Hey chicken whisperers. The newbie here has been voraciously reading everything I can get my hands on to figure out how to tend my 5 pullets. From Storey's Guide to Raising Chickens, I came across this advice:
"To balance the calcium supplement, offer phosphorus in the form of defluorinated rock phosphate or phosphorus-16 in a separate hopper and make it available at all times."
Not only can I not find a source to purchase this supplement, but employees at my local feed store have never heard of the practice.
Thoughts?
and you won't find it, either.
Offering phosphorus separately has gone the way of the dodo.
**Most** biological processes (except shell creation), use calcium and phosphorus at a ratio of 2:1. So you will frequently find (non-layer) chicken feed formulations with around 1% calcium +/- 0.25% with phosphorus at 0.5%. Chickens can't process phytate - which is the primary means by which plants store phosphorus. Phytates also block absorption of a number of important things - iron, magnesium, calcium, zinc (among others). Your guaranteed feed label will show non-phytate phosphorus, which they can use.
I like to look for a feed with 0.6% - 0.7% phosphorus, because moderrn science has found that chickens aren't quite as efficient at absorbing phosphorus in the diet from non-phytate source as they are at absorbing calcium.
When that's not available, and you are concerned for phosphorus levels (either due to a knowingly deficient feed, or free ranging on deficient soils), you should suppliment with
dicalcium phosphate or calcium diphosphate instead of oyster shell. SO sayeth the research. and as an added bonus, "excess" phosphorus acts as a buffer against calcium toxicity, protecting young birds, roosters at all ages, etc somewhat from that condition. While those substances are primarily used elsewhere in the world, where calcium in the form of oyster shell is not readily available (such as the Mediterranean Basin), they are available here in the US and Canada with a bit of searching (
Amazon, NOT the farm store!)
Hope that helps.
and yeah, I read Storey too.
