Dietary supplementation with Thymol reduces Japanese quail fear behaviour.

LABAQUE, M. C.; KEMBRO J. M.; LUNA A.; MARIN R. H.

Nantes

Congreso; XVIII Congress of the World Veterinary Poultry Association; 2013

In recent years, dietary supplementation with essential oil or their compounds has been proposed as an animal nutrition strategy because they could possess a variety of beneficial bioactive properties. In poultry, Thymol (main compound of Oregano essential oil) has been shown to improve the oxidative stability of eggs and meat during storage. In vitro evidence shows that Thymol can also act as a positive allosteric modulator of the GABAA receptor, similar to its analogue phenolic compound Propofol, but with significantly lower potency. Thus, it is conceivable that Thymol would show fear reducing and/or sedative properties. The present study evaluates potential fear reducing properties of Thymol feed supplementation and its potential effects on locomotor activity by assessing adult Japanese quail (N=168) behavioral responses respectively during brief mechanical restraint (5 min) and open-field (10 min) tests. Quail were exposed to feed supplementation with Thymol (2000 mg/Kg balanced food), Control (Vehicle), or Butylated hydroxytoluene (2000 mg/Kg balanced food) (a synthetic phenolic antioxidant compound massively used in poultry industry). All birds were evaluated after 2 and 15 days of supplementation. During brief mechanical restraint the latency to struggle was shorter (lower fear response) in the Thymol than in the Control group (Fig. 1a), suggesting a fear reducing effect of this compound when incorporated into diet. No differences were observed between dietary suplementation groups during open-field testing (Fig. 1b-d), although overall latency to ambulate (Fig. 1b) was significantly lower the second time the birds were evaluated (after 15 days) in comparison to the first time (after 2 days of supplementation), which suggest a rapid habituation to this test. No sedative effect of Thymol was detected. As expected in both behavioral tests Butylated hydroxytoluene did not differ from control groups. Also, body weight was also measured before and after supplementation and no changes were observed between groups. Our results suggest that dietary suplementation with Thymol have added beneficial properties by lowering bird?s behavioural fear response when exposed to a stressful situation, without neither causing sedation nor decrease in body weight. Future studies are necessary to further explore the anxiolytic properties of Thymol as a dietary supplement.