A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and Technology, Arusha, TanzaniaDairy cattle farmers in Tanzania experience a huge decline in milk production due to insufficient feed supply to their animals particularly during the dry seasons. This poses a great challenge to sustainability of smallholder dairy farming systems (SHDFSs) in the country. The aim of this study was to evaluate fodder resources availability, utilization practices and seasonal variations; as well as to assess potentials for improving pasture production and utilization in the SHDFSs of Western Usambara Highlands (WUHs), Tanzania. Integrated approaches were used in this study including review of literature, household and farm surveys, planting and evaluating suitability of four Pennisetum purpureum Schumach varieties (local Napier, Bana, Ouma and Kakamega 2) in improving ruminant feed availability. In addition, an experiment was conducted during a dry season to assess the potential of graded levels of homemade supplementary ration (HSR) consisting of Calliandra calothyrsus leaf-meal, maize bran, molasses and mineral-vitamin premixes on dairy cattle milk productivity. Results indicated that fodder scarcity was the major challenge during the dry season (July-October). On-farm fodder resources contributed most of the cattle diet. Natural pasture and Napier grass were the most important feeds in wet season and maize stover in dry seasons. Processing and supplementation of poor roughages with protein-energy concentrates were unpopular. Milk yields were 5.57 and 3.01 litres/cow/day in the wet and dry seasons respectively. The findings also demonstrated that Ouma and Kakamega 2 can be promoted in the WUHs for forage use due to higher biomass production. HSR improved the dry season milk yields significantly (P<0.001). Nonetheless, simulated year-round daily milk yields indicated that 4 and 6 kg HSR/cow/day would double the milk yields. There was overall significant difference (P=0.02) in the income to cost ratios (ICR) across the HSR levels. However, the ICR for 4 and 6 kg HSR/cow/day did not differ significantly (P<0.05). In conclusion, the supplementation level of 4 kg HSR/cow/day to the fibrous basal diets is suitable for profitable milk yields in the WUHs. It is therefore, recommended to increase fodder production and adopt proper supplementation practices to meet sustainable dairy production in the WUHs and elsewhere with similar environment.