A short-term study of growth and digestibility indices in Mong Cai pigs fed rubber seed meal

Nguyen Thi Thuy

 nthithuyen@chi.edu.vn

Abstract 

Growth characteristics of cultivated or wild, ulcultivated duckweed  (Lemna minor) either fertilized or not were studied in an on farm status according to a 2x2 factorial arrangement with three replications per treatment. Cultivated duckweed (CD) was from UTA ponds at the ecological farm were uncultivated duckweed (UCD) was from an adjacent lake. Duckweed was cultivated in plastic 3 baskets 20 L capacity and surface area of 0.13 m² and fertilized or not (20 mg N/L) with effluents from a biodigester charged with pig manure. 

 There was no significant (P>0.10) interaction type of duckweed x fertilization. A high yield of duckwed was obtained from the cultivated macrophyte (CD 13.8 g/day; UCD 10.3 g/day). Root length was short in the cultivated duckweed, but there were no significant differences between both types of duckweed in DM and crude protein content (CD 0.74 cm, 5.56 and 46.09%; UCD 0.83 cm, 6.04 and 45.56%). Root length was short in duckweed cultivated with effluent (0.61 cm) as compared with no effluent (2.13 cm). A quadratic relationship (R² 0.33) between biomass yield and root length in duckweed was obtained.

 Duckweed from uncultivated origin can grow as fast as the macrophyte from cultivated origin if ponds are fertilized with effluent. More details concerning duckweed growth characteristics as affected by different factors is recommended for this valuable on farm source of protein.

Key words: Biodigester effluent, nitrogen, Lemna minor,  pH, DM, Ammonia, cultivated and uncultivated duckweed