[Characterization of straw pellets. 3. Preparation of straw pellets with 14C- and 15N-labeled degradation products and their chemical analysis]

[Results of comparative studies on ammoniated straw pellets conducted in two research institutions of animal nutrition]

Ammoniated straw pellets were produced from pure wheat straw in a pelleting press reaching temperatures of more than 90 degrees C, 4% NH4HCO3 being added as degradation agent. Digestibility trials with sheep gave 389 energetic feed equivalents (cattle) per kg straw dry matter. This value exactly agrees with the formula Energetic feed equivalents (cattle)/kg DM = 650 -6x x = % crude fibre in dry matter which had been reported first in 1973 by Bergner and Marienburg (Arch. Tierernährung 23, 423 [193]) for chemically treated straw pellets. When testing the digestibility of the same straw pellets charge in the Animal Nutrition Division of the Dummerstorf-Rostock Research Centre for Livestock Production, considerably lower values were found which would allow to calculate energy concentration to amount to 310 energetic feed equivalents (cattle)/kg DM (see Arch. Tierernährung Vol. 28, page 393). The reason for this 20% lower feed value of the straws pellets lies possibly in the reversibility of the degradation effect when using ammoniacal media. The digestibility of the straw pellets had been tested in the Berlin research Institution one year earlier than at the Rostock Institute. The possible causes of the reversibility of the ammoniacal degradation effect are discussed.

A selected bibliography of biomedical and environmental applications of stable isotopes. III--15N 1971-1976

A compilation of selected references of the use of 15N in biochemical, pharmacological, clinical and environmental applications for the period 1971--1976 is presented. Author and subject indices have been compiled to enable the reader to make further use of this information.

[Digestibility and utilization of rations containing differently treated straw. 2. Energetic utilization by sheep of rations containing differently treated straw]

A total of 59 complete metabolic periods of adult sheep were used to compare energy balance and energy utilization of rations containing 45, 60 and 99% of straw previously subjected to different treatments. In addition, some indices of rumen physiology were determined. The straw was fed in the following forms: chopped, chopped and treated with 6% sodium hydroxide, pelleted with and without NPN-addition (ammonium bicarbonate and/or urea) during the pelleting process. Notwithstanding pressing temperatures above 90 degrees C during compaction, the addition of NPN-compounds did not result in increased digestibility. The NaOH-treatment of the straw increased the energy digestibility of the ration containing 45% straw by 5 to 6 digestibility units. All experiments revealed a higher energy balance and, consequently, a higher energy utilization than could be expected from calculations on the basis of equations derived from earlier experiments with adult sheep. The variations are discussed under the aspect of energetic feed evaluation and with regard to consequence for the efficient use of straw in rations for ruminants.

[Digestibility and utilization of rations containing differently treated straw. I. Digestibility by sheep of rations containing differently treated straw]

During 63 digestibility periods of adult sheep, the digestibility of wheat and oat straw sujected to different kinds of treatment was compared. The straw was fed in the following forms: chopped, chopped and treated with 6% sodium hydroxide, pelleted without and with NPN-addition (ammonium bicarbonate and/or urea) during pelleting. Notwithstanding pressing temperatures over 90 degrees C and light moistening of the straw during pellet production, the addition of the two NPN-components did not allow to increase digestibility and energetic feed value. Two replications averaged an increase in energetic feed value by 42% due to NaOH-treatment. Energy digestibility went up by 39 to 55%, and energy concentration increased from 322 to 457 energetic feed equivalents (cattle) per kg DM. In addition, a number of rumen-physiological indices were obtained.