Milk is composed of approximately 87.2% water, 3.7% fats, 3.5% protein, 4.9% lactose 0.7% ash and has a pH 6.8. Milk is universally recognized as a complete diet due to its essential nutritional components.Milk is a valuable source of protein, fat, carbohydrates, vitamins and minerals.Milk protein contains all the nine essential amino acids required by humans, especially young ones, for growth and development. The key factor for quality dairy products is to avoid contamination of the raw milk and milk products. Failure to maintain adequate sanitation practices has been contribute to contamination of milk with undesirable or pathogenic micro-organisms or chemical or physical hazards. Because quality of dairy products are easily affected due to different factors of which performance of milking procedures and cleanness of the milking utensils and equipment are the major one. The key sources of contamination are: faeces, from soiled animals, especially teats, udders and tails; bacteria, from poor milking practices, soiled hands, inadequately cleaned and disinfected equipment (including bulk milk tanks), and failure to clean and disinfect teats prior to milking; failure to detect abnormal milk (mastitis pathogens, blood and clots); foreign bodies, especially from perished components in milking machines and bulk tanks, dust, bedding materials, dung, insects and animal hair; chemicals, metals, organics, etc., from veterinary product residues, cleaning chemicals and use of non-food grade equipment.

The study was conducted to determine productive performances, constraints, and opportunities of Bovans Brown (BB), Sasso, and crossbred chickens under village production system in Gindeberet district of West Shewa, Ethiopia. A total of 139 randomly selected smallholder chicken producers were involved in the study from six purposefully selected peasant associations (PAs) from the district. Information was gathered on average egg production/year, age at the first egg laying, constraints, and opportunities of improved chicken production during the study. The data collected were analyzed using Statistical Package for Social Science (SPSS) version 24, and Z-test was employed to test the difference among agro-ecologies on a certain variable. The mean annual eggs produced by BB (189.34 ± 0.99 eggs/hen/year) and by Sasso (180.82 ± 0.9 eggs/hen/year) were higher than those of crossbred chicken (111.26 ± 0.77 eggs/hen/year). Moreover, a significant difference ( ) was observed for crossbred and exotic chickens' egg production performances between agro-ecological zones. The mean age at the first egg laying (182.28 ± 1.61 days) of crossbred chickens was higher than the mean age at the first egg laying (164.29 ± 0.41 days) of exotic chickens. Also, the mean age at the first egg laying of improved chicken breeds was statistically significant (p < 0.05) between agro-ecological zones. Prevalence of disease, inadequate veterinary services, predators, and shortage of balanced concentrate mixture feeds were among the constraints hindering improved chicken production in the study area. However, high demand of chicken and chicken products, participation of NGOs in dissemination of improved chicken, presence of government policy, and availability of manpower were the major potentials encouraging chicken production in the study area. Therefore, practical poultry production training and extension should get primary emphasis to combat the existing constraints. Therefore, good poultry management practices should be promoted to improve chicken productivity in the study area.