Thyme leaves as an eco-friendly feed additive improves both the productive and reproductive performance of rabbits under hot climatic conditions

The present study examined the efficiency of thyme in improving the productive and reproductive performances in male rabbits living in hot climates with the further lowering of the faecal ammonia and adverse heat stress. One hundred and twenty-five Zealand-White male rabbits were assigned to five dietary treatments [age: 60-day-old; body weight (b.w.): 1 362 ± 20 g] (n = 25). The basal diet was supplemented with either 0 (control), 4, 8, 12 or 16 g/kg of thyme leaves. The experiment lasted for 90 days. The feed and water were provided ad libitum. The animals were housed in an open system (39 °C ambient-temperature and 30-35% relative-humidity). The dietary thyme leaf levels significantly improved the appetite, body weight gain and growth performance compared to the control (P < 0.001). The weight gain and feed conversion ratio were directly proportional to the thyme leaves intake. The faecal ammonia was markedly lowered in response to the feeding with thyme leaves. The thyme leaves significantly improved the liver and kidney functions as indicated by their biomarkers. The testosterone concentrations and semen characteristics were also significantly improved in the thyme leaves-treated groups compared to the control (P < 0.01). In conclusion, thyme leaves, at an optimum dose of 16 g/kg of the diet, could be an efficient feed additive for rabbits surviving under hot climatic conditions.