cattles are fed with roughage and concentrates . why ? Which feed activities are added in the cattle field apart from nutrients ?

The two forms of animal feed are roughage an concentrates.

• Roughage which largely consists of fibre. Concentrates have high levels of protein and other nutrients but it has low-fibre. But, they have more of digestible nutrients. Concentrates used in animal feeds are cereals ( wheat, rice), grains and millet by products. 

• Feed additives promote health of cattle and milk production. They are minerals, vitamins etc to promote growth and milk production and medicated additives, which can prevent and treat diseases.