Background: Poultry is the fastest-growing animal in the agriculture sector, and feed cost contributes 70%–80% of

production cost; therefore, many efforts have been evaluated to reduce feed cost. One of these ways to improve feed

efficiency is the use of natural feed additives in the diet, especially after reducing the use of antibiotics in poultry diets.

Flaxseed contains bioactive compounds, particularly omega-3 fatty acids (α-linolenic acid) and lignans, which are used

to improve energy metabolism and play antioxidant and anti-inflammatory effects in poultry diets. Vitamin E plays a

vital function in protecting polyunsaturated fatty acids from oxidative damage, preserving cell membrane integrity, and

supporting immune functions.

Aim: This study aimed to evaluate the physiological and productive effects of flaxseed (Linum usitatissimum) and

vitamin E supplementation, individually or in combination, in Japanese quail (Coturnix japonica).

Methods: A total of 120 quails were randomly assigned to four dietary treatments: commercial diet (control),

commercial diet with flaxseed, commercial diet with vitamin E, and commercial diet with both flaxseed and vitamin

E, each group comprising three replicates with 10 chicks per replicate, and the study lasted 5 weeks following 1 week

of adaptation.

Results: The combined supplementation markedly enhanced growth performance, improving body weight gain, feed

efficiency, and survivability compared with the control group. Serum biochemical analysis revealed improved protein

metabolism and a healthier lipid profile, with reductions in cholesterol, triglycerides, and low-density lipoprotein,

alongside an increase in high-density lipoprotein. Antioxidant indices confirmed strengthened defense mechanisms, as

glutathione levels increased and malondialdehyde concentrations decreased, while liver enzyme activities, aspartate

transaminase and alanine transaminase were reduced, indicating improved hepatic function. The synergistic interaction

between omega-3 fatty acids from flaxseed and the antioxidant role of vitamin E contributed to better metabolic

efficiency and oxidative stability.

Conclusion: These findings highlight that flaxseed and vitamin E can be fed to Japanese quail as promising natural

feed additives that can enhance productivity, health status, and sustainability in quail production.