Differential responsiveness between broiler and layer embryos upon different doses of L-carnitine administration. 1. Hatchability and blood parameters

L-carnitine enhances the transport of long chain fatty acids through mitochondrial membrane. It can be produced by animals' organism from lysine and methionine. However, it was reported that chicken embryos have a limited capacity to synthesize L-carnitine. For this study, hatching eggs from Ross and Isa Brown breeders of 35 wk old (600 eggs per line) were used. At d 18 of incubation, eggs from each genotype were divided into 4 groups i.e. control eggs, Saline (injection of saline solution), eggs injected with L-carnitine of 500 μmol (LC500) or 1000 μmol (LC1000). At hatch and 7 d post hatch, blood samples were collected for triglyceride, glucose, total protein, uric acids, triiodothyronine (T3), thyroxine (T4) and corticosterone concentrations determination. Results indicate that hatchability and percentage of chick of optimal quality were higher in Ross than Isa Brown. Overall, layer chicks had higher levels of T4, total protein and uric acid than broiler chicks. With regard to L-carnitine injection, eggs of LC1000 groups had the lowest hatchability and this negative effect was more pronounced in Isa Brown eggs. At hatch and 7 d post-hatch, control chicks had the lowest levels of triglyceride and T3 but the highest levels of T4. At 7 d-old, the highest and the lowest levels of corticosterone were obtained in chicks of LC1000 and LC500 groups, respectively, compared to control and saline groups. In conclusion, L-carnitine administration during embryonic life affected differentially hatchability and blood parameters during post-hatch juvenile growth and this in a dose dependent manner. © Verlag Eugen Ulmer, Stuttgart.