Biomass in crop-livestock systems in the context of the livestock revolution

Mixed crop-livestock systems are the dominant source of livelihood supporting more 80% of people living in the developing world and producing 50% of world , around 34% of the global beef production and about 30% of global milk . However, mixed systems are coming under increasing pressure with their population predicted to increase from 1,099 million in 2000 to 1,670 million in 2030 and their cattle population to increase from 230 million to 317 million from 2000 to 2030. Coupled with this increase in human and livestock , cereal yields have been stagnating in sub-Saharan Africa (SSA) for the 40 years (in contrast to growth rates of 1.5-2% per year for the rest of the world), with most increase in overall cereal production arising from of arable land. Such trends cannot be maintained as land suitable for is scarce, and additional cropland might also be more marginal and subject greater climatic risks. There is increasing pressure on biomass in mixed systems and are strong needs to find ways out of this ‘‘biomass trap’’ through increasing biomass yield and fodder quality and through increasing the efficiency of production. Biomass from crop residues (CR) is used as a feed resource and mulch to improve crop yields. Biomass is becoming scarcer and competition for CR becoming more severe. This is reflected in changes of CR use from grazing to and storage, longer distances across which CR are transported and and decreasing CR to grain ratios. The predicted increase in demand for products, the so-called livestock revolution, will further fuel feed demand and the usage of CR for livestock feeding. Use of CR for mulch and conservation demands about 2 to 3 tons of CR per hectare which is often equal to their yield under rain-fed conditions in the semi-arid tropics. Multidimensional crop can mitigate competition for biomass by increasing CR quantity and by fodder quality. Increased CR yield will facilitate partitioning of CR between and soil improvement and improved CR fodder quality will support of livestock production where more animal sourced foods (ASF) can be with less feed. It is important to realize that feed biomass requirement is very specific and decreases with increasing per unit animal productivity