Livestock contribute 40 percent of the global value of agricultural output and support the livelihoods and food security of almost a billion people. Rapidly rising incomes and urbanization, combined with underlying population growth, are driving demand for meat and other animal products in many developing countries. These changes and the speed with which they are occurring have created systemic risks for livelihoods, human and animal health and the environment. To meet the challenges and constraints of the twenty-first century, the livestock sector requires appropriate institutions, research, development interventions and governance that reflect the diversity within the sector and the multiple demands placed upon it. 9789251062159 http://www.fao.org/docrep/012/i0680e/i0680e00.htm.