Intra-amniotic injection of L-carnitine reveals age-related effects on tissue total antioxidant status and increases plasma testosterone levels in male broiler chicks.

BACKGROUND

L-carnitine, derived from methionine and lysine, is present in plasma and tissues as free active carnitine in poultry. L-carnitine (L-car) plays a role in mitochondrial metabolism by enhancing β-oxidation and as an antioxidant molecule in the mitochondria. L-car synthesis is limited during embryonic development of birds. Therefore, the aim of this study was to investigate the influence of intra-amniotic injection of L-car on total antioxidant status (TAS) in tissues, plasma testosterone level and developmental parameters in male broiler chicks at the posthatching stage. The 360 eggs used as experimental material were divided into 3 groups: a non-injection group (control group) and in ovo (IO) injection groups, which were pure water (PW) group, or pure water + L-carnitine (PW + L-car) group. The 2.5 mg of L-car in 500 µl of PW was injected to fluid of the amnion membrane at day 18 of incubation. The total antioxidant status in the yolk before incubation and yolk membranes at day 19 of incubation and at hatching was analysed. Blood plasma testosterone and liver TAS levels were measured at hatching and at days 3 and 7 of age. Organ development, morphological characteristics and relative asymmetry (RA) of bilateral lengths were quantified at the same measuring days.

RESULTS

The TAS levels of yolk and residual yolk membranes decreased in comparison to the TAS in the initial yolk. The TAS in yolk membrane was higher than in residual yolk membrane in the IOPW + L-car group. Male chicks in the IOL-car group had the lowest TAS level in the liver at day 3 of age. Plasma testosterone level was significantly found higher in the IOPW + L-car group than in the other groups at all the ages. The chick development was not affected by IOPW + L-car injection. At hatching, IOPW + L-car group had shorter beak, face and middle toe lengths and lower RA of face length than control group at day 7 of age.

CONCLUSION

In conclusion, IOPW + L-car injection reveals age-related effects on tissue TAS levels and increases testosterone level interacted with the formation of the hypothalamic-pituitary-testicular axis of male broiler chicks at posthatching stage.