The effects of dietary oleuropein and organic selenium supplementation on performance and heat shock protein 70 response of brain in heat-stressed quail

Abstract

The study aimed to investigate whether dietary supplementation of oleuropein (O) alone or with organic selenium (OSe) will show the similar effects as the dietary supplementation of α-tocopherol acetate (TA) on performance, blood Heterophil/Lymphocyte ratio (H/L ratio) and brain Hsp70 gene in Japanese quails reared under heat stress (34°C). A total of 800 Japanese quails were kept in wire cages in a temperature-controlled room at either 22°C (thermoneutral, TN) or 34°C (heat stress, HS) for 8 h/days and fed 5 different dietary treatments. Quails were fed on a basal diet (NC) or the diets supplemented with TA (TA200) or O (O200) at 200 mg/kg alone or with OSe (TA200+OSe and O200+OSe) to NC. HS decreased the final body weights (BWs) (P<0.05), the body weight gains (BWGs) (P<0.01) and feed intake (FI) (P<0.05) and also deteriorated feed conversion ratio (FCR) (P<0.05) of quails from 21 to 35 d of age. Moreover, feeding with the TA200, O200, TA200+OSe and O200+OSe diets increased final BWs and BWGs and FI of quails from 21 to 35 d of age (P<0.05). While HS increased blood H/L ratio (P<0.05) and brain Hsp70 gene expression (P<0.001). All dietary treatments except the NC diet on blood H/L ratio and O200+OSe on brain Hsp70 gene expression had positive effects. Consequently, the present study showed that supplementation of O alone or with OSe eliminated the deleterious effects of heat stress on growth performance, blood H/L ratio and brain Hsp70 gene expression of Japanese quails.