Effect of Dietary Supplementation with a Herbal Extract on Growth Performance and Meat Quality in Quails Raised under Thermal-Neutral and Heat Stress Conditions

The present study was conducted to evaluate the effect of dietary supplementation of the herbal extract on growth performance, carcass yield, and meat quality in quails raised under thermal-neutral (TN) and heat stress (HS) conditions. For this purpose, a total of 384 one-day-old Japanese quail chicks (Coturnix coturnix japonica) were randomly allocated to 4 treatments in a 2 × 2 factorial arrangement with two levels of dietary herbal extract (Digestarom® Poultry; 0 and 100 mg/kg of diet) and two thermal environments (TN and GS). A corn-soybean meal-based diet was prepared for starter and grower phases according to NRC (1994) recommendations. Growth performance along with carcass and meat quality characteristics including color, pH levels, L* , a* , and b* values, cooking loss, and water holding capacity were recorded. Heat stress negatively affected the feed intake of birds during the second phase of the experiment (P < 0.001). Meat pH levels were decreased at the 15th minute postmortem in quails subjected to HS (P < 0.05), while other meat quality parameters were not affected. The HS also had no significant effect on blood stress indicators such as heterophil/lymphocyte ratio or malondialdehyde concentration. The herbal extract could not extremely improve growth performance and meat quality in quails, but it helped to some extent to buffer the negative effects of HS. In conclusion, it seems quails have a high tolerant capacity and the beneficial effect of dietary herbal extract addition might be achieved when quails are subjected to higher thermal conditions.