Discussion on Silica (and Denta and Urinary Ailments)

[Pipp]

Can anybody find (or figure out) a silica content chart in varieties of hay and also in veggies, etc? I found one with wood and a few hays, but nothing with veggies. (It was interesting that willow leaves had high silica content, I'm going to look into that for Pipp).

Here's my post in the latest hay thread...

Pipp wrote:

I'm not convinced Bermuda is that much lower in silica content or that the local grass hay (and straw) isn't that much higher. Silica is higher in dry climates which is why the prairie timothy is good. But straw has an even higher content (although no nutrients). Texas hay could have something going for it, you never know.

BTW, I think silica is measured as a percentage of the ash content. It varies within that content, but checking the ash level in rabbit food might be somewhat relevant? I'll have to look into that.

BTW2, love to do a survey of dental health in Oregon near Mnt St Helens.

Also, the article below article isn't all that related, but I thought this was good information about dental issues in general.

excerpt from:

Dentistry of rabbits (Proceedings)

Apr 1, 2008
By: Angela Lennox, DVM, DABVP

Pathophysiology of dental disease

Dental disease is a result of anatomical or physiologic abnormalities of incisor teeth, cheek teeth, or both. Any process interfering with normal eruption of or wearing of continuously growing teeth will result in dental disease. Disease of incisors can be secondary to primary disease of cheek teeth, and vice versa. For example, primary congenital malocclusion of incisors prevents proper wearing of the incisal edges of the teeth, and subsequent overgrowth. Elongation of incisors prevents proper occlusion of cheek teeth, with subsequent overgrowth and possible development of sharp points or spurs.

Insufficient wearing has been proposed as a leading cause of acquired dental disease. This theory is based on evidence that the diet of pet rabbits often significantly differs from that of their wild European counterparts, who consume rough grasses with higher silica content. Jaw movements of rabbits consuming rough hay have a significantly wider horizontal component than rabbits consuming a concentrated pelleted diet. This decreased horizontal jaw motion in pet rabbits eating pellets may result in decreased normal wear of continuously erupting teeth.

Any process that interferes with eruption of elodont teeth can potentially impact normal occlusion. Francis Harcourt-Brown has proposed metabolic bone disease (MBD) as a potential cause of acquired dental disease. Studies have demonstrated demineralization of skull bones, lower serum calcium and higher PTH levels in severely affected rabbits. MBD produces demineralization of bone matrix and subsequent changes in skull and teeth structure, interfering with normal occlusion and wearing of continuously growing teeth.

Regardless of the initiating cause of abnormal wearing of elodont teeth, the result is elongation of crowns. Overgrown, elongated incisors may develop a number of abnormal growth patterns, including lateral deviation with or without subsequent damage to soft tissues. Elongated cheek teeth produce excessive pressure on tooth roots when the rabbit chews, causing deformation of the root, increased interproximal spaces and bending and rotation of the tooth itself. These processes contribute to increased cheek teeth malocclusion and worsening of dental disease. Ultimately bone is lost as roots perforate cortical bone. Fractures and tooth root abscesses are common sequela. In end-stage acquired dental disease of cheek teeth, eruption of teeth either is delayed or ceases altogether, and bone is reabsorbed.

 

[pamnock]

In the wild, rabbits avoid the very high silica content forages. For example, some plants evolved with a very high silica content (such as scouring rush) to make them less palatable to animals. A plant very high in silica actually feels like sandpaper - not something a rabbit especially likes to eat.

I don't believe the the minimal difference in silica content of hay makes any difference in normal tooth wear.

I had done some reading on the subject a couple years ago (silica content in forages) because I am fascinated with the scouring rush and its extremely high silica content. It's an ancient plant that has survived millions of years.

Pam

 

[Pipp]

pamnock wrote:

I had done some reading on the subject a couple years ago (silica content in forages) because I am fascinated with the scouring rush and its extremely high silica content. It's an ancient plant that has survived millions of years.

Does it come in banana flavor?

Pipp seems pretty close to grinding them down herself so I'm hoping even a tiny bit of difference may help?

I'll be on the hunt for willow leaves just in case. Although I can never get Pipp to chew the leaves, sticks and baskets I buy for her. She far prefers my clothes and my house...

But hey... This might be the ticket. How's this for a new wardrobe?

And a new house?

sas :biggrin2:

 

[naturestee]

I want that skirt... for the rabbits to eat!:biggrin2:

Pipp, I don't see anything in that article that actually compares silica in various grasses and other whole leaves for dental wear, just grass vs. pellets. With grass vs. pellets who cares what the silica content is, the chewing motion is very different and the grass requires more chewing and therefore more wear on the teeth.

