Background and Aim: Silicon dioxide and betaine supplements are essential in the poultry diet to improve growth and laying performance. This study aimed to determine the effect of activated silicon dioxide (ASD) and betaine supplementation on quails' growth performance during the starter period and on follicular development and productive parameters at the onset of the laying period.

Materials and Methods: The research used 1064 quails, aged 7 days. Four treatments were employed: A basal diet (control), a diet supplemented with 200 ppm ASD, a diet supplemented with 0.12% betaine, and a diet supplemented with a combination of 200 ppm ASD and 0.12% betaine (ASD+Betaine). Each diet group included seven replicates of 38 quails. The observed parameters were the quails' growth performance during the starter period and follicular development and egg production during the onset of the laying period.

Results: The results showed that combined supplementation with ASD+Betaine improved the quails' growth performance during the starter period (p<0.05). However, these supplements, either as single feed additives or in combination, did not affect ovarian and follicular characteristics during the onset of the laying period. Still, ASD and betaine enhanced egg production and weight. The highest magnitude of change resulted from combined supplementation with ASD+Betaine (p<0.05).

Conclusion: The ASD+Betaine could be productively applied to quails' diets during the starter period and at the onset of the laying period.

Keywords: betaine, follicle, productive parameters, quail performance, silicon dioxide.