The use of by-products in animal feeds

Abstract

Over the last 30 years there has been spectacular growth in the UK broiler industry (Richardson, 1976), intensification in the UK pig industry and a move to larger herds and higher yields in the cattle industry. These trends have meant that farmers have bought more livestock feed both as compounds and as straights. Parallel to these changes, the move from ‘target’ to ‘least cost’ formulation by the compounder and computerized home mixer has increased the ability to deal with different raw materials and to utilize these successfully in compounded diets (Wilson, 1975).In spite of all these technical advances, livestock still depend on large quantities of cereals and other raw materials which are potential food for man (Wilson, 1977) as illustrated in Table 1. This is in spite of the fact that, over the past 15 years, the general trend-line in the ‘carry over’ stocks of world grain has been downwards (Brown, 1977). It follows that, in considering future feeding policies for livestock, there are good reasons why prudent steps should be taken to find and utilize alternative sources of both energy and protein for animal feeds. Holland has been more successful in this respect than the UK (De Boer, 1978) as instanced by the increasing imports of cassava which in part replaces European-grown barley and wheat (Walters, 1978).