**3.1 The study area**

The study was carried out in the peri-urban areas of Nairobi City in the Republic of Kenya. The area was chose owing to its high number of smallholder zero-grazing dairy units. The high number of smallholder zero-grazing dairy units is instigated by the availability of market to which farmers sell milk and the value-added dairy products. The market is from the high number of city dwellers and workers. Nairobi and its peri-urban region have an area of 696 km2 with estimated over 2.5 million people. It is located between latitude 01° 18′S and longitude 36° 45′E with an altitude of 1798 m above sea level. The estimated annual rainfall is maximum of 765 mm in the season from March to June, and a minimum of 36 mm in the season from October to December. The other areas from where samples for the study were collected included an abattoir in Kiserian centre of Kajiado County, Kenya and a slaughter slab in Wangige area of Kiambu County, Kenya.
