associated with high grain feeding, but have not eliminated them...."

But unlike human athletes, it turns out that there's been a good bit of work done on the effect of a fat-based diet on horse's athletic performance. Now mind you, they're not people, or even mice, but based on the similarities of the ill effects on the horses from a high carbohydrate diet, it's an interesting possibility that the benefits would be the same.

It turns out there's also a Maffetone Method for horses:

"Training to Facilitate the Aerobic Pathway

"The aerobic metabolism provides energy for slow-twitch muscle fibres and therefore stamina. It also provides much of the energy for explosive exercise, which cannot be met by energy from the anaerobic process alone. Training the horse to facilitate aerobic metabolism, is advantageous to performance in all disciplines as a result of the elevated ATP production.

"With training, horses have a higher number of mitochondria and enzymes in their muscles, which produce more energy. Training also increases the blood's ability to carry oxygen to the muscles, through increased haemoglobin concentration in blood. Training allows horses to carry out aerobic energy production more efficiently...."

The article goes through a variety of information about feeding fat to horses. "Horses exhibit a preference for vegetable oils over animal fats (Potter n.d.).", thank heavens, but that got me worried about the ill effects of vegetable oils on horses...

"The Link Between Dietary Fats and Cancer.

"In humans nd [sic] rodents, dietary fats have been implicated in carcinogenesis, partly via the mechanism of oxidative DNA damage (Loft et al 1998). Loft et al (1998) found high total energy intake (rather than simply high fat intake), to be the major cause of oxidative DNA damage in rats, irrespective of degree of saturation of dietary fat consumed. D'Aquino et al (1991) reported that unlike coconut oil, fish oils are highly susceptible to oxidative deterioration and challenge the antioxidant defence system in rats, thereby increasing susceptibility of tissues to free radical oxidative damage.

"An experiment involving tumour-bearing mice indicated that the level of dietary linoleic acid consumed was proportional to the weight of their tumours and to the number of macroscopic metastases. Mice that consumed proportionally more saturated fatty acids (in the form of coconut oil) had lighter tumours and fewer macroscopic metastases (Rose et al 1993).

"Reddy (1992) noted that diets containing coconut oil, olive oil or fish oil had no colon-tumour enhancing effects regardless of whether they were fed at rates of 23% or less. However rats fed diets containing 23% corn oil, safflower oil, beef tallow or lard had increased incidence of colon tumours.

"The links between dietary fats -their type and level of consumption- and impact on CHD and carcinogenesis are poorly understood. However, it appears that coconut oil may play a non-promotional role with regard to carcinogenesis...."

I won't get into beef tallow at the moment, but I agree that feeding lots of linoleic acid to anything is a bad idea.

"Benefits of Feeding Fat

"Fat supplemented diets for horses have proven to be beneficial beyond that mentioned above. Adding fats to the diets of growing and breeding horses has increased milk energy yield in lactating mares and increased growth rate in weanlings (Scott et al 1989; Davison et al 1991). However, the most exciting effects of feeding fat to horses have been observed in the equine athlete.

"The effect of fat supplementation on muscle glycogen storage and utilisation has been widely tested. Other areas - such as effect of extra dietary fat on thermoregulation, energy requirement, management of Equine Rhabdomyolysis, and other exercise parameters - have also been explored...."

Needless to say, read the whole thing. I regard the effects of a fat-based diet on human athletes as somewhat contradictory. Glycogen storage is reduced, according to some studies, but according to others, training in the fasted state increases glycogen stores. I was looking for information to shed some more light when I came across this article. I find it very interesting that a fat-based diet is a full-on benefit to glycogen management in horses. After all, in some respects, humans are better runners than horses...

Of course these folk are selling fat-based feeds for horses, so they have an axe to grind, but it seems consistent with what I've been reading about other species.

I'm beginning to come around to Gary Taubes' view... Easily-digested carbohydrates may be best avoided, regardless of what species you are.

"Should We Feed Fat to Horses?

"Current research indicates that fat supplementation is a viable energy source for performance horses which is of greater benefit than simply caloricifically. However, almost all studies investigating the effects of fat supplementation on horses have been relatively short term, involved a small number of horses and produce results which are not always highly repeatable. In order that more confidence be placed in the long term feeding of fats to horses, studies need to be of longer duration, involve more horses and more consistent results are necessary. The best type of fat for horses should also be ascertained...."

Sounds to me like these folks are on the right path.

P.S. 10/15/2024

I re-read this today and it occurred to me that the likely issue here isn’t easily-digested carbs vs. fat, as I thought in 2012, but Ω-3 vs. Ω-6. One of the things we discussed with Prof. Hulbert was how the Omega Balance (Ω-3/(Ω-3+Ω-6)) affects insulin resistance, something I wasn’t really aware of back then. Well, one of his points is that Ω-3 fats are leaf fats, and Ω-6 fats are seed fats. So shifting from a pasture diet to a grain diet should also entail a shift away from Ω-3, and a lowering of the Omega Balance.

