A total number of 270 Domyati ducklings at 21-day-old were used, weighed
and divided into five experimental groups to investigate the effect of dietary L-carnitine (LC)
supplementation level (0, 150, 300, 450 and 600 mg/kg) on growth performance, carcass
quality, hematological and blood serum constituents as well as economic efficiency in
summer season. The results indicated that dietary LC supplementation resulted in a
significant (P≤0.01) improvement in live body weight at 63 and 84 day of age, while body
weight gain, feed conversion ratio and production index were significantly (P≤0.01)
improved as compared to the control group during the overall experimental period (21-84
day of age). Eviscerated carcass and total edible parts (%) were significantly (P≤0.05)
improved by supplementing different LC levels to the diet as compared to the control, but
abdominal fat (%) was significantly (P≤0.01) decreased. Breast and thigh yield (%) were
significantly (P≤0.01) higher for ducklings fed diets supplemented with 450 and 600 mg
LC/kg than those fed the control diet. Dietary supplementation of different LC levels resulted
in a significant improvement in muscles (%) for both breast and thigh, while skin with
subcutaneous fat (%) was significantly decreased as compared to the control. Dietary
supplementation of different LC levels resulted in a significant (P≤0.01) increase in crude
protein and decrease in ether extract content for breast and thigh muscles than the control
group. Hemoglobin content was significantly higher for ducklings fed diet supplemented
with 300 up to 600 mg LC/kg as compared to those fed the control diet. Lymphocytes (L)
cells (%) was significantly (P≤0.01) increased, while heterophils (H) cells (%) and H/L ratio
were significantly (P≤0.01) decreased for ducklings fed diets supplemented with different
LC levels than the control. Serum triglycerides constituent was significantly decreased for
ducklings fed diets supplemented with different LC levels than those fed the control diet,
while, total cholesterol was significantly decreased by feeding these diets except for 150 mg
LC/kg diet which was insignificantly decreased. Economic efficiency was significantly
higher for ducklings fed diets supplemented with different LC levels, while, 300 and 450 mg
LC/kg diet recorded the best values than those fed the control diet .