Bui Huy Nhu Phuc et al., 2001. Asian-Aust. J. Anim. Sci., 14 (7): 994-1002

In a balance experiment with rats either 0, 25 or 50% of the crude protein (CP) provided as casein in the control diet was replaced with cassava leaves (CL) (Manihot esculenta Crantz) or sweet potato vines (SPV) (Ipomoea batata). CL were either sun-dried or oven-dried at 60oC or 105oC or ensiled, while the SPV were either sun-dried or ensiled. The experiment included 3 blocks with 30 rats in each and six individuals per treatment group. Drying at 105oC resulted in a reduction of the lysine (Lys) content, suggestive of the occurrence of Maillard reactions. Ensiling CL and SPV slightly decreased the CP content as well as the sum of essential amino acids. The apparent fecal CP digestibility (dCP) and nitrogen retention were negatively affected by increasing the level of replacement (p<0.01 and p<0.001, respectively). The impaired amino acid profile observed when drying CL at 105oC was found to be related to a slight decrease in dCP (p<0.001) as well as N retention (p<0.005). The effects of sun-drying and oven-drying in reducing the HCN content in CL were more potent than when ensiling. By increasing the total dietary HCN supply serum thiocyanide level, as well as urinary thiocyanate and linamarin output, were increased, with a weak relationship between them. Sun-drying and ensiling with cane molasses as additive successfully preserved the nitrogenous constituents and could be a means of preserving fresh green feed under tropical conditions.