Microbial degradation in the rumen of wheat straw and anhydrous ammonia treated wheat straw observed by electron microscopy.

With the exception of the phloem and the crown of the parenchyma, which borders the medullary lacuna, the walls of the tissues of both treated and untreated straw were lignified. The walls of the treated straw were not fluorescent in the ultraviolet probably because the treatment had modified the phenolic acids. They also had a stronger reaction to Schiff reagent particularly in the sclerenchyma indicating that their polysaccharides were more accessible. The tissues of the treated straw degraded faster in the rumen. The walls of the sclerenchyma of the treated straw were attacked by micro-organisms. Both treated and normal straw were abundantly colonized by rumen fungi, especially in the sclerenchyma. The increase in the digestibility of the treated straw was due to the greater access the micro-organisms had to the polysaccharides of the lignified walls.