A new technology of a tower heat-dryer was developed to dry brewer s grain (BG) when it was flew constantly through a tower (10 m length) against a current of pressure heated air from 180ºC (LAT) to 240ºC (HAT) with a pressure suction cooling. Dried samples were obtained from the lowest and the highest applied air temperature then ground to pass through a 2-mm screen and incubated in a buffered rumen fluid medium. Fifty-five ml of medium was supplied into a 100 ml bottle containing 0.45 g of feed DM (n = 6). Then, each bottle was inoculated under carbon dioxide with 5 ml of mixed rumen microbes. Rumen fluid was obtained from three sheep (49.5 ± 2.5 kg, body weight) fitted by rumen fistulae, before the morning feeding, and immediately strained through four layers of cheesecloth. The animals were fed 1.5 kg/ d DM alfalfa hay and 0.3 kg/ d DM concentrates (165 g CP/ kg DM). The bottles were incubated for 4, 8, 16, 24, 48 and 72 h at 38.6ºC. Then, each bottle contents were filtered through a 42 µm filter, and then NDF of the unfiltered medium was determined. Non- linear first order model was used to estimate the degradation kinetic parameters. The model was: D(t) = D (i).exp (-kd.t)+ I; where, D(t) is residual DM at any time (t), D(i) is potentially degradable fraction , kd is fractional rate constant of digestion (/h) and I is indigestible fraction. Results of the present study indicated that the air temperature of the drying process had a significant (p<0.05) effect on both D(i) and I parameters of NDF of BG (LAT = 0.65 ± 0.03 and 0.32 ± 0.02, HAT = 0.78 ± 0.03 and 0.21 ± 0.03, respectively). It was concluded that the applying of higher air temperature caused to increase the digestible potential of BG as the D(i) and I fractions of NDF of HAT was higher and lower, respectively, compared with LAT.

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