Vitamin D & how much sun required?

[fatcatx]

We live in a hot summer climate so we placed our coop with heat control in mind. Only a VERY small portion of the run gets full sunlight for 1-2 hours a day. The top birds hog the spot for sunbathing. The rest are stuck in the shade all day. Will I need to add Vitamin D to their diet/water to compensate? How much should I add? Should I wait until they are laying to check egg shell quality before supplementing?

I guess to get to the point - how much sun do they need to get for proper Vitamin D absorption?

 

[chfite]

Sunshine notwithstanding, the chickens should get adequate Vitamin D from their commercially prepared feed.

Chris

 

[fatcatx]

It is in their feed but I've read quite a few thread re: shell quality and D deficiency. In all cases they were on a balanced feed. Wondering if anyone knows how much sun is required (for humans to get Vit D it is pretty small - like 30 minutes per day) or ideas on how much to supplement if necessary.