Phosphate Vs Phosphite

[Maine farmer]

While quizzing the vet about the treatment of phosphorous deficiency in dairy cattle (something I have never had to do)  He was explaining that phosphite can be safely mixed with calcium, but phosphate will bind to the calcium.  He also said the phosphate was more readily available to the cow .  Having barely made it through one semester of college chemistry, I would like it if someone could explain in detail exactly why.

 

Thanks

Edited March 18, 2017 by Farming guy

[exchemist]

One of the products that is coming to light is thephosphite fertilizers manufactured using phosphorous acid (H₃PO₃). Not to be confused with the phosphate materials that are traditionally used, which are manufactured using phosphoric acid (H₃PO₄).

Thanks I'd missed this post of Farming Guy's. I do not know much about this but found the following: http://www.spectrumanalytic.com/support/library/pdf/Phosphite_Fertilizers_What%20are%20they.pdf

 

which suggests that as phosphites are more soluble than phosphates the ions may be taken up more readily. I wonder if this is what the vet was getting at when he said phosphates bind more to calcium. Lower solubility, perhaps?