Effects of Phytogenic Feed Additives on Body Weight Gain and Gut Bacterial Load in Broiler Chickens

Phytogenic feed additives (PFAs) have promising importance in chicken production as antibiotic alternatives to balance chicken gut microorganisms and improve productivity. The objectives of this study were to evaluate the body weight gain (BWG) and gut bacterial load of broiler chicks fed on selected herbs. For this experiment, 360 unsexed one-day-old broiler chicks of Cobb 500 with an average weight of 40.74 g were randomly allocated into six treatment groups with three replicates of 20 chicks in each pen. The treatment 1 (T1) group was fed by a basal diet alone. Chickens of T2, T3, T4, T5, and T6 were fed the basal diet containing 1% of basil, lemongrass, peppermint, rosemary, and thyme leaves powder, respectively for 49 days. Body weight (BW), BWG, and average daily weight gain (ADWG) data were recorded every week and at the end of every phase. On days 21 and 42, three chickens from each replicate were slaughtered for microbiological analysis (pathogenic and normal flora) of cecum contents aseptically. The obtained result showed that chickens kept on T3 had significantly higher BW, BWG, and ADWG during the starter and grower phases. Significantly highest final BW was recorded during the finisher phase on T3 and T6. Chickens that consumed T3 and T6 had significantly higher overall BWG and ADWG. The lowest Escherichia coli counts were seen in chickens fed on rosemary (T5) on both days 21 and 42 of the experimental time. Similarly, the highest Lactobacilli counts were recorded on chicken fed on T5 (day 21) and T3 (day 42). On the other hand, almost all treatment herbs showed a higher Enterococcal count, with the highest recorded for T3 (day 21) and T6 (day 42). The present findings suggest that supplementing lemongrass and thyme leaf powder improves BW performance and gut microbial composition. Likewise, rosemary leaf powder enhances the beneficial microbial composition and reduces pathogenic bacteria. However, the underlying detailed biological mechanisms and dose standardization of these herbs for inclusion in the diet of broiler chickens need to be studied further.