¹Master Program of Animal Science, Faculty of Agriculture, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Surakarta 57126, Indonesia

²Department of Animal Science, Faculty of Agriculture, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Surakarta 57126, Indonesia

Email: ratriyanto@staff.uns.ac.id

As environmental stressors, decreased production performance due to heat stress in poultry often occurs in tropical environments. Tonic immobility (TI) is an index of fear level used to measure heat stress. This study aims to see TI’s response, body temperature, and production performance of quail raised in different floor spaces and supplemented with betaine. The study was designed as a CRD, consisting of floor space treatment (225 and 164 cm²/bird) and supplementation treatment (0% and 0.15% betaine). ANOVA test and DMRT were conducted to determine the treatments’ significance. Body temperature measurements showed that rectal, wing and average temperatures in quail with betaine supplementation were lower than the control treatment (P<0.05). The TI’s interaction showed that betaine supplementation to floor spaces of ​​225 cm²/bird and 164 cm²/bird was lower than the control (P<0.05). These results are in line with the feed, protein, and energy efficiency with betaine supplementation, which is better than the control (P<0.05). The egg production at floor spaces ​​225 cm² and 164 cm² supplemented with betaine was higher than in the non-supplemented group (P<0.05). It is concluded that betaine supplementation to ​​225 cm²/bird and 164 cm²/bird floor spaces reduced heat stress and improved performance quality in laying quail.