B. - Contaminants in Bovine Milk

Abstract

This chapter presents a discussion on contaminants in bovine milk. A large number of environmental contaminants have been detected in bovine milk. These compounds, termed xenobiotics, enter the cows as residues of pesticides, herbicides, et cetera, on feedstuffs or as drugs given to the cow orally, by injection, or as intramammary infusions for the treatment of mastitis; contaminants also enter milk from equipment after milking. DDT is the classic example of an environmental contaminant in milk. When first used the pesticides decimated insect populations, reducing the spread of disease and the loss of food. Somewhat later, insects developed resistance to the pesticides and their accumulation in fatty tissues including milk fat was observed. A large number of ticks, flies, mites torment dairy cattle. Dairy equipment must be rinsed and cleaned after each use, and disinfected prior to the introduction of milk. The ultimate purpose is to remove bacteria that may be adhering to surfaces or in milk residues. The metals of concern are lead, cadmium, and mercury, which at sufficient levels in milk and dairy products could cause problems. Contaminants in milk are caused by accidents, carelessness, and overzealous use of antibiotics. All could have and can be prevented by long-term planning, training of personnel, and monitoring with economic penalties.