Prof. Birhan TamirIsrael Yakob2023-12-092023-12-092023http://etd.aau.edu.et/handle/123456789/532The study targeted evaluation of garlic (Allium sativum L.), thyme (thymus vulgaric) powders and their mixtures in broiler diets on growth performance, carcass yield and gut microbial population. The experimental trial was conducted using 156 unsexed day-old broiler chicks of cobb500 breed which were divided into four treatment groups. Each treatment had a total of 39 chicks with three replicates and each replicate containing 13 chicks in completely randomized design. The treatments groups were diet containing 1% garlic powder (T1), 1% thyme powder (T2), 0.5% garlic + 0.5% thyme mixture powder (T3) and control group only basal diet (T4). Daily feed refusal, weekly body weight gain (BWG), carcass yield and fecal microbial counts were measured. The study showed that inclusion of 1% of garlic in the diet chicks had lower feed intake (1060.4g) during the grower phase followed by the control group (1063.05g), while higher feed intake was from 1% of thyme (1072.8g) followed by combination group (1070.9g). The results also showed that there was significantly lower feed intake (996.1g) for finisher phase and the entire period (2332.7g) for 1% thyme group. There was a higher feed intake (1716.1g) for 1% garlic and combined group (3055.0g) in the finisher phase and overall period, respectively. However, average final body weight, weight gain, feed conversion ratio, and carcass yield were not significantly improved by inclusion of dietary treatments compared to the control. Also, E. coli and lactobacillus count in the gut of broilers did not show any significant difference among treatment groups. The economic analysis revealed, highest profitability was acquired from herbal treatments than the control with sole garlic and thyme treatments showing a higher positive impact on the profitability of broiler production. The study also showed that addition of phytobiotic additives had a favorable impact on the quality of broiler meat, as demonstrated in the sensory taste. Therefore, it can be concluded that incorporating garlic and thyme into the diet of broiler chickens can yield a higher economic advantage and increase the quality of broiler meat.enBroiler chickenFeed additivesThymeGrowth performanceMicrobial loadCarcass traitsThesis