[Digestibility and utilization of rations containing differently treated straw. 3. Energetic utilization by fattening bulls of rations containing differently treated straw].

In 136 complete metabolic periods of fattening bulls (live weight range 250 to 440 kg) comparative studies were performed on rations containing 30 to 40% straw previously subjected to different treatments. In addition, several rumen-physiological and blood indices were determined. Chopped straw without and with NaOH (6%) treatment and straw pellets without and with NPN-addition (ammonium bicarbonate and/or urea) during the pelleting process were used. No significant differences were found between comparable rations as to energy digestibility. The rations containing 60% straw revealed a higher evergy balance and, consequently, a higher energy utilization than could be expected from calculations on the basis of equations derived from previous experiments with adult steers. The importance of straw as energy source for ruminant feeding is highlighted.