The Determination of Chemical Characteristics, Rumen Fermentation and Digestibility of Faba Bean (Vicia faba L.) Seeds, Pods and Seed Hulls by In Vitro Methods

[1] Pulses are important crops belonging to the Leguminosae family. Faba bean (Vicia faba L.) production has a long history of numerous and valuable uses in feed and food. Faba beans have been successfully used as a substitute for soybean meal or rapeseed meal in dairy cow rations. Faba bean pods can be used as feed for ruminants. Good quality silage can be made from faba bean plants. Technological treatments may have an impact on the degradability of nitrogen of faba bean. Molasses-urea mixed is a liquid feed supplement suitable for adding into the dry part of the diet or any other component during the processing of complete mashes or feeds. The purpose of the study was the determination of nutritional value of pods, seed hulls and seeds of faba bean (vicia faba L.) and survey the effect of different levels of urea and molasses on nutritional value faba bean pods silage using in vitro methods.

 In order to determine the chemical composition and in vitro ruminal degradability pods, seed hulls and seeds of faba bean cell wall, nylon bag and test gas technique were applied. After preparation of faba bean and isolating pods, seed hulls and seeds and drying, chemical composition analysis for dry matter, crude protein, ether extract, organic matter, ash, neutral detergent fibre (NDF) and acid detergent fibre (ADF) were done as AOAC. This research was carried out in a completely randomized design with 10 treatments and 3 replicates per treatment in two runs including: 1- faba bean pods of untreated (control), 2- faba bean pods of processed molasses (1.5% DM), 3- faba bean pods processed with molasses (3% DM), 4 - faba bean pods of processed molasses (4.5% DM), 5 - pods processed with urea (1.5% DM), 6- faba bean pods processed with molasses + urea (1.5% and 1.5% DM), 7 - faba bean pods of processed caraway with molasses + urea (3 and 1.5% DM, respectively), 8 - faba bean pods of processed with molasses + urea (4. 5% and 1.5% DM), 9- seeds hulls of faba bean and 10- faba bean seeds. Faba bean pod processing with urea and molasses was performed according to Chaudhry method (2000a) and Hue et al (2008) method. The digestibility of rumen according to Holden (1999) method and digestibility of intestinal according to Mc Niven method were investigated inside the simulator’s (DiasyII Incubator) digestive tract incubated. Amount and rate of gas production were estimated according to Orskov and McDonald model. The amount of DMD, OMD, DOMD (in percentage terms) and ME (in MJ/kg) for the amount of gas production at 2, 4, 6, 8, 12, 24, 48, 72, and 96 hours after incubation were recorded and the average parameters of fermentation with gas production (ml /200 mg DM), in vitro OMD (percent), ME (MJ/kg DM) and short-chain fatty acids (mmol) were calculated. This experiment was conducted in a completely randomized design with 10 treatments and 3 replicates by 2 run in each treatment and analyzed using Mixed procedure of SAS.

There was a significant difference between treatments in the chemical composition of different parts of faba bean. Treatment compounds 5, 6 and treatment compound 7 were the highest and the lowest ADF, respectively. Processing faba bean pods with 3% of DM molasses +1.5% of DM urea reduced ADF due to at the same time the provision and suitable carbon skeleton and nitrogen materials and in the other words lead to increasing digestibility faba bean pods. Also results in this experiment showed that the ruminal DM and CP digestibility of treatments were significant. The highest DM digestibility was related to faba bean seeds and pods of processed with molasses and urea (3-1.5) and (4.5-1.5), respectively, and the lowest DM digestibility was related to seed hulls. With increased levels of molasses, total the digestive tract DM digestibility of bean pods had increased. The post ruminal digestibility was not significantly different between treatments of bean pod silage except for treatments 3 and 4 compared to control.
The comparison of the process gas produced (ml/200 mg DM) of showed that the highest amount of gas produced was in the 24 hours after incubation in faba bean pod treatments in molasses (1.5% dry matter) resulting in more ME compared to control treatment. Among all treatments, the highest produced gas in the 96 hours after incubation was related to faba bean seeds due to (60.3 ml/200 mg DM), and therefore, the ME was higher, and the lowest amount was related to faba seed hulls (20.3 ml/200 mg DM). Probably one of the reasons for lowering the amount of gas produced in the faba seed hulls compared to the bean seeds is related to the highest cell wall of hulls.

 The variation in the results of opposite studies with the results of this experiment on the nutritional value of the different faba bean components depends on the level and quality of the processing and the amounts of rapidly digested carbohydrate for facilitating the synergy of nutrient supply. In this experiment, the chemical composition, potential and rate of gas production, OMD, ME, SCFA and MP were significantly different between different bean components. Although more studies are needed to determine the best percentage of addition of molasses to different levels of urea or the use of other compounds that are able to bind to possible anti-nutritional compounds, but bean pod processing with 3% molasses and 1.5% urea caused a decrease in the amount of ADF, in other words, its digestibility, due to its coherent and suitable synchronicity with the carbon frames and nitrogenous materials. The seed of faba bean had the heist nutritional value than other parts of faba bean and amount of NDF was the highest in seed hulls. Totally seed of faba bean with 24.71% CP and 8.94 Mj/kg ME is a valuable nutritional source for feeding of animal. But the bean pods also have a good nutritional value as a non-forage fiber source for ruminants.