Balancing Ca:Ph ratio by adding limestone flour - HELP!

[Spyda]

I feed Copra which has the Cah ratio of 0.07% Ca : 0.51% Ph

Does anyone know how much limestone flour I'd have to add to a dry Kg of Copra to balance the Ca ratio?

Or how I can work it out?

 

[Nocturnal]

My maths is terrible, so someone feel free to correct me, but I think that means it has 0.7g of calcium per kg and 5.1g of phosporus. So you need an extra 4.4g of calcium for every kg of copra. You'd have to check your brand of limestone flour to see how much calcium is in it, but in Baileys there is 39.4%, which means you'd need to feed about 11g of limestone flour.

I think.

 

[Ali2]

Please bear in mind that this only balances the copra and does not take account of the rest of the diet!

We'll assume you are aiming for a Ca ratio of 2:1

Copra, per kg, provides 0.7 g of Ca and 5.1 g of P. In order to get the 2:1 ratio you need to provide a total of 10.2 g of Ca so you need to add (10.2-0.7) = 9.5 g of calcium per kg of Copra.

Limestone flour is 39.4 % Ca so you need to add ((9.5/39.4)x100) = 24.1 g of limestone flour per kg of Copra.

 

[Spyda]

Brilliant, that's a great help

 

[Mike007]

Not so fast!!. Unfortunately it doesnt quite work like that. An inconvenient fact that is regularly overlooked is that im many feedstuffs ,Phosphorous is bound up (Chelated) by Phytic acid and the animal can use part of it. Think in terms of 50 to 70% unavailable to the horse. Unfortunately because it is difficult to assay ,it is often overlooked . I do wonder how many feeds with supposedly carefully ballanced Ca/P ratios of the ideal 2 to 1. really have anything like that. Your Copra has about 0.2% available Phosphorous. My figures for Copra are Ca 0.12% and P 0.43 by the way,but obviously there is some variation.If all the rest of the horses feed has been carefully and methodicly"ballanced" ignoring phytic phosphorous, you are in danger of unballancing tha ratio the oposite way with too much Calcium.

 

[Spyda]

Not so fast!!. Unfortunately it doesnt quite work like that. An inconvenient fact that is regularly overlooked is that im many feedstuffs ,Phosphorous is bound up (Chelated) by Phytic acid and the animal can use part of it. Think in terms of 50 to 70% unavailable to the horse. Unfortunately because it is difficult to assay ,it is often overlooked . I do wonder how many feeds with supposedly carefully ballanced Ca/P ratios of the ideal 2 to 1. really have anything like that. Your Copra has about 0.2% available Phosphorous. My figures for Copra are Ca 0.12% and P 0.43 by the way,but obviously there is some variation.If all the rest of the horses feed has been carefully and methodicly"ballanced" ignoring phytic phosphorous, you are in danger of unballancing tha ratio the oposite way with too much Calcium.

I'm feeding sugar beet (500g dry), copra (500g dry), dried grass (1kg), linseed meal (350g), a complete supplement and Cortaflex HA per day. Plus 7kg good hay at night and access to 6 hrs of winter grazing during the day.

 

[Nocturnal]

Ok, clearly I'm missing something. Could someone please explain this 2:1 ratio for me? What I understood was that phosphorus needs calcium in order to be absorbed into the body, and if there is not enough available calcium then it can be leeched from the bones. But the literature I've read only recommend at least as much calcium as phosphorus in the diet, not a 2:1 ratio.

ETA: Feeding more than 3x the RDA of calcium can cause inbalances in the absorption of other minerals, and judging by how much phosphorus is in my horse's diet, this would be a risk.

 

[Spyda]

Ok, clearly I'm missing something. Could someone please explain this 2:1 ratio for me? What I understood was that phosphorus needs calcium in order to be absorbed into the body, and if there is not enough available calcium then it can be leeched from the bones. But the literature I've read only recommend at least as much calcium as phosphorus in the diet, not a 2:1 ratio.

ETA: Feeding more than 3x the RDA of calcium can cause inbalances in the absorption of other minerals, and judging by how much phosphorus is in my horse's diet, this would be a risk.

Here's a useful link giving a bit more info http://www.understanding-horse-nutrition.com/calcium.html

Excerpt:

Calcium Toxicity
It has been thought in the past that osteochondrosis may be caused by excess Ca in the diet. However, in many studies, Ca has been fed at high levels (sometimes exceeding 5 times the recommended daily intake) with no ill effects, provided that the calcium : phosphorus ratio remained correct.
So it would appear that an imbalanced Ca ratio is of much more concern than excess dietary Ca intake.

Calciumhosphorus Ratio
The ideal Ca ratio in horse diets is the range of 1:1 to 2.5:1. If the ratio falls below 1:1, Ca absorption will be impaired, causing a Ca deficiency.
Ratios as high as 6:1 may be acceptable in growing horses, provided that the amount of phosphorus in the diet is adequate.

 

[Nocturnal]

Here's a useful link giving a bit more info http://www.understanding-horse-nutrition.com/calcium.html

Excerpt:

Calcium Toxicity
It has been thought in the past that osteochondrosis may be caused by excess Ca in the diet. However, in many studies, Ca has been fed at high levels (sometimes exceeding 5 times the recommended daily intake) with no ill effects, provided that the calcium : phosphorus ratio remained correct.
So it would appear that an imbalanced Ca ratio is of much more concern than excess dietary Ca intake.

Calciumhosphorus Ratio
The ideal Ca ratio in horse diets is the range of 1:1 to 2.5:1. If the ratio falls below 1:1, Ca absorption will be impaired, causing a Ca deficiency.
Ratios as high as 6:1 may be acceptable in growing horses, provided that the amount of phosphorus in the diet is adequate.

Thanks for that . So it is at least 1:1 that is recommended and not nec. 2:1. This article http://www.iceep.org/pdf/iceep2/_1129110000_001.pdf is where I read that 3x RDA of calcium should be avoided (excerpt starts 4th page, last paragraph). It doesn't mention osteochondrosis, just a disruption of the absorption of other minerals as a result of too much calcium.

 

[Ali2]

Not so fast!!. Unfortunately it doesnt quite work like that. An inconvenient fact that is regularly overlooked is that im many feedstuffs ,Phosphorous is bound up (Chelated) by Phytic acid and the animal can use part of it. Think in terms of 50 to 70% unavailable to the horse. Unfortunately because it is difficult to assay ,it is often overlooked . I do wonder how many feeds with supposedly carefully ballanced Ca/P ratios of the ideal 2 to 1. really have anything like that. Your Copra has about 0.2% available Phosphorous. My figures for Copra are Ca 0.12% and P 0.43 by the way,but obviously there is some variation.If all the rest of the horses feed has been carefully and methodicly"ballanced" ignoring phytic phosphorous, you are in danger of unballancing tha ratio the oposite way with too much Calcium.

I hadn't appreciated that (and really should have done!), make sense though