ABSTRACT
This study was conducted to determine in vitro crude protein degradation [IVDP] parameters and effective crude protein degradability [EPD] of various feeds using the modified in vitro gas production [GP] technique. Feed samples were alfalfa hay, soybean meal, soybean, rapeseed meal, sunflower meal and fish meal. Rumen fluid was collected before the morning feeding from four rumen fistulated lambs [49.4 +/- 3.5 kg, body weight]. Approximately 90 ml of buffered rumen fluid [BRF], 400 mg of feed samples and carbohydrates [maltose, xylose and starch] at four concentrations [100, 200, 300, and 400 mg] were added to screw-cap bottles. Gas production [ml] and ammonia nitrogen concentration [mg] in each bottle were measured at 4, 8, 12, 16, 24, and 30 h post incubation and IVDP was calculated via estimated intercept of linear regression between GP [as main variable, X] and ammonia nitrogen [as dependent variable, Y] using the linear regression procedure. Feed, time and feed x time interaction had significant effect on IVDP [P<0.001]. Estimated EPD values at the outflow rate of 0.06/h for alfalfa hay, soybean meal, soybean, rapeseed meal, sunflower meal and fish meal were 0.56, 0.77, 0.59, 0.45, 0.50 and 0.38, respectively