EFFECT OF GAMMA RADIATION ON THE UTILIZATION OF WHEAT STRAW BY RUMEN MICROORGANISMS

Abstract

The effects of gamma radiation from Cobalt-60 upon the feeding value of wheat straw were determined by in vitro fermentations with rumen microorganisms. Exposure of the straw to dosages of 1 × 10⁷ rads caused a slight increase in dry matter digestion whereas exposures of 1 × 10⁸ rads or more caused a marked increase. The solubility of straw was also increased with dosages of 1 × 10⁸ rads or more. However, increases in the volatile acid production from the fermentations were found only up to dosages of 2.5 × 10⁸ rads, suggesting that above this level of radiation the carbohydrates are disintegrated to such a degree that they are no longer suitable substrates for rumen microorganisms. These findings confirm the presence of nutrients entrapped in wheat straw which can be made available to the rumen microorganisms, but the levels of gamma irradiation necessary for their release are well above what is practical for commercial operations.