Abstract: In vitro gas production and in situ techniques were used to evaluate nutritional value of some alternative weed forages e.g., Sorghum halepense, Salsola kali, Convolvulus arvensis and Portulaca oleracea. Cumulative gas production was recorded at 2, 4, 8, 12, 24, 48, 72, 96 and 120 h of incubation also, in situ disappear of dry matter for these weed forage was measured at 0, 2, 4, 8, 16, 24, 48, 72 and 96 h of incubation and gas production constants (b and c) were described using the equation y = b (1-e-ct). The most cumulative gas production was for Sorghum halepense in time of 120 h incubation (116.67 mL/300 mg of sample incubated) and Portulaca oleracea was the lowest cumulative gas production for 120 h incubation (66.35 mL/300 mg of sample incubated). The NDF, OM, Pr and DM were different among weed forages used in this study. The equation of y = a+b (1-e-ct) was applied for degradability of DM. The constant (readily soluble fraction, 53.53%) of Convolvulus arvensis was higher but, the constant of Salsola kali was lowest (45.82%). The b constant (insoluble fraction but degradable in rumen) for Sorghum halepense (44.48%) was significantly higher than other treatments and the c constant (rate of degradation of b per hour) was significantly higher for Portulaca oleracea (0.089%). According to results from gas production and in situ techniques, it seems that the Sorghum halepense has a higher nutritive value than other treatments, but more experiments were required for accurate determination of nutritional values of these forages.
M. Kazemi, A.M. Tahmasbi, R. Valizadeh, A.A. Naserian and M.M. Moheghi, 2009. Assessment of Nutritive Value of Four Dominant Weed Species in Range of Khorasan Distict of Iran by in vitro and in situ Techniques. Journal of Animal and Veterinary Advances, 8: 2286-2290.