The present study was performed to investigate the effect of feeding citric acid with different protein levels on duck performance, carcass traits and blood parameters. A total
number of 40 two weeks old Molar ducklings were randomly distributed into 4 equal
groups, each of 10. The control diet was formulated to contain approximately crude protein
(CP) (16%) and metabolizable energy (3000 kcal/kg diet) as recommended by NRC (1994).
The first group was fed on control diet (16% CP) without any feed additives, while groups
2, 3 and 4 (T2, T3 and T4) were fed on basal diets containing 16, 14 and 12% CP respectively and supplemented with citric acid at 1.50% of the grower-finisher diet. The results
showed that, birds fed on 16% protein diet supplemented with citric acid recorded significantly the best live body weight, body weight gain, feed intake and feed conversion compared with other treatments. There were no significant differences in hot carcass
percentage, eviscerated percentage, dressing percentage and relative percentage of internal
organs (gizzard, heart, liver and spleen) between different experimental groups. There were
no significant differences in the level of serum total protein and triglycerides, while there
were significant (P<0.05) differences in serum albumin, globulin, cholesterol and uric acid
between control group and other treatments. There were no significant differences in the
intestinal pH between different experimental groups. The relative economic feed efficiency
was the highest in birds fed 16% protein diet supplemented with citric acid compared with
other treated groups. It could be concluded that, dietary inclusion of 1.50 % citric acid in
16% protein diet improved body weight, weight gain, feed intake and feed conversion ratio
and carcass traits.