Effects of Probiotics and Aromatic Plant Blends on Productive Performance and Meat Quality of Broiler Chicks under Heat Stress Conditions

• Ruya Fareed Jasim1*

  Author

Heat stress (HS) represents a major challenge in modern poultry production. It causes physiological imbalances that adversely affect the growing performance and meat quality of broilers. This study evaluated the effectiveness of supplementing broiler diets with two types of probiotics (Bacillus subtilis and a Lactobacillus blend) and two aromatic plant blends (Thymus vulgaris + Rosmarinus officinalis and Syzygium aromaticum + Cinnamomum zeylanicum) under heat stress conditions. A total of 300 one-day-old broiler chicks with uniform body weight were randomly assigned to six dietary treatment groups in a completely randomized design (CRD). Each treatment included five replicate floor pens with 10 birds per pen. The experimental groups were negative control (HS), Probiotic A (B. subtilis), Probiotic B (Lactobacillus), Herbal A (T. vulgaris + R. officinalis), Herbal B (S. aromaticum + C. verum), and a synbiotic group combining the most promising probiotic and herbal mixture. The experiment lasted for 35 days, with HS (32-34 °C, 8 hours a day) induced between days 21 and 35. The findings demonstrated that final body weight increased by approximately 14%, and the feed conversion ratio (FCR) improved from 1.89 to 1.63 in the synbiotic group compared to the control (P < 0.05), with no marked differences in feed intake among treatments. Furthermore, carcass characteristics were enhanced, particularly breast yield. Meat quality also improved, as evidenced by reduced TBARS values after 10 days of refrigerated storage, with the aromatic plant blends exhibiting the greatest antioxidant activity. The fatty acid profile was positively altered, showing an increased presence of polyunsaturated fatty acids, which indicates a decrease in lipid peroxidation. Supplementing broiler diets with probiotics and aromatic plant blends, particularly when used in combination, effectively prevents the adverse effects of heat stress. This dietary strategy enhances the productive performance of broilers and secures the stability of the oxidative properties and overall meat quality.

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