Chemical Composition and Digestion Kinetics of ... - icdd@uaf.edu.pk

disappearance of DM, CP, NDF and ADF for ensiled oat grass silage. For each time point, 10g sample, in triplicate was poured into bags. Two bags were used to determine DM, CP, NDFand ADF disappearance and the third bag served as blank. The bags were closed and tiedwith nylon fishing line. Before incubation in the rumen, the bags were soaked in tap waterfor 15 minutes to remove the sample particles having less than 50 µm size. The weight losswhile soaking was recorded as pre-ruminal incubation disappearance. The bags wereincubated in the rumen for 0, 1, 2, 4, 6, 10, 16, 24, 36, 48 and 96 h, in reverse order and wereremoved all at the same time to reduce variations associated with washing procedure (Sarwaret al., 2004). After removal from the rumen, bags were washed in running tap water until therinse was clear. The bags were then dried in a forced air oven at 55°C for 48 h. Degradationrates were determined by subtracting the indigestible residue (i.e. the 96 h residence) from theamount in the bag at each time point and then regressing the natural logarithm of thatvalue against time after correcting for lag time (Sarwar et al., 2004). The lag time wascalculated according to method described by Mertens and Loften (1980) by using formula.Lag time = ln (100) – Intercept / Rate of digestionChemical AnalysisDry matter of oat silage was determined by drying at 105 o C for 4 h followed byequilibration in desiccators (AOAC 1990) and OM was calculated as weight loss upon ignitionat 600 ° C. The CP contents were determined using Kjeldahl method described by AOAC (1990).Neutral detergent fiber and ADF contents were determined with the ANKOM fiber analyzerusing reagents described by Van Soest et al (1991). For silage pH determination, 10g freshsample of oat grass was taken just after un-sealing of the silo and was dissolved in 100 mL ofdistilled water in a 250 mL beaker. Filtrate from water-silage solution was then used todetermine pH using a pH-mV meter (HM-21P, TOA Corporation, Tokyo, Japan).Statistical AnalysisThe data collected for each parameter was subjected to analysis of variance techniqueusing multivariate analysis in General Linear Model option of SPSS 17.0 (SPSS Inc., Chicago,39