The Use of Dry Cassava Roots and Silage from Leaves for Pig Feeding in Yunnan Province of China

Since 1990 we have undertaken a large number of experiments and conducted research on the development and use of cassava roots and leaves as animal feed resources, in order to explore the possibility of substituting cassava-based feeds for those of grain, thus saving grain for human consumption that was previously used for feeding animals. We have conducted chemical analyses to determine the nutrient composition of cassava roots and leaves, conducted animal feeding trials using cassava, and experimented with the substitution of cassava-powder for maize in raising animals and fish, as well as the feeding of pigs with silage of cassava leaves. The results are very satisfactory. At present we have introduced 32 improved varieties of cassava and we have set up a 200 ha production base for selection and multiplication of these varieties. Use of cassava in animal feeds now accounts for 32.2% of total output of cassava in Yunnan province. The cassava cultivated area increased from 2,453 ha in 1988 (five counties) to 14,000 ha in 1998, resulting in a production increase of 6.5 times compared with the output in 1988. This has removed some of the competition between people and animals for grain, and promoted the development of animal husbandry in Honghe district. INTRODUCTION With the rapid development of the animal husbandry industry in Honghe district, there is more and more demand for animal feed, especially high energy feed from grains. But grain crop production can not meet the ever increasing demand for animal feed. Since 1990 we have conducted many experiments and have researched the possible use of cassava-based feed stuff in order to explore the possibility of substituting cassava for grainbased feeds. This would eliminate the existing competition between people and animals for grain crops. We have conducted chemical analyses to determine the nutrient composition of cassava roots and leaves, experimented with the use of cassava dry root powder to feed livestock, poultry and fish, and the use of cassava leaf silage to feed pigs. The results indicate that it is possible to substitute cassava roots and leaves for grain-based feeds. For that reason we have introduced a series of improved varieties of cassava, such as Hainan 124 (SC124), Hainan 205 (SC205) and Nanzhi-188. In Yunnan the area planted with cassava was only 2,450 ha in 1988, but increased to 14,000 ha in 1998, a 5.7 times increase over the past ten years; production of dry cassava chips increased from 5,520 tonnes in 1988 to 36,200 tonnes in 1998. The development and application of cassava feed resources have become an important measure to promote the development of animal husbandry in Honghe district. More then 140 million pigs were slaughtered in 1998. The slaughter rate reached 72%, an increase in number of 163% over the last ten years. The consumption of meat increased to an average of 37.8 kg per person, an increase of 425% over the last ten years. The total value of animal products reached 7.4 billion Yuan (RMB), an increase of 7 billion Yuan over the last ten years. The development and application of cassava-based feed resources 1 Honghe Animal Husbandry Station of Yunnan, Menzhi, Honghe, Yunnan, China.