Inclusion of Ensiled Cassava KM94 Leaves in Diets for Growing Pigs in Vietnam Reduces Growth Rate But Increases Profitability (Report‪)‬

INTRODUCTION In Vietnam, cassava production has rapidly changed from a food crop to an industrial crop. Each year more and more land area is used for cultivation of cassava, yielding more and more cassava roots and leaves. New high-yielding cassava varieties, such as KM94 and KM98-5 and KM140 have been distributed to various provinces in Viertnam over recent years. In 2007/2008, 560,000 ha were planted with cassava of which more than 350,000 ha with new varieties, mainly KM94 (GSO, 2008). At the time of root harvest, the yield of fresh foliage of a variety like KM94 is approximately 9 tons/ha and leaf yield approximately 5-7 tons/ha (Phuoc, 2004; Ly and Ngoan, 2007). Cassava variety KM94 has been specifically developed for its high root yield and may provide farmers an increased return. The leaves of cassava variety KM94 have a level of crude protein which ranges between 25 to 34.7% in DM (Phuc et al., 2000; Kinh, 2003; Ly and Ngoan, 2007) and after suitable treatment to reduce the HCN content, it be used as a protein source in animal feeds. Phuc et al. (2000) showed that cassava variety KM94 has a higher HCN content compared to other varieties. Ly and Ngoan (2007) found that the HCN content of fresh KM94 cassava leaves was 1,745 mg/kg DM which was decreased by 51% after 24 h of wilting (sun drying). The initial inclusion of rice bran or cassava root meal in cassava silage at levels of 5 or 10% produces a good quality silage that can be stored for at least five months (Ly and Ngoan, 2007). The HCN content of the ensiled KM94 cassava leaves decrease very quickly during the first 30 days of ensiling, and after 90 days of ensiling it is only 10 to 13% of the initial concentration (Ly and Ngoan, 2007). There have been no studies investigating the nutritive value of ensiled KM94 cassava leaves in the diet for pigs.