Investigating chicken production systems, along with the ecotype's productive and morphological traits, as well as the challenges and opportunities in chicken production is crucial for developing sustainable breeding programs. The aim of the dissertation was to phenotypically characterize the indigenous chicken ecotypes and evaluate the effect of Enteromorpha prolifera polysaccharide on growth performance and anticoccidial efficacy. The dissertation is based on four manuscripts mentioned as chapters (Chapter 4 - Chapter 7). The first manuscript (Chapter 4) explores the husbandry practices and selection criteria of chicken producers in Northwest Ethiopia. In this chapter, data collected from a total of 360 households from six districts (stratified into lowland, midland, and highland agro-ecologies) was analyzed. In the study area, egg production performance was a priority by chicken owners when selecting female chickens across all agro-ecologies. For male chickens, plumage color, appearance, and growth rate were the main traits considered. Farmers primarily raised chickens for income generation through the sale of eggs and birds. There were significant differences among agro-ecologies in terms of chicken feeding management, housing, chicken flock composition, brood modification methods, and reproductive performance traits. The inbreeding coefficient was higher in the highland agro-ecology compared to the midland and lowland areas. To enhance chicken productivity sustainably, breeding programs should align with farmers' production objectives and trait preferences specific to each agro-ecology. The second manuscript (Chapter 5) focuses on characterizing the morpho-biometric variations of indigenous chicken ecotypes in Northwest Ethiopia. Sampling was done using a multi-stage purposive, stratified, and random approach. Morpho-biometric data collected from a total of 1200 adult chickens were analyzed for 12 qualitative and 11 quantitative traits. Red plumage color, white and red earlobe color, and yellow shank color were the most prevalent trait categories. Body measurements were significantly influenced by sex, agro-ecology, location, and the interaction of sex and location. Shank traits (Shank length and circumference) x exhibited high discriminatory power in both sexes. Female and male sample populations were classified with overall rates of 57.47% and 69.97%, respectively. Significant squared Mahalanobis distances were observed between locations/sites. Canonical variates analysis separated sample populations based on location. Cluster analysis classified the indigenous chickens into four ecotypes: ecotype 1 (Banja, Dembecha, and Aneded), ecotype 2 (North Achefer), ecotype 3 (Sinan), and ecotype 4 (Jawi). The third manuscript (Chapter 6) was based on an on-station comparison of the growth performance of indigenous chickens and evaluates the effect of Enteromorpha polysaccharide (EP) supplementation on their growth. A total of 180 indigenous chicken ecotypes (Sinan, Dembecha, North Achefer, and Jawi) were used in the study. Both ecotype and sex had a significant effect on body weight and average daily gain (ADG). Jawi ecotype exhibited the highest final body weight and ADG, followed by North Achefer. Males had higher body weight and ADG than females. Enteromorpha polysaccharide supplementation resulted in significantly higher body weight and ADG compared to non-supplemented chickens. The interaction between ecotype and feed type was not significant, except at week nine. Sinan ecotype showed the highest survivability rate in the first four weeks. Overall, Jawi and North Achefer ecotypes performed better in terms of growth, while Sinan ecotype showed relatively higher survivability. Supplementation of EP showed potential for improving chicken growth. The fourth manuscript (Chapter 7) was about the anticoccidial potential of Enteromorpha prolifera polysaccharide in indigenous chickens in Northwest Ethiopia. The study included 78 male indigenous chickens divided into two treatment groups: EP non-supplemented and EP supplemented. Each group had five replications. After 14 days of EP supplementation, chickens were inoculated with 1.5×10 mixed Eimeria oocysts. The EP-supplemented chickens exhibited significantly lower oocyst counts and less severe lesion scores compared to non-supplemented chickens. The EP supplementation provided relatively a higher protection rate against lesions and resulted in higher weight gain. Enteromorpha polysaccharide showed promise as a potential strategy for combating coccidiosis in chickens. Further research is needed to understand the mechanisms underlying its protective effects.