The experiments were carried out at the Integrated Farming Demonstration center of Champasack University, situated about 13 km from Pakse city, Pakse District, Champasack Province; Laos PDR.
The first experiment was on the effect of rice distillers’ by-product on growth performance and digestibility of Moo Laat and Mong Cai pigs fed rice bran and water spinach. Sixteen growing female pigs (8 Moo Laat and 8 Mong Cai) with an initial weight of 11 to 13 and 25 to 26 kg, respectively, were allocated to a 2*2 factorial arrangement with four replications of four treatments in a Completely Randomized Design (CRD). The factors were: breed of pigs and supplementation with or without rice distillers’ by-product. The basal diet was a mixture of rice bran and fresh water spinach. The diets were offered in amounts based on an expected DM intake of 4 % of live weight. For the control diets (no distillers’ byproduct) the water spinach comprised 30% of the diet DM. For the diets with rice distillers’ by-product the proportions (% DM) were 70, 20 and 10 for rice bran, water spinach and rice distillers’ byproduct, respectively.
Mong Cai pigs grew faster than Moo Laat pigs but the latter tended to have better feed conversion. There was an interaction between breed and rice distillers’ supplementation for both DM intake per unit LW and live weight gain. Supplementation increased the intake and growth rate in the Mong Cai pigs. During the first 6 weeks of the experiment the Moo Laat pigs fed the rice distillers’ product grew more slowly than those not fed the supplement. During the final 6 weeks the response of the Moo Laat pigs was reversed with higher gains observed for the pigs fed the supplement. Coefficients of digestibility determined by the insoluble ash method were not affected by supplementation with rice distillers’ by-product but appeared to be higher for the Mong Cai compared with the Moo Laat.
The second experiment was on the effect of a supplement of water spinach on digestibility by growing Mong Cai pigs fed a basal diet of rice bran. Three Mong Cai gilts weighing from 67 to 70 kg were allocated at random to three treatments within a 3*3 Latin Square design with periods of 10 days (5 days for adaptation and 5 days for collection of data). The treatments were: RB: rice bran only; RBWS15: rice bran supplemented with 15% of water spinach; and RBWS30: rice bran supplemented with 30% of water spinach. Feeding level was 4% of live weight as dry matter (DM). The ratios of rice bran to water spinach were on a DM basis.
Intake of DM and apparent digestibility of DM and crude protein were increased when water spinach replaced up to 15% of the DM of the basal diet of rice bran. Using the “difference” method it was estimated that the coefficients of apparent digestibility of the DM and crude protein of the water spinach were 99 and 150%, implying that the effects of the water spinach on the digestibility of the mixed diet with rice bran were synergistic.