Abstract
The present study aimed to evaluate the influence of dietary supplementation of different levels of L‐carnitine and/or lysine–methionine (Lys‐Met) on reproductive performance of breeder ducks. Three L‐carnitine (0, 75 and 150 mg/kg) and three lysine–methionine (100%, 110% and 120% above the NRC (
Nutrient requirements of poultry
, 1994, National Academy Press) recommendations) levels were fed to 180 breeder ducks (144 females and 36 males) in a completely randomized design for 49 days. Laying performance and reproductive traits were evaluated; additionally, uric acid, total protein total, triglycerides, total cholesterol, low‐density lipoprotein, high‐density lipoprotein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were assessed. The Lys‐Met above 100% NRC (
Nutrient requirements of poultry
, 1994, National Academy Press) recommendations with or without L‐carnitine improved feed utilization (
p
< .05). Furthermore, Lys‐Met above 100% recommendations without L‐carnitine improved egg fertility and hatchability. Fertility and hatchability improved in breeders fed on L‐carnitine with 120% Lys‐Met (
p
< .05). Serum glucose increased and total cholesterol reduced on 100% Ly‐Met without L‐carnitine or 110% Ly‐Met with 150 mg L‐carnitine (
p
< .05). Glucose was reduced, while total cholesterol increased on 75 mg L‐carnitine and 100% Lys‐Met (
p
< .05). Increasing Lys‐Met without L‐carnitine reduced serum protein (
p
< .05). Albumin and ALT increased on 75 mg L‐carnitine–100% Lys‐Met and reduced on 150 mg L‐carnitine–120% Lys‐Met (
p
< .05). There were no interaction effects on globulin, uric acid and AST (
p
> .05). Thus, based on findings, breeder ducks responded to dietary Lys‐Met more efficiently than L‐carnitine; however, more research is needed to evaluate also economic aspects related to L‐carnitine dietary supplementation.