Ninety-six crossbred ducks fed with shrimp by-products (SBP) were used in this experiment, in which four
experimental diets were fed following a factorial design, with 3 replicates of 4 ducks (1:1 sex ratio) in one experimental
unit. The first factor was the digestion technique (ileal and total tract digestibility) and the second factor was the diets.
Four diets included a basal diet (SBP0), which consisted of fish meal 20% (FM), broken rice 80% (BR) and the other
three diets, in which the content of FM was 25.0, 50.0 and 100% of the FM level in the basal diet and was replaced by
ensiled shrimp by-products corresponding the SBP1, SBP2 and SBP3 diet, respectively. Daily intakes of ether extract
(EE) and fiber fractions increased with increasing levels of SBP. The apparent total tract digestibility of dry matter
(DM), organic matter (OM), ether extract (EE), and nitrogen-free extract (NFE), as well as nitrogen retention, decreased linearly with increasing SBP (P acids was greater than their apparent ileal digestibility (P (P

Keywords | Crossbred duck, amino acids, ileal and excreta digestibility, shrimp by-products,