Arizona Hoof Rehab

Type of plant :
In general, C3 cool season grasses like orchard, timothy, brome, crested wheatgrass are higher in NSC (carbohydrates)than C4 warm season grasses like Bermuda, summer prairie grasses, and other grasses of tropical origin. This is because C4 grasses store starch instead of fructan. Starch forms in specialized organelles in the grass. When those organs are full, starch production stops, so starch production is self-limiting. In C3 grasses, fructan is stored in various places all over the plants and can continue as long as conditions are conducive to formation of sugar, while growth is limited.

Varietal differences:
Even grass of the same genus and species, but of a different variety, may differ in NSC content, even under the same conditions. So one kind of Kentucky bluegrass (timothy, orchard, etc.) may plant metabolismbe significantly different from another variety of Kentucky bluegrass. ... The only varieties I have tested under my 'worst case environmental conditions' that are consistently safe for an insulin resistant, chronically laminitic horse are native species. Unfortunately, these low sugar grasses are going to be extremely difficult to maintain under intensive grazing. They will have lower yield potential, and will die out quickly if overgrazed. Those wishing to grow low sugar hay may have to be content with one cutting per year, and half the production of high NSC species. Please do not think that just planting native grass will solve your problems. Information on the best management practices necessary to maintain native species under intensive grazing do not exist, and may not even be possible. A system of rotational grazing will be imperative. Native grass seed is expensive, and establishing a native grass pasture may require a full year for establishment before it can be grazed at all. If you want to experiment, start with a small section of pasture to see which species will live under your environmental conditions and management practices.

Species like orchard, timothy, fescue, Kentucky bluegrass and perennial ryegrass have the highest genetic potential for NSC. These grasses are generally consider 'best' due to their relatively higher nutrient content, and palatability. They are prized by horse farms raising 16 hand 2 YO TB's ready for racing, and cattle producers. I have frequently found these to be 25+% under worst case environmental conditions. This is about twice the NSC that an insulin resistant horse should get. No wonder our horses like them! Perennial ryegrass is usually the highest in studies comparing NSC content of grasses in studies done all around the world. I'm calling it the Quintessential Founder Fodder. If your climate is cloudy, you may still be able to find batches of hay of these species that are appropriate for a carbohydrate intolerant horse. Remember: environmental conditions are more important than genetic potential! Some TB's are slow and lazy; some orchard grass may be low in sugar. Don't buy a racehorse without a watching him run, don't buy hay for an lamintic horse without testing for NSC.

Grain Hays:
In general, avoid hays made from grain crops like oats, wheat, barley, rye or triticale. These have been selected for high starch content and when cut in flower stage these are full of sugar held ready for use by the developing seed. I have samples of oat hay grown in Colorado, and 3 way forage (wheat, oats, rye) grown in California that were over 30% NSC, over twice average. According to the database at Dairy One, oat hay averages 22% NSC, with a normal range of 15-29, while other grass hays average 13.8 with a normal range of 9-18. You may get lucky and find some in the low range, but make sure you test before feeding grain hays to a carb intolerant equine.

Legumes-alfalfa and clover:
There is a lot of conflicting data regarding carb levels. They will test high in NFC, but nearly half of that may be pectin, which is a safe form of carbohydrate. The NSC, or sugar and starch, of legumes is variable with stage of growth and environmental conditions, but generally lower in NSC than grass growing next to it. Neither alfalfa nor clover has appreciable levels of fructan. There is anecdotal evidence of horses foundering on straight alfalfa, but this may well be from excess protein, or other as yet undetermined factors that may include phytoestrogens or fungal toxins produced by pathogens infesting the legumes. Clover may have much higher levels of phytoestrogens under certain growing conditions. I am not aware of any research on the effect of phytoestrogens on horses, but some of the effects documented in sheep, including infertility and permanent changes in sexual organs, cause me concern.  I have spoken to vets who felt that clover was involved in worsening of symptoms in equines with metabolic dysfunction, so we have to at least consider it a risk factor for horses prone to laminitis of metabolic origin. It should be important to note that laminitis experts in the UK do feel that alfalfa (they call it lucerne) is an appropriate ingredient in feeds tailor made for laminitic equines. But also note that the cloudy climate is such that the alfalfa grown there is very different from the high quality alfalfa such as grown in the US. Because really high quality alfalfa in the SW of the US can average up to 25% protein, which can be utilized as energy when in such excess, and up to 20% NSC, this type of forage is totally inappropriate for any horse prone to laminitis, unless fed in small quantities. A lot of horses seem to tolerate straight alfalfa diets fairly well, while some horses cannot tolerate any alfalfa. Perhaps a horses’ particular metabolic make up will determine it’s sensitivity? My severely insulin resistant horses are doing very well with up to 20% of their diet as mature, stemmy, alfalfa, so I’m not too afraid of a little bit. If the protein of the available grass hay is less than about 8-9%, your horse might tolerate a small amount of mature, stemmy alfalfa, with a lot of purple flowers. Avoid the premium, dairy quality stuff, which unfortunately is far more common. Be careful, so slow, be observant, and keep it at a minimum to provide adequate, but not excessive, protein.

