Prolonged thymol dietary supplementation does not affect liver morphophisiology of laying quails

LABAQUE, M. C.; BALLESTEROS, M. L.; FERNANDEZ, M. E.; KEMBRO, J. M.; MARIN, R. H.

Plougan

Simposio; Xth European Symposium on Poultry Welfare; 2017

World's Poultry Science Association

Phytogenic feed additives, such as thymol, operate as growth and health promoters, which could lead to major improvements in modern intensive poultry production. The concentration of phytogenics appears to be one of the most important factors in achieving the aforementioned effect. However, conflicting results have been reported regarding thymol influence on histopathology/toxicology of organs such as the liver. We assessed semi-quantitative potential histopathological changes in quail liver caused by a 4-week dietary supplementation with thymol and the effect of a recovery period following cessation of dietary supplementation. Fifty adult female quail were randomly assigned to 1 of 10 treatments depending on the diet supplied (CONTROL: basal diet; VEHICLE: basal diet plus ethanol; THYMOL80, 160 and 250: basal diet supplemented with 80, 160 or 250mg of thymol/day/animal, respectively) and whether the birds went through a 3-week recovery period (R) or not (NR). In 89% of the livers, regardless of treatment, lipid degeneration was observed, which may be due to high food intake or to the bird´s reproductive status (laying). Reversible changes such as sinusoidal dilatation and vascular congestion were found in 35% and 26% of livers, respectively. Small necrotic foci (12%), oval cell foci (5%, associated with tissue regeneration), infiltration (