Effect of farm household income levels and rice-based diet or water hyacinth (Eichhornia crassipes) supplementation on growth/cost performances and meat indexes of growing and finishing pigs in the Mekong Delta of Vietnam

An on-farm trial was carried out to improve the current low-income farmers' diet and to assess farm conditions that could accept the new ingredients using locally available feed resources in the Mekong Delta region. A total of 42 local Large White-type pigs, comprising 20 barrows and 22 gilts with initial-to-final mean live weight of 34.2-93.0 kg, were used. The trial was designed as a 3 x 3 factorial with three agricultural gross income levels of seven farm households and three dietary treatments. The annual income levels were high income (HI; $US2355 on average), medium income (MI; $US1439) and low income (LI; $US1116). The three types of diets were farmers' common diet (FCD), rice-based diet (RBD) and water-hyacinth (Eichhomia crassipes)-supplemented diet (WHD). A total of 12 pigs, consisting of two barrow-gilt couples in each diet treatment, were slaughtered at the end of the trial. The daily weight gain (DG) was higher and the feed conversion ratio (FCR) was lower in the MI and LI pigs than in the HI pigs over the entire fattening period (p < 0.01). No significant effect of the diet treatments was observed on the aforementioned two parameters, but the backfat thickness was least in WHD (16.8 mm) and next least in RBD (17.1 mm), compared with that of FCD pigs (19.4 mm; P < 0.05). The iodine values of RBD and WHD backfat were lower (P < 0.001) than those of FCD backfat. The cost performance, defined as feed cost per kg weight gain, was lowest for MI, intermediate for LI and highest for HI levels (P < 0.05). Therefore, the benefit was highest at the MI level and lowest at the HI level (P < 0.05). In contrast, cost performance of the diet treatments tended to be higher in FCD, and lower in RBD and WHD (P < 0.1). Then, the benefit tended to be higher in RBD and WHD than in the FCD diet (P < 0.1). Overall, these results suggest that the RBD and WHD diets be recommended especially to households with medium and low agricultural incomes.