Effect of dietary fiber sources on feed intake and nutrient digestibily, growth rate, and economic return of growing rabbits fed water spinach (Ipomoea aquatica) or sweet potato vines (Ipomoea batatas) with or without supplements of Wedelia trilobata and Saciolepsis indica                       

Nguyen Thi Kim Dong, Nguyen Van Thu and T R Preston*

               Cantho University, Cantho City, Vietnam
ntkdong@ctu.edu.vn
* UTA, TOSOLY, AA#48, Socorro, Santander, Columbia

Two experiments were carried out in the experimental farm of Cantho University to evaluate the effects of  dietary fiber sources from vetagetables and fiber supplements. Both experiments were 2*3 factorial designs, with 3 replications and two male rabbits in one experimental unit. The first factor was kind of vegetable (water spinach (WS), and sweet potato vines (SPV); the  second one was fiber source with Wedelia trilobata (WT), Saciolepsis indica (SI) or none). The feeding trial (Expt. 1) was done on growing crossbred rabbits at 8 weeks of age to evaluate feed intake, growth performance and economic returns. In the digestibility trial (Expt. 2) nutrient digestibility, nitrogen retention and caecum fermentation were determined in twelve week old rabbits.

In Expt. 1, the dry matter (DM) and organic intakes were similar (P>0.05) between vegetables and among fiber source supplement. The final weight and weight gain were significantly higher (P< 0.05) in the  diets with only WS compared to SPV, and for the no fiber supplement. The lower feed cost resulting in higher benefits was found in the diets fed only SPV and the diet WT . In Expt. 2 the apparent digestibility (%) of  DM, OM were significantly higher in the diet fed of WS (P<0.05), and the diets without fiber supplemented or supplemented WT (P<0.001). NDF and ADF digestibility values were significatly lower (P<0.01) in the diet with SI supplement. The total volatile fatty acids (VFAs) were similar between WS and SPV diets, but significantly higher (P<0.05) in the diets with WT supplement and none compared to the supplemented SI. There was no significant difference (P>0.05) of gas production in caecum contents from the two vegetables, and among the fibre supplements or none.

It is concluded that water spinach is superior to sweet potato vine as the basal diet for rabbits and that there are no nutritional benefits from offering higher fibre supplements such as Wedelia trilobata or Saciolepsis indica.

Key words: Digestibility, growing rabbit, Saciolepsis indica, sweet potato, water spinach, Wedelia trilobata