Maejo International Journal of Science and Technology (Nov 2008)
Nutritive composition of soybean by-products and nutrient digestibility of soybean pod husk
Abstract
Soybean by-products (soybean germ, soybean milk residue, soybean hull, soybean pod husk and soybean stem) were subjected to proximate analysis, and in vitro digestibility of DM (IVDMD), ADF (IVADFD) and NDF (IVNDFD) were determined after digesting the by-products in buffered rumen fluid for 24 or 48 h in 2 ANKOMII Daisy Incubators using Completely Randomised Design. Four native cattle (body weight 210 + 13.5 kg) were used to determine nutrient digestibility of soybean pod husk. They were randomly assigned by Cross-over Design to receive two roughage sources, i.e. guinea grass and guinea grass + soybean pod husk (60:40 DM basis), in two experimental periods. Guinea grass was harvested on the 35th day after the first cut of the year and used as green forage. Total collection method was used to determine the digestibility coefficients and digestibility by difference was used to calculate nutrient digestibility of soybean pod husk.The nutritive composition showed that soybean germ was highest in CP content (42.27% of DM) and EE content (5.07% of DM) but lowest in NDF and ADF content (20.09 and 21.53% of DM respectively). The average CP content of soybean straw, soybean stem and soybean pod husk was low (4.91, 4.67 and 5.04% respectively), while ADF content was high (42.76, 38.01 and 42.08% respectively). In vitro digestibility of DM (IVDMD), ADF (IVADFD) and NDF (IVNDFD) showed that all of them, except soybean stem, can be used as cattle feed, e.g. as supplemented feed or admixture in concentrate feed. Digestibility coefficients of guinea grass were higher in CP, CF and EE when compared to the other groups. The apparent digestibility of CP and CF were highly different (P0.05). The digestibility of nutrients (DM, OM, CP, CF, NFE, NDF and ADF) of soybean pod husk were 53.81 + 4.3, 59.69 + 4.6, 42.38 + 3.8, 30.71 + 3.2, 50.74 + 4.3, 75.26 + 4.0, 45.78 + 3.7 and 30.53 + 4.2 % respectively. Soybean pod husk was higher in total digestible nutrients (TDN) (51.87 + 3.3 vs.48.75 + 3.1 %DM) and digestible energy (DE) (2.11 + 0.3 vs. 2.08 + 0.2 Mcal/kg.DM) than guinea grass.
