Efficiency of using inactivated glutathione yeast in the feeding of meat-and-egg quails

The aim of this study was to evaluate the effect of inactivated glutathione yeast EnzActive Protein on body weight gain dynamics and feed conversion ratio in meat-and-egg type Manchurian quails under commercial rearing conditions. The experiment was carried out on three groups of quails (15 birds per group) formed by the principle of analogues: control (basal diet), trial 1 (basal diet + 0.3 kg/t EnzActive Protein) and trial 2 (basal diet + 0.5 kg/t). Starting from day 20 of age, birds received the respective diets until day 47. Live body weight was recorded weekly; absolute and average daily gains as well as feed conversion ratio were calculated for each growth period and for the overall experimental period. Feeding inactivated glutathione yeast did not cause any adverse clinical effects and was associated with a marked stimulation of growth performance. As early as day 27, body weight in the supplemented groups exceeded the control by 6.9–10.6%, whereas on days 34 and 47 this difference increased to 18.6–25.2% and 23.6–39.8%, respectively (P<0.001). Average daily gains remained consistently higher in both experimental groups throughout the study, and during the peak growth phase (days 27–34) they were almost twice as high as in the control. Feed conversion ratio improved by 8–24% in individual periods, and over days 20–47 the amount of feed required per kilogram of gain was lower in the supplemented birds, with the most pronounced effect at the dose of 0.5 kg/t. These results indicate a clear dose-dependent productive response to EnzActive Protein and support its economic and practical suitability as a functional feed additive for meat-and-egg type quails.