This study aimed to assess the availability and utilization of phytogenic feed additives among chicken producers and to evaluate the effects of neem, bitter-leaf, and garlic on egg production, egg quality, blood parameters, and gut and cecal bacteria in Bovans Brown layer hens, as well as on growth performance, carcass traits, blood parameters, and cecal bacterial load in Koekoek chickens. Data collection methods included farm observations, individual interviews, key informants and focus group discussions, supplemented by secondary information from agricultural office records and research publications. For the second and third research objectives, 128 Bovans Brown layer hens with 1.73 ± 0.05 kg/chicken initial body weight (IBW) were randomly assigned to four dietary treatments, each with four replications in a completely randomized design (CRD). The treatments included a control diet (T1) with no additives and three experimental diets supplemented with 2.5% neem leaf meal (T2), bitter-leaf leaf meal (T3), and garlic powder (T4). Each treatment consisted of 32 hens, and the study lasted for 12 weeks. Data collected included production performance, egg quality, blood parameters and bacterial load. Blood samples were taken for haematological and serological analyses. At the end of the study, two chickens per replicate were slaughtered for bacterial load analysis. For the fourth objective, 192 Koekoek chicks were randomly allocated to four dietary treatments in a completely randomized design (CRD): a basal control diet (T1) and three experimental diets with the inclusions of neem leaf meal (T2), bitter-leaf meal (T3) and garlic powder (T4) at a 2.5% level of inclusion for each. Growth performance, carcass characteristics, blood parameters and cecal bacterial load were assessed. At the end of the study, 32 chickens (8 per treatment) were slaughtered for carcass analysis, and cecal content was collected for microbial assessment. Blood samples were also taken prior to slaughter for haematological and serum chemistry evaluation. The survey result revealed that phytogenic feed additives were used by farmers in urban (58.3%), peri-urban (56.3%), and rural (52.5%) areas, with neem, bitter-leaf, and garlic being the most commonly available and utilized. Awareness of these additives was highest among urban (70.9%) and peri-urban (73.8%) producers. The highest feed intake occurred in T2 (117.77 g/hen) and T4 (117.12 g/hen), with the lowest in T3 (108.20 g/hen) in layer hens. Hen-day egg production was the highest in (T2) (92.45%), followed by (T4) (89.78%), and lowest in (T3) (83.86%). T2 also had the highest egg mass. No significant differences (P > 0.05) were observed in other internal and external egg quality parameters. Haematological analysis showed significant differences in packed cell volume (PCV) and haemoglobin concentration. The red blood cell (RBC) count was also highest in T2 (2.61 × 10⁶/mm³) compared to the control (1.3 × 10⁶/mm³). However, lymphocytes, MCH, MCHC, and MCV were not significantly affected (P > 0.05). Serum biochemical parameters were also unaffected (P > 0.05). Gut bacteria results indicated reduced E. coli and Salmonella counts and increased Lactobacillus in treated groups. Phytogenic diets (T2–T4) significantly improved ADBWG, final body weight, and several carcass traits, with T3 showing the best FCR, although dressing percentage remained unchanged. Supplemented groups also showed improved health indicators and elevated total protein in T2. Cecal analysis confirmed enhanced beneficial bacteria. In conclusion, phytogenic additives such as neem, bitter-leaf, and garlic commonly used by chicken producers show strong potential, with neem leaf meal (T2) notably improving egg production and yolk color in layers. The use of 2.5% inclusion rates for neem, bitter-leaf, and garlic showed no adverse effects on blood profiles and in fact, improved haematological parameters and gut microbiota. In Koekoek chickens, these additives improved growth, feed efficiency, and gut health, with no negative effects on performance. Further nationwide studies are needed to standardize protocols and quantify the potential of phytogenic feed additives and bitter-leaf supplementation in chicken production, with a focus on optimizing dosage, assessing long-term effects on health and carcass traits, and evaluating levels below 2.5% in layer hens.