How to solve the problem that Cherry Valley Duck is easy to peck when it is gasified?

At the end of this post, edited by majj2006 at 11:10 on 2009-12-17, dry Cherry Valley ducks are prone to hair pecking in the climate change season. is it the result of nutrition or stress? Metabolic energy 2650, crude protein 14.5%, lysine 0.7%, egg + cysteine 0.62%, the main raw materials are corn, secondary flour, rice bran, rapeseed meal, brewer's grains, DDGS, feather powder, palm kernel meal; water-raised ducks do not have this phenomenon. After 45 days of feeding, it weighs about 7 jin. Majj2006 added the following at 11:07 from 2009-12-17 11:07: lysine content should be 0.7%-if you calculate the sulfur amino acid content, you can consider adding sulfur ion raw materials: sodium sulfate, calcium zinc sulfate ion content You can consider adding zinc methionine in 2009-12-17 12:26 to add the following, as well as the addition of anti-stress drugs of sodium ions, or farm self-supplement-0.62% sulfur-containing amino acids, 2.5kg sodium sulfate, 2.2kg salt, no gypsum powder. There is no phenomenon of pecking hair in cherry valley ducks raised in ponds, but there is a phenomenon of pecking in dry land, which is more common. -the effect of adding gypsum powder is obvious. You may consider adding some gypsum powder to try, but why only use dry Cherry Valley Duck to peck at the feathers of the same material? Is there no such phenomenon raised by the pond?