Pam, do they mention scouring rush in forage studies? Or were you doing your own comparison? I didn't know anything actually ate horsetails.:?

 

[pamnock]

I know that geese will eat scouring rush and it is used by people as an herbal medicine. I don't know what else will feed on it.

I just think the stuff is so cool because it's an ancient speices of plant, so tough that it's survived for millions of years.

The silicon content is so high, you can actually feel it.

Pam

 

[Hazel-Mom]

Here's what it says (about silica in grasses and hay) in: http://www.grassbioenergy.org/downloads/Bioenergy_Info_Sheet_5.pdf

"Silica (Si) is the largest mineral component of perennial grasses. Silica content is greatly influcenced by soil type, water uptake and grass species. There can be over a 4-fold range in silica content in grass simply due to soil type. Clay soils have much more available soluble silica than other soil types. Warm-season grasses (e.g. switchgrass) have a much lower uptake of water compared to cool-season grasses (e.g. reed canarygrass), and generally contain half as much silica.
Ash content of plant parts differs, offering one option for a reduction in overall ash. Grass inflorescence typically has 5 times the silica content of stems. Grass leaves have over 3 times the silica content of stems. Delayed harvest can increase the proportion of stem remaining at harvest and lower ash content."

I have found some articles on silica content in veggies too, with charts:
jn.nutrition.org/cgi/reprint/11/1/55.pdf
journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=924612

There are others, but they are mainly abstracts, and I have no access to them from here.

 

[tonyshuman]

Silica content can also be listed as ash content in hays, I think.

edit: hazel-mom: if you give me the citation I might be able to get the article (unless it's from some really obscure journal) via the University here.

 

[Pipp]

Naturestee, that's why I noted that the article was off-topic, but it was interesting so I didn't want to loose track of it. On of the articles that got me started on this was an opinion that pre-historic horses died out in North America because of the high silica content wearing down their teeth. Long-toothed horses survived much longer than shorter toothed horses.

Pipp's teeth are from a genetic defect, but I really think I can continue to control them with diet and finding other sources of silica may be the key.

Hazel-Mom and Tonyshuman, great info, thanks! And TH, I'll take you up on trying for access to some articles, I'm constantly looking at abstracts and wishing I could access the articles.

Meanwhile, I've added 'Urinary Ailments' to the title because of this paragraph I just ran across. (I'd be pretty interested in doing an informal study into diet and environment for the bunnies on the board with stones and sludge issues).

Silica

Silica is an indigestible structural component of most grasses. Silica may affect intake rates in a fashion similar to fibrous compounds. Grasses with higher silica content generally have more rigid leaves and stems with sharper edges that can reduce harvest rates and relative bite mass. Silica can also bind with nutritious compounds in the plant to reduce digestibility. Additionally, high silica content of plant tissues can be detrimental to herbivores by promoting rapid tooth wear. Tooth wear may require culling of otherwise productive animals because they cannot bite and chew enough forage to realize their production potential. Silica content in forages may further reduce animal health by causing urolithiasis, the formation of calculi in the urinary tract.

 

[naturestee]

Is the silica absorbed? Anyway the majority of kidney/bladder stones that are tested are calcium-based anyway.

I'm also wondering about this quote from your post: Silica can also bind with nutritious compounds in the plant to reduce digestibility. Wouldn't that indicate that silica is not absorbed into the body? It would also mean that the more silica is in hay, the more it is empty fiber with few nutrients.

Have to argue on the North American horse point due to one thing: Native Americans. One major theory in the extinction of the many species of large animals in North America was due to hunting. The animals predated humans on the continent, and when humans came over the Bering Strait with their weapons and their hunting strategies they were able to quickly and easily kill many. There is a fair bit of archeological evidence for this, mainly stacks of bones of these large animals (such as horse relatives, giant sloths, etc) with arrowheads, spearpoints, and notable weapon wounds on the bones. Seriously, North America would have been a hunter's paradise back then.

:biggrin2:

Aaaaaany way, as far as narrowing down a more perfect diet for the dental-patient bunny, I'd be most interested in seeing detailed reports of grasslands of the Iberian peninsula (aka Spain/Portugal) and nutritional analyses of the most frequent food-source plants there. That's where rabbits originated and they are only elsewhere in the world due to the work of humans. So theoretically that would provide the most "accurate" diet.

I know what dry grasslands are like in the US (did an internship analyzing them) but that's not necessarily the same. Although in those cases a healthy, natural dry grassland would be grass, grass, and more grass with a sprinkling of forbs (flowering plants/others).