questions: asking for the veterinary expert. 
 answers:  the intestine if chicken & non edible portion ( except plumage  plumage are nothing but a caratanised stracture [a protein]   can be given after melting   in other animal  diet after processing   )mineral & other constituent which are agreable for duck- can be given as diet, after processing i.e by adding salt & mineral in required amount to increase the palatability of feed