How grass is being changed

My most recently planted grass paddock was established in conjunction with a research project that required a ‘common commercially standard variety’. Around here, that’s Regar brome, (Bromus riparius)an 'improved' variety developed for intensive grazing and high quality hay production. When I first allowed my most grass sensitive horse to graze in that paddock for 30 minutes, she was sore footed within 48 hours. When I started looking into the reasons why, I emailed and phoned several grass seed companies who recommend this and other nutrient dense grass varieties for horse pasture. I asked ‘what is the criteria for choosing these varieties for horse pasture?’ They said ‘Relative Feed Value’, to which I asked, ‘And how is that determined?’ and they said’ by feeding trials maximizing milk production in dairy cows’. To which I asked, ‘so why would I want to feed my horses like dairy cows?!’. And they said ‘ hey, lady, we don’t do the research, we just give the horse people what they want, and they say they want the best'. Well, perhaps we had better evaluate what ‘the best’ is, and how forage breeders are changing our grass.

These feral, free ranging horses on the Navajo Indian Reservation at Shiprock, NM look fat and healthy eating this sparse, native grass. This picture was taken after a wet winter and spring. This is actually far more green vegetation than in previous years. If this type of grass is what Indian ponies are supposed to eat, no wonder they can't handle the forage developed to fatten cattle. Interesting to note that Native Amercians in this area are known to have extremely high rates of Type 2 diabetes, since they have been eating the typical white man's diet.

Forage research and breeding is focused on fattening animals intended for meat, and producing the most milk out of a dairy cow who’s productive life is not more than 5-6 years. I have been looking everywhere for a forage expert on equine specific forage issues, and I can’t find one. (if you are out there, please contact me). What is considered the ‘best’ pasture grass for cows is just assumed to be the same for horses. It may be great if you’re going to eat a cow when it’s 2 years old. Not so great for a pony that you want to keep healthy until he’s well beyond 30 years old. Brood mares, or extremely athletic horses may benefit from these nutrient dense forages. But for the average recreational horse, and for many of the ‘easy keeper’ breeds, this may be way too much sugar. Throw in the fact that we have a lot of new, inexperienced horse owners, and grain companies who are telling them that horses are supposed to eat grain (which I dispute for 90% of the horse population) only adds to the problem.

People say 'But horses evolved to eat grass', but they don't realize that grass has changed, and plant breeders are on a fast track to make grass even more nutrient dense and easily digestible to maximize nutrition in cattle and sheep. The ability to store carbohydrates, in particular fructan, is intrinsically linked to winter-hardiness in cool season grasses, as well as early spring growth in cool conditions, and adaptation to other stress factors such as drought, salt tolerance, or even optimum growth under low management inputs. Even if not part of the selection criteria of the plant breeder, those grasses selected for these traits will be higher in both sugar and fructan. Knowing that many horse owners are not well versed in farming, forage specialists may feel obliged to recommend those varieties that may withstand abuse and neglect for horse pasture, and those may be highest in non structural carbohydrates.

Many people think they have native grass in their pastures, because it was never purposely planted. This does not assure that your horses graze native species. Very little native grass pasture has survived in the United States due to incursion of 'naturalized' grass species that were introduced by early settlers. Native grass will not survive continuous grazing by animals in small pastures. Species that developed in cool regions of Europe, where intensive grazing had been practiced for centuries were introduced by settlers in the late 1800's. Hungarian, or smooth brome now flourishes over most of the United States, pushing out less competative native species.Because brome is high in NSC, it has a competative advantage, especially when native species are weakened by over grazing.

Plant breeders are selecting grass with lower fiber content, and changing the chemical structure of fiber so that it is more digestible. When feeding cattle, it’s most efficient to get them to eat as much as possible. Get them fat; get them to the packers. To increase palatability, and therefore intake, new varieties of pasture grasses have been purposely selected for high sugar and fructan content, and lower fiber, so they don’t feel so full. Dr. Hank Mayland , of USDA has done work to encourage hay growers to cut hay in the afternoon, when sugar levels are higher. (Please note the list of researchers at the end who are involved in studying and increasing carbohydrate content in forage.) In feeding trials with horses, cattle, sheep and goats, animals preferred hay cut in the afternoon over the same hay cut in the morning. [Mayland, 2000)] Remember our discussion above about diurnal fluctuations? Grazing animals like sugar just as much as we do. Whether or not it’s a good diet for an animal expected to live 30 years will be up to equine nutritionists to prove or disprove, and I’m not even sure they realize that the new grass varieties are different...

Mayland, Shewmaker, Harrison, Chatterton, (2000) Nonstructural Carbohydrates in Tall Fescue Cultivars: Relationship to Animal Preference, Agron. Jrnl Vol. 92, No. 6