Abera Teshome Aleli
This paper has reviewed factors affecting both milk yield and chemical compositions of dairy cow milk. Genetics, stage of lactation, and level of milk production, age of cow, environment, disease (for example, mastitis) and nutrition are some factors which could influence milk chemical compositions. Therefore, this article summarized that season, parity, and stage of lactation significantly influenced milk performance and somatic cell count; it increased with parity and reduced milk yield and lactose but increased fat and protein content in milk. Season, temperature, humidity and environmental stress are also non-genetic and non-nutritional factors that affect both the quality and quantities of milk. Milking frequency and milking intervals are other factors that strongly affect both composition and milk yield.