Sure enough:

“Effects of Ω-3 (n-3) Fatty Acid Supplementation on Insulin Sensitivity in Horses”

“Disposition index (combined SI [Sensitivity to Insulin] and β pancreatic response) increased… by 53% in the MARINE- and 48% in the FLAX-supplemented horses and did not change with time in the CON group. In insulin-resistant mares, MARINE- and FLAX-treated horses had an increase in SI…” (Hess, 2013)

And, as research continued:

“As in human nutrition, it was revealed that fats with higher levels of omega-3 fatty acids compared to omega-6 fatty acids exhibited more positive effects on many aspects of the body. This included key benefits in the areas of reproduction, bone development, red blood cell synthesis and production, and numerous inflammatory conditions in horses” (McMillan, 2016).

Unlike in human nutrition, however, this seems to be very mainstream. Even Purina, one of the leaders in ultra-processed animal foods has embraced it.

(Land O'Lakes, Inc., 2024)

“Omega-3 fatty acids (O-3) are a popular topic in equine nutrition, but it is not commonly acknowledged that a prevalent source of O-3 in a horse’s diet can be from pasture. Pasture is low fat, but O-3 are the largest fraction, and horses on pasture have higher circulating O-3 than horses without pasture access. Therefore, the objective of these studies was to test the hypothesis that a feed high in O-3 that also matches the ratio of O-3:omega-6 (O-6) in pasture, would increase stalled horses’ plasma O-3 and result in a similar fatty acid profile to pastured horses.

“Conversely, plasma O-6 levels decreased from baseline (47.21 ± 3.86) to d 30 (42.56 ± 5.47) and remained lower at d 60 (43.89 ± 4.78) in horses consuming OM (P < 0.05). At d 60, horses consuming OM had similar plasma levels of O-3 (6.29 ± 1.82 vs 6.76 ± 2.01, P = 0.45) and O-6 (43.89 ± 4.78 vs 42.36 ± 5.80, P = 0.37) as horses on pasture, respectively.” (Gordon, 2021)

Land O’Lakes, which makes human food, owns Purina.

So while human nutrition experts propose ignoring the omega balance, the veterinary world seems to to be moving ahead at fixing it.

Indeed, the addition of n-3 FA to the equine diet may improve mobility, reduce markers of inflammation, reduce lameness, and may ultimately improve athletic performance in these animals (Woodward et al., 2007; Manhart et al., 2009; Ross-Jones et al., 2014; Brennan et al., 2017; Caron et al., 2019). Additionally, there is evidence that EPA and DHA fed to adult and senior companion animals, including dogs, cats, and horses, can assist in slowing retinal degeneration, improving cognitive function, regulating the immune system, managing inflammatory airway diseases and improving insulin sensitivity (Lascelles et al., 2010; Bauer, 2011; Hess et al., 2013; Nogradi et al., 2015; Goffin et al., 2017; Pan et al., 2018; Elzinga et al., 2019). (Burron, 2024)

Original post from August 28, 2012

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References

Burron, S., Richards, T., Krebs, G., Trevizan, L., Rankovic, A., Hartwig, S., Pearson, W., Ma, D. W. L., & Shoveller, A. K. (2024). The Balance of N-6 and N-3 Fatty Acids in Canine, Feline, and Equine Nutrition: Exploring Sources and the Significance of Alpha-Linolenic Acid. Journal of Animal Science, 102, skae143. https://doi.org/10.1093/jas/skae143

Carney, A. (2012). Feeding Oil or Fat for Horses [Advertisement]. Knowledge Base | Stance Global | Horse Nutrition. https://stanceknowledge.com/feeding-oil-or-fat-for-horses

Gordon, M. E., & Jacobs, R. D. (2021). 42  Feeding stalled horses a diet high omega-3 fatty acids results in a plasma fatty acid profile similar to horses on pasture. Journal of Equine Veterinary Science, 100, 103505. https://doi.org/10.1016/j.jevs.2021.103505

Hess, T. M., Rexford, J., Hansen, D. K., Ahrens, N. S., Harris, M., Engle, T., Ross, T., & Allen, K. G. (2013). Effects of Ω-3 (n-3) Fatty Acid Supplementation on Insulin Sensitivity in Horses. Journal of Equine Veterinary Science, 33(6), 446–453. https://doi.org/10.1016/j.jevs.2012.07.007

Land O’Lakes, Inc. (2024). Omega Match^TM Ration Balancing Horse Feed [Advertisement]. Purinamills.Com. https://www.purinamills.com/horse-feed/products/detail/purina-omega-match-ration-balancing-horse-feed

McMillan, M. (2016, September 12). Feeding Fat to Horses: A Review [Advertisement]. Hi-Pro Feeds. https://hiprofeeds.com/blog/feeding-fat-to-horses-a-review/