The need for Vit D depends upon the ratio of calcium to phosphorous. The need for Vit D is increased in ducks by the lack of calcium or phosphorus by the improper ratios of these minerals in their diet. Good old sunshine is the best way for them to get their Vit D. If kepted inside or under cloudy conditions, they may not get enough sun to get the required amount. Alot of layer feeds don't contain the required levels for a optimum nutritional diet. Mazuri feed does have the recommended levels in their feed.
Recommended dosage is 200 IU/kg
You can get regular human consumption Vit D3 at Walmart, Walgreens, GNC, etc. Both forms capsulated pills or gel form can be given orally. If using capsulated form, it can be crushed up and added to the feed as well but there's a chance it won't all get eaten for optimum effect.
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